Pronounced temporal changes in soil microbial community and nitrogen transformation caused by benzalkonium chloride

As one typical cationic disinfectant, quaternary ammonium compounds (QACs) were approved for surface disinfection in the coronavirus disease 2019 pandemic and then unintentionally or intentionally released into the surrounding environment. Concerningly, it is still unclear how the soil microbial community succession happens and the nitrogen (N) cycling processes alter when exposed to QACs. In this study, one common QAC (benzalkonium chloride (BAC) was selected as the target contaminant, and its effects on the temporal changes in soil microbial community structure and nitrogen transformation processes were determined by qPCR and 16S rRNA sequencing-based methods. The results showed that the aerobic microbial degradation of BAC in the two different soils followed first-order kinetics with a half-life (4.92 vs. 17.33 days) highly dependent on the properties of the soil. BAC activated the abundance of N fixation gene (nifH) and nitrification genes (AOA and AOB) in the soil and inhibited that of denitrification gene (narG). BAC exposure resulted in the decrease of the alpha diversity of soil microbial community and the enrichment of Crenarchaeota and Proteobacteria. This study demonstrates that BAC degradation is accompanied by changes in soil microbial community structure and N transformation capacity.     

黄孢原毛平革菌对碱性紫5BN的脱色降解研究

目的 建立黄孢原毛平革菌与10、50、100mg/L碱性紫5BN的共培养体系,研究菌种和培养条件对脱色降解效果的影响。方法 采用分光光度法测定培养液最大吸收波长处吸光度的改变,确定染料的脱色率及降解率。结果 (1)OGC101菌株的降解能力明显强于BKM-F-1767菌株,培养液最大吸收波长向短波方向移动,说明染料的N-去甲基化和降解中间物的形成;(2)琥珀酸钠缓冲液、04mM藜芦醇(VA)、浅层静置培养的参数组合较佳;(3)共培养30d后,各样品的脱色降解率为54％-98％;(4)染料浓度与脱色降解效应的相关性,因菌种而异。     

微生物法脱臭及其应用

文章介绍了用微生物方法处理恶臭气体的原理，方法以及国内外研究应用发展的现状，表明用微生物地脱臭具有广阔的应用前景。     

生物组合技术在河蟹人工育苗水质净化中的应用研究

为探索河蟹人工育苗中的水质净化和减少换水量的方法，通过基础试验和河蟹人工育苗生产性试验，对一种生物组合技术进行了研究考察，结果表明，依据生态养殖原理设计，在养殖池内投放和接触氧化水循环处理装置内接种挂膜光合细菌、消化细菌和放线菌等环境有益微生物，并与微藻、光合细菌等活饵料应用技术相结合的成套技术可使育苗池水循环利用，降低生产成本，减少对周边水环境的污染。试验苗池DO高于7.5mg/L，NH3－N基本低于0.5mg/L，水质明显优于对照苗池，符合河蟹育苗要求。试验苗池触苗总成活率19.4%，产量175.8g/m^3，触菌成活率、产量和质量均明显优于对照苗池，藕效益和环境效益显著。     

环境微生物降解有机磷农药研究进展

微生物降解是有机磷农药在环境中去毒降解的主要方式，该文从环境微生物筛选、降解基因的识别、降解酶的种类及其特性、微生物降解底物特异性及微生物降解效果的评价等5个方面，综述了近年来有机磷农药微生物降解方面的研究进展，展望了微生物降解有机磷农药的研究方向。     

农药废水处理工艺研究

通过采用特定的“物化＋生化＋物化”的处理工艺，对某农药厂阿特拉津和乙草混胺混合废水进行试验研究，结果表明：采用该工艺可使废水ＣＯＤＣｒ从４０００ｍｇ／Ｌ降到１００ｍｇ／Ｌ以下，ＢＯＤ５从６５０ｍｇ／Ｌ降到５ｍ／Ｌ左右，去除率分别超过９７％和９９％；特征因子阿特拉津和乙草胺的去除率达到９３％和９６％，类高难度有机废水的处理提供了依据和必要的工程设计参数。     

Microbiological analysis of multi-level borehole samples from a contaminated groundwater system

A range of bacteriological, geochemical process-related and molecular techniques have been used to assess the microbial biodegradative potential in groundwater contaminated with phenol and other tar acids. The contaminant plume has travelled 500 m from the pollutant source over several decades. Samples were obtained from the plume using a multi-level sampler (MLS) positioned in two boreholes (boreholes 59 and 60) which vertically transected two areas of the plume. Activity of the microbial community, as represented by phenol degradation potential and ability to utilise a range of substrates, was found to be influenced by the plume. Phenol degradation potential appeared to be influenced more by the concentration of the contaminants than the total bacterial cell numbers. However, in the areas of highest phenol concentration, the depression of cell numbers clearly had an effect. The types of bacteria present were assessed by culture and DNA amplification by polymerase chain reaction (PCR). Bacterial groups or processes associated with major geochemical processes, such as methanogenesis, sulphate reduction and denitrification, that have the potential to drive contaminant degradation, were detected at various borehole levels. A comparative molecular analysis of the microbial community between samples obtained from the MLS revealed the microbial community was diverse. The examination of microbial activity complemented those results obtained through chemical analysis, and when combined with hydrological data, showed that MLS samples provided a realistic profile of plume effects and could be related to the potential for natural attenuation of the site.     

Application of Bacillus subtilis strain for microbial-enhanced oil recovery

In order to improve the oil recovery, injection of exogenous bacteria into the oil reservoir is one of the most widely used microbial flooding methods. In this study, a screened strain of Bacillus subtilis (B. subtilis) was introduced to perform the microbial flooding. The biosurfactants produced by B. subtilis was one kind of cyclic lipopeptides, which could reduce the surface tension of the culture solution from 68 mN/m to 25 mN/m and also decrease the interfacial tension of water/oil from 25.6 to 4.6 mN/m. Emulsification tests indicated that the strain and the biosurfactants could degrade and emulsify the crude oil. In the oil displacement experiments, oil recovery was increased by 32.4% by injecting fermentation broth into the simulated formation. By respectively performing the emulsification and oil displacement tests, it was demonstrated that the biosurfactants and degradation of the microbes in the heavy components of the crude oil are the main factors to enhance the oil recovery. Besides, the optimal cultural temperature for strain of B. subtilis was set as 40°C. Nevertheless, the strain was inappropriate for the oil displacement under acidic conditions. In addition, the hydrophilic sands and an optimal culture solution volume of 0.7 pore volume (PV) would be in favor of the oil recovery. It was further confirmed that the efficiency of microbial flooding was much higher than that of the chemical oil displacement.     

Investigation of physico-chemical properties and microbial community during poultry manure co-composting process

Co-composting of poultry manure and rubber wood sawdust was performed with the ratio of 2:1 (V/V) for a period of 60 days. An investigation was carried out to study the extracellular enzymatic activities and structural degradation utilizing Fourier transform infrared spectroscopy (FT-IR), thermogravimetry and differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The microbial succession was also determined by using denaturing gel gradient electrophoresis (DGGE). The compost was able to reach its highest temperature of 71°C at day 3 and stabilized between 30 and 40°C for 8 weeks. CMCase, FPase and β-glucosidase acted synergistically in order to degrade the cellulosic substrate. The xylanase activities increased gradually during the composting and reached the peak value of 11.637 U/g on day 35, followed by a sharp decline. Both LiP and MnP activities reached their peak values on day 35 with 0.431 and 0.132 U/g respectively. The FT-IR spectra revealed an increase in aromaticity and a decrease in aliphatic compounds such as carbohydrates as decomposition proceeded. TGA/DTG data exhibited significant changes in weight loss in compost samples, indicating degradation of organic matter. SEM micrographs showed higher amounts of parenchyma exposed on the surface of rubber wood sawdust at day 60, showing significant degradation. DGGE and 16S rDNA analyses showed that Burkholderia sp., Pandoraea sp., and Pseudomonas sp. were present throughout the composting process. Ornithinibacillus sp. and Castellaniella ginsengisoli were only found in the initial stage of the composting, while different strains of Burkholderia sp. also occurred in the later stage of composting.     

Microbial communities in acid water environments of two mines, China

To understand the compositions and structures of microbial communities in different acid-aqueous environments, a PCR-based cloning approach was used. A total of five samples were collected from two mines in China. Two samples, named as G1 and G2, were acid mine drainage (AMD) samples and from Yunfu sulfide mine in Guangdong province, China. The rest of the three samples named as D1, DY and D3, were from three sites undertaking bioleaching in Yinshan lead-zinc mine in Jiangxi province, China. Phylogenetic analysis revealed that bacteria in the five samples fell into six putative divisions, which were α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Firmicutes, Actinobacteria and Nitrospira. Archaea was only detected in the three samples from Yinshan lead-zinc mine, which fell into two phylogenentic divisions, Thermoplsma and Ferroplasma. In addition, the results of principal component analysis (PCA) suggested that more similar the geochemical properties in samples were, more similar microbial community structures in samples were.