科学家发现食岩细菌可将火星变“绿色地球”

近日,研究人员称,微小的食岩细菌可以采集火星宝贵的资源,并为人类首次殖民拓展提供基础条件。但是,通过食岩细菌改造火星表面成为新地球的计划并非短暂时间内完成的。     

Potential neoplastic effects of parathion-methyl on rat liver

The mutagenic and carcinogenic effects of parathion-methyl were examined by bacterial reverse assay and a long term experiment with Wistar rats. The potential mutagenic effect of parathion-methyl in Salmonella typhimurium TA100 bacterial cells was observed without rat liver S9 metabolic activation. Parathion-methyl was further investigated for pathological changes in rat pancreas and liver. The long-term rat experiments showed that parathion-methyl exposure for 3 months can cause pathological changes in rat pancreases acinar cells and pancreatic hepatocytes. Atypical acinar cell focuses (AACF) were determined in the liver and pancreas of the rats. The results from short-term Ames test and long-term rat experiments suggest that parathion-methyl would be potential carcinogenic.     

Characteristics of the microbial communities in the integrated vertical-flow constructed wetlands

Microorganisms play an important role in removing pollutants from constructed wetlands. We investigated the microbial characteristics in a novel integrated vertical-flow constructed wetland (IVCW), which has been in operation in Wuhan, China since 1998. We used phospholipid fatty acid (PLFA) and amoA gene to analyze the structure and diversity of the microbial community within the IVCW. PLFA results suggested that the amount of bacterial PLFA was significantly higher than that of fungal PLFA, but the total microbial biomass represented by PLFA index was low in the system. Microbial spatial distribution showed significantly higher bacterial (both G⁺ and G⁻) and fungal biomass in the surface than in the subsurface layers. The ratios of monounsaturated to branched PLFA demonstrated that an anaerobic layer sandwiched by two aerobic layers existed in the IVCW, consistent with the redox potential results. Analysis of the amoA revealed the presence of Nitrosomonas-like sequences in the surface substrate of the downflow chamber and apparent diversities of ammonia-oxidizing bacteria in the system. These results suggest that microorganisms, despite their relatively low biomass, have inhabited the IVCW, and the results will offer some valuable information on microbe to system designers and managers.     

Quantification of anaerobic ammonium-oxidizing bacteria in enrichment cultures by quantitative competitive PCR

The anaerobic ammonium-oxidizing (ANAMMOX) bacteria were enriched from a sequencing batch biofilm reactor (SBBR). A quantitative competitive polymerase chain reaction (QC-PCR) system was successfully developed to detect and quantify ANAMMOX bacteria in environmental samples. For QC-PCR system, PCR primer sets targeting 16S ribosomal RNA genes of ANAMMOX bacteria were designed and used. The quantification range of this system was 4 orders of magnitude, from 103 to 106 copies per PCR, corresponding to the detection limit of 300 target copies per mL. A 312-bp internal standard was constructed, which showed very similar amplification e ciency with the target amxC fragment (349 bp) over 4 orders of magnitude (103–106). The linear regressions were obtained with R2 of 0.9824 for 103 copies, 0.9882 for 104 copies, 0.9857 for 105 copies and 0.9899 for 106 copies, respectively. Using this method, ANAMMOX bacteria were quantified in a shortcut nitrification/denitrification-anammox system which was set for piggery wastewater treatment.     

固定化氨氧化细菌短程硝化稳定性研究

以高分子聚合物为载体,采用细胞增殖技术固定氨氧化细菌,研究了氨氮负荷、HRT、初始游离氨(FA)和有机物等因素对短程硝化过程稳定性的影响.实验结果表明,当进水氨氮负荷分别为100、150和200 mg/L时,出水氨氮浓度均小于10 mg/L;当进水氨氮浓度为25.8、51.1和93.3 mg/L时,分别经历3、6、12 h后,出水氨氮浓度低,亚硝化效果好,可以根据进水氨氮浓度的变化,适当地凋整系统水力停留时间(HRT)并优化系统的运行;当游离氨(FA)浓度>9 mg/L时,对氨氧化细菌会产生抑制;低分子有机物的存在对氨氧化细菌的活性具有一定的促进作用,有机物浓度对亚硝化率基本不产生影响,实验过程中在有机物存在的条件下.发生了短程硝化反硝化反应.使得系统总氮减少.     

利用ATP生物发光法快速检测丽娃河中细菌总数

利用ATP生物发光法对丽娃河中细菌总数进行了快速检测。结果表明,丽娃河中细菌总数维持在0.72×106～1.2×107CFU/mL,较综合整治前的水质有了明显地改善。研究了游离ATP以及浮游生物等对发光强度的影响,发现对样品采用过滤的方法进行预处理是提高ATP生物发光法精确度的一种重要手段。     

我国含盐废水生物处理的研究进展

综述了目前我国在含盐废水生物处理的研究进展,包括传统活性污泥法、SBR、生物接触氧化法、厌氧生物处理等,在不同的运行条件和处理状况下取得的较好的处理效果。并在此基础上介绍了耐盐细菌法和物化一生化组合工艺法两种非常有效的处理工艺。     

16S rDNA 克隆文库法分析Biostyr 曝气生物滤池处理城市污水的细菌多样性研究

采用分子生物学手段16SrDNA克隆文库方法,对第三代生物膜法代表工艺Biostyr曝气生物滤池（BAF）中滤料表面细菌进行了多样性研究.从16SrDNA克隆文库中随机挑选了50个克隆子进行序列测定（约1.5kb）,对测序结果进行了BLAST对比.结果表明,BiostyrBAF系统中的细菌群落具有高度多样性,有41个克...     

成熟锰砂表面细菌的分离及其氧化铁锰能力

从取自不同电厂成熟锰砂表面的活性滤膜中分离出7种细菌,经鉴定分别属于纤发菌属、球衣菌属、鞘铁细菌属.研究表明,这3个菌属的微生物对水中Fe2+都具有较好的去除效果,其中鞘铁细菌1号对铁的去除效果最好;纤发菌和鞘铁细菌对水中Mn2+都具有良好的去除效果,其中鞘铁细菌1号的去除能力最强,鞘铁细菌2号次之.将分别堵养的具有氧...     

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.