西安黑河流域水体细菌群落分布调查与研究

利用常规细菌培养方法进行分离鉴定,检测黑河流域水体和底泥中的细菌群落,并与水库建成前进行比较,以期对现阶段西安黑河水体微生物分布状况进行分析。结果表明:现阶段黑河水样中细菌群落总数为3 10~800cfu/mL,底泥中细菌群落总数为20×10 3~1100×10 3cfu/m L,主要以气单胞菌属(Aeromonas)、芽孢杆菌属(Bacillus)和微球菌属(Micrococcas)为细菌优势菌群,水库建成前水体中存在的大肠杆菌和占较大比重的条件致病菌无色细菌属和假单胞菌属等此次都没有检测出,表明经过近年来的综合治理,黑河水源得到了较好的保护;但是从微生物角度仍然存在着一定的环境风险。     

Biosynthesis of polyhydroxyalkanoate by Gamma proteobacterium WD-3 from volatile fatty acids

The production of copolymers of poly-β-hydroxyalkanoates (PHA) is generally a high cost process. To reduce the production costs, inexpensive carbon sources such as volatile fatty acids (VFAs) from acidified wastewater can be used. Therefore, isolation of bacterial strains that can produce PHA copolymers using VFAs as a sole carbon source would be a beneficial alternative. In this study, a strain of PHA accumulating bacterium was isolated from the wastewater treatment plant of a soybean processing facility in Harbin. The strain was identified as γ-proteobacterium according to its 16S rDNA information and was originally named as strain WD-3. The strain accumulated a mass of PHA up to 45% of its dry cell weight when it was cultured under the optimum fermentation condition in this study when butyrate was used as the carbon source. In addition, WD-3 could synthesize PHA copolymers of poly-hydroxybutyrate and poly-hydroxyvalerate (PHV) either from C-even substrates or from C-odd substrates, and one-third of the copolymer was PHV. Results from this study demonstrated that small molecule organic acids can be used by the strain of WD-3 as the carbon source for growth and PHA production. The maximum PHA yield in the study was 0.45 g g⁻¹ dry cell.     

Hydrocarbon-utilizing microorganisms naturally associated with sawdust

Sawdust, one of the materials used as sorbent for removing spilled oil from polluted environments was naturally colonized by hydrocarbon-utilizing fungi, 1 × 10⁵-2 × 10⁵ colony forming units (CFU) g⁻¹, depending on the hydrocarbon substrate. This sorbent was initially free of hydrocarbon-utilizing bacteria. Incubating wet sawdust at 30 °C resulted in gradually increasing the fungal counts to reach after 6 months between 5 × 10⁶ and 7 × 10⁶ CFU g⁻¹, and the appearance of hydrocarbon-utilizing bacteria in numbers between 8 × 10⁴ and 3 × 10⁵ cells g⁻¹. The fungi belonged to the genera Candida (32% of the total), Penicillium (21%), Aspergillus (15%), Rhizopus (12%), Cladosporium (9%), Mucor (7%) and Fusarium (4%). Based on their 16S rRNA gene sequences the bacteria were affiliated to Actinobacterium sp. (38%), Micrococcus luteus (30%), Rhodococcus erythropolis, (19%) and Rhodococcus opacus (13%). Individual pure fungal and bacterial isolates grew on a wide range of individual pure aliphatic (n-alkanes with chain lengths between C₉ and C₄₀) and aromatic (benzene, biphenyl, anthracene, naphthalene and phenanthrene) hydrocarbons as sole sources of carbon and energy. Quantitative determinations revealed that all fungal and bacterial isolates could consume considerable proportions of crude oil, phenanthrene (an aromatic hydrocarbon) and n-hexadecane (an aliphatic hydrocarbon) in batch cultures. It was concluded that when sawdust is used as a sorbent, the associated microorganisms probably contribute to the bioremediation of oil and hydrocarbon pollutants in the environment.     

Dissipation gradients of phenanthrene and pyrene in the Rice rhizosphere

An experiment was conducted to reveal the effects of rice cultivation as well as polycyclic aromatic carbohydrates (PAHs) degrading bacterium (Acinetobacter sp.) on the dissipation gradients of two PAHs (PHE and PYR) in the rhizosphere. The results showed that the presence of rice root and bacteria significantly accelerated the dissipation rate of PHE and PYR. The root exudates contributed to the formation of dissipation gradients of PHE and PYR along the vertical direction of roots, with a higher dissipation rate in the rhizosphere and near rhizosphere zone than the soil far away the rhizosphere.     

碳钢在淡水环境中的腐蚀行为

介绍了碳钢在淡水环境中的腐蚀行为及影响因素。淡水环境中碳钢主要存在电化学腐蚀和微生物腐蚀。在淡水环境中,碳钢的电化学腐蚀行为与淡水中的含氧量,淡水的流速以及淡水中的溶解成分等因素关系密切。此外,在含沙的淡水环境中,沙粒对碳钢的冲刷腐蚀也是一种重要的腐蚀行为。而在碳钢的微生物腐蚀中,目前的研究主要是围绕硫酸盐还原菌展开。     

Effect of cell physicochemical characteristics and motility on bacterial transport in groundwater

The influence of physicochemical characteristics and motility on bacterial transport in groundwater were examined in flow-through columns. Four strains of bacteria isolated from a crystalline rock groundwater system were investigated, with carboxylate-modified and amidine-modified latex microspheres and bromide as reference tracers. The bacterial isolates included a gram-positive rod (ML1), a gram-negative motile rod (ML2), a nonmotile mutant of ML2 (ML2m), and a gram-positive coccoid (ML3). Experiments were repeated at two flow velocities, in a glass column packed with glass beads, and in another packed with iron-oxyhydroxide coated glass beads. Bacteria breakthrough curves were interpreted using a transport equation that incorporates a sorption model from microscopic observation of bacterial deposition in flow-cell experiments. The model predicts that bacterial desorption rate will decrease exponentially with the amount of time the cell is attached to the solid surface. Desorption kinetics appeared to influence transport at the lower flow rate, but were not discernable at the higher flow rate. Iron-oxyhydroxide coatings had a lower-than-expected effect on bacterial breakthrough and no effect on the microsphere recovery in the column experiments. Cell wall type and shape also had minor effects on breakthrough. Motility tended to increase the adsorption rate, and decrease the desorption rate. The transport model predicts that at field scale, desorption rate kinetics may be important to the prediction of bacteria transport rates.     

毛发载体生物膜法对印染、化工废水脱色处理的试验研究

利用经特定脱脂处理后的毛发作载体,固定脱色混合菌。依赖毛发自身营养,不需外加营养物质,对印染和化工有色废水作脱色处理。试验研究结果表明,在一定pH和温度下,废水脱色率可稳定在85％以上;在低温或大于32℃时,仍可保持较高的脱色率,并可同时去除废水中的硫化物、氰化物、酚类等有毒有害污染物,其去除率>80％。     

含机油废水微生物降解实验研究

从油污土壤中筛选分离出两株高效机油降解菌ZL1，ZL2，初步鉴定了黄杆菌属和微球菌属，通过生长条件正交实验测定了温度，底物浓度和pH对其降解能力的影响，在废水油浓度较高条件下进行了连续降解实验。结果表明：2d左右对于含油270mg/L的去除率分别达到67.9%和76．2％，其中ZL2菌对底物浓度和pH值有较广的适应范围。     

苏州某湖水体细菌污染状况及分析

概述了近年来苏州某湖水体中细菌污染状况，对部分水质理化因素与细菌数量之间的相关性作了分析。研究了该湖水体中细菌的分布，变化情况，并讨论了利用微生物数量作为指标对湖泊的污染状况和富营养水平的评价。