Use of <Emphasis Type="Italic">rpoB</Emphasis> sequences and rep-PCR for phylogenetic study of <Emphasis Type="Italic">Anoxybacillus</Emphasis> species

This study was conducted to investigate the applicability of rpoB, which encodes the β subunit of RNA polymerase, to be used as an alternative to 16S rRNA gene sequence similarity analysis in the thermophilic genus Anoxybacillus. Partial rpoB sequences were generated for the 14 type strains of Anoxybacillus species and 6 other strains of four Anoxybacillus species. The sequences and the phylogenetic tree of rpoB were compared with those obtained from 16S rRNA gene analysis. The rpoB gene was found to provide a better resolution for Anoxybacillus species, with lower interspecies sequence similarities. The rpoB sequence similarity analysis permitted a more accurate discrimination of the species within the Anoxybacillus genus than the more commonly used 16S rRNA gene. Furthermore, rapid and reproducible repetitive extragenic palindromic fingerprinting techniques (REP-, ERIC-, and BOX-PCR) were employed for the specimens of genus Anoxybacillus. Through comparison of the three methods, it was found that the BOX-PCR method generated more informative results than REP-PCR for the studied strains; BOX-PCR profiles were more distinct for the different strains, including a higher number of bands. Rapid and reproducible repetitive extragenic palindromic fingerprinting techniques (rep-PCR) constitute a suitable molecular approach for the validation and maintenance of taxonomy within the Anoxybacillus genus. The results of this study show that rpoB and rep-PCR provide rapid and reliable methods for molecular typing of Anoxybacillus species.     

Identification and characterization of thermophilic bacteria isolated from hot springs in Turkey

The present study was conducted to identify and characterize the thermophilic bacteria isolated from various hot springs in Turkey by using phenotypic and genotypic methods including fatty acid methyl ester and rep-PCR profilings, and 16S rRNA sequencing. The data of fatty acid analysis showed the presence of 17 different fatty acids in 15 bacterial strains examined in this study. Six fatty acids, 15:0 iso, 15:0 anteiso, 16:0, 16:0 iso, 17:0 iso, and 17:0 anteiso, were present in all strains. The bacterial strains were classified into three phenotypic groups based on fatty acid profiles which were confirmed by genotypic methods such as 16S rRNA sequence analysis and rep-PCR genomic fingerprint profiles. After evaluating several primer sets targeting the repetitive DNA elements of REP, ERIC, BOX and (GTG)₅, the (GTG)₅ and BOXA1R primers were found to be the most reliable technique for identification and taxonomic characterization of thermophilic bacteria in the genera of Geobacillus, Anoxybacillus and Bacillus spp. Therefore, rep-PCR fingerprinting using the (GTG)₅ and BOXA1R primers can be considered as a promising genotypic tool for the identification and characterization of thermophilic bacteria from species to strain level.     

<Emphasis Type="Italic">Geobacillus zalihae</Emphasis> sp. nov., a thermophilic lipolytic bacterium isolated from palm oil mill effluent in Malaysia

Background  

Thermophilic Bacillus strains of phylogenetic Bacillus rRNA group 5 were described as a new genus Geobacillus. Their geographical distribution included oilfields, hay compost, hydrothermal vent or soils. The members from the genus Geobacillus have a growth temperatures ranging from 35 to 78°C and contained iso-branched saturated fatty acids (iso-15:0, iso-16:0 and iso-17:0) as the major fatty acids. The members of Geobacillus have similarity in their 16S rRNA gene sequences (96.5–99.2%). Thermophiles harboring intrinsically stable enzymes are suitable for industrial applications. The quest for intrinsically thermostable lipases from thermophiles is a prominent task due to the laborious processes via genetic modification.     

Characterization of a Chromobacterium haemolyticum population from a natural tropical lake

Aim: To study genetic diversity of Chromobacterium haemolyticum isolates recovered from a natural tropical lake. Methods and Results: A set of 31 isolates were recovered from a bacterial freshwater community by conventional plating methods and subjected to genetic and phenotypic characterization. The 16S ribosomal RNA (rRNA) gene phylogeny revealed that the isolates were related most closely with C. haemolyticum. In addition to the molecular data, our isolates exhibited strong β‐haemolytic activity, were nonviolacein producers and utilized i‐inositol, d ‐mannitol and d ‐sorbitol in contrast with the other known chromobacteria. Evaluation of the genetic diversity in the 16S rRNA gene, tRNA intergenic spacers (tDNA) and 16S‐23S internal transcribed spacers (ITS) unveiled different levels of genetic heterogeneity in the population, which were also observed with repetitive extragenic palindromic (rep)‐PCR genomic fingerprinting using the BOX‐AR1 primer. tDNA‐ and ITS‐PCR analyses were partially congruent with the 16S rRNA gene phylogeny. The isolates exhibited high resistance to β‐lactamic antibiotics. Conclusion: The population genetic heterogeneity was revealed by 16S rRNA gene sequence, ITS and BOX‐PCR analysis. Significance and Impact of the Study: This study provides for the first time an insight into the genetic diversity of phylogenetically close isolates to C. haemolyticum species.     

Application of <Emphasis Type="Italic">gyrB</Emphasis> and <Emphasis Type="Italic">parE</Emphasis> sequence similarity analyses for differentiation of species within the genus <Emphasis Type="Italic">Geobacillus</Emphasis>

The primary structures of the genes encoding the β-subunits of a type II topoisomerase (gyrase, gyrB) and a type IV topoisomerase (parE) were determined for 15 strains of thermophilic bacteria of the genus Geobacillus. The obtained sequences were used for analysis of the phylogenetic similarity between members of this genus. Comparison of the phylogenetic trees of geobacilli constructed on the basis of the 16S rRNA, gyrB, and parE gene sequences demonstrated that the level of genetic distance between the sequences of the genes encoding the β-subunits of type II topoisomerases significantly exceeded the values obtained by comparative analysis of the 16S rRNA gene sequences of Geobacillus strains. It was shown that, unlike the 16S rRNA gene analysis, comparative analysis of the gyrB and parE gene sequences provided a more precise determination of the phylogenetic position of bacteria at the species level. The data obtained suggest the possibility of using the genes encoding the β-subunits of type II topoisomerases as phylogenetic markers for determination of the species structure of geobacilli.     

Phylogenetic diversity of isolates belonging to genera Geobacillus and Aeribacillus isolated from different geothermal regions of Turkey

The phylogenetic diversity of 31 thermophilic bacilli belonging to genera Geobacillus and Aeribacillus were investigated which were isolated from various geothermal sites of Turkey. Twenty-seven of these isolates were found to be belonged within the genus Geobacillus, whereas 4 of them were identified as Aeribacillus pallidus. The comparative 16S rRNA gene sequence analyses revealed that the A. pallidus isolates displayed sequence similarity values from 98.0 to 99.6% to their closest relative. Furthermore, Geobacillus isolates showed sequence similarity values from 88.9 to 99.8% with the reference type strains. According to the phylogenetic analysis, isolates belonging to genus Geobacillus were diverged into nine clusters and among these isolates, 19 of them were identified as strains related to G. caldoproteolyticus, G. thermodenitrificans, G. stearothermophilus, G. thermoglucosidasius and G. toebii with the most abundant 13 isolates from G. caldoproteolyticus. Four of the Geobacillus isolates were named as unidentified mix group, as they found to be genetically very homogenous like their closely related type species: G. thermoleovorans, G. vulcani, G. lituanicus, G. kaustophilus, G. caldovelox, G. caldotenax, and G. uralicus. Moreover, the sequence comparisons of E173a, E265, C161ab and A142 isolates demonstrated that they represented novel species among genus Geobacillus as they shared lower than 96.7% sequence similarity to all the described type species. The AluI-, HaeIII- and TaqI-ARDRA results were in congruence with the 16S rRNA gene sequence analyses. By ARDRA results, the isolates were able to be differentiated and clustered, the discriminative restriction fragments of these isolates and type species were determined and the novelty of E173, E265, C161ab and A142 isolates could be displayed. Some differentiating phenotypic characters and the ability of amylase, glucosidase and protease production of these bacilli were also studied and biotechnologically valuable thermostable enzyme producing isolates were introduced in order to use in further studies.     

Unusual intragenomic and interspecific variability of <Emphasis Type="Italic">Geobacillus</Emphasis> 16S-23S rRNA internal transcribed spacers

The aim of this study was to evaluate the inter-and intraspecific as well as intragenomic variability of Geobacillus 16S–23S rRNA internal transcribed spacers without tRNA genes and to compare these sequences with sequences bearing tRNA genes. In this study the structural analysis was performed in a unique way because the length and the sequence of the structural blocks were adjusted to fit the structure of 16S–23S rRNA internal transcribed spacers of five different Geobacillus species. Our study demonstrated the mosaic-like structure of 16S–23S rRNA internal transcribed spacers in Geobacillus. Some characteristics of these spacers of geobacilli were not previously reported for other bacteria: unusually short conserved sequence in the 5′ end region, some identical conserved blocks in both 5′ and 3′ regions of 16S–23S rRNA internal transcribed spacers, the same sequence blocks in both 16S–23S and 23S–5S rRNA intergenic spacers. Our study demonstrated quite uniform arrangement of the sequence blocks in Geobacillus thermodenitrificans. This species diverged early in the phylogenetic tree of the genus Geobacillus. For the phylogenetically recent species Geobacillus kaustophilus and Geobacillus lituanicus the low inter-and intraspecific, but high intragenomic variability, as a consequence of recent phylogenetic events, was established.     

Identification of <Emphasis Type="Italic">Bacillus</Emphasis> Probiotics Isolated from Soil Rhizosphere Using 16S rRNA, <Emphasis Type="Italic">recA</Emphasis>, <Emphasis Type="Italic">rpoB</Emphasis> Gene Sequencing and RAPD-PCR

Some Bacillus species, especially Bacillus subtilis and Bacillus pumilus groups, have highly similar 16S rRNA gene sequences, which are hard to identify based on 16S rDNA sequence analysis. To conquer this drawback, rpoB, recA sequence analysis along with randomly amplified polymorphic (RAPD) fingerprinting was examined as an alternative method for differentiating Bacillus species. The 16S rRNA, rpoB and recA genes were amplified via a polymerase chain reaction using their specific primers. The resulted PCR amplicons were sequenced, and phylogenetic analysis was employed by MEGA 6 software. Identification based on 16S rRNA gene sequencing was underpinned by rpoB and recA gene sequencing as well as RAPD-PCR technique. Subsequently, concatenation and phylogenetic analysis showed that extent of diversity and similarity were better obtained by rpoB and recA primers, which are also reinforced by RAPD-PCR methods. However, in one case, these approaches failed to identify one isolate, which in combination with the phenotypical method offsets this issue. Overall, RAPD fingerprinting, rpoB and recA along with concatenated genes sequence analysis discriminated closely related Bacillus species, which highlights the significance of the multigenic method in more precisely distinguishing Bacillus strains. This research emphasizes the benefit of RAPD fingerprinting, rpoB and recA sequence analysis superior to 16S rRNA gene sequence analysis for suitable and effective identification of Bacillus species as recommended for probiotic products.     

New bacilli from shallow hydrothermal vents of Panarea Island (Italy) and their biotechnological potential

Aims: To characterize bacilli isolated from shallow hydrothermal vents of Panarea Island (Italy) and evaluate their biotechnological potential. Methods and Results: Fifteen isolates were characterized by culture and molecular methods. Eleven isolates were thermophilic, six isolates were alkalophilic and four of them were haloalkalophilic. After 16S rRNA gene sequencing, four strains, exhibiting sequence similarity below 95% with deposited strains, may represent novel species of bacilli. One strain was strictly related to Geobacillus subterraneus, but shared phenotypic characteristics for which it could be considered a new strain of this species. Four strains were affiliated with different Bacillus spp. Most isolates produced gelatinase, lipases and amylase, and some were mercury tolerant. Exopolysaccharides (EPS) production was tested adding different sugars (glucose, sucrose, trehalose, fructose, ribose, xylose and mannose, 1% w/v) as a carbon source in a minimal medium. The highest EPS yield (185 mg l^?1) was reached by strain 1A70 utilizing ribose as a carbon source. Conclusions: Novel strains of Geobacillus and indigenous ribotypes of Bacillus with biotechnological potential inhabit shallow vents of Panarea Island. Significance and Impact of the Study: New strains of thermophilic bacilli from Panarea are producers of useful biomolecules for industrial purposes as well as environmental and biotechnological applications.     

Phylogenetic diversity of thermophilic carbohydrate degrading bacilli from Bulgarian hot springs

Phylogenetic diversity of culturable bacteria from genus Bacillus and related genera, isolated from 18 Bulgarian hot springs was investigated in association with their functional diversity. Sixty-seven thermophilic and facultative thermophilic strains were isolated under aerobic conditions at 60°C. Sixty-six of them belonged to eight species in four genera from Bacillus group: Anoxybacillus, Geobacillus, Brevibacillus and Bacillus. Representatives of the genus Anoxybacillus predominated. Based on phylogenetic analysis (<97% sequence similarity) four strains belonged to groups representing potentially novel species. Producers of carbohydrases, degrading 12 from the tested 13 substrates were isolated. About half of the isolates degraded amylose by exo- or endo-mechanism of action of their enzymes. The isolates degrading hemicellulose carbohydrates like arabinan, arabinoxylan, β-glucan, galactan, galactomannan and xyloglucan were reached to. Some of the microorganisms were able to uptake microbial polysaccharides like curdlan and gellan and their enzymes were between first reported thermostable enzymes in their groups, like gellan lyase and curdlan lyase A relation between species affiliation and their functional activity was observed—all A. gonensis strains were producer of amylolytic enzymes, most of Brevibacillus ruber strains were able to grow in a minimal medium with xanthan.     

<Emphasis Type="Italic">Bacillus deserti</Emphasis> sp. nov., a novel bacterium isolated from the desert of Xinjiang,China

A Gram-positive, rod-shaped, motile and spore-forming bacterium, designated ZLD-8^T, was isolated from a desert soil sample collected from Xinjiang Province in north-west China, and subjected to a polyphasic taxonomic analysis. This isolate grew optimally at 30°C and pH 7.0. It grew with 0–4% NaCl (optimum, 0–1%). Comparative 16S rRNA gene sequence analysis showed that strain ZLD-8^T was closely related to members of the genus Bacillus, exhibiting the highest 16S rRNA gene sequence similarity to Bacillus kribbensis DSM 17871^T (98.0%). The levels of 16S rRNA gene sequence similarity with respect to other Bacillus species with validly published names were less than 96.3%. The DNA G + C content of strain ZLD-8^T was 40.1 mol%. The strain contained MK-7 as the predominant menaquinone. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acids (>5% of total fatty acids) were anteiso-C15:0 (39.56%), iso-C14:0 (25.69%), C16:1 ω7c alcohol (10.13%) and iso-C15:0 (5.27%). These chemotaxonomic results supported the affiliation of strain ZLD-8^T to the genus Bacillus. However, low DNA–DNA relatedness values and distinguishing phenotypic characteristics allowed genotypic and phenotypic differentiation of strain ZLD-8^T from recognized Bacillus species. On the basis of the polyphasic evidence presented, strain ZLD-8^T is considered to represent a novel species of the genus Bacillus, for which the name Bacillus deserti sp. nov. is proposed. The type strain is ZLD-8^T (=CCTCC AB 207173^T = KCTC 13246^T).     

佳西热带雨林土壤芽胞杆菌分离与多样性分析

采用热处理法从海南省佳西热带雨林土壤中分离到147株芽胞杆菌,并利用16S rDNA PCR-RFLP与序列分析技术对其遗传多样性进行了研究。16S rDNA PCR-RFLP酶切图谱UPGMA聚类分析结果表明,在100%的相似性水平上,这些芽胞杆菌分属13个遗传类群。不同遗传类型代表菌株的16S rRNA基因序列分析结果显示,它们分布在Bacillaceae、Planococcaceae和Paenibacillaceae科的Bacillus、Lysinibacillus、Paucisalibacillus、Bhargavaea和Paenibacillus五个属,其中Bacillus为优势属(占50%);有3株芽胞杆菌的16S rRNA基因序列与数据库中相应模式菌株的最大相似性在98.3%~98.9%之间。结果表明,佳西热带雨林土壤中芽胞杆菌有着较为丰富的遗传多样性。     

Bacillus locisalis sp. nov., a new haloalkaliphilic species from hypersaline and alkaline lakes of China, Kenya and Tanzania

A polyphasic taxonomic study was performed on seven Bacillus-like bacteria isolated from three hypersaline and alkaline lakes located in China, Kenya and Tanzania. All strains were moderately halophilic and alkaliphilic, Gram positive, motile rods. The DNA G+C content from the seven isolates ranged from 42.2 to 43.4 mol% and their major fatty acid was anteiso-C_15:0. Strain CG1^T, selected as representative strain of the isolates, possesses meso-diaminopimelic acid in the cell wall peptidoglycan, MK-7 as the predominant menaquinone and diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. Comparative 16S rRNA gene sequence analysis indicated that the isolates belonged to the genus Bacillus. The seven isolates shared 97.7–99.9% 16S rRNA gene sequence similarity, and formed a branch that was distinct from the type strains of the recognized species of the genus Bacillus. They were most closely related to Bacillus agaradhaerens DSM 8721^T (92.6–93.8% 16S rRNA sequence similarity). DNA–DNA hybridization values between the seven isolates were 85–100%. According to the polyphasic characterization, the strains represent a novel species, for which the name Bacillus locisalis sp. nov. is proposed. The type strain is CG1^T (CCM 7370^T = CECT 7152^T = CGMCC 1.6286^T = DSM 18085^T).     

Genetic Diversity among Thermophilic Bacteria Isolated from Geothermal Sites by Using Two PCR Typing Methods

Microbial communities thriving at two hot springs, Hammam Pharaon (Pharaoh's Bath) and Oyoun Mossa (Moses springs), in Egypt was studied by cultural and molecular methods. Thirteen morphologically distinct strains of facultative anaerobic thermophilic bacterial isolates have been characterized and identified using phenotypic and genotypic characters including RAPD-PCR, ERIC-PCR typing, plasmid analysis and 16S rRNA sequencing. All isolates produced plasmid DNA with various sizes ranging from 0.7 kb to a larger plasmid 7.2 kb. The bacterial strains could tolerate a temperature range between 45 to 85°C and a pH between 4–11. Also, sulphate-reducing bacteria (SRB) in the thermal springs were investigated with combined biochemical and molecular approaches. A sulphate-reducing bacteria medium containing lactate was used for enrichment and isolation, which yielded Gram negative, rod shaped, anaerobic, non-spore-forming and motile bacteria capable of reducing sulphate to sulphide. These grew at temperatures ranging from 30 to 50°C and could use pyruvate, lactate and ethanol as electron donors. The dissimilatory sulphite reductase (DSR) gene sequences of eleven representative isolates revealed that the strains belonged to the sulphur reducing bacterial species Desulfovibrio vulgaris. 16S rRNA gene partial sequence results indicated the presence of novel or existing species of Bacillus (one species), Anoxybacillus (four species) and Geobacillus (eight species). In this study phenotypic and genotypic diversity were applied for the first time to differentiate thermophilic bacteria of such geothermal sites in Sinai, Egypt.     

Effects of Continuous Thermophilic Composting (CTC) on Bacterial Community in the Active Composting Process

The method of continuous thermophilic composting (CTC) remarkably shortened the active composting cycle and enhanced the compost stability. Effects of CTC on the quantities of bacteria, with a comparison to the traditional composting (TC) method, were explored by plate count with incubation at 30, 40 and 50°C, respectively, and by quantitative PCR targeting the universal bacterial 16S rRNA genes and the Bacillus 16S rRNA genes. The comparison of cultivatable or uncultivatable bacterial numbers indicated that CTC might have increased the biomass of bacteria, especially Bacillus spp., during the composting. Denaturing gradient gel electrophoresis (DGGE) analysis was employed to investigate the effects of CTC on bacterial diversity, and a community dominated by fewer species was detected in a typical CTC run. The analysis of sequence and phylogeny based on DGGE indicated that the continuously high temperature had changed the structure of bacterial community and strengthened the mainstay role of the thermophilic and spore-forming Bacillus spp. in CTC run.     

Phylogenetic analysis of Methanobrevibacter isolated from feces of humans and other animals

Comparative 16S rRNA gene sequence and genomic DNA reassociation analyses were used to assess the phylogenetic relationships of Methanobrevibacter fecal isolates. The 16S rRNA gene sequences of Methanobrevibacter smithii strain PS and the human fecal isolates B181 and ALI were essentially identical, and their genomic DNA reassociated at values greater than 94%. The analysis of 16S rRNA sequences of the horse, pig, cow, rat, and goose fecal isolates confirm that they are members of the genus Methanobrevibacter. They had a high degree of sequence similarity (97–98%) with the 16S rRNA gene of M. smithii, indicating that they share a common line of descent. The 16S rRNA genes of the horse and pig isolates had 99.3% sequence similarity. Sequence analysis of the 16S rRNA gene of the sheep fecal isolate showed that it formed a separate line of descent in the genus Methanobrevibacter. Genomic DNA reassociation studies indicate that the horse, pig, cow, and goose fecal isolates represent at least three new species. The horse and pig isolates were the only animal isolates that had > 70% genomic DNA reassociation and represent strains of a single species. The cow, goose, and sheep isolates had little or no genomic DNA reassociation with M. smithii or with each other. The relationship of the rat isolate to the other animal isolates was not determined. An evaluation of the relationship of 16S rRNA gene sequence similarity and genomic DNA reassociation of Methanobrevibacter and other methanogenic archaea indicated that genomic DNA reassociation studies are necessary to establish that two methanogenic organisms belong to the same species. Received: 17 November 1997 / Accepted: 16 January 1998     

Geobacillus galactosidasius sp. nov., a new thermophilic galactosidase-producing bacterium isolated from compost

Two thermophilic spore-forming strains, with optimum growth temperature at 70 °C, were isolated from compost of the “Experimental System of Composting” (Teora, Avellino, Italy). A phylogenetic analysis based on 16S rRNA gene sequences showed that these organisms represented a new species of the genus Geobacillus. Based on polyphasic taxonomic data the strains represented a novel species for which the name Geobacillus galactosidasius sp. nov. is proposed. The type strain is CF1B^T (= ATCC BAA-1450^T = DSM 18751^T).     

Antagonistic activity of <Emphasis Type="Italic">Bacillus</Emphasis> sp. obtained from an Algerian oilfield and chemical biocide THPS against sulfate-reducing bacteria consortium inducing corrosion in the oil industry

The present study enlightens the role of the antagonistic potential of nonpathogenic strain B21 against sulfate-reducing bacteria (SRB) consortium. The inhibitor effects of strain B21 were compared with those of the chemical biocide tetrakishydroxymethylphosphonium sulfate (THPS), generally used in the petroleum industry. The biological inhibitor exhibited much better and effective performance. Growth of SRB in coculture with bacteria strain B21 antagonist exhibited decline in SRB growth, reduction in production of sulfides, with consumption of sulfate. The observed effect seems more important in comparison with the effect caused by the tested biocide (THPS). Strain B21, a dominant facultative aerobic species, has salt growth requirement always above 5% (w/v) salts with optimal concentration of 10–15%. Phylogenetic analysis based on partial 16S rRNA gene sequences showed that strain B21 is a member of the genus Bacillus, being most closely related to Bacillus qingdaonensis DQ115802 (94.0% sequence similarity), Bacillus aidingensis DQ504377 (94.0%), and Bacillus salarius AY667494 (92.2%). Comparative analysis of partial 16S rRNA gene sequence data plus physiological, biochemical, and phenotypic features of the novel isolate and related species of Bacillus indicated that strain B21 may represent a novel species within the genus Bacillus, named Bacillus sp. (EMBL, FR671419). The results of this study indicate the application potential of Bacillus strain B21 as a biocontrol agent to fight corrosion in the oil industry.     

Comparison of pulsed‐field gel electrophoresis and three rep‐PCR methods for evaluating the genetic relatedness of Stenotrophomonas maltophilia isolates

Aims: In this study, three facile repetitive‐sequence PCR (rep‐PCR) techniques have been compared with the pulsed‐field gel electrophoresis (PFGE) method for differentiating the genetic relatedness of clinical Stenotrophomonas maltophilia isolates. Methods and Results: The dendrograms of 20 S. maltophilia isolates were constructed based on the data obtained from PFGE and three PCR‐based methods, i.e. enterobacterial repetitive intergenic consensus‐PCR (ERIC‐PCR), BOX‐PCR and repetitive extragenic palindromic‐PCR (REP‐PCR). When compared with PFGE, ERIC‐PCR displayed a much lower discriminatory power, whereas BOX‐PCR and REP‐PCR had a comparable discriminatory power for close genetic‐related isolates. Conclusion: BOX‐PCR and REP‐PCR can be convenient and effective methods for evaluating the close genetic relatedness of clinical S. maltophilia isolates. Significance and Impact of the Study: A rapid method for determining S. maltophilia’s close genetic relatedness provides a convenient tool for understanding the epidemiology of S. maltophilia.     

The Phylogenetic Diversity of Aerobic Organotrophic Bacteria from the Dagang High-Temperature Oil Field

The distribution and species diversity of aerobic organotrophic bacteria in the Dagang high-temperature oil field (China), which is exploited with water-flooding, have been studied. Twenty-two strains of the most characteristic thermophilic and mesophilic aerobic organotrophic bacteria have been isolated from the oil stratum. It has been found that, in a laboratory, the mesophilic and thermophilic isolates grow in the temperature, pH, and salinity ranges characteristic of the injection well near-bottom zones or of the oil stratum, respectively, and assimilate a wide range of hydrocarbons, fatty acids, lower alcohols, and crude oil, thus exhibiting adaptation to the environment. Using comparative phylogenetic 16S rRNA analysis, the taxonomic affiliation of the isolates has been established. The aerobic microbial community includes gram-positive bacteria with a high and low G+C content of DNA, and γ and β subclasses of Proteobacteria. The thermophilic bacteria belong to the genera Geobacillus and Thermoactinomyces, and the mesophilic strains belong to the genera Bacillus, Micrococcus, Cellulomonas, Pseudomonas, and Acinetobacter. The microbial community of the oil stratum is dominated by known species of the genus Geobacillus (G. subterraneus, G. stearothermophilus, and G. thermoglucosidasius) and a novel species “Geobacillus jurassicus.” A number of novel thermophilic oil-oxidizing bacilli have been isolated.__________Translated from Mikrobiologiya, Vol. 74, No. 3, 2005, pp. 401–409.Original Russian Text Copyright © 2005 by Nazina, Sokolova, Shestakova, Grigoryan, Mikhailova, Babich, Lysenko, Tourova, Poltaraus, Qingxian Feng, Fangtian Ni, Belyaev.