Study on Coconut Shell Activated Carbon Temperature Swing Adsorption of Benzene and Formaldehyde

Adsorption can be used to recover effectively the volatile organic gases(VOCs)in the exhaust gas from factories through using an appropriate adsorption bed.Due to form a physical or chemical bond,adsorption occurs between the porous solid medium and the liquid or gas multi component fluid mixture.The regeneration capa-city of the adsorbent is as important as the adsorption capacity and it determines the economics of the adsorption system.The regeneration of adsorbent can be realized through changing the pressure or temperature of the system.Here,activated carbon samples from coconut shell were prepared and characterized.Benzene or formal-dehyde in the mixed air was used as the adsorption object,and the adsorption experiment was carried out in a U-shaped bed.Discussed how adsorption was affected by activated carbon type,adsorbate and temperature.The results show that oxidation modifed activated carbon can increase the adsorption effect of form aldehyde,but will reduce the ad sorption effect of benzene,because their ad sorption mechanism is different.At 30℃,the saturated adsorption apacity of AC-0 for benzene is 437.0 mg/g.and that of AC-1 for formaldehyde is 670.5 mg/g.In the experimental range,it is found that the adsorption capacity increases with the decrease of temperature,and their changes are very consistent with the ftted ExpDecay1 function.

Enhanced straw fermentation process based on microbial electrolysis cell coupled anaerobic digestion

The low quality and yield of methane severely hinder the industrial application of straw biogas fermentation, and no effective solution has been found so far. In this study, a novel method was developed when a microbial electrolysis cell(MEC) was coupled with normal anaerobic fermentation to enhance methane yield and purity. The fermentation process achieved a methane purity of more than 85%, which is considerably higher than that of previously published reports. With microbial stimulation and an electric current, the degradation of fibers has been greatly enhanced. The MEC system substantially improved the yield and purity of biogas, bringing a new path to the synthesis of methane by carbon dioxide and hydrogen ions in solution under electron irradiation. Electrochemical index analysis showed extra methane synthesis, due to the external circuit electron transfer. The results of the gas chromatography and solid degradation rate showed that the carbon source of extra methane was CO_(2) produced during normal fermentation and additional volatile solid degradation. These results show that the MEC considerably enhanced the quality and yield of methane in the straw fermentation process, providing insights into normal anaerobic fermentation.

The transcriptional activator Klf5 recruits p300-mediated H3K27ac for maintaining trophoblast stem cell pluripotency

The effective proliferation and differentiation of trophoblast stem cells(TSCs)is indispensable for the development of the placenta,which is the key to maintaining normal fetal growth during pregnancy.Kruppel-like factor 5(Klf5)is implicated in the activation of pluripotency gene expression in embryonic stem cells(ESCs),yet its function in TSCs is poorly understood.Here,we showed that Klf5 knockdown resulted in the downregulation of core TSC-specific genes,consequently causing rapid differentiation of TSCs.Consistently,Klf5-depleted embryos lost the ability to establish TSCs in vitro.At the molecular level,Klf5 preferentially occupied the proximal promoter regions and maintained an open chromatin architecture of key TSC-specific genes.Deprivation of Klf5 impaired the enrichment of p300,a major histone acetyl transferase of H3 lysine 27 acetylation(H3K27ac),and further reduced the occupancy of H3K27ac at promoter regions,leading to decreased transcriptional activity of TSC pluripotency genes.Thus,our findings highlight a novel mechanism of Klf5 in regulating the self-renewal and differentiation of TSCs and provide a reference for understanding placental development and improving pregnancy rates.

Analysis of bacterial community in bulking sludge using culture-dependent and -independent approaches

The bacterial community of a bulking sludge from a municipal wastewater treatment plant with anoxic-anaerobic-oxic process was investigated by combination of cultivation and 16S rRNA gene clone library analysis for understanding the causes of bulking.A total of 28 species were obtained from 63 isolates collected from six culture media.The most cultivable species belonged to γ-Proteobacteria including Klebsiella sp.,Pseudomonas sp.,Aeromonas sp.and Acinetobacter sp.Further analysis of these strains by repetitive sequence based on polymerase chain reaction （rep-PCR） technology showed that rep-PCR yielded discriminatory banding patterns within the same genus using REP and BOX primer sets.While the culture-independent assessment revealed that β-Proteobacteria was the dominant group in the bulking sample.Sequence analysis revealed that the highest proportion （14.7%） of operational taxonomic units was 98% similar to Candidatus Accumulibacter phosphatis,which is used to remove phosphorous from wastewater.Our results indicated that combining different approaches can produce complementary information,thus generate a more accurate view of microbial community in bulking sludge.

Molecular analysis of long-term biofilm formation on PVC and cast iron surfaces in drinking water distribution system

To understand the impacts of different plumbing materials on long-term biofilm formation in water supply system, we analyzed microbial community compositions in the bulk water and biofilms on faucets with two different materials-polyvinyl chloride （PVC） and cast iron, which have been frequently used for more thanlO years. Pyrosequencing was employed to describe both bacterial and eukaryotic microbial compositions. Bacterial communities in the bulk water and biofilm samples were significantly different from each other. Specific bacterial populations colonized on the surface of different materials. Hyphomicrobia and corrosion associated bacteria, such as Acidithiobacillus spp., Aquabacterium spp., Limnobacter thiooxidans, and Thiocapsa spp., were the most dominant bacteria identified in the PVC and cast iron biofilms, respectively, suggesting that bacterial colonization on the material surfaces was selective. Mycobacteria and Legionella spp. were common potential pathogenic bacteria occurred in the biofilm samples, but their abundance was different in the two biofilm bacterial communities. In contrast, the biofilm samples showed more similar eukaryotic communities than the bulk water. Notably, potential pathogenic fungi, i.e., Aspergillus spp. and Candida parapsilosis, occurred in similar abundance in both biofilms. These results indicated that microbial community, especially bacterial composition was remarkably affected by the different pipe materials （PVC and cast iron）.

Phylogenetically diverse endozoic fungi in the South China Sea sponges and their potential in synthesizing bioactive natural products suggested by PKS gene and cytotoxic activity analysis

Sponges are well documented to harbor large amounts of microbes.Though it is known that spongederived fungi are important sources for marine natural products,the phylogenetic diversity and biological function of sponge-associated fungi remain largely unknown.In this study,the diversity of culturable endozoic fungi in sponges from the South China Sea was revealed based on the ITS phylogenetic analysis.Meanwhile the fungal potential for producing bioactive natural products was estimated according to the detection of Beta-ketosynthase in the polyketide synthase(PKS)gene cluster and cytotoxic activity bioassay.As a result,diverse fungi including 14 genera(Aspergillus,Penicillium,Scolecobasidium,Eurotium,Alternaria,Fusarium,Hypocreales,Yarrowia,Candida,Hypoxylon,Sporidiobolus,Schizophyllum,Bjerkandera,and Trichosporon)in ten orders(Xylariales,Moniliales,Pleosporales,Saccharomycetales,Hypocreales,Eurotiales,Sporidiobolales,Agaricales,Aphyllophorales and Tremellales)of phyla Ascomycota and Basidiomycota were isolated with Aspergillus as the predominant component in the culturable fungal community.Particularly,genera Schizophyllum,Sporidiobolus,and Bjerkandera in phylum Basidiomycota and genus Yarrowia in phylum Ascomycota were isolated from marine sponges for the first time.PKS genes were detected in 12 isolates suggesting their potential for synthesizing PKS compounds.Among the 12 isolates with PKS genes,9 isolates displayed strong in vitro cytotoxic activity(e.g.IC50<50μg/ml)against human cancer cell lines A549,Bel-7402,A-375 and MRC-5.This study demonstrates the phylogenetically diverse endozoic fungi in South China Sea sponges,and highlights the potential of spongeassociated fungi in producing biologically active natural products.

Molecular characterization of microbial communities in bioaerosols of a coal mine by 454 pyrosequencing and real-time PCR

Microbial diversity and abundance in bioaerosols of a coal mine were analyzed based on 454 pyrosequencing and real-time polymerase chain reaction（PCR）. A total of 37,191 high quality sequences were obtained and could be classified into 531, 1730 and 448 operational taxonomic units respectively for archaea, bacteria and fungi at 97% sequence similarity. The Shannon diversity index for archaea, bacteria and fungi was respectively 4.71, 6.29 and 3.86, indicating a high diversity in coal mine bioaerosols. Crenarchaeota, Proteobacteria and Ascomycota were the dominant phyla for archaea, bacteria and fungi, respectively. The concentrations of total archaea, bacteria and fungi were 1.44 × 10^8, 1.02 × 10^8 and 9.60 × 10^4cells/m^3, respectively.Methanotrophs observed in bioaerosols suggested possible methane oxidation in the coal mine. The identified potential pathogens to coal miners, such as Acinetobacter schindleri,Aeromonas cavernicola, Alternaria alternata, Aspergillus penicillioides, Cladosporium cladosporioides,and Penicillium brevicompactum were also observed. This was the first investigation of microbial diversity and abundance in coal mine bioaerosols. The investigation of microbial communities would be favorable in promoting the progress of methane control based on microbial technique and concern on coal miners＇ health.

Inhibitor tolerance and bioethanol fermentability of levoglucosan-utilizing Escherichia coli were enhanced by overexpression of stress-responsive gene ycfR:The proteomics-guided metabolic engineering

Pretreatment of lignocellulosic biomass is crucial for the release of biofermentable sugars for biofuels production,which could greatly alleviate the burgeoning environment and energy crisis caused by the massive usage of traditional fossil fuels.Pyrolysis is a cost-saving pretreatment process that can readily decompose biomass into levoglucosan,a promising anhydrosugar;however,many undesired toxic compounds inhibitory to downstream microbial fermentation are also generated during the pyrolysis,immensely impeding the bioconversion of levoglucosan-containing pyrolysate.Here,we took the first insight into the proteomic responses of a levoglucosan-utilizing and ethanol-producing Escherichia coli to three representative biomass-derived inhibitors,identifying large amounts of differentially expressed proteins(DEPs)that could guide the downstream metabolic engineering for the development of inhibitor-resistant strains.Fifteen up-and eight down-regulated DEPs were further identified as the biomarker stress-responsive proteins candidate for cellular tolerance to multiple inhibitors.Among these biomarker proteins,YcfR exhibiting the highest expression fold-change level was chosen as the target of overexpression to validate proteomics results and develop robust strains with enhanced inhibitor tolerance and fermentation performance.Finally,based on four plasmid-borne genes encoding the levoglucosan kinase,pyruvate decarboxylase,alcohol dehydrogenase,and protein YcfR,a new recombinant strain E.coli LGE-ycfR was successfully created,showing much higher acetic acid-,furfural-,and phenol-tolerance levels compared to the control without overexpression of ycfR.The specific growth rate,final cell density,ethanol concentration,ethanol productivity,and levoglucosan consumption rate of the recombinant were also remarkably improved.From the proteomics-guided metabolic engineering and phenotypic observations,we for the first time corroborated that YcfR is a stress-induced protein responsive to multiple biomass-derived inhibitors,and also developed an inhibitors-resistant strain that could produce bioethanol from levoglucosan in the presence of inhibitors of relatively high concentration.The newly developed E.coli LGE-ycfR strain that could eliminate the commonly-used costly detoxicification processes,is of great potential for the in situ cost-effective bioethanol production from the biomass-derived pyrolytic substrates.

Unravelling how biochar and dung amendments determine the functional structure and community assembly related to methane metabolisms in grassland soils

Biochar and dung amendments have been extensively employed in soil remediation and fertilization of grasslands,which are the largest terrestrial sinks for methane.However,how these exogenous amendments regulate methane metabolisms at the molecular and community levels remains elusive.In this study,we investigated the functional genes and community assemblies of methanogens and methanotrophs using Geochip 5.0 and high-throughput sequencing to reveal the impacts of biochar and dung on soil methanogenesis and methane oxidation.The interac-tions between methane metabolic genes and other biogeochemical genes were also examined.According to Geo-chip microarrays,methanogenic gene mcrA decreased and increased with dung or biochar amendment,respectively;The methanotrophic gene pmoA showed a reverse but not significant tendency.Undominated processes contributed 65.51%to replace homogeneous selections as primary driving forces of methanogen assembly after dung amend-ment;the contribution of dispersal limitation increased to 46.13%in methanotroph assembly after biochar amend-ment.The diversity and association of co-occurrence networks for carbon-nitrogen cycling genes decreased after exogenous amendments.These results indicated that biochar and dung amendments prominently regulated the functional genes and community assembly involved in methane metabolisms.The co-existence patterns of methane metabolic genes and other related geochemical genes were also shaped by these amendments.This study provides the scientific reference for the development of grassland management in the context of global warming.

Validation of Bacteroidales-based microbial source tracking markers for pig fecal pollution and their application in two rivers of North China

In China,pig feces is the predominant source of excrement produced b y animal husbandry.Improper use or direct discharge of pig feces can result in contamination of natural water systems.Microbial source tracking(MST)technology can identify the sources of fecal pollution in environmental water,and contribute to the management of pig fecal pollution by local environmental protection agencies.However,the accuracy of such assays can be context-dependent,and they have not been comprehensively evaluated under Chinese conditions.We aimed to compare the performance of five previously reported nig-specific MST assays(PF,Pig-Bac 1 STBR,Pig-Bac2 SYBR,Pig-1-Bac TaqMan,and Pig-2-Bac TaqMan,which are based on Bacteroidales 16S rRNA gene markers)and apply them in two rivers of North China.We collected a total of 173 fecal samples from pigs,cows,goats,chickens,humans,and horses across China.The PF assay optimized in this study showed outstanding qualitative performance and achieved 100%specificity and sensitivity.However,the two SYBR green qPCR assays(Pig-Bac1 SYBR and Pig-Bac2 SYBR)cross-reacted with most non-pig fecal samples.In contrast,both the Pig-l-Bac TaqMan and Pig-2-Bacr TaqMan assays gave 100%specificity and sensitivity.Of these,the Pig-2-Bac TaqMan assay showed higher reproducibility.Our results regarding the specificity of these pig-specific MST assays differ from those reported in Thailand,Japan,and America.Using the PF and Pig-2-Bac TaqMan assays,a field test comparing the levels of pig fecal pollution in rivers near a pig farm before and after comprehensive environmental pollution governance indicated that pig fecal pollution was effectively controlled at this location.