Effects of intrinsic characteristics of Salmonella enterica strains isolated from foods and humans, and their interaction with food matrices during simulated gastric conditions.

The stomach's acidic pH is a crucial barrier against foodborne pathogens such as Salmonella enterica. This study investigated the survival of S. enterica under simulated oral and gastric conditions (SGC; pH 2 for 120 min) as a function of intrinsic pathogen characteristics and food matrix. Fifty-seven S. enterica strains isolated from food and human infections (previously characterized by serotype, virulotype, multi-drug resistance, isolation source, and isolation season) were subjected to SGC using water as a vehicle. Population reduction among the 57 isolates ranged from 2.7 to 4.7 log CFU, revealing that human isolates were inactivated less than food isolates (p = 0.0008). Among food strains, strains isolated during the cold season (food sampled from December to February) displayed the highest reduction (p = 0.00002). Six representatives of the 57 S. enterica strains were selected according to their virulotype and antimicrobial profile. They were further used to evaluate their survival under SGC in four food matrices (water, mango, tomato, and chicken), measuring S. enterica at 30 min intervals. The strains in chicken showed the lowest reduction and inactivation rate (1.42 ± 0.35 log CFU; 0.03 ± 0.005 min-1), followed by tomato (3.75 ± 0.57 log CFU; 0.15 ± 0.02 min-1), water (4.23 ± 0.27 log CFU; 0.17 ± 0.02 min-1), and mango (4.49 ± 0.39 log CFU; 0.17 ± 0.03 min-1). These data suggest that not all S. enterica strains have the same ability to survive under SGC, influencing the probability of arriving into the small intestine.

Composition and functionality of bacterioplankton communities in marine coastal zones adjacent to finfish aquaculture.

Finfish aquaculture is a fast-growing primary industry and is increasingly common in coastal ecosystems. Bacterioplankton is ubiquitous in marine environment and respond rapidly to environmental changes. Changes in bacterioplankton community are not well understood in semi-enclosed stratified embayments. This study aims to examine aquaculture effects in the composition and functional profiles of the bacterioplankton community using amplicon sequencing along a distance gradient from two finfish leases in a marine embayment. Results revealed natural stratification in bacterioplankton associated to NOx, conductivity, salinity, temperature and PO4. Among the differentially abundant bacteria in leases, we found members associated with nutrient enrichment and aquaculture activities. Abundant predicted functions near leases were assigned to organic matter degradation, fermentation, and antibiotic resistance. This study provides a first effort to describe changes in the bacterioplankton community composition and function due to finfish aquaculture in a semi-enclosed and highly stratified embayment with a significant freshwater input.

The effect of fishmeal inclusion and prebiotic supplementation on the hindgut faecal microbiota of farmed Tasmanian Atlantic salmon (Salmo salar L.).

AIMS: Factors such as seasonal temperature and diet components, for example, fishmeal (FM) inclusion, can influence the composition of the gut microbiota of fish. In this study, we examined changes in the gut bacterial populations, in particular lactic acid bacteria (LAB), of farmed Tasmanian Atlantic salmon in response to different diets, during periods of higher water temperature. METHODS AND RESULTS: Between December 2011 and March 2012 hindgut faecal samples were collected from Atlantic salmon from a commercial fish farm in south of Hobart, Tasmania, fed with one of four trial diets containing either high or low FM inclusion levels with or without prebiotics. Overall there was little difference in the cultivatable bacterial populations in response to varying levels of FM and prebiotic supplementation, with LAB counts decreasing in response to increased water temperatures. However, it was observed that the high FM diet supported the presence of LAB in January, when these were not detected in the low FM diets. CONCLUSIONS: Our study indicates that the inclusion of higher amounts of FM rather than the addition of prebiotics has a greater effect on LAB colonization of the gut in Atlantic salmon. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the importance of the new fish feeds for promoting salmon health in aquaculture industry.

Pyrosequencing-based characterization of gastrointestinal bacteria of Atlantic salmon (Salmo salar L.) within a commercial mariculture system.

AIMS: The relationship of Atlantic salmon gastrointestinal (GI) tract bacteria to environmental factors, in particular water temperature within a commercial mariculture system, was investigated. METHODS AND RESULTS: Salmon GI tract bacterial communities commercially farmed in south-eastern Tasmania were analysed, over a 13-month period across a standard commercial production farm cycle, using 454 16S rRNA-based pyrosequencing. Faecal bacterial communities were highly dynamic but largely similar between randomly selected fish. In postsmolt, the faecal bacteria population was dominated by Gram-positive fermentative bacteria; however, by midsummer, members of the family Vibrionaceae predominated. As fish progressed towards harvest, a range of different bacterial genera became more prominent corresponding to a decline in Vibrionaceae. The sampled fish were fed two different commercial diet series with slightly different protein, lipid and digestible energy level; however, the effect of these differences was minimal. CONCLUSIONS: The overall data demonstrated dynamic hind gut communities in salmon that were related to season and fish growth phases but were less influenced by differences in commercial diets used routinely within the farm system studied. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides understanding of farmed salmon GI bacterial communities and describes the relative impact of diet, environmental and farm factors.

Culturable microbiota of ranched southern bluefin tuna (Thunnus maccoyii Castelnau).

AIMS: The Australian tuna industry is based on the ranching of wild southern bluefin tuna (SBT, Thunnus maccoyii). Within this industry, only opportunistic pathogens have been reported infecting external wounds of fish. This study aimed to identify different culturable bacteria present in three cohorts of SBT and to determine normal bacteria and potential pathogens in isolates from harvest fish and moribund/dead fish. Post-mortem changes in the microbiota were also studied. METHODS AND RESULTS: Moribund/dead showed a greater proportion of members from the family Vibrionaceae than harvested fish; the latter presented mainly non-Vibrio species. In harvested fish spleens, Vibrio splendidus I complex was the most commonly identified group among Vibrio isolates, while most groups from the family Vibrionaceae were isolated from gills. For moribund/dead, Vibrio chagasii and Photobacterium damselae subsp. damselae were common in gill, spleen and kidney samples. Non-Vibrio isolates from gills were characterized using 16S rRNA sequencing as Flavobacteriaceae and classes Gammaproteobacteria and Alphaproteobacteria, mainly from the genera Winogradskyella and Tenacibaculum. Post-mortem changes showed dynamic shifts in bacterial dominance in gills, with Vibrionaceae and non-Vibrio spp. found in similar proportions initially and types related to Pseudoalteromonas ruthenica prevailing after 27 h. Spleen samples showed little bacterial growth until 5 h post-mortem, while various Vibrio-associated species were isolated 27 h post-mortem. CONCLUSIONS: Bacterial isolates found include a range of potentially pathogenic bacteria that should be monitored though most of them have yet to be associated with disease in tuna. SIGNIFICANCE AND IMPACT OF THE STUDY: This study forms a foundation for future research into the bacterial population dynamics under different culture conditions of SBT. An understanding of the bacterial compositions in SBT is necessary to evaluate the effects of some bacterial species on their health.

Molecular analysis of the bacterial communities in the live Pacific oyster (Crassostrea gigas) and the influence of postharvest temperature on its structure.

AIMS: To evaluate the effect of postharvest temperature on bacterial communities in live Pacific oysters (Crassostrea gigas) using nonculture-based methods. METHODS AND RESULTS: Live oysters were compared before and after storage at 4, 6, 15, 20 and 30°C using terminal restriction fragment length polymorphism (T-RFLP). Bacterial communities in freshly harvested (control) vs stored oysters were significantly different. Changes in bacterial communities at 4, 15 and 30°C observed by T-RFLP were further investigated by clone library analysis. Members of the Proteobacteria predominated (43·0-57·0% of clones) in control oysters, while storage altered the bacterial profile. At 4°C, Psychrilyobacter spp. (phylum Fusobacteria) predominated (43·8% of clones), while at 15 and 30°C, members of the phylum Bacteroidetes represented 63·0 and 60·2% of clones, respectively. High microbial diversity in oysters was observed, with at least 73 different genera-related clones among all samples. CONCLUSIONS: Changes in the overall bacterial community of Pacific oysters were influenced by storage temperature and would likely not be detected by standard culture-based methods currently used to assess oyster quality. Certain dominant genera, such as Psychrilyobacter, Polynucleobacter and a bacterial group related to Alkaliflexus, should be further studied as possible indicators for postharvest temperature control. SIGNIFICANCE AND IMPACT OF THE STUDY: This work is the first report describing the effect of different storage temperatures on bacterial diversity in postharvest live Pacific oysters using molecular-based methods.

Evaluation of thermal inactivation of Escherichia coli using microelectrode ion flux measurements with osmotic stress.

AIMS: To elucidate the potential use of microelectrode ion flux measurements to evaluate bacterial responses to heat treatment. METHODS AND RESULTS: Escherichia coli K12 was used as a test bacterium to determine whether various heat treatments (55-70°C for 15 min) affected net ion flux across E. coli cell membranes using the MIFE™ system to measure net K(+) fluxes. No difference in K(+) fluxes was observed before and after heat treatments regardless of the magnitude of the treatment. Applying hyperosmotic stress (3% NaCl w/v) during flux measurement led to a net K(+) loss from the heat-treated E.coli cells below 65°C as well as from nonheated cells. In contrast, with E. coli cells treated at and above 65°C, hyperosmotic stress disrupted the pattern of K(+) flux observed at lower temperatures and resulted in large flux noise with random scatter. This phenomenon was particularly apparent above 70°C. Although E. coli cells lost the potential to recover and grow at and above 62°C, K(+) flux disruption was not clearly observed until 68°C was reached. CONCLUSIONS: No changes in net K(+) flux from heat-stressed E. coli cells were observed directly as a result of thermal treatments. However, regardless of the magnitude of heat treatment above 55°C, loss of viability indicated by enrichment culture correlated with disrupted K(+) fluxes when previously heated cells were further challenged by imposing hyperosmotic stress during flux measurement. This two-stage process enabled evaluation of the lethality of heat-treated bacterial cells within 2 h and may be an alternative and more rapid method to confirm the lethality of heat treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability to confirm the lethality of thermal treatments and to specify minimal time/temperature combinations by a nonculture-dependent test offers an alternative system to culture-based methods.

Bacterial exopolysaccharides from extreme marine environments with special consideration of the southern ocean, sea ice, and deep-sea hydrothermal vents: a review.

Exopolysaccharides (EPSs) are high molecular weight carbohydrate polymers that make up a substantial component of the extracellular polymers surrounding most microbial cells in the marine environment. EPSs constitute a large fraction of the reduced carbon reservoir in the ocean and enhance the survival of marine bacteria by influencing the physicochemical environment around the bacterial cell. Microbial EPSs are abundant in the Antarctic marine environment, for example, in sea ice and ocean particles, where they may assist microbial communities to endure extremes of temperature, salinity, and nutrient availability. The microbial biodiversity of Antarctic ecosystems is relatively unexplored. Deep-sea hydrothermal vent environments are characterized by high pressure, extreme temperature, and heavy metals. The commercial value of microbial EPSs from these habitats has been established recently. Extreme environments offer novel microbial biodiversity that produces varied and promising EPSs. The biotechnological potential of these biopolymers from hydrothermal vent environments as well as from Antarctic marine ecosystems remains largely untapped.

Biogeographic and quantitative analyses of abundant uncultivated gamma-proteobacterial clades from marine sediment.

16S rRNA gene-based molecular analyses revealed the presence of several large and so far uncultivated clades within class gamma-Proteobacteria, designated gamma-proteobacterial marine sediment (GMS) clades 1 to 4, in marine sediment. The GMS clades appear only indigenous to marine sediment and so far have an unknown functionality. SYBR Green-based real-time PCR analyses using GMS clade-specific primers indicated GMS clades were a significant part of the bacterial community (0.3-8.7% of total 16S rRNA genes) in both polar and temperate marine sediment samples. Univariate statistical analyses indicated that GMS clade communities were indistinguishable in two temperate coastal sediment samples even though these possessed very different mean grain sizes, organic contents, and organic loading rates. GMS clade communities were slightly different (p < 0.05) between polar and temperate sites, suggesting that psychrophilic adaptation among GMS clade taxa corresponds only to subtle phylogenetic differences. Similar levels of difference were also observed through a sediment core reflecting that through the sediment core history, which spanned approximately 3000 years, GMS clonal diversity shifted only marginally.

Psychrophilic prokaryote structural-functional relationships, biogeography and evolution within marine sediment.

Prokaryote diversity has been found to be surprisingly high in cold marine sediments with numerous clades detected spread throughout many phyla. Marine benthic sediment clades are largely ecotypically distinct and autochthonous. Since almost all marine sediment prokaryotic taxa have yet to be cultivated, functionality is currently overwhelmingly cryptic for most benthic prokaryotic taxa except those falling into specific lineages for which there is cultivation or detailed biogeochemical data. Multivariate statistical comparisons of 16S rRNA gene sequence and denaturing gradient gel electrophoresis (DGGE) data show distinct distribution patterns of prokaryotic communities in sediment layers. By comparison geographical differences and differences related to the physical texture and organic content seem to result in generally smaller differences.

Salmonid gill bacteria and their relationship to amoebic gill disease.

16S ribosomal RNA gene analysis was used to assess the bacterial community associated with Atlantic salmon, Salmo salar L., gills which were either affected by amoebic gill disease (AGD) or were AGD-negative, in order to determine the role that bacteria may play in the development of AGD. AGD-positive specimens were either infected in the laboratory with Neoparamoeba pemaquidensis, the causative agent of AGD, or were obtained from commercial salmon cages. Samples from laboratory fish maintained in sea water possessed a marine-type community while field samples which had been treated by a series of freshwater baths possessed a more diverse community which included variable proportions of different bacterial ecotypes, including groups typically associated with soil, skin surfaces and faeces. Samples from fish infected with AGD in the laboratory and a sample from one of two salmon cage fish specimens were dominated by a phylotype belonging to the strictly marine bacterial genus Psychroserpens (family Flavobacteriaceae, phylum Bacteroidetes). The phylotype was not detected in any of the AGD-negative samples or in one of two AGD-positive samples obtained from fish subjected to temporary freshwater immersion. The possibility of certain Psychroserpens species as potential opportunistic pathogens associated with salmonid AGD is proposed.

Production of exopolysaccharides by Antarctic marine bacterial isolates.

AIMS: This study was undertaken to examine and characterize Antarctic marine bacterial isolates and the exopolysaccharides (EPS) they produce in laboratory culture. METHODS AND RESULTS: Two EPS-producing bacterial strains CAM025 and CAM036 were isolated from particulate material sampled from seawater and sea ice in the southern ocean. Analyses of 16S rDNA sequences placed these isolates in the genus Pseudoalteromonas. In batch culture, both strains produced EPS. The yield of EPS produced by CAM025 was 30-fold higher at -2 and 10 degrees C than at 20 degrees C. Crude chemical analyses showed that these EPS were composed primarily of neutral sugars and uronic acids with sulphates. Gas chromatographic analysis of monosaccharides confirmed these gross compositional findings and molar ratios of monosaccharides revealed differences between the two EPS. CONCLUSIONS: The EPS produced by Antarctic bacterial isolates examined in this study appeared to be polyanionic and, therefore, 'sticky' with respect to cations such as trace metals. SIGNIFICANCE AND IMPACT OF THE STUDY: As the availability of iron as a trace metal is of critical importance in the southern ocean where it is know to limit primary production, the role of these bacterial EPS in the Antarctic marine environment has important ecological implications.

Prokaryotic metabolic activity and community structure in Antarctic continental shelf sediments.

The prokaryote community activity and structural characteristics within marine sediment sampled across a continental shelf area located off eastern Antarctica (66 degrees S, 143 degrees E; depth range, 709 to 964 m) were studied. Correlations were found between microbial biomass and aminopeptidase and chitinase rates, which were used as proxies for microbial activity. Biomass and activity were maximal within the 0- to 3-cm depth range and declined rapidly with sediment depths below 5 cm. Most-probable-number counting using a dilute carbohydrate-containing medium recovered 1.7 to 3.8% of the sediment total bacterial count, with mostly facultatively anaerobic psychrophiles cultured. The median optimal growth temperature for the sediment isolates was 15 degrees C. Many of the isolates identified belonged to genera characteristic of deep-sea habitats, although most appear to be novel species. Phospholipid fatty acid (PLFA) and isoprenoid glycerol dialkyl glycerol tetraether analyses indicated that the samples contained lipid components typical of marine sediments, with profiles varying little between samples at the same depth; however, significant differences in PLFA profiles were found between depths of 0 to 1 cm and 13 to 15 cm, reflecting the presence of a different microbial community. Denaturing gradient gel electrophoresis (DGGE) analysis of amplified bacterial 16S rRNA genes revealed that between samples and across sediment core depths of 1 to 4 cm, the community structure appeared homogenous; however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. Sequencing of DGGE bands and rRNA probe hybridization analysis revealed that the major community members belonged to delta proteobacteria, putative sulfide oxidizers of the gamma proteobacteria, Flavobacteria, Planctomycetales, and Archaea. rRNA hybridization analyses also indicated that these groups were present at similar levels in the top layer across the shelf region.

A comparative 3-month clinical investigation of the safety and efficacy of a battery-operated and a rechargeable oscillating-rotating power toothbrush.

PURPOSE: To compare the safety and efficacy of two oscillating-rotating power toothbrushes, the rechargeable Braun Oral-B D8 and the battery-powered Colgate Actibrush. MATERIALS AND METHODS: This was a randomized, examiner-blind, parallel-group study, carried out over 3 months of product use, involving a total of 113 healthy subjects with a plaque score of > or = 1.5 and a gingivitis score of > or = 1.1. Subjects were given written and verbal instructions in the use of their respective power brushes and were told to brush twice per day. At baseline, hard and soft tissues were examined, and plaque scores and gingival scores were recorded after 12-18 hrs of no oral hygiene. Subjects returned after 3 months, at which time soft and hard tissues were re-examined and plaque and gingivitis scores were recorded. RESULTS: No evidence was found of soft or hard tissue trauma and both brushes were considered to be safe when used according to the manufacturers' instructions. After 3 months, whole mouth plaque scores had decreased by 7% in the D8 group but had increased by 4.3% in the Actibrush group. The decrease from baseline in the D8 group was statistically significant, but the increase in the Actibrush group was not. The difference between the two groups was statistically significant both for the whole mouth and all individual sites. Whole mouth gingivitis scores were also reduced significantly from baseline in both groups, by 22.5% in the D8 group and by 17.5% in the Actibrush group. For whole mouth scores and all individual sites (interproximal, buccal and lingual), the D8 was significantly more effective than the Actibrush.

A molecular phylogenetic survey of sea-ice microbial communities (SIMCO).

16S rDNA clone library analysis was used to identify bacterial biodiversity in a variety of sea-ice microbial communities (SIMCO). DNA was extracted from seven Antarctic sea-ice samples and one Arctic sea-ice sample and 16S rDNA PCR-amplified using universal and Archaea-specific primers. Recombinant 16S rDNA clones were obtained and dereplicated using restriction fragment length polymorphism analysis (RFLP). After RFLP analysis, 100 distinct phylotypes (a unique clone or group of clones with sequence similarity of >0.98) were defined. From the clone libraries 16S rDNA sequences of bacterial and eukaryotic origin were detected, however Archaea were not detected either with universal or Archaea-specific 16S rDNA primer sets. Bacterial phylotypes grouped within the alpha and gamma proteobacteria, the Cytophaga-Flavobacterium-Bacteroides division, the Gram-Positive bacteria and the orders Chlamydiales and Verrucomicrobiales. The majority of bacterial phylotypes were affiliated with heterotrophic taxa and many grouped closely with cultivated genera and species. Eukaryotic clones were affiliated with a variety of autotrophic and heterotrophic nanoplankton and included a large number of chloroplast 16S rDNA genes. The findings of this investigation corroborated culture data indicating bacterial biodiversity increased in SIMCO displaying high levels of primary production, however the bacterial communities within SIMCO were highly heterogeneous at the genus/species-level between different samples. A comparison of Antarctic and Arctic SIMCO revealed certain sea-ice dwelling bacterial genera are common at both poles.

Desulfosporosinus meridiei sp. nov., a spore-forming sulfate-reducing bacterium isolated from gasolene-contaminated groundwater.

Eight strains of spore-forming, sulfate-reducing bacteria, isolated from groundwater contaminated with motor fuel [mostly benzene, toluene ethylbenzene and xylene (BTEX) compounds] in sandy soil near Perth, Australia, were closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 765T (95.3-97.3% 16S rDNA sequence similarity). Whole-cell fatty acids were dominated by even-carbon, straight-chain saturated and mono-unsaturated fatty acids, in particular 16:0, 16:1cis9, 14:0 and 18:1cis11. The strains grew at temperatures between 4 and 42 degrees C and in medium containing up to 4% NaCl. The eight strains clustered into two main groups based on phylogeny, randomly amplified polymorphic DNA (RAPD)-PCR patterns and nutritional characteristics. Representatives of the two groups, strain S5 (group A) and strain S10T (group B) had 81% DNA-DNA homology with each other and therefore should be accommodated in the same species. Strain S10T had less than 38% homology with Desulfosporosinus orientis DSM 765T, the most closely phylogenetically related type strain available. The new strains were distinguished from Desulfosporosinus orientis DSM 765T by different banding patterns in a RAPD-PCR, and phenotypically by their inability to utilize fumarate as a carbon and energy source with sulfate as the electron acceptor and by their lower tolerance to NaCl. The DNA G+C contents were 46.8 and 46.9 mol% for strains S5 and S10T, respectively (Desulfosporosinus orientis DSM 765T 45.9 mol%). It is proposed that these new strains be placed in a new species of the genus Desulfosporosinus. The name Desulfosporosinus meridiei is proposed, with strain S10T as the type strain (= DSM 13257T = NCIMB 13706T).

Oral malodor control afforded through the use of sodium bicarbonate-containing chewing gum.

Published research indicates that regular use of toothpaste containing sodium bicarbonate is effective in reducing volatile sulfur compounds (VSCs) and oral malodor. Gaffar initially reported on the use of sodium bicarbonate as an agent to affect VSCs, indicating that sodium bicarbonate had the potential to alter the VSCs to nonvolatile compounds. Chewing gum would also be suspected of providing benefits in controlling oral malodor through its claimed ability to mechanically aid in the removal of dental plaque. Based on the length of chewing time, the opportunity exists for chewing gum to reach places in the mouth that might be missed during brushing. This activity could contribute to reductions in the amount of viable plaque mass that could produce VSCs.

Description of Cellulophaga algicola sp. nov., isolated from the surfaces of Antarctic algae, and reclassification of Cytophaga uliginosa (ZoBell and Upham 1944) Reichenbach 1989 as Cellulophaga uliginosa comb. nov.

A group of strains with potent extracellular enzymic activity were isolated from the surfaces of the chain-forming sea-ice diatom Melosira and from an unidentified macrophyte collected from the Eastern Antarctic coastal zone. 16S rDNA sequence analysis indicated that the strains belonged to the genus Cellulophaga and showed greatest similarity to the species Cellulophaga baltica (sequence similarity 97%). Phenotypic characteristics, DNA base composition and DNA-DNA hybridization values clearly separate the Antarctic strains from Cellulophaga baltica and other Cellulophaga species. Thus, the strains form a distinct and novel species and have the proposed name Cellulophaga algicola sp. nov. (type strain IC166T = ACAM 630T). In addition, it was recognized that the species Cytophaga uliginosa (ZoBell and Upham 1944) Reichenbach 1989, a species phylogenetically remote from the type species of the genus Cytophaga, possessed 16S rDNA sequences and phenotypic and chemotaxonomic traits similar to those of other Cellulophaga species. Thus, it was proposed that the species Cytophaga uliginosa be renamed as Cellulophaga uliginosa comb. nov.

Taxonomy of Antarctic Flavobacterium species: description of Flavobacterium gillisiae sp. nov., Flavobacterium tegetincola sp. nov., and Flavobacterium xanthum sp. nov., nom. rev. and reclassification of [Flavobacterium] salegens as Salegentibacter salegens gen. nov., comb. nov.

16S rRNA phylogenetic analysis of a number of yellow- and orange-pigmented strains isolated from a variety of Antarctic habitats including sea ice, lakewater and cyanobacterial mats indicated a close relationship to the genus Flavobacterium but distinct from known Flavobacterium species. Phenotypic properties, DNA G+C content and whole-cell fatty acid profiles of the Antarctic strains were consistent with those of the genus Flavobacterium. DNA-DNA hybridization analysis indicated the presence of two distinct and novel genospecies each isolated from a different Antarctic habitat. From polyphasic taxonomic data it is proposed that the two groups represent new species with the following proposed names: Flavobacterium gillisiae (ACAM 601T) and Flavobacterium tegetincola (ACAM 602T). In addition polyphasic analysis of the species '[Cytophaga] xantha' (Inoue and Komagata 1976), isolated from Antarctic mud, indicated it was a distinct member of the genus Flavobacterium and was thus revived as Flavobacterium xanthum. Phylogenetic and fatty acid analyses also indicate that the species [Flavobacterium] salegens (Dobson et al. 1993), from Organic Lake, Antarctica, is misclassified at the genus level. It is proposed that this species belongs to a new genus, Salegentibacter salegens gen. nov., comb. nov.

Sterols in a psychrophilic methanotroph, Methylosphaera hansonii.

A suite of six sterols, lanosterol, lanost-8(9)-en-3beta-ol, 4, 4-dimethylcholesta-8(14),24-dien-3beta-ol, 4, 4-dimethylcholest-8(14)-en-3beta-ol, 4-methylcholesta-8(14), 24-dien-3beta-ol and 4-methylcholest-8(14)-en-3beta-ol, were identified in the psychrophilic methanotrophic bacterium, Methylosphaera hansonii. Their presence suggests that the capacity for sterol biosynthesis in methanotrophic bacteria is limited to the family Methylococcaceae but which have widely different optimal growth temperatures.