一株苯乙烯高效降解菌的分离鉴定及降解特性研究

从某橡胶厂的活性污泥中筛选得到一株可高效降解苯乙烯的微生物菌株WJ,通过透射电镜(TEM)、生理生化试验、Biolog鉴定和16S rRNA基因的系统发育树建立等分析方法,鉴定该菌株为恶臭假单胞菌(Pseudomonas putida).通过环境单因素试验,确定该菌株WJ在温度30℃、pH值7.0的培养条件下具有良好的降解效果.通过不同初始浓度苯乙烯的降解及生长特性,确定该菌株的最大底物耐受浓度达到1500mg/L,且其生长动力学过程符合Haldane’s方程,相应动力学参数为: vmax=0.282h-1,Ks=23.57mg/L,Ki=1784.56mg/L.底物宽泛性试验表明,该菌株对苯系物(BTEX)、正己烯等与苯乙烯结构类似的碳氢化合物都具有良好的降解能力,表明其具备良好的底物宽泛性.该菌株对苯乙烯的氧化降解途径主要为乙烯基侧链的氧化.     

Toxic effect of sodium perfluorononyloxy-benzenesulfonate on Pseudomonas stutzeri in aerobic denitrification,cell structure and gene expression

• OBS inhibited the growth of P. stutzeri and destroyed its structure. • OBS was toxic to the aerobic denitrification process of P. stutzeri. • OBS induced the production of ROS in P. stutzeri. • OBS affected the expression of key genes involved in denitrification and SOD. The toxicities of sodium perfluorononyloxy-benzenesulfonate (OBS) to animals and plants are similar to those of perfluorooctane sulfonate. However, the mechanism of its toxicity to aerobic denitrifying bacteria is still unclear. In the present study, the ecotoxicity of OBS on an aerobic denitrifying strain, Pseudomonas stutzeri, was evaluated. The results showed that a dosage of OBS clearly affected the growth and aerobic denitrification of P. stutzeri. When compared with an unamended control, the degradation efficiency of the total nitrogen decreased by 30.13% during exposure to 200 mg/L of OBS, and the complete degradation time of nitrate-nitrogen was delayed by 4 h. The lactate dehydrogenase and superoxide dismutase produced by the bacteria increased with the concentration of OBS, and reactive oxygen species were also detected by confocal laser scanning microscope imaging. Transmission electron microscope imaging revealed chromosome deformation of the cells and damage to cell content; moreover, outer membrane vesicles were secreted from the bacteria, which was the important detoxification mechanism of P. stutzeri to OBS. Expression of the genes involved in aerobic nitrification and oxidative stress were also changed under OBS stress, which further confirmed the toxicity of OBS to P. stutzeri. This study reveals the environmental exposure risk of OBS from the perspective of microorganisms.     

Effects of microbial inoculations and surfactant levels on biologically- and chemically-assisted phytoremediation of lead-contaminated soil by maize (Zea Mays L.)

Assisted phytoremediation has been widely used for decontamination of potentially toxic elements contaminated soils. A greenhouse experiment was conducted to evaluate the effectiveness of different microbial inoculations and surfactant levels on the phytoremediation of a Pb-polluted calcareous soil by maize. The results showed that application of surfactant increased both root and shoot dry matter yields. Microbial inoculations, however, had no significant effect on the root or shoot dry matter yield. Mean Pb uptake in maize root or shoot increased only following the application of some surfactant levels. Inoculation with microorganisms significantly increased both mean Pb concentration and uptake in maize root but not in maize shoot. Application of 4?mmol surfactant kg?1 along with inoculation with Priformospora indica was effective in increasing Pb phytostabilisation potential. While the application of 2?mmol surfactant kg^?1 along with inoculation with Pseudomonas fluorescens was effective in increasing Pb phytoextraction potential. The fact that the values of translocation efficiencies were low in all treatments, demonstrated the low capability of maize for translocation of Pb from root to shoot. Inoculation with P. fluorescens was the most effective treatment in increasing metal micronutrient uptake. Microbial inoculation and surfactant levels enhanced Pb phytoremediation mostly through phytostabilisation of this metal by maize.     

两株假单胞菌降解酚类化合物的特性

从焦化废水中分离得到2株可降解对氯酚的假单胞菌(Pseudomonas)CO-1和CO-44.其最适降解温度为35~40℃,最适pH值为6.0~8.0.菌株降解对氯酚的速度与对氯酚初始浓度呈负相关.2株细菌均能较快地降解苯酚和甲酚,其中CO-1还能够降解1-萘酚和萘.在添加对氯酚的焦化废水中,CO-1和CO-44能够在42h内将苯酚、甲酚和对氯酚完全降解.从2株细菌中均检测到了苯酚羟化酶基因,分别从菌株CO-1和CO-44中检测到邻苯二酚1,2-双加氧酶基因和邻苯二酚2,3-双加氧酶基因.     

Experimental study on Cr(Ⅵ) reduction by Pseudomonas aeruginosa

Investigation on Cr(Ⅵ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) can be effectively reduced to Cr(Ⅲ) by Pseudomonas aeruginosa. The effects of the factors affecting Cr(Ⅵ) reduction rate including carbon source type, pH, initial Cr(Ⅵ) concentration and amount of cells inoculum were thoroughly studied. Malate was found to yield maximum biotransformation, followed by succinate and glucose, with the reduction rate of 60.86%, 43.76% and 28.86% respectively. The optimum pH for Cr(Ⅵ) reduction was 7.0, with reduction efficiency of 61.71% being achieved. With the increase of initial Cr(Ⅵ) concentration, the rate of Cr(Ⅵ) reduction decreased. The reduction was inhibited strongly when the initial Cr(Ⅵ) concentration increased to 157 mg/L. As the amount of cells inoculum increased, the rate of Cr(Ⅵ) reduction also increased. The mechanism of Cr(Ⅵ) reduction and final products were also analysed. The results suggested that the soluble enzymes appear to be responsible for Cr(Ⅵ) reduction by Pseudomonas aeruginosa, and the reduced Cr(Ⅲ) was not precipitated in the form of Cr(OH)3.     

废纸造纸循环废水高效好氧菌的筛选和研究

利用平板分离方法,从废纸造纸封闭循环废水处理的生物接触氧化池中筛选出优势的高效菌株,采用形态学观察和生理生化试验发现主要由动胶菌属(Zoogloea sp.)和假单胞菌属(Pseudomona sp.)组成。用吸光光度法,确定其最佳生长时间。通过平行对比实验,在不同时间取样测定COD值,比较得出高效菌对废纸造纸循环废水的处理能力远高于普通菌。     

Biodegradation of anthracene and phenanthrene by bacteria isolated from oil-contaminated soil of Bangladesh

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants entering into the environment through natural and anthropogenic activities. Owing to their toxicity to various life forms including humans, detoxification of PAHs is crucial to reduce their effects on cells. In this study, we have isolated two bacteria capable of degrading two common PAHs, anthracene and phenanthrene, from contaminated soil samples by using selective enrichment culture supplemented with test PAHs as the sole source of carbon and energy. The isolated bacteria were identified and affiliated as Pseudomonas aeruginosa strain KD and Stenotrophomonas maltophilia strain RC based on their 16s rRNA gene sequences. The degradation of anthracene and phenanthrene was estimated indirectly by measuring the decolourisation extent of a redox indicator, 2, 6-dichlorophenolindophenol, incorporated into PAH-supplemented mineral salt media. In the case of anthracene, ≥90% decolourisation was recorded at 20 and 48 days for P. aeruginosa and S. Maltophilia, respectively. On the other hand, ≥94% decolourisation was recorded at 56 and 52 days for P. aeruginosa and S. maltophilia, respectively during the utilisation of phenanthrene.     

不适宜生长条件对混茵降解苯胺的影响

分别从台州和衢州某化工厂的好氧池中分离筛选得到2株苯胺降解菌TZl和JH1，经16SrDNA测序鉴定为Comamonassp．TZ1和Pseudomonassp．JH1，均具有较强的苯胺降解能力，培养24h后，可使初始浓度为800mg／L的苯胺去除率达到96．4％～98．4％。在此基础上，按体积比l：1将2株菌液进行混合构建了混合菌体系，进而对比考察了苯胺初始浓度、pH、盐度和重金属等环境因子对单一菌和混合菌生长量及降解苯胺效果的影响，重点探讨混合菌对不适宜生长环境的适应性及其对苯胺的降解特性。通过单一菌和混合菌对比实验发现，在适宜苯胺初始浓度、pH和盐度条件下，混合菌的生长量略高于单一菌；在不适宜生长的高浓度苯胺、pH和盐度条件下，混合菌也表现出了更强的适应性和苯胺矿化能力。Zn2＋和Cr6＋耐受实验则表明，对于Cr6＋混合菌表现出了更强的耐受能力，而对于zn2＋并没有表现出更强的耐受能力。     

Molecular identification and nanoremediation of microbial contaminants in algal systems using untreated wastewater

Wastewater-algal biomass is a promising option to biofuel production. However, microbial contaminants constitute a substantial barrier to algal biofuel yield. A series of algal strains, Nannochloris oculata and Chlorella vulgaris samples (n = 30), were purchased from the University of Texas, and were used for both stock flask cultures and flat-panel vertical bioreactors. A number of media were used for isolation and differentiation of potential contaminants according to laboratory standards (CLSI). Conventional PCR amplification was performed followed by 16S rDNA sequencing to identify isolates at the species level. Nanotherapeutics involving a nanomicellar combination of natural chitosan and zinc oxide (CZNPs) were tested against the microbial lytic groups through Minimum Inhibitory Concentration (MIC) tests and Transmission Electronic Microscopy (TEM). Results indicated the presence of Pseudomonas spp., Bacillus pumilus/ safensis, Cellulosimicrobium cellulans, Micrococcus luteus and Staphylococcus epidermidis strains at a substantial level in the wastewater-fed algal reactors. TEM confirmed the effectiveness of CZNPs on the lytic group while the average MICs (mg/mL) detected for the strains, Pseudomonas spp, Micrococcus luteus, and Bacillus pumilus were 0.417, 3.33, and 1.458, respectively. Conclusively, CZNP antimicrobials proved to be effective as inhibitory agents against currently identified lytic microbial group, did not impact algae cells, and shows promise for in situ interventions.     

Water quality supply in a Portuguese teaching hospital: monitoring and studies on detection of critical points

Surveillance of drinking water quality is extremely important to human health, assuming greater relevance in hospital environments, especially to those individuals who are immunocompromised. This study is aimed to determine the effect of increasing free chlorine (Cl) concentration in a hospital water network in regard to water quality monitoring and microbial growth control, between 2010 and 2013 in Porto. The average of free Cl concentration in the period under analysis showed some heterogeneity per floor, varying between 0.84 and 1.25 mg/L. In addition, there was a rise in proportion of samples that exceeded WHO guidelines (free Cl ≥ 0.5 mg/L), particularly in the last two years of the same period. With respect to microbial analysis, 22.4% of the samples were positive for Legionella spp., 6.4% for Pseudomonas aeruginosa, 15% and 30.4% for aerobic plate counts at 36 and 22 ºC, respectively. The proportion of positive samples decreased throughout the period under analysis, in particular for Legionella spp. (41.7% in 2010 vs. non-detectable in 2013) and P. aeruginosa (10.8% in 2010 vs. 3.3% in 2013). These results are in accordance with the gradual rise in free Cl concentration (0.78 ± 0.94 mg/L in 2010 vs. 1.16 ± 0.51 mg/L in 2013). In conclusion, a suitable plan for drinking water quality was instituted which resulted in reducing microbiological growth in the waterwork network, improving public health protection. However, the detection of critical points associated with lower levels of free Cl were found on certain floors/points-of-use, requiring the need to improve the monitoring water treatment system and/or implementation of additional technologies.