Isolation,identification and desulfurization mechanism of a sulfur-oxidizing bacterium with salt tolerance北大核心CSCD

Micro-organism with efficient desulfurization performance is a key factor in the biological desulfurization technology. This study aimed to seek such a sulfur-oxidizing strain and understand its desulfurization mechanism. Wastewater in a sewage station of natural gas purification plant was used to screen the sulfide-oxidizing strain, and to identify it based on sequence similarity analysis of 16S rDNA and the morphological characteristics. Thiosulfate was used as substrate for investigating the sulfur oxidation performance and salinity tolerance; the OD600, content change of thiosulfate, sulfate, sulfur, pH and total alkalinity in the cultural system were also investigated. The strain DS-B was found to share the highest sequence similarity with Thioalkalivibrio thiocyanoxidans ARh2, therefore determined as Thioalkalivibrio. At the optimum temperature of 35 °C for growth and degradation, the removal efficiency of thiosulfate could reach 98.7% after 7 days. Strain DS-B had strong resistance to thiosulfate, and the optimal concentration of S2O32- was 2 × 104 mg/L. The analysis for sulfur oxides showed that it could oxidize thiosulfate by the pathway of S2O32-→SO42- / S2O32- → S → SO42-. Therefore the strain DS-B is a sulfur-oxidizing bacterium with great application prospect for its strong salt tolerance and conspicuous removal capability for thiosulfate.     

芽孢杆菌SeRB-2还原亚硒酸盐的动力学研究

微生物还原亚硒酸盐的动力学研究具有重要的现实意义,可以为Se (IV)污染场地的微生物修复设计提供理论依据。本文研究了兼性厌氧菌Bacillus sp.SeRB-2对亚硒酸钠的还原动力学。通过指数方程模型、对数方程模型和米氏方程模型的分析可知,Se (IV)的细菌还原符合一级反应动力学,还原反应主要集中在对数期和稳定生长前期,米氏方程模型能更好的反映细菌对亚硒酸盐的还原过程。通过对不同Se (IV)浓度下的米氏常数(K_m)和最大反应速率(V_max)的分析发现,当Se (IV)浓度较低时,K_m值较小,V_max值较大,这表明Se (IV)浓度越低,还原亚硒酸盐的酶与Se (IV)的结合能力越强,此时细菌对亚硒酸盐的还原速率越大、还原效率也越高。在本研究中,当Se (IV)浓度为1 mmol/L时,其还原效率最高可达90%,能够有效去除或降低Se (IV)污染,说明该菌在Se (IV)污染场地的生物修复上具有应用潜力。     

Characterization of a salt-tolerant bacterium Bacillus sp. from a membrane bioreactor for saline wastewater treatment

High salt concentrations can cause plasmolysis and loss of activity of cells, but the salt-torlerant bacterium can endure the high salt concentrations in wastewater. In this research 7 salt-torlerant bacteria, which could survive in dry powder products and could degrade organic contaminants in saline wastewater, were isolated from a membrane bioreactor. The strain NY6 which showed the fastest growth rate, best property for organic matter degradation and could survive in dry powder more than 3 months was selected and characterized. It was classified as Bacillus aerius based on the analysis of the morphological and physiological properties as well as the 16 S rRNA sequence and Neigh borjoining tree. The strain NY6 could survive in the salinity up to 6% and the optimal growth salinity is2%; it belongs to a slightly halophilic bacterium. The capability of its dry powder products for COD removal was 800 mg COD/(g·day) in synthesized saline wastewater with salinity of 2%. According to salt-tolerant mechanism research, when the salinity was below 2%, the stain NY6 absorbed K+and Na+to maintain osmotic equilibrium, and when the salinity was above 2%, the NY6 kept its life by producing a large amount of spores.     

固定化高效降解菌处理PTA废水的研究

研究了聚乙烯醇(PVA)加少量海藻酸钠及SiO2、CaCO3的方法固定高效菌处理PTA污水.结果表明,采用质量分数分别为PVA 10%、海藻酸钠0.3%、特种菌种10%、SiO2 3%、CaCO30.3%,用饱和硼酸溶液(pH为4.0)作为交联剂,制得的颗粒处理PTA废水时,废水COD负荷为2.91kg/m3·d时,CODcr、TOC、TA去除率均为85%以上;废水COD负荷为12.2kg/m3j·时,CODcr去除率仍为50%以上、TOC去除率为60%以上,当pTA废水pH从55降至35时,CODcr、TOC、TA去除率仍在86%以上.     

沉降法测定大气细菌粒子含量公式的检验

在沈阳市对文献［６］提出的由大气细菌粒子的沉降量计算大气细菌粒子含量的公式进行了检验．结果表明，在同泽小学由公式计算的大气细菌粒子的含量为３３２４个／ｍ３，Ａ·Ｓ采样器测定的大气细菌粒子的含量为３７９２个／ｍ３，二者之间的比值为０．９，ｔ＝０．７８５，Ｐ＞０．０５，两种方法得出的大气细菌粒子的含量没有明显差异，比传统的奥梅梁斯基公式有比较好的准确性和实用性．     

兰州市空气微生物分析

对兰州市30个点的空气微生物进行了监测研究报道。结果表明：兰州市空气微生物属于中度污染，主要优势菌种有蜡样芽胞杆菌，枯草芽胞杆菌，金黄色葡萄球菌和8叠球菌。白曲霉，青霉属，黄曲霉，木霉，交链孢霉，空气微生物含量与地面人类活动关系密切，与人流量（人口密度）和车流量显著相关；绿地对空气微生物年代有显著的杀灭作用。尤其是乔灌草相结合的复合型绿地杀菌作用很理想。     

溶藻细菌BS03分离、鉴定及其对塔玛亚历山大藻生长的影响

从福建漳江口红树林区筛选出一株对产贝毒赤潮原因藻——塔玛亚历山大藻(Alexandrium tamatense)具有强溶藻能力的细菌,命名为BS03,通过生理生化及16S rDNA序列分析对该菌株进行鉴定,并探讨了菌株BS03对塔玛亚历山大藻的溶藻特性和溶藻代谢产物的初步性质.结果发现,菌株BS03属于微泡菌属(Microbulbifer sp.)相似性达99％;对塔玛亚历山大藻的杀藻效果具有一定浓度效应,在一定浓度范围内处理浓度越高,溶藻效果越好;菌株BS03对处于不同生长时期的塔玛亚历山大藻都表现出较好的杀藻效果,其中对处于延滞期的塔玛亚历山大藻表现出最佳的杀藻效果,处理96 h后,抑藻率达98.17％;不同生长期菌株对塔玛亚历山大藻溶藻作用无明显差异;菌株BS03通过间接作用方式溶藻,所分泌的胞外活性物质的分子量小于1 kDa,耐酸碱、具热稳定性,推测为非蛋白质、非核酸和非多糖类物质.     

Analysis of bacterial community structures in two sewage treatment plants with different sludge properties and treatment performance by nested PCR-DGGE method

The bacterial community structures in two sewage treatment plants with different processes and performance were investigated by denaturing gradient gel electrophoresis （DGGE） of nested polymerase chain reaction （nested PCR） amplified 16S rRNA gene fragments with group-specific primers. Samples of raw sewage and treated effluents were amplified using the whole-cell PCR method, and the activated sludge samples were amplified using the extracted genomic DNA before the PCR products were loaded on the same DGGE gel for bacterial community analysis. Ammonia-oxidizing bacterial and actinomycetic community analysis were also carried out to investigate the relationship between specific population structures and system or sludge performance. The two plants demonstrated a similarity in bacterial community structures of raw sewage and activated sludge, but they had different effluent populations. Many dominant bacterial populations of raw sewage did not appear in the activated sludge samples, suggesting that the dominant bacterial populations in raw sewage might not play an important role during wastewater treatment. Although the two plants had different sludge properties in terms of settleability and foam forming ability, they demonstrated similar actinomycetic community structures. For activated sludge with bad settling performance, the treated water presented a similar DGGE pattern with that of activated sludge, indicating the nonselective washout of bacteria from the system. The plant with better ammonium removal efficiency showed higher ammonia-oxidizing bacteria species richness. Analysis of sequencing results showed that the major populations in raw sewage were uncultured bacterium, while in activated sludge the predominant populations were beta proteobacteria.     

油田硫酸盐还原菌快速定量检测方法

现有油田废水中硫酸盐还原菌检测周期长、检测费用较高,本研究应用聚合酶链式反应(PCR)技术与倍比稀释法(MPN)相结合的DSR-MPN-PCR法,对硫酸盐还原菌进行快速定量检测.从废水中制备了直接用于PCR扩增的菌液,保证了定量准确性;建立以硫酸盐还原菌亚硫酸盐还原酶基因(Dsr)为靶位点的通用探针DSR1F和DSR5R的反应体系和扩增条件.结果表明,该方法检测灵敏度明显比液体稀释培养法高2个数量级,真实地表征了废水中实际的SRB菌数量,整个操作过程需要3～4　h,检测结果非常稳定,降低了检测费用,可以在生产中应用.     

有机污染物的微生物处理研究进展

微生物处理是一种费用低，效果好，无二次污染且操作简单的处理方法。本文就国内外污泥中有机污染物的微生物处理进行了论述，总结了微生物处理有机污染的研究进展及其主要研究方向。