Screening and Toxicity Determination of Intestinal Aerobic Bacteria in 2^(nd) instar Larvae of Dendrolimu Kikuchii

[ Objective ] The paper was to screen intestinal aerobic bacteria from 2nd instar larvae of Dendrolimu kikuchii and determine its toxicity. [ Method ] The intestinal samples of 2nd instar larvae of D. kikuchii were diluted in gredient and coated on plates to isolate strains, and a total of 5 strains of aerobic bacteria were isolated. With bacterial genomic DNA as template, the universal primers of bacterial 16S rDNA （27f and 1 492r） were used to amplify the template, 4 restriction enzymes Hae Ⅲ and Hind Ⅲ, Hinf Ⅰ and Taq Ⅰ were used to carry out ARDRA polymorphism analysis on PCR products. [ Result] Clustering map analysis showed that 5 strains of aerobic bacteria clustered into two different taxonomic operating units （OTU） in 95% similarity level, this indicated that the genetic diversity level of intestinal aerobic bacteria in 2nd instar larvae of D. kikuchii was relatively low. The indoor toxicity test showed that the death peaks of insects killed by intestinal bacteria were during 4 - 10 d, the insecticidal effect of strain 4 was the best with corrected mortality rate of 53.57% at 12 d. [ Conclusion] The paper provided reference for control of D. kikuchii.

Effect of lactic acid bacteria and propionic acid on conservation characteristics,aerobic stability and in vitro gas production kinetics and digestibility of whole-crop corn based total mixed ration silage

This study was conducted to evaluate the effect of lactic acid bacteria and propionic acid on the fermentation quality, aer- obic stability and in vitro gas production kinetics and digestibility of whole-crop corn based totalmixed ration （TMR） silage. Total mixed ration was ensiled with four treatments： （1） no additives （control）; （2） an inoculant （Lactobacillus plantarum） （L）; （3） propionicacid （P）; （4） propionic acid＋lactic acid bacteria （PL）. All treatments were ensiled in laboratory-scale silos for 45 days, and then subjected to an aerobic stability test for12 days. Further, four TMR silages were incubated in vitro with buffered rumen fluid to study in vitro gas production kinetics and digestibility. The results indicated that all TMR silages had good fermentation characteristics with low pH （〈3.80） and ammonia nitrogen （NH3-N） contents, and high lactic acid contents as well as Flieg points. Addition of L further improved TMR silage quality with more lactic acid production. Addition of P and PL decreased lactic acid and NH3-N contents of TMR silage compared to the control （P〈0.05）. After 12 days aerobic exposure, P and PL silages remained stable, but L and the control silages deteriorated as indicated by a reduction in lactic acid and an increase in pH, and numbers of yeast. Compared to the control, addition of L had no effects on TMR silage in terms of 72 h cumulative gas production, in vitro dry matter digestibility, metabolizable energy, net energy for lactation and short chain fatty acids, whereas addition of PL significantly （P〈0.05） increased them. L silage had higher （P〈0.05） in vitro neutral detergent fiber digestibility than the control silage. The results of our study suggested that TMR silage prepared with whole-crop corn can be well preserved with or without additives. Furthermore, the findings of this study suggested that propionic acid is compatible with lactic acid bacteria inoculants, and when used together, although they reduced lactic acid production of TMR silage, they improved aerobic stability and in vitro nutrients digestibility of TMR silage.

Analysis of cultivable aerobic bacterial community composition and screening for facultative sulfate-reducing bacteria in marine corrosive steel

Anaerobic, aerobic, and facultative bacteria are all present in corrosive environments. However, as previous studies to address corrosion in the marine environment have largely focused on anaerobic bacteria, limited attention has been paid to the composition and function of aerobic and facultative bacteria in this process. For analysis in this study, ten samples were collected from rust layers on steel plates that had been immersed in seawater for diff erent periods (i.e., six months and eight years) at Sanya and Xiamen, China. The cultivable aerobic bacterial community structure as well as the number of sulfate-reducing bacteria (SRB) were analyzed in both cases, while the proportion of facultative SRB among the isolated aerobic bacteria in each sample was also evaluated using a novel approach. Bacterial abundance results show that the proportions are related to sea location and immersion time;abundances of culturable aerobic bacteria (CAB) and SRB from Sanya were greater in most corrosion samples than those from Xiamen, and abundances of both bacterial groups were greater in samples immersed for six months than for eight years. A total of 213 isolates were obtained from all samples in terms of CAB community composition, and a phylogenetic analysis revealed that the taxa comprised four phyla and 31 genera. Bacterial species composition is related to marine location;the results show that Firmicutes and Proteobacteria were the dominant phyla, accounting for 98.13% of the total, while Bacillus and Vibrio were the dominant genera, accounting for 53.06% of the total. An additional sixfacultative SRB strains were also screened from the isolates obtained and were found to encompass the genus Vibrio (four strains), Staphylococcus (one strain), and Photobacterium (one strain). It is noteworthy that mentions of Photobacterium species have so far been absent from the literature, both in terms of its membership of the SRB group and its relationship to corrosion.

Abundance of general aerobic heterotrophic bacteria in the Bering Sea and Chukchi Sea and their adaptation to temperature

The abundance of general aerobic heterotrophic bacteria(GAB) from the water and sediment in the Bering Sea and the Chukchi Sea was determined by using petri dish cultivation and counting method. The abundance of GAB among the different sea areas, sampling sites, layers of sediments surveyed and adaptability to differential temperatures was studied. The result obtained showed that: the occurrence percentage of GAB in the surface water was higher than that in sediment, but the abundance was only 0.17% of sediment. The occurrence percentage of GAB in surficial layer of sediment was higher than that in the other layers. The occurrence percentage of GAB in surficial layer of sediment was higher than that in the other layers. The occurrence percentage, abundance and its variation of GAB in the Bering Sea were higher than that in the Chukchi Sea respectively. The average value of the abundance in the all sediment surveyed was 3166.3×10 2 CFU·g -1(wet.). The abundance of GAB in sediment showed a trend: roughly higher in the lower latitudinal area than higher latitude. The results from temperature test mean that: the majority of bacteria tested were cold-adapted ones, minority might be mesophilic bacteria. The results indicated that, Arctic ocean bacteria had a stronger adaptability to environmental temperature.

Phylogenetic analysis of aerobic anoxygenic phototrophic bacteria and their relatives based on farnesyl pyrophosphate synthase gene

The study aims to reveal phylogenetic and evolutionary relationship between aerobic anoxygenic phototrophic bacteria（AAnPB） and their relatives,anaerobic anoxygenic phototrophic bacteria（AnAnPB） and nonphototrophic bacteria（NPB,which had high homology of 16S rDNA gene with AAnPB and fell into the same genus）,and validate reliability and usefulness of farnesyl pyrophosphate synthase（FPPS） gene for the phylogenetic determination.FPPS genes with our modified primers and 16S rDNA genes with general primers,were amplified and sequenced or retrieved from GenBank database.In contrast to 16S rDNA gene phylogenetic tree,AAnPB were grouped into two clusters and one branch alone with no intermingling with NPB and AnAnPB in the tree constructed on FPPS.One branch of AAnPB,in both trees,was located closer to outgroup species than AnAnPB,which implicated that some AAnPB would be diverged earlier in FPPS evolutionary history than AnAnPB and NPB.Some AAnPB and NPB were closer located in both trees and this suggested that they were the closer relatives than AnAnPB.Combination codon usage in FPPS with phylogenetic analysis,the results indicates that FPPS gene and 16S rRNA gene have similar evolutionary pattern but the former seems to be more reliable and useful in determining the phylogenic and evolutionary relationship between AAnPB and their relatives.This is the first attempt to use a molecular marker beside 16S rRNA gene for studying the phylogeny of AAnPB,and the study may also be helpful in understanding the evolutionary relationship among phototrophic microbes and the trends of photosynthetic genes transfer.

Community structure of aerobic anoxygenic phototrophic bacteria in algae-and macrophyte-dominated areas in Taihu Lake,China

Aerobic anoxygenic phototrophic bacteria(AAPB)repre sent a major group of bacterioplankton assemblages in many water systems and some are assumed to be closely associated with phytoplankton.However,studies on relationships between AAPB and cyanobacterial blooms are in scarcity.The dynamics of the abundance and diversity of AAPB was compared based on pufM gene in Meiliang Bay(featured by cyanobacterial blooms)and East Bay(featured by macrophyte)of Taihu Lake,a shallow subtropical lake in the East China plain.AAPB abundance was not significantly different between the two sites,and they were positively correlated with dissolved organic carbon(DOC)concentration.The ratios of AAPB to total bacteria varied from 3.4%to 11.5%and peaked in winter in both site s.No significant differences of AAPB community compositions were detected between the two sites,but there was a separation between warm seasons(June,August,and October)and cold seasons(December,February,and April).Rhizobiales and Limnohabitans-like pufM sequences were significantly contributors for the difference between two seasons,and specially enriched in cold seasons.Chlorophyll a(Ch1 a)and DOC were the most significant variables influencing the AAPB community structure.Furthermore,Porphyrobacter and Rhodospirillales-like pufM sequences were positively correlated with Ch1 a,indicating potential influence of cyanobacterial blooms on these AAPB taxa.These results suggested that diverse AAPB ecotypes coexisted in Taihu Lake,and their ecological role in carbon cycling in the lake may not be ignored.

Isolation of aerobic bacteria from ticks infested sheep in Iraq

Objective:To highlight the presence of aerobic bacteria in live ticks infested sheep,in Diyala Governorate,Iraq.Methods:One hundred and thirty adult alive ticks were picked up from sheep which were reared in different farms in Diyala Governorate,Iraq,during the period from November 2012 to May 2013.Ticks were classified in the Natural History Museum in Baghdad.They were dissected aseptically for extraction of the salivary gland and midgut.The removed tissue from each organ was inoculated in buffer peptone water(1%)and incubated for 2 h at 37 °C,to maintain weak and/or injured bacterial cells,then transmitted to nutrient broth incubated at 37 °C for 18 h.Culturing was done on three solid bacteriological media(nutrient,blood and McConkey agars),and then incubated at37 ℃ for 24 h.Bacterial identification was performed by using multiple biochemical tests and API-20 strips.Data were analyzed by using Statistical Analysis System version 9.1,2010.Chi-square test was used for comparison at significant level of P ≤ 0.05.Results:Two species of ticks were identified[Rhipicephalus(Boophilus) annulatus and Hyalomma turanicum].High bacterial isolation rate was observed(483 isolates).A significant high isolation rate was recorded from Rhipicephalus annulatus(63.14%).Six bacterial species were identified[Escherichia coli(28.36%),Pseudomonas aeruginosa(18.01%),Bacillus cereus(14.69%),Staphylococcus aureus(13.66%),Citrobacter freundii(13.04%),and Enterobacter species(12.21%)].Also the high bacterial isolation rates were recorded in the temperate months(November,March and April);these coincided with high reproductive performance of ticks.Conclusions:The high isolation rate of aerobic pathogens from ticks might reflect the active contribution of this arthropod in environmental contamination and increase the probability of transmitting bacterial pathogens to their hosts.

Molecular Characterization of Aerobic Heterohophic Bacteria Isolated from Petroleum Hydrocarbon Polluted Brackish Waters of Bodo Creeks, Rivers State Nigeria

Surface water sources in the oil producing Niger Delta region of Nigeria are highly susceptible to pollution by petroleum hydrocarbons and so it is important to understand the microbial diversity of such ecosystems. Water and sediment samples were collected between April-August, 2013 from Bodo creeks and taken to Environmental Microbiology laboratory of University of Portharcourt for analysis. A total of thirty aerobic heterotrophic bacterial strains isolated ranged from 3.0 - 7.0 × 104 cfu for surface water and 1.6 - 5.6 × 104 cfu for sediment samples of Bodo creek using serial dilution and spread plate technique. Pure cultures of bacteria were obtained on the basis of their morphological characteristics and subjected to biochemical tests and further classified on the basis of 16S rRNA gene sequence analysis. The DNA was isolated from size fractionated samples and the diversity of bacteria in each fraction was studied using PCR amplification of partial 16S rRNA. The sequences were submitted to NCBIGen bank for identification and assigning of accession numbers. The isolated aerobic heterotrophic bacteria belong to the families of Enterobacteriaceae, Bacilliceae, Alcaligenaceae, Pseudomonadaceae, Flavobactericeae and Planococcaceae.

Geographical distribution of general aerobic heterotrophic bacteria in surficial sediments from the Chukchi Sea and Canadian Basin

This paper determined the abundance of General Aerobic heterotrophic Bacteria （GAB） in surficial sediments from the Chukchi Sea and the Canadian basin by using MPN and discussed their geographical distribution. The result shows that the determination percentages of the GAB were high, even till 100 percentage. The abundance range and averages of GAB for 4℃and 25℃ were from 4.00 × 10^2 to 2.40× 10^6 , 1.71×10^6 ind.·g^-1 （wet sample ） and from 2.40 ×10^5 to 2.40×10^7 , 1.10×10^7 ind. ·g^-1 （wet sample ） respectively. Not only the abundance range but also the averages of GAB in 25℃ were higher than that in 4℃. The abundance of GAB in sediments show a tendency that it is roughly greater in the lower latitudinal area than in the higher latitudinal area. The abundance of GAB increased from east to west as for the longitudinal distribution. With the water depth increasing, the abundance of GAB at 4℃ decreased, but GBA at 25℃ is not changed obviously with water depth. It seems that warmer circumstantial temperature is more suitable for some GAB.

Diversity and ecological assembly process of aerobic anoxygenic phototrophic bacteria in a low irradiation area,Three Gorges Reservoir

Aerobic anoxygenic phototrophic bacteria(AAPB)are significant bacterial groups in aquatic ecosystems,known for their rapid growth and photoheterotrophic characteristics.However,the distribution and ecological assembly process of AAPB in low irradiation freshwater basins remain unclear,warranting further investigation.In this study,we present the diversity,abundance,spatial variations,ecological process,and community interaction of AAPB in sediment of Three Gorges Reservoir(TGR)under low irradiation.Our findings demonstrate the dominant genera of AAPB community that exist in the TGR area also are appeared in different waters,with some regional preference.Moreover,the concentration of pufM gene,an indicator for AAPB,maintains a consistently high numerical level ranging from(2.21±0.44)×10^(4)to(9.98±0.30)×10^(7)gene copies/g.Although solar irradiation is suggested as the major factor affecting AAPB,it remains unclear whether and how AAPB differ between regions due to varying solar irradiation levels.Our results show spatial differences between total bacteria and AAPB communities,with significant differences observed only in AAPB.Geographical and environmental factor contributed less than 10%to the spatial difference of community,with sediment type and environmental factors being the key factors influencing microbial community structure.The stochastic process plays a dominant role in the aggregation and replacement of AAPB communities,among which the most contribution is dispersal limitation.For AAPB network,Yoonia and Gemmobacter are the hubs for modules.Those results valuable insights into the AAPB communities in TGR with low irradiation.

Diversity of the aerobic anoxygenic phototrophy gene pufM in Arctic and Antarctic coastal seawaters

Aerobic anoxygenic phototrophic（AAP） bacteria serve important functions in marine carbon and energy cycling because of their capability to utilize dissolved organic substrates and harvest light energy.AAP bacteria are widely distributed in marine environments,and their diversity has been examined in marine habitats.However,information about AAP bacteria at high latitudes remains insufficient to date.Therefore,this study determined the summer AAP bacterial diversity in Arctic Kongsfjorden and in the Antarctic coastal seawater of King George Island on the basis of puf M,a gene that encodes a pigment-binding protein subunit of the reaction center complex.Four puf M clone libraries were constructed,and 674 positive clones were obtained from four investigated stations（two in Kongsfjorden and two in the Antarctic Maxwell Bay）.Arctic clones were clustered within the Alphaproteobacteria,whereas Antarctic clones were classified into the Alphaproteobacteria and Betaproteobacteria classes.Rhodobacteraceae-like puf M genes dominated in all samples.In addition,sequences closely related to puf M encoded on a plasmid in Sulfitobacter guttiformis were predominant in both Arctic and Antarctic samples.This result indicates the transpolar or even global distribution of puf M genes in marine environments.Meanwhile,differences between the Arctic and Antarctic sequences may prove polar endemism.These results indicate the important role of Rhodobacteraceae as AAP bacteria in bipolar coastal waters.

Environmental control of growth and BChl a expression in an aerobic anoxygenic phototrophic bacterium, Erythrobacter longus (DSMZ6997)

anoxygenic phototrophic bacteria （AAPB）, which form a unique functional group of heterotrophic bacteria, have the abilit,to utilize light energy. The impact of carbon source and light intensity on the growth and bacteriochlorophyn a （ BChl a） expression of a typical strain of AAPB, Erythrobacter longus strain DSMZ6997 was examined during batch culture and continuous culture. The results showed that the expression of BChl a in DSMZ6997 was regulated by both carbon-source and light conditions, and was stimulated by low availability of carbon but inhibited by light to a certain extent at 300 lx and completely at 1 500 lx. In contrast, cell abundance, and even cell size of this strain, was substantially enhanced under light/dark cycle cultivation conditions over dark conditions, indicating the promotion of growth by light. These results led to the conclusion that utilization of light through BChl a helps AAPB to survive under carbon stress, while light at high intensity is harmful to the synthesis of BChl a in AAPB.

A comparable study of microbial community in aerobic granular sludge and activated sludge for wastewater treatment

Effect of ammonia at different concentrations on aerobic granular sludge and activated sludge was investigated in this study. Meanwhile, bacterial diversity variation and ammonia oxidizing bacterium （AOB） quantification within both kinds of sludge were monitored by terminal restriction fragment length polymorphism （T-RFLP） and real-time PCR （RT-PCR） technique, respectively. The results showed that the COD removal of both kinds of sludge changed slightly when the ammonia removal efficiency decreased gradually with the ammonia concentration increased from 100 mg L^-1 to 500 mg L^-1 Furthermore, activated sludge demonstrated higher ammonia removal ability than that of aerobic granular sludge （10%- 16%）. As revealed by T-RFLP, activated sludge was of higher ammonia removal ability and more abounding bacterial diversity than that of aerobic granular sludge, suggesting that the bacterial diversity was probably relevant to the ammonia removal. The RT-PCR results indicated that the AOB population size of activated sludge and aerobic granular sludge were 2.80× 10^4-3.44× 10^4cells （g dried sludge）^-1 and 7.83×10^4-1.18×10^5cells （g dried sludge）^-1, respectively. There is no obvious positive correlation between the ammonia removal ability and number of AOB in both kinds of sludge.

The assessment of good and bad bacteria in holy basil(Ocimum sanctum)leaves

Holy basil(Tulsi,Ocimum sanctum)is considered to be a pious plant.It is used not only in many of the rituals of Hindus but is also known for its innumerable medicinal qualities.Holy basil leaves(HBLs)are often consumed raw thus it is pertinent to detect the bacteria on Tulsi leaves.This study was conducted to understand the diversity of the aerobically growing microbiome of edible holy basil leaves.A total of 112 samples of leaves were collected from households of six localities in and around Bareilly,India for detecting culturable bacteria growing aerobically.A sum of 579 bacterial isolates belonging to 106 different species was identified.Pantoea agglomerans isolates were detected in 43 samples followed by isolates Virgibacillus pantothenticus(21),Bacillus coagulans(18),Bacillus cereus(17),Geobacillus stearothermophilus(16),Klebsiella pneumoniae(13),Citrobacter freundii(12),Lysinibacillus sphaericus(12),Acinetobacter calcoaceticus(11),Escherichia coli(11),and Xenorhabdus bovienii(11).Isolates of 95 species of bacteria were detected on<10 samples of HBLs.Of 579 isolates,161 isolates detected in 68(60.71%)samples were of putatively good bacteria belonging to eight genera(Bacillus,Brevibacillus,Lysinibacillus,Paenibacillus,Photobacter,Siccibacter,Virgibacillus,Xenoirhabdus)and 23 species.However,418 bacterial isolates detected in 108(96.43%)of the HBL samples were classified as potentially pathogenic for humans and animals belonging to 34 genera and 73 species.There were only four samples(three from Mahanagar and one from Bhojipura)that had no potential pathogenic bacteria detected in this study.The analysis indicated that HBL leaves from the ICAR-IVRI campus had a lower probability(P<0.04)of harbouring good bacteria than samples from Bhojpura,Mahanagar,North City and Rajendra Nagar.Cinnamaldehyde inhibiting 96.72%of the isolates and carvacrol inhibiting 96.37%of the isolates were the best herbal antimicrobials and among antibiotics,meropenem inhibited 98.96%of bacterial isolates.Antimicrobial resistance in non-pathogenic or good bacteria was significantly more common(P<0.01)for ajowan oil but they were more often(P<0.05)susceptible to holy basil oil,lemongrass oil,citral,P.embalica leaf extract,P.longifolia seed oil,nitrofurantoin,ciprofloxacin,chloramphenicol,colistin and minocycline than isolates of potentially pathogenic bacteria.The study concludes that HBLs may harbour both good and bacteria,and should be consumed raw only after proper decontamination.

不同种类添加剂对全株玉米发酵特性及营养品质的影响

试验旨在筛选适用于全株玉米青贮调制的添加剂种类及添加量,促进青贮玉米产业化开发。以蜡熟期全株玉米为原料,研究甲酸、乳酸菌和糖蜜对全株玉米发酵特性、营养品质及有氧稳定性的影响。结果显示:与自然发酵相比,6 mL/kg甲酸可显著降低青贮饲料中不良微生物的数量及氨态氮(NH_(3)-N)含量(P<0.05),提高了可溶性碳水化合物(WSC)含量及有氧稳定性。添加布什乳杆菌或植物乳杆菌+布什乳杆菌复合菌剂可显著增加乙酸含量(P<0.05),降低不良微生物数量及NH_(3)-N含量,提高有氧稳定性。添加糖蜜显著增加了青贮饲料中有害菌的数量及NH_(3)-N含量(P<0.05),降低了乙酸、干物质(DM)和WSC含量。研究表明,综合考虑全株玉米青贮饲料的发酵特性、营养品质及有氧稳定性,生产中推荐采用6 mL/kg甲酸、单独添加布氏乳杆菌或按1∶5配比添加植物乳杆菌与布氏乳杆菌复合菌剂对全株玉米进行青贮。

菌酶添加对喀斯特地区全株青贮玉米发酵品质和有氧稳定性的影响

试验旨在研究添加菌酶对喀斯特地区全株青贮玉米发酵品质和有氧稳定性的影响,为新型青贮菌剂的应用提供参考。以真空袋法青贮全株玉米,设5个试验组和1个对照组,分别为添加等量纯化水(对照组)、植物乳杆菌(试验A组)、纤维素分解菌(试验B组)、纤维素酶(试验C组)、植物乳杆菌+纤维素分解菌(试验AB组)、植物乳杆菌+纤维素酶(试验AC组)。其中植物乳杆菌添加1×10^(5) CFU/g;纤维素分解菌为黑曲霉∶枯草芽孢杆菌=2∶1,添加量为3.0×10^(5)、1.5×10^(5) CFU/g,纤维素酶按0.3%添加。发酵60 d后同时采样并测定全株玉米的发酵特性、乳酸菌数量、营养成分、有氧稳定性指标。结果表明:试验组均有微弱香味,对照组则气味较平淡,综合评分均到达一级;试验组pH均低于4.2,达到优质青贮料标准,C、AC组pH显著低于A、B、AB组(P<0.05);A、B、C组乳酸(LA)含量显著高于对照组(P<0.05);试验组乙酸(AA)含量高于对照组,但差异不显著(P>0.05),丙酸(PA)和丁酸(BA)均未检测出;A、B、C、AB组氨态氮(NH3-N)含量显著高于对照组(P<0.05);试验组有氧稳定性(AS)时间均显著高于对照组(P<0.05);AB组粗蛋白(CP)显著高于其他试验组(P<0.05);试验组干物质(DM)含量显著高于对照组(P<0.05);B、AB组粗灰分(Ash)含量显著低于对照组(P<0.05)。采用隶属函数法综合各项指标进行评价,各组优劣排序为AC组>C组>AB组>B组>A组>对照组。说明AC、AB组可有效改善全株青贮玉米的青贮品质,提高有氧稳定性,以AC组效果最好;因此,纤维素分解菌可在一定程度上替代纤维素酶用于全株青贮玉米发酵。

好氧-厌氧耦合法处理奶牛场污水工艺分析

【目的】筛选降解奶牛场粪污水的微生物,为奶牛场粪污处理提供科学依据。【方法】选择可用于降解污水的微生物菌株,测定微生物处理奶牛场粪污水后的化学需氧量(COD)、生物需氧量(BOD_(5))、总磷(TP)和pH的数值。【结果】从具有降解污水功能的微生物中,筛选出降解效果较好的3株好氧微生物,分别为枯草芽孢杆菌、巨大芽孢杆菌、胶质芽孢杆菌;3株厌氧微生物,分别为沼泽红假单胞菌、荧光假单胞菌、沙雷氏菌;将6种好氧-厌氧菌耦合处理降解奶牛场粪污水,其降解效率均有不同程度的提升,好氧-厌氧耦合法处理奶牛场粪污水的工艺参数为菌种接种量5%、曝气量0.05 m^(3)/h(每隔10 h曝气2 h)、温度30℃、处理时间96 h。【结论】奶牛场污水中COD去除率为91.38%、BOD_(5)去除率为96.82%、TP去除率为82.6%,出水pH值为7.2~7.6,符合国家农田灌溉水标准。

蔬菜废弃物堆肥中耐高温菌QK降解木质纤维素的特征

为探究添加微生物对好氧堆肥中木质纤维素降解特征,本研究以番茄、甜瓜蔬菜废弃物为原料,设置不添加菌剂对照组CK和添加自主筛选的耐55℃高温芽孢杆菌QK进行高温好氧堆肥试验,采集0、7、15和31 d样品分析木质纤维素含量、酶活性以及微生物多样性,探究蔬菜废弃物堆肥中耐高温菌QK降解木质纤维素的特征。结果表明,添加QK对纤维素、半纤维素、木质素的降解率分别为65.14%、58.28%、48.51%,较CK提高了8.27%、7.26%、15.21%。添加QK提升了羧甲基纤维素酶、半纤维素木聚糖酶、木质素过氧化物酶、锰过氧化物酶、漆酶活性,较CK显著提升22.64%、25.46%、50%、186.25%、61.70%。添加QK改变了细菌和真菌群落结构及多样性,其Shannon指数均得到显著提高,增加促进木质纤维素降解的拟诺卡氏菌属(Nocardiopsis)、短杆菌属(Brachybacterium)等相对丰度,同时降低病原菌棒杆菌属(Corynebacterium)、气球菌属(Aerococcus)相对丰度。耐高温芽孢杆菌QK的表现特征掲示它可以作为堆肥的良好促腐菌剂,并为解析木质纤维素降解转化机制提供了理论依据。

饲用油菜中优势乳酸菌的分离鉴定及其对青贮发酵品质和有氧稳定性的影响

本研究旨在筛选出饲用油菜(Brassica napus)青贮中天然附着的优势乳酸菌,明确其对饲用油菜青贮发酵品质和有氧稳定性的影响,为饲用油菜资源高效饲料化利用提供指导。首先利用分子生物学法(16S rDNA测序)对分离出的乳酸菌进行鉴定,鉴定出的乳酸菌菌株进行产酸和生长特性分析。进一步将筛选的优势乳酸菌接种至饲用油菜中青贮,采用裹包青贮法,试验设置4个处理:对照(CK)处理不接种菌株;布氏乳杆菌(LB)处理接种布氏乳杆菌,接种量为2×10^(8) CFU/g;屎肠球菌(EF)处理接种屎肠球菌,接种量为2×10^(8) CFU/g;布氏乳杆菌+屎肠球菌(LBEF)处理接种布氏乳杆菌+屎肠球菌(1∶1),接种量均为1×10^(8) CFU/g。结果表明:1)试验共计分离出26株乳酸菌,鉴定后得出25株为布氏乳杆菌,1株为屎肠球菌,其中2株表现出最强的产酸和生长特性。2)发酵60 d时,LBEF处理的中性洗涤纤维和丙酸含量显著低于CK和EF处理(P<0.05);EF和LBEF处理的酸性洗涤纤维含量显著低于CK和LB处理(P<0.05),乳酸含量显著高于CK和LB处理(P<0.05);LB、EF和LBEF处理的pH、氨态氮含量、霉菌数量均显著低于CK处理(P<0.05)。3)开包5 d时,EF和LBEF处理的乳酸含量和乳酸菌数量显著高于CK和LB处理(P<0.05),LBEF处理的丙酸含量显著低于其余处理(P<0.05),LB和LBEF处理的氨态氮含量显著低于其余处理(P<0.05),LBEF和LB处理的酵母菌和霉菌数量显著低于CK和EF处理(P<0.05)。由此可见,在饲用油菜青贮中联合接种布氏乳杆菌和屎肠球菌,可利用底物较少的营养物质产生乳酸,以降低发酵体系pH,抑制蛋白质腐败和霉菌生长,提高饲用油菜有氧稳定。

超嗜热菌对乡村有机固体废弃物发酵过程减量化的影响研究

传统发酵在废弃物资源化处理中已经广泛应用,但是存在发酵周期长、发酵温度低、容量大、水分高、减量化效果不佳等缺陷。采用超高温好氧发酵技术对乡村有机固体废弃物进行处理,将超高温环境下培养出的以芽孢杆菌(Bacillus)为核心的超嗜热菌剂添加到有机固体废弃物中,采用高通量测序技术,对堆体不同阶段的微生物种群进行分析,同时,对堆体温度、含水率、碳氮比(C/N,质量比)、pH、种子发芽指数(GI)和电导率(EC)等指标进行分析。结果表明:堆体的最高温度为86℃,以80℃为节点,发酵超高温期占比达到2/3,含水率从44.57%下降到29.09%,总减重率和总减容率分别为85.50%、50.51%,发酵结束时C/N、pH分别为15.56、7.55,发酵结束时物料的GI和EC分别为110.24%和3.72 mS/cm,发酵过程中芽孢杆菌目(Bacillales)和放线菌目(Actinomycetales)是达到堆体减量化效果的主要菌目。综上所述,超嗜热菌对好氧堆肥有一定的促进作用,是乡村固体废弃物减量化处理较为理想的发酵菌剂。