Biotic transformation of anticoccidials in soil using a lab-scale bio-reactor as a precursor-tool

Two anticoccidial agents, salinomycin and robenidine, heavily used in the worldwide veterinary meat production, were investigated for their potential biotic degradation by cultured soil bacteria. The degradation-study was performed in lab-scale bio-reactors under aerobic and anaerobic conditions incubated for 200 h with a mixed culture of soil bacteria. Samples were analyzed by LC-MS/MS and potential transformation products were tentatively identified. Salinomycin was degraded under aerobic conditions and traces could be found after 200 h, however, seems more persistent under anaerobic conditions. Four transformation products of salinomycin were discovered. Robenidine was degraded under aerobic and anaerobic conditions, however, traces of robenidine were observed after 200 h. Five biotic transformation products of robenidine were discovered.     

接种不同污泥源条件下厌氧氨氧化菌的特性

2组ASBR接种污泥源分别为好氧硝化污泥、好氧硝化污泥和厌氧氨氧化污泥按2：1比例}昆合的混合污泥。在相同条件下，经过驯化培养均实现了厌氧氨氧化的稳定运行。接种好氧硝化污泥的反应器的适应期为29d，经过105d的培养反应器成功启动；接种混合污泥的反应器的适应期为13d，经过49d反应器启动成功。从2组ASBR污泥中提取细菌总DNA，经过厌氧氨氧化菌特异引物Pla46rc／Amx820对污泥样品进行PCR扩增、克隆和测序等分析。实验结果表明，接种不同污泥源条件下的反应器中厌氧氨氧化菌的特性存在差异，接种污泥源为好氧硝化污泥的反应器中存在的厌氧氨氧化菌种为CandidatusKuenenia，而接种混合污泥的反应器中存在的厌氧氨氧化菌种为CandidatusAnammox—oglobus，与最初接种的混合污泥中的厌氧氨氧化菌相同。当接种污泥中存在厌氧氨氧化菌时，该菌株经过长时间的驯化可成为优势菌种，而当接种污泥中无厌氧氨氧化菌存在时，CandidatusKueneniasp．可以在反应器中占主导，具有更强的竞争优势。     

Long-term Hg pollution-induced structural shifts of bacterial community in the terrestrial isopod (Porcellio scaber) gut

In previous studies we detected lower species richness and lower Hg sensitivity of the bacteria present in egested guts of Porcellio scaber (Crustacea, Isopoda) from chronically Hg polluted than from unpolluted environment. Basis for such results were further investigated by sequencing of 16S rRNA genes of mercury-resistant (Hg^r) isolates and clone libraries. We observed up to 385 times higher numbers of Hg^r bacteria in guts of animals from polluted than from unpolluted environment. The majority of Hg^r strains contained merA genes. Sequencing of 16S rRNA clones from egested guts of animals from Hg-polluted environments showed elevated number of bacteria from Pseudomonas, Listeria and Bacteroidetes relatives groups. In animals from pristine environment number of bacteria from Achromobacter relatives, Alcaligenes, Paracoccus, Ochrobactrum relatives, Rhizobium/Agrobacterium, Bacillus and Microbacterium groups were elevated. Such bacterial community shifts in guts of animals from Hg-polluted environment could significantly contribute to P. scaber Hg tolerance.     

零价铁-反硝化菌在地下水硝酸盐污染修复中的应用

综述了应用零价铁-反硝化菌复合体系去除地下水中硝酸盐氮污染的研究进展.脱氮技术主要包括物理化学法、化学还原法和生物反硝化法,但单独使用任何一种方法都无法得到令人满意的处理效果.以零价铁在水中厌氧腐蚀所释放的氯气供给微生物进行反硝化,可以同时解决这两种技术单独使用时所存在的弊端.在此复合体系中,主要反应包括产氨、析氢和反硝化,降低脱氮产物中的氨氮比例就要减少产氨反应的发生几率.此外,使用纳米铁代替零价铁和反硝化细菌复合,可以大大提高脱氮反应速率.然而,该技术的研究在国内外尚处于起步阶段,在反应机理、产物控制、条件优化等方面都存在不足,还需要深入研究.     

硅酸盐细菌解钾兼拮抗活性菌株的筛选

从紫色土壤中分离筛选出具有解钾拮抗双重活性的硅酸盐细菌CS1和CS29菌株。接菌处理，其水溶性钾分别增加75％和65％，转化率达0．82％和0．72％。两株菌对革兰氏阳性的蜡样芽孢杆菌，金黄色葡萄球菌，藤黄八叠球菌等和革兰氏阴性的大肠杆菌均有较强的抑菌活性。筛选菌株中91．2％具有解钾活性，但拮抗活性菌株只占总数的11．6％，表明二性状之间无相关关系。表4参7     

石油类污染地下水中挥发性有机物低温生物降解性能的研究

针对地下水石油类污染的问题,从某污染场地土壤中筛选驯化出了适用于处理挥发性有机物的3株低温高效降解菌,并以苯和萘作为特征组分考察了pH、DO、温度、氮磷等因素对降解效果的影响;实验结果表明,在8℃左右的地下环境中,DO和氮磷的含量对污染物的降解影响较大;在pH 7.5、DO＞4 mg/L和投加氮磷的条件下,18 d内降...     

pH、盐度对微生物还原硫酸盐的影响研究

采用厌氧生物处理工艺，研究了在不同盐度下pH连续降低对硫酸盐还原和有机物去除率的影响。实验结果表明，硫酸盐还原菌有很强的适应pH变化的能力，在pH值达到4以下仍有60％的硫酸盐去除率。NaCl浓度由4g／L增加到50g／L抑制了各厌氧菌的活性，导致硫酸盐和有机物去除率的下降，但硫酸盐还原菌耐受性高于产甲烷菌等其他厌氧菌，在NaCl浓度为50g／L下，硫酸盐去除率能达到50％，而有机物去除率则低于30％。qRT—PCR表明了系统菌落中SRB随着环境的变化情况与化学指标结果相一致，该反应器体系中SRB在整个厌氧菌群落中只占了很小部分。     

Dynamic of functional microbial groups during mesophilic composting of agro-industrial wastes and free-living (N2)-fixing bacteria application

Although several reports are available concerning the composition and dynamics of the microflora during the composting of municipal solid wastes, little is known about the microbial diversity during the composting of agro-industrial refuse. For this reason, the first parts of this study included the quantification of microbial generic groups and of the main functional groups of C and N cycle during composting of agro-industrial refuse. After a generalized decrease observed during the initial phases, a new bacterial growth was observed in the final phase of the process. Ammonifiers and (N₂)-fixing aerobic groups predominated outside of the piles whereas, nitrate-reducing group increased inside the piles during the first 23 days of composting. Ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), showed an opposite trend of growth since ammonia oxidation decreased with the increase of the nitrite oxidation activity. Pectinolytics, amylolytics and aerobic cellulolytic were present in greater quantities and showed an upward trend in both the internal and external part of the heaps.Several free-living (N₂)-fixing bacteria were molecularly identify as belonging especially to uncommon genera of nitrogen-fixing bacteria as Stenotrophomonas, Xanthomonas, Pseudomonas, Klebsiella, Alcaligenes, Achromobacter and Caulobacter. They were investigated for their ability to fix atmospheric nitrogen to employ as improvers of quality of compost. Some strains of Azotobacter chrococcum and Azotobacter salinestris were also tested. When different diazotrophic bacterial species were added in compost, the increase of total N ranged from 16% to 27% depending on the selected microbial strain being used. Such microorganisms may be used alone or in mixtures to provide an allocation of plant growth promoting rhizobacteria in soil.     

Antibiotic resistant bacteria/genes dissemination in lacustrine sediments highly increased following cultural eutrophication of Lake Geneva (Switzerland)

This study investigates faecal indicator bacteria (FIB), multiple antibiotic resistant (MAR), and antibiotic resistance genes (ARGs), of sediment profiles from different parts of Lake Geneva (Switzerland) over the last decades. MARs consist to expose culturable Escherichia coli (EC) and Enterococcus (ENT) to mixed five antibiotics including Ampicillin, Tetracycline, Amoxicillin, Chloramphenicol and Erythromycin. Culture-independent is performed to assess the distribution of ARGs responsible for, β-lactams (blaTEM; Amoxicillin/Ampicillin), Streptomycin/Spectinomycin (aadA), Tetracycline (tet) Chloramphenicol (cmlA) and Vancomycin (van). Bacterial cultures reveal that in the sediments deposited following eutrophication of Lake Geneva in the 1970s, the percentage of MARs to five antibiotics varied from 0.12% to 4.6% and 0.016% to 11.6% of total culturable EC and ENT, respectively. In these organic-rich bacteria-contaminated sediments, the blaTEM resistant of FIB varied from 22% to 48% and 16% to 37% for EC and ENT respectively, whereas the positive PCR assays responsible for tested ARGs were observed for EC, ENT, and total DNA from all samples. The aadA resistance gene was amplified for all the sediment samples, including those not influenced by WWTP effluent water. Our results demonstrate that bacteria MARs and ARGs highly increased in the sediments contaminated with WWTP effluent following the cultural eutrophication of Lake Geneva. Hence, the human-induced changing limnological conditions highly enhanced the sediment microbial activity, and therein the spreading of antibiotic resistant bacteria and genes in this aquatic environment used to supply drinking water in a highly populated area. Furthermore, the presence of the antibiotic resistance gene aadA in all the studied samples points out a regional dissemination of this emerging contaminant in freshwater sediments since at least the late nineteenth century.     

Isolation and characterization of lead-tolerant Ochrobactrum intermedium and its role in enhancing lead accumulation by Eucalyptus camaldulensis

In this study, the potential of rhizospheric bacteria in promoting the growth and Pb accumulation by the woody plant Eucalyptus camaldulensis under hydroponic conditions was investigated for the first time. Three Pb-tolerant bacteria were isolated from the rhizosphere of E. camaldulensis grown in Pb-contaminated soils in the Bo Ngam Pb mine, Thailand. Based on analysis of partial 16S rRNA gene sequence, the three isolates were identified as Microbacterium paraoxydans BN-2, Ochrobactrum intermedium BN-3, and Bacillus fusiformis BN-4. Among these strains, O. intermedium BN-3 showed the highest tolerance to not only Pb but also Cd and Zn. After growth in the presence of Pb, the membranes of O. intermedium BN-3 cells exhibited an increase in unsaturated fatty acid levels but a decrease in fluidity. In hydroponic studies, inoculation of O. intermedium BN-3 significantly increased the biomass and Pb accumulation by E. camaldulensis compared to the uninoculated control. The results suggested the role of the natural rhizospheric bacteria localized to the root surface of E. camaldulensis in promoting Pb accumulation and plant growth. Our results indicate that O. intermedium BN-3 and other indigenous rhizospheric bacteria have the potential to improve the efficiency of phytoremediation of Pb-contaminated sites.