Biodegradation of geosmin in drinking water by novel bacteria isolated from biologically active carbon

Three strains of Gram-negative bacteria capable of removing geosmin from drinking water were isolated from biologically active carbon and identified to be Chryseobacterium sp., Sinorhizobium sp. and Stenotrophomonas sp. based on physio-biochemistry analysis and 16S rRNA gene sequence analysis. Removal e ciencies of 2 mg/L geosmin in mineral salts medium were 84.0%, 80.2% and 74.4% for Chryseobacterium sp., Sinorhizobium sp. and Stenotrophomonas sp., respectively, while removal e ciencies of 560 ng/L geosmin in filter influent were 84.8%, 82.3% and 82.5%, respectively. The biodegradation of geosmin was determined to be a pseudo first-order reaction, with rate constants at 2 mg/L and 560 ng/L being 0.097 and 0.086 day??1, 0.089 and 0.084 day??1, 0.074 and 0.098 day??1 for the above mentioned degraders, respectively. The biomass of culture in the presence of geosmin was much higher than that in the absence of geosmin.     

Succession of bacterial community along with the removal of heavy crude oil pollutants by multiple biostimulation treatments in the Yellow River Delta, China

Multiple biostimulation treatments were applied to enhance the removal of heavy crude oil pollutants in the saline soil of Yellow River Delta. Changes of the soil bacterial community were monitored using the terminal restriction fragment length polymorphism (T-RFLP) and clone library analyses. The 140-day microcosm experiments showed that low C:N:P ratio, high availability of surfactant and addition of bulking agent significantly enhanced the performance, leading to the highest total petroleum hydrocarbon removal. Meanwhile, the bacterial community was remarkably changed by the multiple biostimulation treatments, with the Deltaproteobacteria, Firmicutes, Actinobacteria, Acidobacteria and Planctomycetes being inhibited and the Alpha- and Beta-proteobacteria and some unknown Gammaproteobacteria bacteria being enriched. In addition, different hydrocarbon-degraders came to power in the following turn. At the first stage, the Alcanivorax-veldXed Gammaproteobacteria bacteria dominated in the biostimulated soil and contributed mainly to the biodegradation of easily degradable portion of the heavy crude oil. Then the bacteria belonging to Alphaproteobacteria, followed by bacteria belonging to Candidate division OD1, became the dominant oil-degraders to degrade the remaining recalcitrant constituents of the heavy crude oil.     

Bacterial community composition and abundance in leachate of semi-aerobic and anaerobic landfills

Different municipal solid waste landfill methods and landfill ages had crucial impacts on bacterial abundance and composition in leachate.     

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

Combination of 16S rRNA gene clone library and cultivation for assessing of bacterial diversity of the microflora in bulking sludge was evaluated in the study.     

Comparison of bacterial community structures in two systems of a sewage treatment plant using PCR-DGGE analysis

Bacterial community was investigated during sludge bulking period using combination of PCR amplification of 16sRNA genes with DGGE analysis.     

稻香湖景酒店景观再生水生产中的细菌群落结构变化

为了解生活污水处理系统对水体细菌群落结构及多样性的影响,以北京稻香湖景酒店生活污水处理系统为例,利用16SrDNA文库技术研究了不同处理阶段水体细菌的群落结构及多样性.结果表明,酒店排放的生活污水中细菌类型较多,Shannon-Weaver多样性指数为3.12,其中ε-变形杆菌纲在克隆文库中所占比例最高,达32%;另外还有9%～15%的克隆分别与CFB类群、γ-变形杆菌纲、梭杆菌门和厚壁菌门的细菌高度同源;经中水站处理后,水体细菌多样性指数下降到2.41,β-变形杆菌纲的细菌占据绝对优势,比例高达73%;进一步经小型人工湿地处理后,细菌的多样性指数提高到3.38,其中放线菌门的细菌比例最高达33%,成为最优势的类群,蓝细菌的比例次之,达26%;而对照样品中蓝细菌为最主要的优势类群,比例高达38%,主要涉及的种属为蓝菌属、聚球藻属和微囊藻属,比例分别为47.1%、17.6%和8.8%,且检测到少量铜绿微囊藻,水体有轻度蓝藻水华暴发.因此,该酒店的生活污水经过逐级处理改造成景观再生水的过程中改变了细菌的优势群落结构和多样性;经过处理的水体未有蓝藻水华出现,水体状况优于对照.该研究对了解景观再生水生产过程中细菌微生态的变化、将来从生态学的角度加强蓝藻水华的控制提供有用的资料.     

絮凝细菌投加量对好氧颗粒污泥性能影响的研究

为研究絮凝细菌对好氧污泥颗粒化的影响,采用气升式内循环序批反应器,在培养好氧颗粒污泥过程中投加絮凝细菌,探讨其投加量对颗粒污泥的理化性能及生物降解效能的影响.结果表明,适量投加絮凝细菌能促进好氧颗粒污泥的形成,絮凝细菌投加量在0～20mL/L时,均可以培养出成熟的好氧颗粒污泥.絮凝细菌最佳投加量为10mL/L,此时颗粒化速度快,颗粒形成时间由未投加的42d缩短为35d,好氧颗粒污泥疏水性好,SVI稳定在40mL/g左右,沉降速度达35.82m/h,COD、氨氮和总磷的去除率分别为97.14%、84.49%和87.59%.而投加量为30mL/L时最终所形成的是白色污泥絮团,没有实现污泥颗粒化.     

生物除铁除锰滤层营养条件的研究

采用模拟生物除铁除锰滤柱,通过测定整个生物滤层对铁、锰的去除效果考察了营养物质对生物滤层综合生化能力的影响,从而探求了生物滤层对铁、碳、氮等营养元素的需求.结果表明,成熟滤层内的铁、锰氧化细菌对进水铁的营养需求极低(0.04 mg/L).成熟滤层对有机物具有一定的去除能力,而无机碳减少量相对较大,大约有3～4 mg/L,溶解在水中的二氧化碳即可保证滤层对碳的需求.成熟滤层将氨氮转化为硝酸盐和亚硝酸盐,但这种转化实际上并没有使水中氮的总量减少,只是氮的形态发生了转化;而滤柱内氮的减少是被生物体利用的结果.极低的氮素含量即可保证成熟生物滤层对氮素的需求.这表明极低的营养条件即可满足铁、锰氧化细菌的正常生理代谢,铁、锰氧化细菌可以在贫营养环境下生存.结合全国大部分地区的地下水水质状况,进而得出地下水生物除铁除锰技术在全国大部分地区可以推广使用.     

氯苯对球形红细菌的毒性效应研究

研究不同质量浓度氯苯对光合细菌球形红细菌(Rhodobacter sphaeroides)生长和脱氢酶活性的影响.结果发现,当氯苯质量浓度达到80 mg/L时,即可抑制球形红细菌的生长;当氯苯质量浓度增加到1 000 mg/L时,球形红细菌的生长被完全抑制.球形红细菌脱氢酶活性随氯苯质量浓度增加而明显降低.在此基础上进一步运用化学品对水生生物急性毒性实验的标准方法研究了氯苯对球形红细菌的毒性效应.结果表明,氯苯对球形红细菌生长的安全质量浓度(最低可见效应质量浓度LOEC)为40 mg/L.抑制球形红细菌生长的96 h-EC50为346.7 mg/L.氯苯与球形红细菌的质量浓度-效应方程为y=11.1459-2.416x,R2=0.989 7.对该质量浓度-效应方程进行χ2检验表明,结果符合精度要求,计算出的96 h-EC50真实可靠.