Eisenbergiella tayi gen. nov., sp. nov., isolated from human blood.

A catalase-positive, rod-shaped, non-proteolytic, non-motile, anaerobic bacterial strain, designated B086562(T), was isolated from a blood culture of an 84-year-old male patient in Israel. According to 16S rRNA gene sequence phylogeny, this strain has no known close relatives among recognized bacteria but should be placed within the family Lachnospiraceae. The most closely related recognized bacteria were from the 'Clostridium clostridioforme group': C. clostridioforme (92.4%) and Clostridium bolteae (92.3%). The isolate produced butyrate, lactate, acetate and succinate as major metabolic end products. The major fatty acids were C16:0 and C18:1 cis 9 DMA and the DNA G+C content was 46.0 mol%. On the basis of the phenotypic properties and phylogenetic distinctiveness, the blood isolate represents a novel species of a new genus in the family Lachnospiraceae, for which the name Eisenbergiella tayi gen. nov., sp. nov. is proposed. The type strain of Eisenbergiella tayi is B086562(T) ( = LMG 27400(T) = DSM 26961(T) = ATCC BAA-2558(T)).

Haloferula chungangensis sp. nov., isolated from marine sediment.

A Gram-stain-negative, non-spore-forming, non-motile, strictly aerobic, rod-shaped bacterial strain, designated CAU 1074(T), was isolated from marine sediment and its taxonomic position was investigated using a polyphasic approach. Strain CAU 1074(T) grew optimally at 30 °C and pH 6.5. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CAU 1074(T) formed a distinct lineage within the genus Haloferula and was most closely related to Haloferula harenae KCTC 22198(T) (96.0% similarity). Strain CAU 1074(T) contained MK-9 as the major isoprenoid quinone, and iso-C(14:0,) C(16:1)ω9c and C(16:0) as the major fatty acids. The cell wall peptidoglycan contained meso-diaminopimelic acid. The major whole-cell sugars were glucose, xylose, mannose and ribose. The polar lipids were composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, aminoglycolipid and two unidentified phospholipids. The DNA G+C content of the strain was 64.0 mol%. On the basis of phenotypic and chemotaxonomic data, and phylogenetic inference, strain CAU 1074(T) should be classified as a member of a novel species in the genus Haloferula, for which the name Haloferula chungangensis sp. nov. is proposed; the type strain is CAU 1074(T) (= KCTC 23578(T) = CCUG 61920(T)). An emended description of the genus Haloferula is also provided.

Evaluation of the DiversiLab typing method in a multicenter study assessing horizontal spread of highly resistant gram-negative rods.

The worldwide prevalence of highly resistant Gram-negative rods (HR-GNR) is increasing rapidly. Reliable typing methods are needed to detect and control outbreaks and to monitor the effectiveness of infection control programs in endemic situations. In this study, we investigated the performance of the DiversiLab typing method in comparison with the amplified fragment length polymorphism (AFLP) typing method. Six hundred fifty-three HR-GNR isolates, which were obtained during a 6-month prospective survey in 18 Dutch hospitals, were typed by AFLP and DiversiLab. Subsequently, the sensitivity and specificity of DiversiLab were calculated, using AFLP as the reference method. In addition, results were compared by means of epidemiological linkage, and Cohen's kappa for agreement was calculated. DiversiLab considered significantly more isolates (275) to belong to a cluster than AFLP (198) (P < 0.001). In direct comparison, the sensitivity was 83.8%, and the specificity was 78.6%. When epidemiological linkage was included in the analysis, DiversiLab considered eight isolates as secondary cases, which were considered unique in AFLP. Only two secondary cases, according to AFLP, were missed by DiversiLab. This results in a kappa for agreement of 0.985. In daily practice, a typing method has to be used in combination with epidemiological information. When this was done, DiversiLab was shown to be a reliable method for the typing of HR-GNR. This, in combination with the ease of use and the speed, makes DiversiLab an appropriate method for screening in routine clinical practice. When a cluster is suspected and the consequences of these findings are substantial, a confirmatory analysis should be performed.

Antimicrobial susceptibility of moxifloxacin against gram-negative enteric rods from colombian patients with chronic periodontitis.

BACKGROUND: Gram-negative enteric rods were associated with periodontal diseases in several populations. The association between enteric and putative periodontal pathogens has received little attention in the literature. The present investigation determined the occurrence and in vitro antimicrobial susceptibility of isolates of Gram-negative enteric rods from Colombian patients with chronic periodontitis. METHODS: Clinical parameters and the in vitro antimicrobial sensitivity of isolates of Gram-negative enteric rods were examined in 76 patients with chronic periodontitis in Medellin, Colombia. Subgingival samples were processed using culture and biochemical tests for the detection of periodontal and superinfecting pathogens. Selected colonies of Gram-negative enteric rods from pure cultures were used to test the susceptibility to amoxicillin/clavulanic acid, ciprofloxacin, and moxifloxacin. Chi-square and Mann-Whitney tests were used to determine differences in clinical variables versus the presence or absence of Gram-negative enteric rods. RESULTS: Klebsiella pneumoniae was found in 12 patients, Pseudomonas aeruginosa was found in four patients, and three other species were recovered with a lower prevalence. Men (38.75%) tended to harbor more of the studied organisms than women (17.7%) (P = 0.04). Gram-negative enteric rods in periodontal pockets correlated positively with the presence of Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Porphyromonas gingivalis, and Prevotella intermedia/nigrescens (respectively, r = 0.66, 0.31, and 0.32; P <0.001). All superinfecting organisms demonstrated a high susceptibility to moxifloxacin and ciprofloxacin but exhibited a variable susceptibility to amoxicillin/clavulanic acid. CONCLUSIONS: This study found high levels of Gram-negative enteric rods in patients with chronic periodontitis. Moxifloxacin and ciprofloxacin appeared capable of eradicating these organisms from periodontal pockets. Its good activity against Gram-negative enteric rods and periodontopathogens suggests the potential use of moxifloxacin as an adjunctive antibiotic in the treatment of mixed periodontal infections.

Caldimicrobium rimae gen. nov., sp. nov., an extremely thermophilic, facultatively lithoautotrophic, anaerobic bacterium from the Uzon Caldera, Kamchatka.

An extremely thermophilic, strictly anaerobic, facultatively chemolithoautotrophic bacterium designated strain DS(T) was isolated from Treshchinnyi Spring, one of the hottest springs of the Uzon Caldera (Kamchatka, Russia). Cells of the novel organism were Gram-negative rods, about 1.0-1.2 microm long and 0.5 microm wide. The temperature range for growth was 52-82 degrees C, with an optimum at 75 degrees C. Growth was observed at pH 6.8-7.4, and the optimum pH was 7.0-7.2. Strain DS(T) was able to grow lithoautotrophically with hydrogen in the presence of CO(2) as a carbon source and thiosulfate or elemental sulfur as an electron acceptor. It also grew well with ethanol, fumarate, succinate or malate in the presence of thiosulfate. Yeast extract was not required for growth and did not stimulate growth. The genomic DNA G+C content was 35.2 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that the novel organism was a member of the family Thermodesulfobacteriaceae. On the basis of phylogenetic and physiological considerations, it is proposed that strain DS(T) represents a new genus and species, Caldimicrobium rimae gen. nov., sp. nov. The type strain of Caldimicrobium rimae is DS(T) (=DSM 19393(T) =VKM B-2460(T)).

Alkalibacterium indicireducens sp. nov., an obligate alkaliphile that reduces indigo dye.

Indigo-reducing, obligately alkaliphilic strains A11T, F11 and F12 were isolated from indigo fermentation liquor obtained from Tokushima Prefecture, Shikoku, Japan. The isolates grew at pH 9.0-12.3, but not at pH 7.0-8.0. The optimum pH range for growth was 9.5-11.5. They were Gram-negative, facultatively anaerobic, rod-shaped strains with peritrichous flagella. The isolates grew in 0-14 % (w/v) NaCl, with optimum growth at 1-11 %. They grew at temperatures of 15-35 degrees C with optimum growth at around 20-30 degrees C. dl-Lactate was the major end product from d-glucose. No quinones were detected. The peptidoglycan type was A4 alpha, l-Lys (l-Orn)-d-Asp. The major cellular fatty acids were C16 : 0, C16 : 17c and C18 : 19c. The DNA G+C contents were 47.0-47.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequence data indicated that the isolates belong to the genus Alkalibacterium. DNA-DNA hybridization revealed low relatedness values between the isolates and the three phylogenetically most closely related species, Alkalibacterium olivapovliticus, Alkalibacterium psychrotolerans and Alkalibacterium iburiense (<41 %). On the basis of phenotypic characteristics, including hydrolysis of cellulose and fermentation of carbohydrates, and chemotaxonomic characteristics, phylogenetic data and DNA-DNA relatedness data, it is concluded that the isolates merit classification as representatives of a novel species of the genus Alkalibacterium, for which the name Alkalibacterium indicireducens sp. nov. is proposed. The type strain of this species is A11T (=JCM 14232T=NCIMB 14253T).

Diverse endophytic bacteria isolated from a leguminous tree Conzattia multiflora grown in Mexico.

Conzattia multiflora is a leguminous tree present only in Mexico and Guatemala. There is no record about its symbiotic or pathogenic microbes. In this study, we found that numerous bacteria with 10(4)-10(6) individuals per gram of fresh epidermis were distributed in the tissue of this plant. All the bacteria isolated from the Conzattia epidermis were Gram-negative, facultative anaerobic rods and formed yellow or colorless colonies. They were identified as endophytes by inoculation tests. Some of the bacteria could significantly promote the growth of Conzattia seedlings. Nine different groups were defined by PCR-based RFLP, which were classified as Pantoea, Erwinia, Salmonella, Enterobacter, Citrobacter and Klebsiella by the phylogenetic analysis of 16S rRNA genes. The existence of plant-borne lineages of Salmonella indicates that the unexplored plants may harbor some unknown microbes.

Zobellella denitrificans gen. nov., sp. nov. and Zobellella taiwanensis sp. nov., denitrifying bacteria capable of fermentative metabolism.

Two denitrifying strains of heterotrophic, facultatively anaerobic bacteria, designated ZD1(T) and ZT1(T), were isolated from sediment samples collected from mangrove ecosystems in Taiwan. The isolates were Gram-negative. Cells grown in broth cultures were straight rods that were motile by means of a single polar flagellum. The isolates grew optimally in 1-3 % NaCl, but NaCl was not an absolute requirement for growth; only strain ZT1(T) grew in 13-14 % NaCl. Both isolates grew between 10 and 45 degrees C, with optimum growth at 30-35 degrees C. They were capable of anaerobic growth by denitrifying metabolism using nitrate or nitrous oxide as terminal electron acceptors or, alternatively, by fermenting glucose, sucrose or mannitol as substrates. C(18 : 1)omega7c was the most abundant fatty acid (32.6-35.7 %). The other major fatty acids included C(16 : 1)omega7c (27.5-29.4 %) and C(16 : 0) (20.1-22.0 %). The two isolates had 16S rRNA gene sequence similarity of 96.8 % and shared 94.1-96.8 % sequence similarity with the most closely related species, Oceanimonas doudoroffii, Oceanimonas baumannii, Oceanimonas smirnovii and Oceanisphaera litoralis. They could be distinguished from these species in that they were capable of fermentative metabolism, had relatively high DNA G+C contents (62.0-64.0 mol%) and contained C(18 : 1)omega7c instead of C(16 : 1)omega7c as the most abundant fatty acid. Characterization data accumulated in this study revealed that the two denitrifying isolates could be classified as representatives of two novel species in a new genus, Zobellella gen. nov., with Zobellella denitrificans sp. nov. (type strain ZD1(T) = BCRC 17493(T) = JCM 13380(T)) as the type species and Zobellella taiwanensis sp. nov. (type strain ZT1(T) = BCRC 17494(T) = JCM 13381(T)) as a second species.

Paenibacillus wynnii sp. nov., a novel species harbouring the nifH gene, isolated from Alexander Island, Antarctica.

Soil taken from 12 different locations at Mars Oasis on Alexander Island, Antarctica, yielded unidentified isolates of endospore-forming bacteria. Soil from four of the locations contained Gram-negative, facultatively anaerobic, motile rods that were able to grow at 4 degrees C and which formed ellipsoidal spores that lay paracentrally or subterminally in swollen or slightly swollen sporangia. All of the strains harboured the nitrogenase gene nifH. Phenotypic tests, amplified rDNA restriction analysis (ARDRA), fatty acid analysis and SDS-PAGE analysis suggested that the isolates represented a novel taxon of Paenibacillus. 16S rRNA gene sequence comparison supported the proposal of a novel species, Paenibacillus wynnii sp. nov. (type strain, LMG 22176(T)=CIP 108306(T)).

Potential for detection of microorganisms and heavy metals in potable water using electronic nose technology.

Studies have been carried out to determine the potential for the detection of different microbial species (Enterobacter aerogenes, Escherichia coli, Pseudomonas aeruginosa), alone and in the presence of low concentrations of different heavy metals (As, Cd, Pb and Zn) in bottled, reverse osmosis (RO) and tap water, using an electronic nose. Studies show that it is possible to discriminate control water samples from water contaminated with 0.5 ppm of a mixture of metals. The presence of heavy metals may modify the activity of microorganisms and thus the volatile production patterns. Bacterial species at 10(2)-10(4) colony forming units (CFUs) ml(-1) could be detected after 24 h of incubation. Work is in progress to identify the limits of detection for a range of other microorganisms, including, fungi and cyanobacteria, and chlorinated phenols using electronic nose technology.

Paenibacillus koleovorans sp. nov., able to grow on the sheath of Sphaerotilus natans.

Two bacterial strains that are able to grow specifically on the sheath of a sheathed filamentous bacterium, Sphaerotilus natans, were isolated from soil samples. The sheath-degrading organisms, designated strains TB(T) and TK, are facultatively anaerobic and form endospores. The Gram reaction was negative at all stages of cultivation. The optimum growth temperature and pH were 30 degrees C and pH 7. The DNA G+C content was 54.0-55.8 mol%. MK-7 was the predominant menaquinone and anteiso-C15:0 was the major fatty acid. Phylogenetic analysis based on the 16S rDNA sequences revealed that the isolates were closely related to Paenibacillus chondroitinus, Paenibacillus alginolyticus, Paenibacillus koreensis, Paenibacillus validus, Paenibacillus larvae subsp. larvae and P. larvae subsp. pulvifaciens. The sequences were found to contain consensus sequences characteristic of all Paenibacillus species. The isolates were able to lyse and utilize the purified sheath of S. natans as the sole carbon and energy source. Acid was not produced from common carbon sources, allowing easy distinction from other members of Paenibacillus. It is concluded that the two strains represent a novel Paenibacillus species, for which the name Paenibacillus koleovorans sp. nov. is proposed. The type strain is strain TB(T) (= JCM 11186T = IAM 14926T = KCTC 13912T).

Oral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci in irradiated, dentate, xerostomic individuals.

This study aimed at investigating the oral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci in head- and neck-irradiated, dentate, xerostomic individuals. Subjects were recruited from a nasopharyngeal carcinoma clinic and were segregated into group A: <60 years (n=25, 48+/-6 years, 5+/-5 years post-irradiation) and group B: >or=60 years (n=8, 67+/-4 years, 2+/-2 years post-irradiation) and were compared with age- and sex-matched normal individuals, group C: <60 years (n=20, 44+/-12 years) and group D: >or=60 years (n=10, 70+/-3 years). Selective culture of the oral rinse samples was carried out to isolate, quantify and speciate (using API 20E kit) aerobic and facultatively anaerobic gram-negative rods and cocci recovery. All test subjects were put under comprehensive oral and preventive care for 3 months, and 12 group A and 5 group B subjects were recalled for reassessment of aerobic and facultatively anaerobic gram-negative rods and cocci colonization. All identical isolates, pre- and post-hygienic care, were phenotypically (Vitek, Hazelwood, MA and antibiogram profile) and genotypically (pulsed-field gel electrophoresis) evaluated. The aerobic and facultatively anaerobic gram-negative rods and cocci isolated from the first round oral rinse samples included: Acinetobacter, Neisseria, Chryseomonas, Flavimonas, Pseudomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, Flavobacterium and Weeksella species. The aerobic and facultatively anaerobic gram-negative rods and cocci isolation rate was high for irradiated individuals, and they were 64/25% and 100/80% for groups A/C and B/D, respectively. Recovery of aerobic and facultatively anaerobic gram-negative rods and cocci and Klebsiella pneumoniae subsp. pneumoniae in oral rinse samples were found to be significantly more prevalent in the irradiated subjects (groups A and B). Enterobacteriaceae were more frequently isolated from oral rinse samples of aged irradiated subjects (group B vs D, P<0.05), where the quantity of Citrobacter freundii (colony-forming units/ml oral rinse) was also significantly elevated. The isolation rate of aerobic and facultatively anaerobic gram-negative rods and cocci after hygienic care remained unchanged; 3 of 12 and 3 of 5 of the recalled subjects from groups A and B, respectively, harbored same aerobic and facultatively anaerobic gram-negative rods and cocci species. However, only two pairs of K. pneumoniae subsp. pneumoniae, sequentially isolated from same patients in group B, were found to be identical by pulsed-field gel electrophoresis. This may be due to reinfection of the microbes from the same source or permanent colonization. In conclusion, irradiation-induced xerostomia seems to favor frequent, repeated, transient intraoral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci.

Muricauda ruestringensis gen. nov., sp. nov., a facultatively anaerobic, appendaged bacterium from German North Sea intertidal sediment.

A gram-negative, facultatively anaerobic bacterium with appendages was isolated from continuous cultures with a seawater-sediment suspension containing hexadecane as the sole carbon source. Although this organism was isolated from a hexadecane-degrading bacterial community, it was not able to degrade hexadecane. However, this bacterium was able to use different sugars and amino acids for growth, indicating that it probably profits from the lysis or from products like surfactants of other cells in the community. 16S rDNA analysis demonstrated that the isolated strain is phylogenetically related to the family Flavobacteriaceae of the phylum 'Cytophaga-Flavobacterium-Bacteroides'. Evidence based on phenotypic characteristics and 16S rDNA analysis supports the conclusion that this bacterium is distinct from its nearest relative, Zobellia uliginosa (90.72% similarity in 16S rRNA gene sequence), and from the other genera of the Flavobacteriaceae. It is therefore proposed that the isolated marine bacterium represents a novel taxon, designated Muricauda ruestringensis gen. nov., sp. nov. The type strain is strain B1T (= DSM 13258T = LMG 19739T).

Infective endocarditis complicated with progressive heart failure due to beta-lactamase-producing Cardiobacterium hominis.

We describe a 66-year-old woman with infective endocarditis due to Cardiobacterium hominis whose condition, complicated by severe aortic regurgitation and congestive heart failure, necessitated aortic valve replacement despite treatment with ceftriaxone followed by ciprofloxacin. The blood isolate of C. hominis produced beta-lactamase and exhibited high-level resistance to penicillin (MIC, >==256 microgram/ml) and reduced susceptibility to vancomycin (MIC, 8 microgram/ml).

Increased susceptibility to gingival colonization by specific HACEK microbes in children with congenital heart disease.

It is well established that infective endocarditis (IE) involving the HACEK (Hemophilus, Actinobacillus, Cardiobacter, Eikenella, Kingella) group of microbes occurs in patients with congenital heart defects (CHD) and in those with prosthetic grafts. Dental caries and gingival disease have been presumed to be the focus of microbial shedding. The purpose of this study was to determine if children with CHD had a more severe gingival inflammatory condition and harbored the HACEK group of microbes to a greater extent than normal children. Two groups of 12 age and sex matched children were selected for this study. The experimental group consisted of twelve children with CHD, 1-1/2 to 8 years of age. The control group consisted of 12 healthy children 2 to 8 years of age. Each child had a gingival index score recorded as described by Massler. Subgingival cultures were obtained. Gingival samples were cultured for HACEK microbes and total Streptococcus (spp) using standard techniques. Fisher's exact test was performed with significance defined at P < 0.05. Children with CHD had more severe gingival inflammatory index than the control group (P < 0.05). 8/12 CHD patient had Actinobacillus actinomycetemcomitans (A.a.) as compared with 2/12 controls (P < 0.05). Furthermore, all cyanotic CHD patients (4/4) had A.a. whereas, only 2/12 controls did (P < 0.05). 4/12 CHD patients harbored Eikenella corrodens (E.c.) compared to 1/12 controls (N.S.). There was no significant difference in colonization with E.c. or A.a. between cyanotic and acyanotic patients. No significant difference in total Streptococcus (spp) was found between the two groups. This study suggests that children with CHD have a more severe gingival inflammatory index and are colonized with specific HACEK microbes more so than normal children.

Oral health status, oral microflora, and non-surgical periodontal treatment of renal transplant patients receiving cyclosporin A and FK506.

OBJECTIVES: To determine the oral health status, oral microflora and the effect of non-surgical periodontal treatment on gingival overgrowth of renal allograft recipients receiving either cyclosporin A (CsA) or FK506 (Tacrolimus) as an immunosuppressant. MATERIALS AND METHODS: A total of 47 patients receiving CsA (mean age 43.1 years) and 10 receiving FK506 (mean age 40.1 years) were included in the study. Stone casts were taken for measurement of gingival overgrowth. An oral rinse technique was used to investigate the prevalence of yeasts, and aerobic and facultatively anaerobic Gram-negative rods (AGNR). RESULTS: The CsA and FK506 patients exhibited a Gingival Overgrowth Index (GOI) of 45.2%, and 25.1%, respectively (p < 0.05). The CsA patients had a GOI of 15.2% after one year of non-surgical periodontal treatment. The difference between pre- and postoperative gingival overgrowth indices was significant (p < 0.0001). Candida albicans and Klebsiella pneumoniae were the most notable yeast and AGRN found. CONCLUSIONS: Renal transplant patients, being immunocompromised, constitute a high-risk group for gingival overgrowth. However, the FK506 regime appeared to ameliorate this effect, compared with CsA. Non-surgical periodontal treatment was effective in reducing established gingival overgrowth in both CsA and FK506 patients (p < 0.05). Adequate pre- and post-transplant oral health care is recommended, for these patients, irrespective of the drug regime.

A study of deep-sea natural microbial populations and barophilic pure cultures using a high-pressure chemostat.

Continuous cultures in which a high-pressure chemostat was used were employed to study the growth responses of (i) deep-sea microbial populations with the naturally occurring carbon available in seawater and with limiting concentrations of supplemental organic substrates and (ii) pure cultures of copiotrophic barophilic and barotolerant deep-sea isolates in the presence of limiting carbon concentrations at various pressures, dilution rates, and temperatures. We found that the growth rates of natural populations could not be measured or were extremely low (e.g., a doubling time of 629 h), as determined from the difference between the dilution rate and the washout rate. A low concentration of supplemental carbon (0.33 mg/liter) resulted in positive growth responses in the natural population, which resulted in an increase in the number of cells and eventually a steady population of cells. We found that the growth responses to imposed growth pressure by barophilic and barotolerant pure-culture isolates that were previously isolated and characterized under high-nutrient-concentration conditions were maintained under the low-nutrient-concentration limiting conditions (0.33 to 3.33 mg of C per liter) characteristic of the deep-sea environment. Our results indicate that deep-sea microbes can respond to small changes in substrate availability. Also, barophilic microbes that are copiotrophic as determined by their isolation in the presence of high carbon concentrations and their preference for high carbon concentrations are versatile and are able to compete and grow as barophiles in the low-carbon-concentration oligotrophic deep-sea environment in which they normally exist.

Primary Shewanella alga septicemia in a patient on hemodialysis.

We report the first Japanese case of primary septicemia with Shewanella alga and also describe the bacteriological characteristics of and results of antibiotic susceptibility tests of the isolate. S. alga was repeatedly isolated, at times simultaneously with Escherichia coli, from the blood of a 64-year-old female undergoing hemodialysis. The isolated organism was determined to be S. alga based on recently published identification criteria, such as hemolysis on sheep blood agar, no acid production from carbohydrates, and growth on agar containing 6. 5% NaCl. Results of antibiotic susceptibility tests demonstrated that the isolate was sensitive to levofloxacin and cefpirome (MICs, 128, 64, and 8 microg/ml, respectively). Although the role of S. alga as a human pathogen has not been fully determined, accumulating data suggest that this organism may be a potential pathogen, especially in compromised hosts.

Polyphasic taxonomy of the genus Shewanella and description of Shewanella oneidensis sp. nov.

The genus Shewanella has been studied since 1931 with regard to a variety of topics of relevance to both applied and environmental microbiology. Recent years have seen the introduction of a large number of new Shewanella-like isolates, necessitating a coordinated review of the genus. In this work, the phylogenetic relationships among known shewanellae were examined using a battery of morphological, physiological, molecular and chemotaxonomic characterizations. This polyphasic taxonomy takes into account all available phenotypic and genotypic data and integrates them into a consensus classification. Based on information generated from this study and obtained from the literature, a scheme for the identification of Shewanella species has been compiled. Key phenotypic characteristics were sulfur reduction and halophilicity. Fatty acid and quinone profiling were used to impart an additional layer of information. Molecular characterizations employing small-subunit 16S rDNA sequences were at the limits of resolution for the differentiation of species in some cases. As a result, DNA-DNA hybridization and sequence analyses of a more rapidly evolving molecule (gyrB gene) were performed. Species-specific PCR probes were designed for the gyrB gene and used for the rapid screening of closely related strains. With this polyphasic approach, in addition to the ten described Shewanella species, two new species, Shewanella oneidensis and 'Shewanella pealeana', were recognized; Shewanella oneidensis sp. nov. is described here for the first time.

Thauera linaloolentis sp. nov. and Thauera terpenica sp. nov., isolated on oxygen-containing monoterpenes (linalool, menthol, and eucalyptol) nitrate.

The monoterpenes menthol, linalool, and eucalyptol were recently used as sole electron donor and carbon source for the isolation of three denitrifying bacterial strains 21Mol, 47Lol, and 58Eu. The motile, mesophilic, Gram-negative rods had a strictly respiratory metabolism. Monoterpenes were completely mineralised to carbon dioxide, nitrate was reduced to dinitrogen. Strain 47Lol utilised aliphatic monoterpenes, strain 21Mol oxygenated monocyclic monoterpenes, and strain 58Eu the bicyclic eucalyptol and monocyclic monoterpene alkenes. The fatty acid composition of the strains indicated an allocation to the rRNA group III of pseudomonads. Comparative 16S rRNA gene sequence analyses revealed that the new isolates can be assigned as members of the genus Thauera within the beta subclass of Proteobacteria. DNA-DNA hybridisation studies indicated a relateness of 68.5% between strains 21Mol and 58Eu which shared 36.0% and 40.6% DNA similarity with strain 47Lol. The strains are described as new species belonging to the genus Thauera, strain 47Lol (DSM 12138T) as T. linaloolentis sp. nov. and strains 21Mol and 58Eu as T. terpenica sp. nov. with strain 58Eu (DSM 12139T) as type strain.