[Show abstract][Hide abstract] ABSTRACT: A Gram-negative, non-motile, non-sporulating bacterial strain, designated LYX05(T), was isolated from coastal sediment of Qingdao, China, on the coast of the Yellow Sea. Strain LYX05(T) was aerobic and heterotrophic. The strain grew optimally at 37 °C and pH 7.5 and in the presence of 2% (w/v) NaCl. Colonies were 1-2 mm in diameter, circular, reddish orange and shiny with entire edges on marine agar medium. Cells were rods (0.3-0.5 µm wide and 0.8-1.6 µm long). The dominant fatty acids were iso-C(15:0) (40.82%) and C(16:0) (10.45%). The DNA G+C content was 42.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain LYX05(T) was phylogenetically related to the members of the genus Algoriphagus and the closest relative was Algoriphagus hitonicola 7-UAH(T) (95.8% 16S rRNA gene sequence similarity). On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain LYX05(T) was considered to represent a novel species of the genus Algoriphagus, for which the name Algoriphagus faecimaris sp. nov. is proposed. The type strain is LYX05(T) (=JCM 16561(T) =DSM 23095(T) =LMG 25474(T)).
Full-text · Article · Dec 2011 · International Journal of Systematic and Evolutionary Microbiology
[Show abstract][Hide abstract] ABSTRACT: A fish pathogen Edwardsiella tarda LTB-4 produced various indole alkaloids, including indole, 2-(1H-indol-3-yl)ethanol, 4-di(1H-indol-3-yl)methylphenol, tri(1H-indol-3-yl)methane and 2-[2,2-bis(1H-indol-3-yl)]ethylphenylamine. Indole was the most abundant among these indole alkaloids. E. tarda LTB-4 produced indoles during its whole growth phase and maintained a high level (around 35.5 µM) during the stationary phase. The relevant tryptophanase (TnaA) gene tnaA was cloned from LTB-4 and conditionally expressed in Escherichia coli; the recombinant TnaA catalysed L-tryptophan to indole. A tnaA in-frame deletion mutant ΔtnaA was constructed through double cross-over allelic exchange by means of the suicide vector pRE118; deletion of tnaA caused some phenotypic changes including decreased swarming and twitching motility, lipopolysaccharide production and multiple antibiotic resistances. Also, subtherapeutic doses of chloromycetin, carbenicillin and tetracyline could cause the decrease of bacterial growth, but greatly induce the production of indole by E. tarda. Most importantly, attenuated virulence of the ΔtnaA mutant to zebra fish by increasing the LD50 for about 55-fold indicated that TnaA involved in the virulence of E. tarda.
No preview · Article · Oct 2011 · Environmental Microbiology Reports
[Show abstract][Hide abstract] ABSTRACT: A novel Gram-negative, non-motile bacterium, designated ZXM137(T), was isolated from seawater collected from a coastal region of Qingdao, China, during a massive green algae (Enteromorpha prolifera) bloom. Strain ZXM137(T) was strictly aerobic and did not accumulate poly-β-hydroxybutyrate. Growth occurred with 0.5-11.0% (w/v) NaCl, at pH 6-9 (optimum of pH 7) and at 4-45 °C (optimum at 28 °C). It contained Q-10 as the predominant ubiquinone and the major polar lipids were phosphatidylglycerol, phospholipids, and an unidentified aminolipid and lipid. The major cellular fatty acids of strain ZXM137(T) were C(18:1)ω7c, C(18:1)ω6c and 11-methyl C(18:1)ω7c. The DNA G+C content was 60.1 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain ZXM137(T) formed a distinct evolutionary lineage within the Roseobacter group in the class Alphaproteobacteria. On the basis of phenotypic, chemotaxonomic and phylogenetic evidence, strain ZXM137(T) represents a novel species in a new genus, for which the name Huaishuia halophila gen. nov., sp. nov. is proposed; the type strain is ZXM137(T) (=CGMCC 1.8891(T)=LMG 24854(T)).
Full-text · Article · Mar 2011 · International Journal of Systematic and Evolutionary Microbiology
[Show abstract][Hide abstract] ABSTRACT: The development of non-antibiotic and environmental friendly agents is one of the key factors for health management in aquaculture. The application of probiotics in aquaculture of China emerged in 1980s; subsequently, commercial probiotic products from USA, Japan and United Kingdom were introduced into China in the middle of 1990s and evaluation experiments were conducted in vivo. In the mean time, scientists in China started to screen for new probiotic strains from local aquaculture rearing unit in an attempt to suit the specific requirements in China. Also, different modes of action of probiotics were studied. As products containing probiotic bacteria are gaining popularity in aquaculture of China, the quality control of probiotics in aquaculture has become an important issue in China. At present, data about the efficacy of probiotics in commercial aquaculture of China are still lacking. This review discusses mainly the studies and applications about species, effects, mechanisms, problems and prospect of probiotics used in aquaculture of China, and highlighted several effective evaluation methods to control the quality of commercial probiotic products.
[Show abstract][Hide abstract] ABSTRACT: Rotifer growth performance and microbial community changes associated with rotifer cultures were monitored while different
feed types (Nannochloropsis oculata paste and the commercial yeast based feed CS-3000), different regimes (daily changes, changes per batch and no changes) and
mixtures of three probionts (Phenylobacterium sp.; Gluconobacter sp. and Paracoccus denitrificans) were provided. It was shown that the dominant bacterial species in the cultures receiving either N.oculata or CS-3000 were different. However, in cultures receiving both feeds (either switching between feeds on a daily basis or
on a batch basis), a high similarity in microbial community fingerprint was found. The presence of probionts was detected
by the end of four batch culture cycles in spite of strong shifts of the bacterial community. By group discriminant analysis,
it was found that Phenylobacterium sp. and Paracoccus sp. contributed positively to the CS-3000-fed group, while Gluconobacter sp. contributed positively to the N.oculata-fed group, although they did not appear as very dominant species.
Full-text · Article · Apr 2009 · Aquaculture International
[Show abstract][Hide abstract] ABSTRACT: The evolution of the composition of microbial communities associated with cultures of 3 different strains belonging to different cryptic species of the rotifer Brachionus plicatilis was monitored during four subsequent cycles of batch cultivation using denaturing gradient gel electrophoresis, cluster analysis, multidimensional scaling and principal component analysis. The data suggest that the evolving microbial communities are different with different B. plicatilis strain cultures. Moreover, large changes in rotifer growth rate were found to be associated with large changes in the microbial community composition, suggesting that there might be a causal link. Finally, Lorenz curves and Gini-coefficient analysis revealed that good performing B. plicatilis cultures showed a more even microbial community structure.