The properties of hydrocarbon-oxidizing bacteria isolated from the oilfields of Tatarstan, Western Siberia, and Vietnam

Eleven strains of hydrocarbon-oxidizing bacteria, isolated from oilfields, representing the genera Rhodococcus, Gordonia, Dietzia, and Pseudomonas, were characterized as mesophiles and neutrophiles. Rhodococci were halotolerant microorganisms growing in a media containing up to 15% NaCl. All the strains oxidized n-alkanes of crude oil. An influence of the cultivation temperatures (28 or 45 degrees C) and organic supplements on the degradation of C12-C30 n-alkanes in oxidized oil by two bacterial strains of the genus Pseudomonas was shown. The introduction of acetate, propionate, butyrate, ethanol, and sucrose led mainly to the decreased oxidation of petroleum paraffins. At certain cultivation temperatures, the addition of volatile fatty acid salts increased the content of individual n-alkanes in oxidized vs. crude oil.     

Physiological and phylogenetic diversity of thermophilic spore-forming hydrocarbon-oxidizing bacteria from oil fields

The distribution and population density of aerobic hydrocarbon-oxidizing bacteria in the high-temperature oil fields of Western Siberia, Kazakhstan, and China were studied. Seven strains of aerobic thermophilic spore-forming bacteria were isolated from the oil fields and studied by microbiological and molecular biological methods. Based on the 16S rRNA gene sequences, phenotypic characteristics, and the results of DNA-DNA hybridization, the taxonomic affiliation of the isolates was tentatively established. The strains were assigned to the first and fifth subgroups of the genusBacillus on the phylogenetic branch of the gram-positive bacteria. Strains B and 421 were classified asB. licheniformis. Strains X and U, located betweenB. stearothermophilus andB. thermocatenulatus on the phylogenetic tree, and strains K, Sam, and 34, related but not identical toB. thermodenitrificans andB. thermoleovorans, undoubtedly represent two new species. Phylogenetically and metabolically related representatives of thermophilic bacilli were found to occur in geographically distant oil fields     

Biodegradation of alkylpyridines by bacteria isolated from a polluted subsurface

Ten bacterial strains were isolated fromalkylpyridine polluted sediments 7.6 m below thesurface. These strains were able to degrade 11different alkylpyridine isomers. Degradation ratesdepended on number and position of the alkyl group. Isomers with an alkyl group at position 3 were moreresistant to microbial attack. Of the 10 strains, 6isolates were selected for detailed study. Theseisolates mineralized the isomers to CO₂,NH₄ ⁺, and biomass. All strains weregram-negative rods with a strict aerobic metabolism. Characterization of physiological and biochemicalproperties revealed similarity between strains. Eeachstrain however, had a limited substrate range whichenabled it to degrade no more than 2 to 3 compounds ofthe 14 alkylpyridine isomers tested. Examination ofthe genetic variability among cultures with therandomly amplified polymorphic DNA technique revealedhigh levels of genomic DNA polymorphism. The highestsimilarity between 2 strains (0.653) was observedbetween 2-picoline and 3-picoline degrading cultures. The molecular basis of the differences in substratespecificity is under investigation.     

印度洋表层海水石油降解菌的多样性分析

【目的】为了研究印度洋石油降解菌多样性,并获得新的石油降解菌。【方法】本研究通过印度洋表层海水样品采集、以柴油与原油1:1混合物作为碳源,从中富集、分离筛选石油降解菌,并通过PCR-DGGE对13个站点富集菌群的菌群结构进行分析。【结果】通过形态观察、生理生化反应和16SrRNA分析,共得到共29个属的51株不同的细菌,它们主要是属于α亚群和γ亚群。其中,Alcanivorax属(占18%),Novosphingobium属(占10%)和Marinobacter(占6%)Thalassospira(占6%)为主要的优势菌。通过生态多样性分析表明,Shannon-Winner指数(H)为4.57968,说明其具有较高的多样性;均匀度指数(E)为0.8664771,表示其分布比较均匀。单菌实验表明,49株具有石油降解能力其中,Sinomonas,Knoellia,Mesoflavibacter等属的细菌为首次发现有降解能力。DGGE分析表明Alcanivorax属的细菌是印度洋表层海水中的重要石油降解菌。【结论】本研究首次揭示了印度洋表层海水中石油降解菌的多样性,并获取了若干在海洋石油污染生物修复中具有应用前景的降解菌。     

Screening of bacteria, isolated from PAH-contaminated soils, for production of biosurfactants and bioemulsifiers

Fifty-seven bacterial strains were isolated from PAH-contaminated soils using PAH-amended minimal medium. The isolates were screened for their production of biosurfactants and bioemulsifiers when grown in liquid media containing selected PAHs. The results suggest that many, but not all, of the isolates are able to produce biosurfactants or bioemulsifiers under the experimental conditions. The majority of the strains isolated on phenanthrene, pyrene, and fluoranthene were better emulsifiers than surface tension reducers and the stability of the formed emulsions was in general high. The strains isolated on anthracene were in general better in lowering the surface tension than in forming emulsions. In all strains, reduction of surface tension and emulsion formation did not correlate. However, in the majority of strains the two factors were associated with the bacterial cell surfaces, rather than the culture supernatants. Nevertheless, supernatants from selected surfactant-producing anthracene isolates increased the aqueous solubility of anthracene. Although a significant potential for surfactant and emulsifier production in the microbiota of the PAH-contaminated soils was found in this study, the ability of individual strains to mineralize PAHs did not coincide with production of surface-active compounds.     

石油污染环境中固氮和寡氮营养细菌的分离鉴定及其特性

[背景]石油污染治理中的生物修复因无二次污染、处理成本低等优点受到人们的广泛关注,但由于石油烃向环境中大量输入,导致环境中氮源的相对不足成为制约生物修复效率的关键因素之一,因此筛选能够适应寡氮环境的微生物具有重要的生态意义.[目的]从辽河油田油藏水中筛选在不添加氮源培养基中生长的微生物,为石油污染环境生物修复提供候选菌...     

Effects of amendments on biodegradation of crude petroleum by sediment bacteria from Bonny River Estuary

The biodegradation of Bonny light crude petroleum by bacteria in batch culture was enhanced by the addition to culture media, of 0.2 mg of urea and soya bean lecithin per 100 ml of crude oil, sediment and water mixture. Biodegradation was found to be purely an aerobic process. There was a direct relationship between hydrocarbon content and proportion (%) of total heterotrophic count that was capable of growing on crude petroleum as sole carbon and energy source.     

血培养中病原菌的分布及其耐药状况分析

目的:了解血培养中病原菌的菌群分布及其耐药状况.方法:血培养标本用Bact/Alert-120自动血液分析系统和Vitek60鉴定仪进行血培养及鉴定,药敏用K-B法,用Whonet 5软件进行分析.结果:在3 680份血培养标本中分离出细菌348株,阳性检出率为9.4%,病原菌中以革兰阴性杆菌为主共分离出189株,占54.3%,其中主要为大肠埃希菌占15.5%,肺炎克雷伯菌占12.4%;革兰阳性菌138株,占39.7%,主要为凝固酶阴性葡萄球菌占14.9%,金黄色葡萄球菌占12.1%;链球菌占6.6%.血培养中的革兰阴性杆菌对亚胺培南、阿米卡星、头孢哌酮/舒巴坦治疗较为敏感:革兰阳性球菌对万古霉素和替考拉宁较为敏感.结论:肠杆菌科细菌和葡萄球菌是血培养中的主要病原菌,而产ESBLs菌株、MRSA、MRCNS耐药严重,提示应高度重视合理使用抗生素,减少细菌耐药性产生,以提高临床治疗效果.     

Temperature-dependent differences in community structure of bacteria involved in degradation of petroleum hydrocarbons under sulfate-reducing conditions

Aim: The aim of this study was to characterize the microbial community involved in anaerobic degradation of petroleum hydrocarbon under low‐ and moderate‐temperature conditions. Methods and Results: Sulfate‐reducing enrichment cultures growing on crude oil and p‐xylene were established at low and moderate temperatures. Bacterial community structures of the cultures were characterized by 16S rRNA gene‐based analysis and organisms responsible for degradation of p‐xylene were investigated by analysis of the bamA gene, involved in anaerobic degradation of aromatic compounds. The PCR‐denaturing gradient gel electrophoresis analysis indicated significant differences in microbial community structures among the cultures, depending on the temperatures of incubation. Difference depending on the temperatures was also observed in the cloning analysis of the bamA gene performed on the p‐xylene‐degrading enrichment cultures. Majority of clones detected in the culture of moderate temperature were related to Desulfosarcina ovata, whereas more diverse bamA gene sequences were obtained from the culture incubated at low temperature. Conclusions: Temperature‐dependent differences in microbial community were demonstrated by the analyses of two genes. It was suggested that sulfate‐reducing bacteria of phylogenetically different groups might be involved in the degradation of petroleum hydrocarbons in different temperature environments. Significance and Impact of the Study: This study is the first report of p‐xylene‐degrading sulfate‐reducing enrichment culture at low temperature. The results of the experiments at low temperature were distinctly different from those reported in previous studies performed at moderate temperatures.     

The influence of saliva on the hydrophobic surface properties of bacteria isolated from oral sites of macaque monkeys

Abstract The surface hydrophobicity of 64 bacterial strains isolated from discrete, intra-oral sites of monkeys ( Macaca fascicularis ) was determined by measuring their affinity for hexadecane. Bacteria were also exposed to monkey saliva which either increased or reduced the surface hydrophobicity of the cells. After exposure to saliva those bacteria isolated solely from the mucosal surfaces were significantly more hydrophobic than bacteria ( Streptococcus mutans and Actinomyces spp.) whose major habitat was the dentition. Streptococcus sanguis strains isolated from all intra-oral sites and among the early plaque formers were as hydrophobic as the organisms isolated only from the mucosal surfaces.     

南海南沙海域沉积物中可培养微生物及其多样性分析

【目的】为了从南沙海域中分离获得微生物菌种资源,【方法】本文通过沉积物采样、可培养菌分离及16S rRNA鉴定,【结果】从22个站点的沉积物样品中获得349株细菌,分属于87个种。发现产芽孢细菌分布最广,并在10个站点的分离株中占多数;它们是Bacillus,Halobacillus,Brevibacillus,Paenibacillus,Pontibacillus和Thalassobacillus。其中芽孢杆菌（Bacillus）无论在数量上还是种类上都最多,分别属于34种,其中有8个可能的新种。此外,g-Proteobacteria是分离率较高的另一亚群;其中,假单胞菌（Pseudomonas）,海杆菌（Marinobacter）,食烷菌（Alcanivorax）属的细菌最多。统计还发现,在深度750~2000 m之间,低GC含量的细菌最丰富,而深度2000 m以下,分离株则全部为g-Proteobacteria。【结论】南沙沉积物可培养微生物中产芽孢细菌及 g-Proteobacteria比较丰富;其中,产芽孢细菌的多样性最高,具有进一步研究开发价值。     

Production of Metallogenium-like particles by heterotrophic manganese-oxidizing bacteria collected from a lake

As a model of chemically stratified structure of environment typical to the chemocline of lakes, a semisolid gradient medium was prepared to cultivate heterotrophic manganese-oxidizing bacteria originally collected from a lake. The bacteria growing under the conditions described produced extracellularly Metallogenium-like particles similar to those which are often detected in the chemocline of lakes. This suggested that the naturally occurring Metallogenium-like particles originated in activities of such heterotrophic manganese-oxidizing bacteria. The manganese oxidation activity usually appeared only at the stationary phase of bacterial growth. The oxidation of Mn²⁺ and the formation of Metallogenium-like particles by the bacteria were observed at neutral or slightly acidic pH. not under alkaline conditions, which is a conspicuous difference from the inorganic oxidation of Mn²⁺ by O₂. Bacterial manganese oxidation was stimulated by bicarbonate (50 or 500 M). An experiment of addition of H₂O₂ to the incubation tubes isolated from atmosphere failed to confirm the availability of externally added H₂O₂ as the electron acceptor, suggesting that the bacterial manganese oxidation required the presence of O₂.     

The Role of Low-Molecular-Weight Nitrogen Compounds in the Osmotolerance of Rhodococcus erythropolis and Arthrobacter globiformis

Investigations showed that Rhodococcus erythropolis E-15 and Arthrobacter globiformis 2F cells respond to osmotic shock by increasing the synthesis of free amino acids, primarily glutamic acid (80% of the intracellular free amino acid pool). The osmoprotective role of glutamic acid follows from its beneficial effect on the growth of bacteria in high-salinity media. It was found that the addition of this amino acid to the growth medium at a concentration of 2 mM shortened the lag phase and increased the growth rate and biomass yield of either of the two bacteria. The addition of another osmoprotectant, trehalose, to the high-salinity growth medium of R. erythropolis E-15 at the same concentration (2 mM), restored the growth parameters of this bacterium to the control values.     

Preliminary observations on psychrotrophic and psychrophilic,heterotrophic bacteria from antarctic water samples

Bacteria isolated from antarctic sea and lake water samples were examined for growth at 5 °C and 25 °C. Of 250 isolates, 249 were psychrotrophic and one was psychrophilic. The effect of temperature on the growth rate of the latter (strain 755) and a typical psychrotroph (strain 203A) was described by the square root of the growth rate constant. T_MIN values calculated from this model confirmed the strains as psychrophile and psychrotroph.Identification of 93 isolates showed the majority to be Pseudomonas (82%), with Flavobacterium and Moraxella representing 13% of the isolates. The remainder were coryneforms and yeasts. Isolate 611 was studied in detail because of its unusual morphology. This strain has features in common with the genera Spirosoma, Runella and Flectobacillus, but cannot be assigned with certainty. It may represent a new taxon of curved, gram negative bacteria.     

Influence of Bulking Agents,Fertilizers and Bacteria on the Removal of Diesel from a Newfoundland Soil

Laboratory experiments in culture flasks, containing diesel-contaminated Newfoundland soil samples, were undertaken to compare the influence of fertilizers, microorganisms and bulking agents on bioremediation. In Phase I experiments only one fertilizer (cow manure or poultry manure), one bulking agent (sand or hay), or one inoculum (cold-tolerant indigenous bacteria or exogenous commercial bacteria) was added to a soil sample. In Phase II experiments, Design-Expert® Version 6 design of experiment software determined the combinations of fertilizers, bulking agents and inocula to be mixed with the soil samples to study the interactions among the amendments. The maximum diesel removal at 90 days occurred in the sample with sand (Phase I) and in the sample with cow manure, an inoculum of cold-tolerant indigenous bacteria, and sand (Phase II). Diesel removal at 45 days for the same two samples was 85.4% (Phase I) and 91.9% (Phase II), suggesting the cow manure and/or cold-tolerant bacteria inoclum accelerated the process. The poultry manure, commercial bacteria and hay were less effective than their counterparts. The commercial bacteria were more sensitive to diesel concentration than the indigenous cold-tolerant bacteria. The addition of sand, cow manure, and poultry manure improved diesel removal.     

Obligately and facultatively autotrophic,sulfur- and hydrogen-oxidizing thermophilic bacteria isolated from hot composts

A variety of autotrophic, sulfur- and hydrogen-oxidizing thermophilic bacteria were isolated from thermogenic composts at temperatures of 60–80° C. All were penicillin G sensitive, which proves that they belong to the Bacteria domain. The obligately autotrophic, non-spore-forming strains were gram-negative rods growing at 60–80°C, with an optimum at 70–75°C, but only under microaerophilic conditions (5 kPa oxygen). These strains had similar DNA G+C content (34.7–37.6 mol%) and showed a high DNA:DNA homology (70–87%) with Hydrogenobacter strains isolated from geothermal areas. The facultatively autotrophic strains isolated from hot composts were gram-variable rods that formed spherical and terminal endospores, except for one strain. The strains grew at 55–75° C, with an optimum at 65–70° C. These bacteria were able to grow heterotrophically, or autotrophically with hydrogen; however, they oxidized thiosulfate under mixotrophic growth conditions (e.g. pyruvate or hydrogen plus thiosulfate). These strains had similar DNA G+C content (60–64 mol%) to and high DNA:DNA homology (> 75%) with the reference strain of Bacillus schlegelii. This is the first report of thermogenic composts as habitats of thermophilic sulfur- and hydrogen-oxidizing bacteria, which to date have been known only from geothermal manifestations. This contrasts with the generally held belief that thermogenic composts at temperatures above 60° C support only a very low diversity of obligatory heterotrophic thermophiles related to Bacillus stearothermophilus. Received: 20 July 1995 / Accepted: 25 September 1995     

Dominant lactic acid bacteria and their technological properties isolated from the Himalayan ethnic fermented milk products

Ethnic people of the Himalayan regions of India, Nepal, Bhutan and China consume a variety of indigenous fermented milk products made from cows milk as well as yaks milk. These lesser-known ethnic fermented foods are dahi, mohi, chhurpi, somar, philu and shyow. The population of lactic acid bacteria (LAB) ranged from 10(7) to 10(8) cfu/g in these Himalayan milk products. A total of 128 isolates of LAB were isolated from 58 samples of ethnic fermented milk products collected from different places of India, Nepal and Bhutan. Based on phenotypic characterization including API sugar test, the dominant lactic acid bacteria were identified as Lactobacillus bifermentans, Lactobacillus paracasei subsp. pseudoplantarum, Lactobacillus kefir, Lactobacillus hilgardii, Lactobacillus alimentarius, Lactobacillus paracasei subsp. paracasei, Lactobacillus plantarum, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris and Enterococcus faecium. LAB produced a wide spectrum of enzymes and showed high galactosidase, leucine-arylamidase and phosphatase activities. They showed antagonistic properties against selected Gram-negative bacteria. None of the strains produced bacteriocin and biogenic amines under the test conditions used. Most strains of LAB coagulated skim milk with a moderate drop in pH. Some strains of LAB showed a high degree of hydrophobicity, suggesting these strains may have useful adhesive potential. This paper is the first report on functional lactic acid bacterial composition in some lesser-known ethnic fermented milk products of the Himalayas.     

小菌虫肠道可培养细菌的分离鉴定及产消化酶活性分析

目的 分离小菌虫肠道可培养细菌,并研究其产消化酶活性,探讨肠道细菌对小菌虫消化食物的影响。方法 采用传统细菌分离培养方法分离小菌虫肠道细菌,利用16S rDNA序列进行细菌分子鉴定;利用筛选培养基鉴别各细菌的产蛋白酶、脂肪酶、淀粉酶和纤维素酶活性。结果 在小菌虫肠道中分离到4种可培养细菌,分别是枯草芽胞杆菌（Bacillus subtilis）、肺炎克雷伯菌（Klebsiella pneumoniae）、Pseudocitrobacter faecalis和芽胞杆菌（Bacillus sp.）。其中,2种芽胞杆菌属细菌有产消化酶活性。枯草芽胞杆菌有产纤维素酶、淀粉酶和蛋白酶活性;芽胞杆菌仅有产蛋白酶活性,但产酶能力低于枯草芽胞杆菌。结论 小菌虫肠道细菌中可培养细菌结构简单,但其中的芽胞杆菌属细菌有产纤维素酶、淀粉酶和蛋白酶能力,说明小菌虫肠道中的2种芽胞杆菌属细菌可能有协助小菌虫进行食物消化的功能。     

Screening and characterization of lipase producing bacteria isolated from the gut of a lepidopteran larvae,Samia ricini

Lipolytic enzymes are an important group of hydrolases that have found immense industrial application in biotechnology. In this study, the ability of gut bacteria isolated from the gut of the Eri silkworm, Samia ricini, to produce lipolytic enzymes was evaluated through qualitative and quantitative assays. The results of lipase screening showed that 28 isolates had lipolytic activity. The results of 16S ribosomal RNA sequencing indicated that the genus Bacillus comprised majority of the lipolytic bacterial isolates (71%) followed by Pseudomonas (15%); whilst Acinetobacter, Enterobacter and Enterococcus comprised 11%. Lipolytic activity was found in bacteria isolates identified from all the three gut compartments of S. ricini larvae with significant activity from isolates extracted from the foregut and midgut. The lipolytic index among the bacterial isolates ranged between 0.63 and 2.81 on Rhodamine B medium, and all isolates exhibited significant lipolytic activity with p-nitrophenyl butyrate (PNPB) with specific activity ranging from 0.52 to 0.82 μmol/min/mg. The effect of pH and temperature showed that lipase activity was optimum at 37 °C and pH 7–9. A phylogenetic relationship of lipase producing gut bacteria indicated high cluster stability for isolates from different stages (>50%) suggesting that the isolates persist across developmental stages of the host. The Eri silkworm is reared for its silk and the knowledge of its gut bacteria with the ability to produce lipases lies in the significance as far as boosting production of this insect via development of probiotics to enhance commercial Eri rearing. In addition, this insect may be a good resource for profiling novel lipolytic microbes for commercial production of lipases as lipases from microbial origin have assumed a great deal of importance as industrial enzymes due to their potential for use in biotechnology.