Background The red macroalgae Asparagopsis is an effective methanogenesis inhibitor due to the presence of halogenated methane(CH_(4))analogues,primarily bromoform(CHBr_(3)).This study aimed to investigate the degrada...Background The red macroalgae Asparagopsis is an effective methanogenesis inhibitor due to the presence of halogenated methane(CH_(4))analogues,primarily bromoform(CHBr_(3)).This study aimed to investigate the degradation process of CHBr3 from A taxiformis in the rumen and whether this process is diet-dependent.An in vitro batch culture system was used according to a 2×2 factorial design,assessing two A taxiformis inclusion rates[0(CTL)and 2%DM diet(AT)]and two diets[high-concentrate(HC)and high-forage diet(HF)].Incubations lasted for 72 h and samples of headspace and fermentation liquid were taken at 0,0.5,1,3,6,8,12,16,24,48 and 72 h to assess the pattern of degradation of CHBr_(3) into dibromomethane(CH_(2)Br_(2))and fermentation parameters.Additionally,an in vitro experiment with pure cultures of seven methanogens strains(Methanobrevibacter smithii,Methanobrevibacter ruminantium,Methanosphaera stadtmanae,Methanosarcina barkeri,Methanobrevibacter millerae,Methanorhermobacter wolfei and Methanobacterium mobile)was conducted to test the effects of increasing concentrations of CHBr3(0.4,2,10and 50μmol/L).Results The addition of AT significantly decreased CH_(4) production(P=0.002)and the acetate:propionate ratio(P=0.003)during a 72-h incubation.The concentrations of CHBr_(3) showed a rapid decrease with nearly 90%degraded within the first 3 h of incubation.On the contrary,CH_(2)Br_(2) concentration quickly increased during the first 6 h and then gradually decreased towards the end of the incubation.Neither CHBr_(3) degradation nor CH_(2)Br_(2) synthesis were affected by the type of diet used as substrate,suggesting that the fermentation rate is not a driving factor involved in CHBr_(3)degradation.The in vitro culture of methanogens showed a dose-response effect of CHBr3 by inhibiting the growth of M.smithii,M.ruminantium,M.stadtmanae,M.barkeri,M.millerae,M.wolfei,and M.mobile.Conclusions The present work demonstrated that CHBr_(3) from A.taxiformis is quickly degraded to CH_(2)Br_(2)in the rumen and that the fermentation rate promoted by different diets is not a driving factor involved in CHBr_(3)degradation.展开更多
Microbial electrosynthesis(MES) can potentially provide a mean for storing renewable energy surpluses as chemical energy. However, the fluctuating nature of these energy sources may represent a threat to MES, as the m...Microbial electrosynthesis(MES) can potentially provide a mean for storing renewable energy surpluses as chemical energy. However, the fluctuating nature of these energy sources may represent a threat to MES, as the microbial communities that develop on the biocathode rely on the continuous existence of a polarized electrode. This work assesses how MES performance, product generation and microbial community evolution are affected by a long-period(6 weeks) power off(open circuit). Acetogenic and H2-producing bacteria activity recovered after reconnection. However, few days later syntrophic acetate oxidation bacteria and H2-consuming methanogens became dominant, producing CH4 as the main product, via electromethanogenesis and the syntrophic interaction between eubacterial and archaeal communities which consume both the acetic acid and the hydrogen present in the cathode environment. Thus,the system proved to be resilient to a long-term power interruption in terms of electroactivity. At the same time, these results demonstrated that the system could be extensively affected in both end product generation and microbial communities.展开更多
Coke plant effluents with high contents of organic compounds are mainly treated by biological aerobic fermentation after physical pre-treatment. In this study, a brown coal condensate wastewater from a low temperature...Coke plant effluents with high contents of organic compounds are mainly treated by biological aerobic fermentation after physical pre-treatment. In this study, a brown coal condensate wastewater from a low temperature coking process was fermented under methanogenic conditions in discontinuous experiments. By this fermentation, acetate, propionate, and the main polyphenolic compounds (catechol, resorcinol and hydroquinone) were degraded to a level below the detection limit. The COD was reduced by 72% with a residual concentration of 2.1 g/L. This anaerobic fermented wastewater had a residual BOD5 of 0.66 g/L and 2.2 L CH4 were formed per litre of wastewater. An abiotic pre-treatment for this wastewater with air had a negative effect on the COD reduction and decrease of colour on the methanogenic fermentation due to the autoxidation of polyphenolic compounds to humic-like compounds. This study showed that methanogenic fermentations in the treatment sequence of brown coal coking wastewaters could reduce energy consumption for aeration in further treatment processes and had the potential for a better effluent quality due to a less formation of recalcitrant humic-like compounds.展开更多
The objective of the present study was to examine the effect of different weaning methods on the ruminal methanogenic archaea composition and diversity in Holstein calves.Thirty-six newborn Holstein bull calves were a...The objective of the present study was to examine the effect of different weaning methods on the ruminal methanogenic archaea composition and diversity in Holstein calves.Thirty-six newborn Holstein bull calves were assigned to 1 of 3 treatments:(1)conventional weaning(d 56)and fed a high proportion of solid feed(CWS);(2)conventional weaning(d 56)and fed a high proportion of liquid feed(CWL);(3)early weaning(d 42)and fed with a high proportion of solid feed(EWS).High-throughput sequencing of the methyl coenzyme M reductase(mcr A)gene,which encodes theα-subunit of methyl coenzyme M reductase-the enzyme that catalyzes the final step in methanogenesis was used to determine the composition and diversity of rumen methanogens.No significant difference(P>0.05)was observed for operational taxonomic units(OTUs)or richness indices,but diversity indices increased(P<0.05)for calves fed high dietary solids.Predominant families across the three treatments were Methanobacteriaceae,Thermoplasmataceae and Methanomassiliicoccaceae.Calves in the EWS treatment had a higher(P<0.05)relative abundance of Methanobrevibacter sp.strain AbM4 and Methanosphaera stadtmanae,while calves in the CWL treatment had a higher(P<0.05)abundance of Methanosphaera sp.strain SM9.A positive(P<0.05)relationship was identified between butyrate and Methanobrevibacter sp.strain AbM4.In conclusion,the composition and diversity of methanogens in the rumen of Holstein calves varied under the different weaning methods.This study identified a positive relationship between butyrate and Methanobrevibacter sp.strain AbM4,potentially reflecting correlations between ruminal fermentation variables and methanogenesis function.These in-depth analyses provide further understanding of weaning methods for intensified production systems.展开更多
Methanogenic archaea reside primarily in the rumen and the lower segments of the intestines of ruminants, where they utilize the reducing equivalents derived from rumen fermentation to reduce carbon dioxide, formic ac...Methanogenic archaea reside primarily in the rumen and the lower segments of the intestines of ruminants, where they utilize the reducing equivalents derived from rumen fermentation to reduce carbon dioxide, formic acid, or methylamines to methane(CH_4). Research on methanogens in the rumen has attracted great interest in the last decade because CH_4 emission from ruminants contributes to global greenhouse gas emission and represents a loss of feed energy. Some DNA-based phylogenetic studies have depicted a diverse and dynamic community of methanogens in the rumen. In the past decade, researchers have focused on elucidating the underpinning that determines and affects the diversity, composition, structure, and dynamics of methanogen community of the rumen. Concurrently, many researchers have attempted to develop and evaluate interventions to mitigate enteric CH_4 emission. Although much work has been done using plant secondary metabolites, other approaches such as using nitrate and 3-nitrooxy propanol have also yielded promising results. Most of these antimethanogenic compounds or substances often show inconsistent results among studies and also lead to adverse effects on feed intake and digestion and other aspects of rumen fermentation when fed at doses high enough to achieve effective mitigation. This review provides a brief overview of the rumen methanogens and then an appraisal of most of the antimethanogenic compounds and substances that have been evaluated both in vitro and in vivo. Knowledge gaps and future research needs are also discussed with a focus on methanogens and methane mitigation.展开更多
The maximum specific methanogenic activity (SMA) of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading ba...The maximum specific methanogenic activity (SMA) of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/(g VSS.d) when biomass was in contact with sulfate at a ratio of 1:0.114 by weight.展开更多
Background: This study investigated changes in rumen protozoal and methanogenic communities, along with the correlations among microbial taxa and methane(CH_4) production of six Belmont Red Composite beef steers fed t...Background: This study investigated changes in rumen protozoal and methanogenic communities, along with the correlations among microbial taxa and methane(CH_4) production of six Belmont Red Composite beef steers fed tea seed saponins(TSS). Animals were fed in three consecutive feeding periods, a high-grain basal diet for 14 d(BD period) then a period of progressive addition of TSS to the basal diet up to 30 g/d for 20 d(TSS period), followed by the basal diet for 13 d without TSS(BDP post-control period).Results: The study found that TSS supplementation decreased the amount of the protozoal genus Entodinium and increased Polyplastron and Eudiplodinium genera. During BDP period, the protozoa community of steers did not return to the protozoal profiles observed in BD period, with higher proportions of Metadinium and Eudiplodinium and lower Isotricha. The addition of TSS was found to change the structure of methanogen community at the subgenus level by decreasing the abundance of methanogens in the SGMT clade and increasing the abundance of methanogens in the RO clade. The correlation analysis indicated that the abundance of SGMT clade methanogens were positively correlated with Isotricha, and Isotricha genus and SGMT clade methanogens were positively correlated with CH_4 production. While RO clade were positively correlated with the proportion of Metadinium genus, which was negatively correlated with CH_4 emission.Conclusions: These results suggest that different genera of rumen protozoa ciliates appear to be selectively inhibited by TSS, and the change in methanogen community at the subgenus level may be due to the mutualistic relationships between methanogens and rumen ciliates.展开更多
Rapid formation of autotrophic partial denitrification(APD)granules is of practical interest to start up an expanded granular sludge bed reactor for wastewater treatment.This study demonstrates that methanogenic granu...Rapid formation of autotrophic partial denitrification(APD)granules is of practical interest to start up an expanded granular sludge bed reactor for wastewater treatment.This study demonstrates that methanogenic granules can be easily acclimated into autotrophic partial denitrification granules in one day,with the ability to remove 82%of 2.7 kg-S/(m^3·d)sulfide into S^0 and to convert 97%of 0.9 kg-N/(m^3·d)nitrate into nitrite,which can provide a promising feedstock for anaerobic ammonia oxidation process.Arcobacter sp.is essential for S^0 accumulation.Under high loadings,the abundance of Arcobacter sp.decreased,while on the contrary the abundance of unclassified_p_Firmicutes increased,leading to the deterioration of autotrophic partial denitrification performance.The granules performance could be recovered by adopting the strategies of properly reducing the influent loadings.展开更多
Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pig...Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis (DGGE) with two primer pairs (344fGC/519r and 519f/915rGC) and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE proifles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no signiifcant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs;however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A (mcrA) gene fragments ampliifed with real-time PCR showed all samples possessed a single peak at 82&#176;C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase (including diet factor) other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.展开更多
The β-1,3-glucan from yeast has been extensively examined for its immuno-enhancing effects in animals.However,investigation on the relationship among β-glucan,gut microbiota and immune-modulating effects remains lim...The β-1,3-glucan from yeast has been extensively examined for its immuno-enhancing effects in animals.However,investigation on the relationship among β-glucan,gut microbiota and immune-modulating effects remains limited particularly in pigs.Considering the critical roles of gut methanogens in the microbial fermentation,energy metabolism and disease resistance,we investigated the phylogenetic diversity of methanogens from fermented cultures of porcine colonic digesta with(G) or without(N) yeast β-glucan based on sequences of the archaeal 16S rRNA gene.A total of 145 sequences in the G library were assigned into 8 operational taxonomic units(OTUs) with the majority of sequences(114/145) related to strains Methanobrevibacter millerae or Methanobrevibacter gottschalkii with high identities ranging from 97.9 to 98.6%,followed by 23 sequences to Methanobrevibacter ruminantium,2 sequences to Methanobrevibacter smithii and one sequence to Methanobrevibacter wolinii.The 142 sequences in the N library were assigned to 2 OTUs with most sequences(127/142) related to strains M.millerae or M.gottschalkii with sequence identities ranging from 97.9 to 98.5%,and 15 sequences related to M.gottschalkii with 97.9% identity.Shannon diversity index showed that the G library exhibited significantly higher archaeal diversity(P0.05) and Libshuff analysis indicated the differences in the community structure between the two libraries were significant(P0.0001).In conclusion,the current study provides evidence that addition of yeast β-glucan significantly increased the diversity of methanogens in in vitro fermented porcine colonic digesta.展开更多
Wetland ecosystems are the most important natural methane(CH_(4))sources,whose fluxes periodically fluctuate.Methanogens(methane producers)and methanotrophs(methane consumers)are considered key factors affecting CH_(4...Wetland ecosystems are the most important natural methane(CH_(4))sources,whose fluxes periodically fluctuate.Methanogens(methane producers)and methanotrophs(methane consumers)are considered key factors affecting CH_(4)fluxes in wetlands.However,the symbiotic relationship between methanogens and methanotrophs remains unclear.To help close this research gap,we collected and analyzed samples from four soil depths in the Dajiuhu subalpine peatland in January,April,July,and October 2019 and acquired seasonal methane flux data from an eddy covariance(EC)system,and investigated relationships.A phylogenetic molecular ecological networks(pMENs)analysis was used to identify keystone species and the seasonal variations of the co-occurrence patterns of methanogenic and methanotrophic communities.The results indicate that the seasonal variations of the interactions between methanogenic and methanotrophic communities contributed to CH_(4)emissions in wetlands.The keystone species discerned by the network analysis also showed their importance in mediating CH_(4)fluxes.Methane(CH_(4))emissions in wetlands were lowest in spring;during this period,the most complex interactions between microbes were observed,with intense competition among methanogens while methanotrophs demonstrated better cooperation.Reverse patterns manifested themselves in summer when the highest CH_(4)flux was observed.Methanoregula formicica was negatively correlated with CH_(4)fluxes and occupied the largest ecological niches in the spring network.In contrast,both Methanocella arvoryzae and Methylocystaceae demonstrated positive correlations with CH_(4)fluxes and were better adapted to the microbial community in the summer.In addition,soil temperature and nitrogen were regarded as significant environmental factors to CH_(4)fluxes.This study was successful in explaining the seasonal patterns and microbial driving mechanisms of CH_(4)emissions in wetlands.展开更多
A series of batch experiments were conducted in 125mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upfl...A series of batch experiments were conducted in 125mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflow anaerobic sludge bed(UASB) and expanded granular sludge bed(EGSB) reactors. The effects of pH value and temperature on toxicity of ammonia nitrogen to anaerobes were investigated. The results show that the specific methanogenic activity of anaerobic granular sludge suffers inhibition from ammonia nitrogen, the concentrations of ammonia nitrogen that produce 50% inhibition of specific methanogenic activity for sludge from UASB and EGSB reactor are 2.35 and 2.75g/L, respectively. Hydrogen utilizing methanogens suffers less inhibition from ammonia nitrogen than that of acetate utilizing methanogens. Hydrogen-producing acetogens that utilize propionate and butyrate as substrates suffer serious inhibition from ammonia nitrogen. The toxicity of ammonia nitrogen to anaerobic granular sludge enhances when pH value and temperature increase. Anaerobic granular sludge can bear higher concentrations of ammonia nitrogen after being acclimated by ammonia nitrogen for 7d.展开更多
Microplastics and nanoplastics are emerging pollutants that substantially influence biological element cycling in natural ecosystems.Plastics are also prevalent in sewage,and they accumulate in waste-activated sludge(...Microplastics and nanoplastics are emerging pollutants that substantially influence biological element cycling in natural ecosystems.Plastics are also prevalent in sewage,and they accumulate in waste-activated sludge(WAS).However,the impacts of plastics on the methanogenic digestion of WAS and the underpinning microbiome remain underexplored,particularly during long-term operation.In this study,we found that short-term exposure to individual microplastics and nanoplastics(polyethylene,polyvinyl chloride,polystyrene,and polylactic acid)at a low concentration(10 particles/g sludge)slightly enhanced methanogenesis by 2.1%−9.0%,whereas higher levels(30−200 particles/g sludge)suppressed methanogenesis by 15.2%−30.1%.Notably,the coexistence of multiple plastics,particularly at low concentrations,showed synergistic suppression of methanogenesis.Unexpectedly,methanogenesis activity completely recovered after long-term exposure to plastics,despite obvious suppression of methanogenesis by initial plastic exposure.The inhibition of methanogenesis by plastics could be attributed to the stimulated generation of reactive oxygen species.The stress induced by plastics dramatically decreased the relative abundance of methanogens but showed marginal influence on putative hydrolytic and fermentation populations.Nonetheless,the digestion sludge microbiome exhibited resilience and functional redundancy,contributing to the recovery of methanogenesis during the long-term operation of digesters.Plastics also increased the complexity,modularity,and negative interaction ratios of digestion sludge microbiome networks,but their influence on community assembly varied.Interestingly,a unique plastisphere was observed,the networks and assembly of which were distinct from the sludge microbiome.Collectively,the comprehensive evaluation of the influence of microplastics and nanoplastics on methanogenic digestion,together with the novel ecological insights,contribute to better understanding and manipulating this engineered ecosystem in the face of increasing plastic pollution.展开更多
The synthesis of 2-butenal,which is a vital raw material for the production of sorbic acid as a food preservative,generates some toxic by-products,so it is urgent to seek better detoxification strategies for the treat...The synthesis of 2-butenal,which is a vital raw material for the production of sorbic acid as a food preservative,generates some toxic by-products,so it is urgent to seek better detoxification strategies for the treatment of 2-butenal manufacture wastewater.In this study,batch experiments were carried out to investigate the inhibition effect of wastewater on the methanogenic activity.To understand the wastewater toxicity to anaerobic granular sludge,variations of the specific methanogenic activity(SMA)and extracellular polymeric substance(EPS)constituents at various wastewater CODs were investigated.Ultraviolet-visible(UV-vis)spectra and Fourier transform infrared(FT-IR)spectra were employed to analyze the structure of the EPS.The results showed that the inhibitory ratio of 2-butenal manufacture wastewater was less than 8.4%on the anaerobic granular sludge when the CODs were less than 959 mg/L.However,the inhibitory ratio increased from 36.4%to 93.6% when CODs increased from 2396 mg/L to 9585 mg/L,with the SMA decreasing from 39.1 mL CH4/(gVSS·d)to 3.2 mL CH4/(gVSS·d).The diversity of the microbial community under various CODs was researched by Illumina 16S rRNA Miseq sequencing and the results demonstrated that Proteiniphilum、Petrimonas and Syntrophobacter were the dominant bacteria genera in all sample.Regarding archaea,Methanobacterium was the most dominated archaea genera,followed by the Methanosaeta group in all samples.Moreover,the bacterial communities had changed obviously with increasing CODs,which indicated high CODs played a negative impact on the richness and diversity of bacterial community in the sludge samples.展开更多
A laboratory scale up-flow anaerobic sludge bed (UASB) bioreactor ted with synthetic wastewater was operated with simultaneous methanogenesis and denitrification (SMD) granules for 235 days with a gradient decreas...A laboratory scale up-flow anaerobic sludge bed (UASB) bioreactor ted with synthetic wastewater was operated with simultaneous methanogenesis and denitrification (SMD) granules for 235 days with a gradient decrease of C/N. Molecular cloning, qRT-PCR and T-RFLP were applied to study tile methanogenic community structures in SMD granules and their changes in response to changing influent C/N. The results indicate that when C/N was 20:1, the methane production rate was tastest, and Methanosaetaceae and Methanobacteriaceae were the primary methanogens within tile Archaea. The richness and evenness of methanogenic bacteria was best with the highest T-RFLP diversity index of 1.627 in the six granular sludge samples. When C/N was reduced from 20:1 to 5:1, tbe methanogenic activity of SMD granules decreased gradually, and the relative quantities of methanogens decreased from 36.5% to 10.9%. The abundance of Methanosaetaceae in Archaea increased from 64.5% to 84.2%, while that of Methanobacteriaceae decreased from 18.6% to 11.8%, and the richness and evenness of methanogens decreased along with the T-RFLP diversity index to 1.155, suggesting that the community structure reflected the succession to an unstable condition represented by high nitrate concentrations.展开更多
基金funded by Blue Ocean Barns.AB has a Ramón y Cajal research contract(RYC2019-027764-I)funded by the Spanish State Research Agency(AEI)。
文摘Background The red macroalgae Asparagopsis is an effective methanogenesis inhibitor due to the presence of halogenated methane(CH_(4))analogues,primarily bromoform(CHBr_(3)).This study aimed to investigate the degradation process of CHBr3 from A taxiformis in the rumen and whether this process is diet-dependent.An in vitro batch culture system was used according to a 2×2 factorial design,assessing two A taxiformis inclusion rates[0(CTL)and 2%DM diet(AT)]and two diets[high-concentrate(HC)and high-forage diet(HF)].Incubations lasted for 72 h and samples of headspace and fermentation liquid were taken at 0,0.5,1,3,6,8,12,16,24,48 and 72 h to assess the pattern of degradation of CHBr_(3) into dibromomethane(CH_(2)Br_(2))and fermentation parameters.Additionally,an in vitro experiment with pure cultures of seven methanogens strains(Methanobrevibacter smithii,Methanobrevibacter ruminantium,Methanosphaera stadtmanae,Methanosarcina barkeri,Methanobrevibacter millerae,Methanorhermobacter wolfei and Methanobacterium mobile)was conducted to test the effects of increasing concentrations of CHBr3(0.4,2,10and 50μmol/L).Results The addition of AT significantly decreased CH_(4) production(P=0.002)and the acetate:propionate ratio(P=0.003)during a 72-h incubation.The concentrations of CHBr_(3) showed a rapid decrease with nearly 90%degraded within the first 3 h of incubation.On the contrary,CH_(2)Br_(2) concentration quickly increased during the first 6 h and then gradually decreased towards the end of the incubation.Neither CHBr_(3) degradation nor CH_(2)Br_(2) synthesis were affected by the type of diet used as substrate,suggesting that the fermentation rate is not a driving factor involved in CHBr_(3)degradation.The in vitro culture of methanogens showed a dose-response effect of CHBr3 by inhibiting the growth of M.smithii,M.ruminantium,M.stadtmanae,M.barkeri,M.millerae,M.wolfei,and M.mobile.Conclusions The present work demonstrated that CHBr_(3) from A.taxiformis is quickly degraded to CH_(2)Br_(2)in the rumen and that the fermentation rate promoted by different diets is not a driving factor involved in CHBr_(3)degradation.
基金the Spanish“Ministerio de Educación,Cultura y Deporte”for the predoctoral FPU Grant(FPU14/01573)the‘Ministerio de Economía y Competitividad’for the support of project ref:CTQ2015-68925-R(MINECO/FEDER,EU)。
文摘Microbial electrosynthesis(MES) can potentially provide a mean for storing renewable energy surpluses as chemical energy. However, the fluctuating nature of these energy sources may represent a threat to MES, as the microbial communities that develop on the biocathode rely on the continuous existence of a polarized electrode. This work assesses how MES performance, product generation and microbial community evolution are affected by a long-period(6 weeks) power off(open circuit). Acetogenic and H2-producing bacteria activity recovered after reconnection. However, few days later syntrophic acetate oxidation bacteria and H2-consuming methanogens became dominant, producing CH4 as the main product, via electromethanogenesis and the syntrophic interaction between eubacterial and archaeal communities which consume both the acetic acid and the hydrogen present in the cathode environment. Thus,the system proved to be resilient to a long-term power interruption in terms of electroactivity. At the same time, these results demonstrated that the system could be extensively affected in both end product generation and microbial communities.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0853)
文摘Coke plant effluents with high contents of organic compounds are mainly treated by biological aerobic fermentation after physical pre-treatment. In this study, a brown coal condensate wastewater from a low temperature coking process was fermented under methanogenic conditions in discontinuous experiments. By this fermentation, acetate, propionate, and the main polyphenolic compounds (catechol, resorcinol and hydroquinone) were degraded to a level below the detection limit. The COD was reduced by 72% with a residual concentration of 2.1 g/L. This anaerobic fermented wastewater had a residual BOD5 of 0.66 g/L and 2.2 L CH4 were formed per litre of wastewater. An abiotic pre-treatment for this wastewater with air had a negative effect on the COD reduction and decrease of colour on the methanogenic fermentation due to the autoxidation of polyphenolic compounds to humic-like compounds. This study showed that methanogenic fermentations in the treatment sequence of brown coal coking wastewaters could reduce energy consumption for aeration in further treatment processes and had the potential for a better effluent quality due to a less formation of recalcitrant humic-like compounds.
基金supported by the Key Program for International S&T Cooperation Projects of China(2016YFE0109000)the National Key R&D Program of China(2017YFF0211702)+1 种基金the National Natural Science Foundation of China(41475126 and 31802085)the Young Scientist Lifting Project,China(2017–2019)
文摘The objective of the present study was to examine the effect of different weaning methods on the ruminal methanogenic archaea composition and diversity in Holstein calves.Thirty-six newborn Holstein bull calves were assigned to 1 of 3 treatments:(1)conventional weaning(d 56)and fed a high proportion of solid feed(CWS);(2)conventional weaning(d 56)and fed a high proportion of liquid feed(CWL);(3)early weaning(d 42)and fed with a high proportion of solid feed(EWS).High-throughput sequencing of the methyl coenzyme M reductase(mcr A)gene,which encodes theα-subunit of methyl coenzyme M reductase-the enzyme that catalyzes the final step in methanogenesis was used to determine the composition and diversity of rumen methanogens.No significant difference(P>0.05)was observed for operational taxonomic units(OTUs)or richness indices,but diversity indices increased(P<0.05)for calves fed high dietary solids.Predominant families across the three treatments were Methanobacteriaceae,Thermoplasmataceae and Methanomassiliicoccaceae.Calves in the EWS treatment had a higher(P<0.05)relative abundance of Methanobrevibacter sp.strain AbM4 and Methanosphaera stadtmanae,while calves in the CWL treatment had a higher(P<0.05)abundance of Methanosphaera sp.strain SM9.A positive(P<0.05)relationship was identified between butyrate and Methanobrevibacter sp.strain AbM4.In conclusion,the composition and diversity of methanogens in the rumen of Holstein calves varied under the different weaning methods.This study identified a positive relationship between butyrate and Methanobrevibacter sp.strain AbM4,potentially reflecting correlations between ruminal fermentation variables and methanogenesis function.These in-depth analyses provide further understanding of weaning methods for intensified production systems.
基金supported by funding(award number:2012-67015-19437) from the Agriculture and Food Research Initiative(AFRI) of National Institute of Food and Agriculture(NIFA),US Department of Agriculture
文摘Methanogenic archaea reside primarily in the rumen and the lower segments of the intestines of ruminants, where they utilize the reducing equivalents derived from rumen fermentation to reduce carbon dioxide, formic acid, or methylamines to methane(CH_4). Research on methanogens in the rumen has attracted great interest in the last decade because CH_4 emission from ruminants contributes to global greenhouse gas emission and represents a loss of feed energy. Some DNA-based phylogenetic studies have depicted a diverse and dynamic community of methanogens in the rumen. In the past decade, researchers have focused on elucidating the underpinning that determines and affects the diversity, composition, structure, and dynamics of methanogen community of the rumen. Concurrently, many researchers have attempted to develop and evaluate interventions to mitigate enteric CH_4 emission. Although much work has been done using plant secondary metabolites, other approaches such as using nitrate and 3-nitrooxy propanol have also yielded promising results. Most of these antimethanogenic compounds or substances often show inconsistent results among studies and also lead to adverse effects on feed intake and digestion and other aspects of rumen fermentation when fed at doses high enough to achieve effective mitigation. This review provides a brief overview of the rumen methanogens and then an appraisal of most of the antimethanogenic compounds and substances that have been evaluated both in vitro and in vivo. Knowledge gaps and future research needs are also discussed with a focus on methanogens and methane mitigation.
基金Project supported by the National Research Center of Environmental and Hazardous Waste Management(NRC-EHWM), Chulalongko1 University,Thailand.
文摘The maximum specific methanogenic activity (SMA) of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/(g VSS.d) when biomass was in contact with sulfate at a ratio of 1:0.114 by weight.
基金supported by grants from the Natural Science Foundation of China (31272472)project grants from Meat & Livestock Australia,Fisheries and Forestry in Australia and Commonwealth Scientific and Industrial Research Organization (CSIRO)。
文摘Background: This study investigated changes in rumen protozoal and methanogenic communities, along with the correlations among microbial taxa and methane(CH_4) production of six Belmont Red Composite beef steers fed tea seed saponins(TSS). Animals were fed in three consecutive feeding periods, a high-grain basal diet for 14 d(BD period) then a period of progressive addition of TSS to the basal diet up to 30 g/d for 20 d(TSS period), followed by the basal diet for 13 d without TSS(BDP post-control period).Results: The study found that TSS supplementation decreased the amount of the protozoal genus Entodinium and increased Polyplastron and Eudiplodinium genera. During BDP period, the protozoa community of steers did not return to the protozoal profiles observed in BD period, with higher proportions of Metadinium and Eudiplodinium and lower Isotricha. The addition of TSS was found to change the structure of methanogen community at the subgenus level by decreasing the abundance of methanogens in the SGMT clade and increasing the abundance of methanogens in the RO clade. The correlation analysis indicated that the abundance of SGMT clade methanogens were positively correlated with Isotricha, and Isotricha genus and SGMT clade methanogens were positively correlated with CH_4 production. While RO clade were positively correlated with the proportion of Metadinium genus, which was negatively correlated with CH_4 emission.Conclusions: These results suggest that different genera of rumen protozoa ciliates appear to be selectively inhibited by TSS, and the change in methanogen community at the subgenus level may be due to the mutualistic relationships between methanogens and rumen ciliates.
基金supported by the National Natural Science Foundation of China (21307160)the Natural Science Foundation of Shandong Province, China (ZR20192019MEE038)+3 种基金the Fundamental Research Funds for the Central Universities (19CX02038A)the Open Project of Key Laboratory of Environmental Biotechnology, CAS (Grant No. kf2018003)the Open Project Program of State Key Laboratory of Petroleum Pollution Control (Grant No. PPC2018006)the CNPC Research Institute of Safety and Environmental Technology
文摘Rapid formation of autotrophic partial denitrification(APD)granules is of practical interest to start up an expanded granular sludge bed reactor for wastewater treatment.This study demonstrates that methanogenic granules can be easily acclimated into autotrophic partial denitrification granules in one day,with the ability to remove 82%of 2.7 kg-S/(m^3·d)sulfide into S^0 and to convert 97%of 0.9 kg-N/(m^3·d)nitrate into nitrite,which can provide a promising feedstock for anaerobic ammonia oxidation process.Arcobacter sp.is essential for S^0 accumulation.Under high loadings,the abundance of Arcobacter sp.decreased,while on the contrary the abundance of unclassified_p_Firmicutes increased,leading to the deterioration of autotrophic partial denitrification performance.The granules performance could be recovered by adopting the strategies of properly reducing the influent loadings.
基金funding from the National Basic Research Program of China (2012CB124705,2013CB127603)the European Community’s Seventh Framework Programme (FP7/2007-2013) under the grant agreement n° 227549+1 种基金the Royal Dutch Academy of Sciences (KNAW) through Project 09CDP006the Fundamental Research Funds for the Central Universities,China (KYZ201153)
文摘Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis (DGGE) with two primer pairs (344fGC/519r and 519f/915rGC) and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE proifles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no signiifcant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs;however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A (mcrA) gene fragments ampliifed with real-time PCR showed all samples possessed a single peak at 82&#176;C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase (including diet factor) other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.
基金supported by the Young Scientist Fund of Department of Education of Sichuan Province,China(112A081)
文摘The β-1,3-glucan from yeast has been extensively examined for its immuno-enhancing effects in animals.However,investigation on the relationship among β-glucan,gut microbiota and immune-modulating effects remains limited particularly in pigs.Considering the critical roles of gut methanogens in the microbial fermentation,energy metabolism and disease resistance,we investigated the phylogenetic diversity of methanogens from fermented cultures of porcine colonic digesta with(G) or without(N) yeast β-glucan based on sequences of the archaeal 16S rRNA gene.A total of 145 sequences in the G library were assigned into 8 operational taxonomic units(OTUs) with the majority of sequences(114/145) related to strains Methanobrevibacter millerae or Methanobrevibacter gottschalkii with high identities ranging from 97.9 to 98.6%,followed by 23 sequences to Methanobrevibacter ruminantium,2 sequences to Methanobrevibacter smithii and one sequence to Methanobrevibacter wolinii.The 142 sequences in the N library were assigned to 2 OTUs with most sequences(127/142) related to strains M.millerae or M.gottschalkii with sequence identities ranging from 97.9 to 98.5%,and 15 sequences related to M.gottschalkii with 97.9% identity.Shannon diversity index showed that the G library exhibited significantly higher archaeal diversity(P0.05) and Libshuff analysis indicated the differences in the community structure between the two libraries were significant(P0.0001).In conclusion,the current study provides evidence that addition of yeast β-glucan significantly increased the diversity of methanogens in in vitro fermented porcine colonic digesta.
基金supported by the National Science Foundation of China(Grant No.31971490).
文摘Wetland ecosystems are the most important natural methane(CH_(4))sources,whose fluxes periodically fluctuate.Methanogens(methane producers)and methanotrophs(methane consumers)are considered key factors affecting CH_(4)fluxes in wetlands.However,the symbiotic relationship between methanogens and methanotrophs remains unclear.To help close this research gap,we collected and analyzed samples from four soil depths in the Dajiuhu subalpine peatland in January,April,July,and October 2019 and acquired seasonal methane flux data from an eddy covariance(EC)system,and investigated relationships.A phylogenetic molecular ecological networks(pMENs)analysis was used to identify keystone species and the seasonal variations of the co-occurrence patterns of methanogenic and methanotrophic communities.The results indicate that the seasonal variations of the interactions between methanogenic and methanotrophic communities contributed to CH_(4)emissions in wetlands.The keystone species discerned by the network analysis also showed their importance in mediating CH_(4)fluxes.Methane(CH_(4))emissions in wetlands were lowest in spring;during this period,the most complex interactions between microbes were observed,with intense competition among methanogens while methanotrophs demonstrated better cooperation.Reverse patterns manifested themselves in summer when the highest CH_(4)flux was observed.Methanoregula formicica was negatively correlated with CH_(4)fluxes and occupied the largest ecological niches in the spring network.In contrast,both Methanocella arvoryzae and Methylocystaceae demonstrated positive correlations with CH_(4)fluxes and were better adapted to the microbial community in the summer.In addition,soil temperature and nitrogen were regarded as significant environmental factors to CH_(4)fluxes.This study was successful in explaining the seasonal patterns and microbial driving mechanisms of CH_(4)emissions in wetlands.
文摘A series of batch experiments were conducted in 125mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflow anaerobic sludge bed(UASB) and expanded granular sludge bed(EGSB) reactors. The effects of pH value and temperature on toxicity of ammonia nitrogen to anaerobes were investigated. The results show that the specific methanogenic activity of anaerobic granular sludge suffers inhibition from ammonia nitrogen, the concentrations of ammonia nitrogen that produce 50% inhibition of specific methanogenic activity for sludge from UASB and EGSB reactor are 2.35 and 2.75g/L, respectively. Hydrogen utilizing methanogens suffers less inhibition from ammonia nitrogen than that of acetate utilizing methanogens. Hydrogen-producing acetogens that utilize propionate and butyrate as substrates suffer serious inhibition from ammonia nitrogen. The toxicity of ammonia nitrogen to anaerobic granular sludge enhances when pH value and temperature increase. Anaerobic granular sludge can bear higher concentrations of ammonia nitrogen after being acclimated by ammonia nitrogen for 7d.
基金supported by the Ministry of Education,Singapore,under Academic Research Fund Tier 2 under project No.:MOE-000033-01Tier 1 under Project No.:R-302-000-239-114。
文摘Microplastics and nanoplastics are emerging pollutants that substantially influence biological element cycling in natural ecosystems.Plastics are also prevalent in sewage,and they accumulate in waste-activated sludge(WAS).However,the impacts of plastics on the methanogenic digestion of WAS and the underpinning microbiome remain underexplored,particularly during long-term operation.In this study,we found that short-term exposure to individual microplastics and nanoplastics(polyethylene,polyvinyl chloride,polystyrene,and polylactic acid)at a low concentration(10 particles/g sludge)slightly enhanced methanogenesis by 2.1%−9.0%,whereas higher levels(30−200 particles/g sludge)suppressed methanogenesis by 15.2%−30.1%.Notably,the coexistence of multiple plastics,particularly at low concentrations,showed synergistic suppression of methanogenesis.Unexpectedly,methanogenesis activity completely recovered after long-term exposure to plastics,despite obvious suppression of methanogenesis by initial plastic exposure.The inhibition of methanogenesis by plastics could be attributed to the stimulated generation of reactive oxygen species.The stress induced by plastics dramatically decreased the relative abundance of methanogens but showed marginal influence on putative hydrolytic and fermentation populations.Nonetheless,the digestion sludge microbiome exhibited resilience and functional redundancy,contributing to the recovery of methanogenesis during the long-term operation of digesters.Plastics also increased the complexity,modularity,and negative interaction ratios of digestion sludge microbiome networks,but their influence on community assembly varied.Interestingly,a unique plastisphere was observed,the networks and assembly of which were distinct from the sludge microbiome.Collectively,the comprehensive evaluation of the influence of microplastics and nanoplastics on methanogenic digestion,together with the novel ecological insights,contribute to better understanding and manipulating this engineered ecosystem in the face of increasing plastic pollution.
基金supported by the China Special S&T Project on Treatment and Control of Water Pollution(2017ZX07402-002).
文摘The synthesis of 2-butenal,which is a vital raw material for the production of sorbic acid as a food preservative,generates some toxic by-products,so it is urgent to seek better detoxification strategies for the treatment of 2-butenal manufacture wastewater.In this study,batch experiments were carried out to investigate the inhibition effect of wastewater on the methanogenic activity.To understand the wastewater toxicity to anaerobic granular sludge,variations of the specific methanogenic activity(SMA)and extracellular polymeric substance(EPS)constituents at various wastewater CODs were investigated.Ultraviolet-visible(UV-vis)spectra and Fourier transform infrared(FT-IR)spectra were employed to analyze the structure of the EPS.The results showed that the inhibitory ratio of 2-butenal manufacture wastewater was less than 8.4%on the anaerobic granular sludge when the CODs were less than 959 mg/L.However,the inhibitory ratio increased from 36.4%to 93.6% when CODs increased from 2396 mg/L to 9585 mg/L,with the SMA decreasing from 39.1 mL CH4/(gVSS·d)to 3.2 mL CH4/(gVSS·d).The diversity of the microbial community under various CODs was researched by Illumina 16S rRNA Miseq sequencing and the results demonstrated that Proteiniphilum、Petrimonas and Syntrophobacter were the dominant bacteria genera in all sample.Regarding archaea,Methanobacterium was the most dominated archaea genera,followed by the Methanosaeta group in all samples.Moreover,the bacterial communities had changed obviously with increasing CODs,which indicated high CODs played a negative impact on the richness and diversity of bacterial community in the sludge samples.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 51678054 and 51378064).
文摘A laboratory scale up-flow anaerobic sludge bed (UASB) bioreactor ted with synthetic wastewater was operated with simultaneous methanogenesis and denitrification (SMD) granules for 235 days with a gradient decrease of C/N. Molecular cloning, qRT-PCR and T-RFLP were applied to study tile methanogenic community structures in SMD granules and their changes in response to changing influent C/N. The results indicate that when C/N was 20:1, the methane production rate was tastest, and Methanosaetaceae and Methanobacteriaceae were the primary methanogens within tile Archaea. The richness and evenness of methanogenic bacteria was best with the highest T-RFLP diversity index of 1.627 in the six granular sludge samples. When C/N was reduced from 20:1 to 5:1, tbe methanogenic activity of SMD granules decreased gradually, and the relative quantities of methanogens decreased from 36.5% to 10.9%. The abundance of Methanosaetaceae in Archaea increased from 64.5% to 84.2%, while that of Methanobacteriaceae decreased from 18.6% to 11.8%, and the richness and evenness of methanogens decreased along with the T-RFLP diversity index to 1.155, suggesting that the community structure reflected the succession to an unstable condition represented by high nitrate concentrations.