Two unidentified aerobic bacterial strains that transform 2,4,6-trinitrotoluene

Several strains of aerobic bacteria tolerant to some chemical toxins were isolated from the water of man-made Yerevan Lake and from the soil and air of different regions of the city of Yerevan. Some of these bacteria were capable of degrading 2,4,6-trinitrotoluene (TNT) during shake-flask fermentation in liquid medium. Two bacterial strains with good ability to degrade TNT were isolated. These strains showed visible morphological and physiological differences during growth on numerous elective media. The comparative ability of these strains to transform TNT was investigated.     

Digestion of dead bacteria by germ-free rats

In fecal smears from germ-free rats on ordinary diets, varying amounts of bacteria can be demonstrated by morphological methods. Due to the present knowledge of the fastidiousness of many intestinal microbes, the origin and status of viability of these bacteria are important. On a diet that was shown by microscopic examination not to contain any microorganisms, the feces of germ-free rats became free of bacteria within 1 week. When animals on such a diet were fed killed bacteria, all Gram-negative strains and certain strains of clostridia were digested, whereas nearly all Gram-positive strains were not. Such differences in digestibility could have both immunological and nutritional implications.     

Quantitative Assessment of Bacterial Adhesion to Eukaryotic Cells of Human Origin

An in vitro system to measure the adhesion of bacteria to human, eukaryotic cells was devised. Adhesion indices for test strains of bacteria could be calculated. Significant differences were then observed between various strains of Escherichia coli from a variety of sources, in their ability to adhere. The possible applications of the test, especially for the routine screening of bacteria for adhesion and for inhibitors of attachment, were considered.     

Surface Properties of Bacteria from Different Wastewater Treatment Plants

The surface properties of the individual members of degradative biocommunities isolated from different laboratory and natural populations were characterized. The bacterial strains isolated from a given origin and degrading a given substrate varied with respect to their hydrophobic and electrostatic properties (e.g. contact angle, adsorption to hexadecane, isoelectric point, adsorption of anionic orcationic dyes). However, despite their specific surface characteristics, in most cases the net charge properties of different bacterial strains (characterized by the zeta potential profiles of the bacteria in relation to the pH) were found to be related to the substrate the bacteria were able to degrade as well as to the consortium the bacteria were isolated from. For one group of specialized bacteria, only oneor at most two characteristic zeta potential profiles were measured. Compared to the differences between different strains, the zeta potential profiles of individual strains were only slightly affected by either growth state or changes in the actual nutrient composition. Even if isolated strains were cultivated in standard nutrient broth for several months, only slight differences in the zeta potential profiles were measured. Only the isoelectric focusing experiments indicated thatcultivation in a complex medium favoured a progressively decreased uniformity of surface charge properties. Thus, measurement of zeta potential profiles under standardized conditions may be a useful means to compare the surface structures of bacteria from different origins.     

Chemical Characterization of Wines Fermented with Various Malo-lactic Bacteria

Six malo-lactic strains of lactic acid bacteria were isolated from California wines and identified as Lactobacillus delbrueckii, L. buchneri, L. brevis, Leuconostoc citrovorum, and two strains of Pediococcus cerevisiae. Malo-lactic fermentation was induced in separate lots of wine by inoculation of each lot with one of the strains of bacteria. Malo-lactic fermentation had occurred in each inoculated wine within 2 months. The resultant wines were subjected to chemical analysis, including gas chromatographic examination of concentrated extracts of the wines. Only a few differences in composition were found when the malo-lactic wines were compared one with another. The differences that were found were in volatile acidity and in concentrations of acetoin (plus diacetyl) and probably diethyl succinate.     

Survival differences among freeze-dried genetically engineered and wild-type bacteria.

Because the death mechanisms of freeze-dried and air-dried bacteria are thought to be similar, freeze-drying was used to investigate the survival differences between potentially airborne genetically engineered microorganisms and their wild types. To this end, engineered strains of Escherichia coli and Pseudomonas syringae were freeze-dried and exposed to air, visible light, or both. The death rates of all engineered strains were significantly higher than those of their parental strains. Light and air exposure were found to increase the death rates of all strains. Application of death rate models to freeze-dried engineered bacteria to be released into the environment is discussed.     

Isolation and characterization of two hydrocarbon-degrading Bacillus subtilis strains from oil contaminated soil of Kuwait

Two strains of hydrocarbon-utilizing bacteria were isolated from soil samples of the Kuwait Burqan oil field at a temperature of 37 degrees C. The bacteria were motile endospore-forming rods with slight differences in their metabolic patterns and 16S rRNA sequence. Vegetative cells of the strains designated as AHI and AHII had an ultrastructure typical of gram-positive bacteria and showed gram-positive staining. The bacteria did not show pigmentation. Best growth was observed at 37 degrees C at neutral pH and NaCl concentrations in the range of 5-10 g per l. Both strains were obligatory aerobic and developed on synthetic media with either Diesel fuel, n-decan or naphthalene as the sole carbon and energy source. No specific growth factors were required. On the basis of their morphological, physiological and biochemical features, as well as their 16S rRNA analysis and electron microscope study, both strains were assigned to the species of Bacillus subtilis.     

Morphological and cell association characteristics of Rochalimaea quintana: comparison of the Vole and Fuller strains.

The vole and Fuller strains of Rochalimaea quintana were grown on monolayers of mouse L cells irradiated 7 days previously and examined by light microscopy and scanning and transmission electron microscopy. Most of the bacteria of both strains were shown to adhere to the L cells but remained in an extracellular location. Cell division was frequently seen among the extracellular bacteria. The few intracellular bacteria seemed to be within vacuoles and did not multiply. Attachment to the eucaryotic cell did not seem to involve pili or other bacterial surface structures. The dimensions of the bacteria were approximately 0.45 micron in width by 1.0 to 1.7 micron in length. The cell envelope consisted of the usual trilaminar cell wall and plasma membranes separated by a layer of low electron density, as found in other gram-negative bacteria. No significant differences between the vole and Fuller strains either in morphology or relationship to eucaryotic cells were encountered.     

Survival and Phospholipid Fatty Acid Profiles of Surface and Subsurface Bacteria in Natural Sediment Microcosms

Although starvation survival has been characterized for many bacteria, few subsurface bacteria have been tested, and few if any have been tested in natural subsurface porous media. We hypothesized that subsurface bacteria may be uniquely adapted for long-term survival in situ. We further hypothesized that subsurface conditions (sediment type and moisture content) would influence microbial survival. We compared starvation survival capabilities of surface and subsurface strains of Pseudomonas fluorescens and a novel Arthrobacter sp. in microcosms composed of natural sediments. Bacteria were incubated for up to 64 weeks under saturated and unsaturated conditions in sterilized microcosms containing either a silty sand paleosol (buried soil) or a sandy silt nonpaleosol sediment. Direct counts, plate counts, and cell sizes were measured. Membrane phospholipid fatty acid (PLFA) profiles were quantified to determine temporal patterns of PLFA stress signatures and differences in PLFAs among strains and treatments. The Arthrobacter strains survived better than the P. fluorescens strains; however, differences in survival between surface and subsurface strains of each genus were not significant. Bacteria survived better in the paleosol than in the nonpaleosol and survived better under saturated conditions than under unsaturated conditions. Cell volumes of all strains decreased; however, sediment type and moisture did not influence rates of miniaturization. Both P. fluorescens strains showed PLFA stress signatures typical for gram-negative bacteria: increased ratios of saturated to unsaturated fatty acids, increased ratios of trans- to cis-monoenoic fatty acids, and increased ratios of cyclopropyl to monoenoic precursor fatty acids. The Arthrobacter strains showed few changes in PLFAs. Environmental conditions strongly influenced PLFA profiles.     

Isolation,Identification and Substrate Assimilation Specificity of Some Aromatic Hydrocarbon Utilizing Bacteria

As a result of screening isoalkyl or isoalkenyl substituted aromatic hydrocarbon assimilating microorganisms, 19 strains of isopropylbenzene assimilating bacteria were isolated. Thirteen of these strains were found to grow on α-methylstyrene and all 4 strains tested were also found to grow on isobutylbenzene.

Among them, 2 strains (S107B1 and S182BI) were selected for further study and were identified as Ps. convexa and Ps. ovalis, respectively.

Furthermore, some examined aromatic hydrocarbon utilizing bacteria were classified into two groups by differences in substrate assimilation specificity.     

Phenotypic and molecular characterization of Lactococcus lactis from milk and plants

AIMS: The aim of this study was to obtain new Lactococcus lactis strains from nondairy materials for use as milk fermentation starters. The genetic and phenotypic traits of the obtained strains were characterized and compared with those of L. lactis strains derived from milk. It was confirmed that the plant-derived bacteria could be used as milk fermentation starters. METHODS AND RESULTS: About 2600 lactic acid bacteria were subjected to screening for L. lactis with species-specific PCR. Specific DNA amplification was observed in 106 isolates. Forty-one strains were selected, including 30 strains of milk-derived and 11 of plant-derived, and their phenotypic traits and genetic profiles were determined. The plant-derived strains showed tolerance for high salt concentration and high pH value, and fermented many more kinds of carbohydrates than the milk-derived strains. There were no remarkable differences in the profiles of enzymes, such as lipases, peptidases and phosphatases. Isolates were investigated by cluster analysis based on randomly amplified polymorphic DNA profiles. There were no significant differences between isolates from milk and those from plant. The L. lactis subsp. cremoris strains were clustered into two distinct groups, one composed of the strains having the typical cremoris phenotype and the other composed of strains having a phenotype similar to subsp. lactis. Fermented milk manufactured using the plant-derived strains were not inferior in flavour to that manufactured using the milk-derived strains. CONCLUSIONS: Plant-derived L. lactis strains are genetically close to milk-derived strains but have various additional capabilities, such as the ability to ferment many additional kinds of carbohydrates and greater stress-tolerance compared with the milk-derived strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The lactic acid bacteria obtained from plants in this study may be applicable for use in the dairy product industry.     

西南地区高山湖泊中可培养细菌多样性及其所产胞外活性物质的特性

【目的】研究西南不同地区的高山湖泊中可培养细菌的多样性及其产胞外蛋白酶、纤维素酶和胞外多糖的能力。【方法】以西南4个不同地区的高山湖泊:雷波的马湖(LB)、中缅边境的凯邦亚湖(ZM)、沙德的莲花湖(SD)、腾冲的青海湖(TC)的水样为研究对象,利用稀释涂布平板方法对可培养细菌进行分离筛选,然后通过对可培养细菌的生理生化指标和16S r RNA基因序列进行分析,初步确定细菌属别;对分离得到的菌株进行产胞外蛋白酶和纤维素酶活性测定和产胞外多糖能力检测。【结果】从西南地区4个湖泊中共分离筛选得到41株细菌,其中LB 15株、ZM 13株、SD 7株、TC 6株。根据16S r RNA基因序列的系统进化分析,4个地区可培养细菌的组成和丰度存在明显差异,其中LB和ZM的优势菌属是芽孢杆菌属(Bacillus),其次是气单胞菌属(Aeromonas)和假单胞菌属(Pseudomonas),分离的TC菌株全部属于芽孢杆菌属(Bacillus),分离的SD菌株特异性较强。进一步酶活性和胞外多糖检测表明,分离得到的41株细菌中有28株菌的发酵产物具有蛋白酶活性,6株具有纤维素酶活性,17株可产胞外多糖(Exopolysaccharides,EPS)。其中有2株细菌同时产蛋白酶、纤维素酶和胞外多糖,10株细菌同时产蛋白酶和胞外多糖,2株细菌同时产蛋白酶和纤维素酶,1株细菌同时产纤维素酶和胞外多糖。【结论】西南4个高山湖泊中存在丰富的微生物菌种资源,且4个湖泊中筛选的可培养细菌受所处环境的影响大。其中莲花湖由于高海拔和较偏僻等特点,人为干扰小,分离得到的细菌类群与其他湖泊相比明显不同;而马湖、凯邦亚湖和青海湖3个湖泊的海拔相对较低,受人类活动影响较大,分离得到的细菌均较常见。此外高山湖泊中的可培养细菌具有分泌多种胞外活性物质特性,为工业化应用奠定了资源基础,极具更深入的开发和研究价值。     

Genetically Engineered Erwinia carotovora: Survival, Intraspecific Competition, and Effects upon Selected Bacterial Genera

Environmental use of genetically engineered microorganisms has raised concerns about potential ecological impact. This research evaluated the survival, competitiveness, and effects upon selected bacterial genera of wild-type and genetically engineered Erwinia carotovora subsp. carotovora to ascertain if differences between the wild-type and genetically engineered strains exist in soil microcosms. The engineered strain contained a chromosomally inserted gene for kanamycin resistance. No significant differences in survival in nonsterile soil over 2 months or in the competitiveness of either strain were observed when the strains were added concurrently to microcosms. For reasons that remain unclear, the engineered strain did survive longer in sterilized soil. The effects of both strains on total bacteria, Pseudomonas and Staphylococcus strains, and actinomycetes were observed. While some apparent differences were observed, they were not statistically significant. A better understanding of the microbial ecology of engineered bacteria, especially pathogens genetically altered for use as biological control agents, is essential before commercial applications can be accomplished.     

Comparative evaluation of commercial test systems for the identification of gram-negative bacteria

Diagnostic efficiency of 5 test-systems i.e. Enterotube 11, Oxi-Ferm Tube, API 20E, API 20NE and MS-2 BID was estimated comparatively with using collection and clinical strains of enteric bacteria and nonfermenting organisms. The accuracy of the enteric bacteria identification as compared to that with the use of the routine methods was more than 90 per cent. The diagnostic mistakes were more frequent with species differentiation of Klebsiella and Enterobacter. In the studies with nonfermenting bacteria the results were less stable and statistically significant differences in identification of separate strains were stated. Advantages and disadvantages of various test-systems are discussed.     

Assessment of mouse strain on bacterial translocation from the gastrointestinal tract

The translocation of indigenous bacteria from the gastrointestinal tract to the mesenteric lymphnodes was compared in ten strains of mice. Indigenous Escherichia coli were cultured from the mesenteric lymphnodes of only two of the six mouse strains examined. Thus, spontaneous translocation of indigenous enteric bacteria across the intestinal barrier did not occur to any significant extent in any of the mouse strains examined. Since bacterial overgrowth in the gastrointestinal tract promotes bacterial translocation, bacterial translocation was tested in ten mouse strains including B10 series after antibiotic-decontaminated and subsequent colonization with streptomycin-resistant E. coli C25. E. coli C25 populated the ceca of the mice at levels of 10(8) to 10(9) per gram and translocated to 90-100% of the mesenteric lymphnodes with mean of 10(1.13) to 10(1.86) per mesenteric lymphnode. However, there were no significant differences between mouse strains as to the translocation incidence or the numbers of viable E. coli C25 per mesenteric lymphnode. Thus, genetic differences between mouse strains did not influence bacterial translocation from the gastrointestinal tract to the mesenteric lymphnodes.     

Protective immunity and granulomatous inflammation is mediated in vivo by T cells reactive to epitopes common to avirulent and listeriolysin-negative mutants of Listeria monocytogenes.

The ability of several listeriolysin O-negative mutants of the EGD and NCTC 7973 strains of Listeria monocytogenes to activate specific T cell responses in vitro and in vivo was determined. T cell lines from different inbred mouse strains and derived T cell clones elicited by L. monocytogenes, strain EGD, which are able to adoptively transfer protection and granuloma formation were examined. Specificity testing revealed no differences between listeriolysin-positive and -negative strains to induce proliferation of the T cell lines and clones. Similar results were obtained when we examined CD4+ T cell-mediated granuloma formation in the livers of mice previously immunized with viable bacteria of the virulent strain. Granulomatous inflammation could be elicited by iv application of heat-killed bacteria of listeriolysin-positive and of -negative bacteria. Protective immunity to listerial infections and granulomatous inflammation therefore appears to be mediated by T cells recognizing epitopes on listerial antigens that are shared by both pathogenic and nonpathogenic Listeria strains.     

环己酮降解细菌的筛选和系统发育分析

通过以环己酮为唯一碳源的选择培养基富集培养和细菌环己酮降解能力的测定,从巴陵石化公司环己酮生产车间排水口的污泥样品中分离到12株降解环己酮性能强的细菌菌株。根据形态观察、部分生理生化试验和16SrRNA基因序列的比对分析,初步确定这些菌株代表8个物种,属于3个大的系统发育类群/门(Actinobacteria,Proteobacteria,Bacteroidetes)的5个科、7个属;大多数菌株与其系统发育关系最密切的典型菌株之间存在一定的遗传差异。结果表明降解环己酮性能强的细菌具有较丰富的系统发育多样性。     

Investigations on influencing plant-associated bacteria in tissue cultures of black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.)

During tissue culture of black locust (Robinia pseudoacacia L.), serious problems with plant-associated bacteria led to a reduction of propagation potential in several clones. Four dominant strains of plant-associated bacteria could be isolated and were assigned to the genera Acidovorax, Dyella, Microbacterium and Sphingomonas. Out of five essential oils tested, thyme and lemongrass oil at a concentration of 0.03% each and 0.015% of both oils in combination clearly inhibited the growth of these bacteria strains on bacteriologic medium. There were no significant differences in total bacterial population density when penicillin, thyme and lemongrass oil or thyme plus lemongrass oil were added to the plant propagation media. The use of lemongrass oil changed the proportion of dominant bacterial strains.     

Studies on the utilisation of carbohydrates and krebs cycle intermediates by Rhizobia,using an agar plate method

An agar plate method for the testing of substrate utilisation is described, and is applied to 108 strains of bacteria belonging to the generaRhizobium andAgrobacterium. With this method, utilisation can be observed without misleading results due to the utilisation of amino acids and other substances present in the medium. Major differences in the utilisation of carbohydrates by the tested species are apparent. In general, strains of fast-growing root-nodule bacteria and agrobacteria were similar in reaction, giving vigorous growth with most of the carbon sources tested. Slow-growing root-nodule bacteria were more specific in their requirements, with most strains utilising only glucose, sodium citrate, xylose, mannitol, arabinose, galactose and fructose. Only six of the 108 strains tested utilised dextrin. The results are related to previous studies on rhizobial taxonomy, and the value of carbohydrate utilisation as a diagnostic feature is discussed.     

Anoxygenic phototrophic bacteria in eutrophic coastal lagoons of the French Mediterranean and Atlantic Coasts (Prévost Lagoon, Arcachon Bay, Certes fishponds)

Sediment samples collected from coastal lagoons on the French Mediterranean (Prévost Lagoon) and Atlantic coasts (Arcachon Bay and Certes fishponds) have been studied in order to determine the population densities and the species diversity of the different groups of anoxygenic phototrophic bacteria (purple sulfur bacteria, purple nonsulfur bacteria and green sulfur bacteria) present in these ecosystems. Several strains of each group were isolated in pure culture and characterized by their physiological properties. The occurrence of purple nonsulfur bacteria in organic rich sediments of the Arcachon Bay and the dominance of purple sulfur bacteria in the Prévost lagoon and Certes fishponds are discussed with respect to their community structure and abundance. The diversity differences of the phototrophic bacterial strains isolated from both environments are also discussed.