Physiological and Biochemical Characteristics of the Halophilic Bacteria Vibrio parahaemolyticus and V. alginolyticus Isolated from Marine Invertebrates of Peter the Great Bay, Sea of Japan

One hundred strains of halophilic vibrios were isolated from 16 species of marine invertebrates of Peter the Great Bay. Based on their morphological and biochemical characteristics, the bacteria were identified as Vibrio parahaemolyticus and Vibrio alginolyticus. Bacterial isolates possessed virulence enzymes (DNAase, lecithinase, catalase) and were characterized by a high enterotoxigenicity. It was determined that 76% of the V. parahaemolyticus strains and 43% of the V. alginolyticus strains were Kanagawa-positive. The isolates showed a high adhesive capability, the average adhesion index was 18.06 cells per erythrocyte for V. parahaemolyticus and 12.55 for V. alginolyticus. The results of this study suggest a high pathogenic potential of the isolated halophilic vibrios, which are an epidemic hazard to marine invertebrates and to humans.     

Characterization of <Emphasis Type="Italic">Vibrio gigantis</Emphasis> and <Emphasis Type="Italic">Vibrio pomeroyi</Emphasis> isolated from invertebrates of Peter the Great Bay,Sea of Japan

Previously unknown associations of Vibrio gigantis with the trepang Apostichopus japonicus and of V. pomeroyi with the sea urchin Strongylocentrotus nudus were described in Vostok Bay of Peter the Great Bay, Sea of Japan. Bacterial isolates were identified based on their morphological, cultural and biochemical characteristics, as well as by 16S rRNA gene sequencing. Strain 915 (V. gigantis) was found to possess amylase, gelatinase, chitinase, pustulanase, glucosidase, galactosidase, and alginase, while strain 929 (V. pomeroyi) possessed amylase, gelatinase, chitinase, and fucoidanase. S. nudus and A. japonicus probably provide favorable niches for V. gigantis and V. pomeroyi and act as natural reservoirs for these bacteria in Peter the Great Bay. The broad spectrum of enzymes in associated vibrios suggests their role in food digestion of the above marine invertebrates.     

Application of the multisubstrate testing method to the characterization of marine microbial fouling communities on metals and alloys

The functional state of marine micro fouling communities of corroding metal plates was analyzed using a modified method of multisubstrate testing. Qualitative and quantitative differences were found in the substrate utilization spectra of the fouling micro flora that were dependent on the type of metal surface and the place of sample exposure. The activity of substrate consumption by fouling micro flora can be used as a criterion for estimating the intensity of corrosion processes on metal surfaces and as a clustering and classification criterion.     

Distribution of the enzymes of carbohydrate metabolism among marine microorganisms in the Sea of Japan and the South Chinese Sea

The ability to produce extracellular enzymes of carbon metabolism was studied in 55 strains related to 18 taxa and isolated from various habitats. Production of a number of enzymes was found to depend on the source from which the strains were isolated. Among the strains associated with algae and marine invertebrates, the highest number of producers were found in the seawater of Primorski krai. The strains isolated from this temperate climatic zone possessed higher enzymatic activity than those isolated from the tropical zone. The results obtained in the current research are useful for further directed searching for the producers of specific O-glycoside hydrolases.     

The taxonomic composition,characteristics, and neurotoxic activities of ribbon worm-associated bacteria from the Sea of Japan

The taxonomic composition of bacteria associated with two species of tetrodotoxin-bearing (TTX-bearing) (Hubrechtella juliae and Lineus alborostratus) and two species of non-TTX-bearing (Quasitetrastemma stimpsoni and Malacobdella grossa) ribbon worms collected from the Peter the Great Bay of Sea of Japan was studied. Bacterial isolates were identified using 16S rRNA gene sequencing and phenotypic characteristics. Thirty-eight strains of heterotrophic bacteria from the eight genera: Pseudoalteromonas, Shewanella, Ruegeria, Pseudomonas, Defluviicoccus, Vibrio, Alteromonas, and Bacillus, were isolated and characterized. γ-Proteobacteria dominated among the associated microflora of nemerteans (76.3% of the total number of isolates). Sensitivity analysis of 38 strains to antibiotics of various classes revealed multiple resistance to three or more antibiotics in all of the studied isolates. The 15 bacterial strains isolated in the study exhibited antimicrobial activities against at least one of five indicator microorganisms, most of which corresponded to the Pseudoalteromonas genus. Screening of the TTX-producing bacteria was performed using confocal laserscanning microscopy and polyclonal antibodies. A TTX-producing strain, Pseudoalteromonas sp., was found in the nemertean H. juliae. A correlation between the presence of TTX-positive microflora and the toxicity of nemerteans was determined.     

Opportunistic bacteria detected in cultivated mussels

As many as 8 Listeria monocytogenes strains, 12 Pseudomonas aeruginosa strains and 5 Staphylococcus aureus strains were isolated from mussels Mytilus edulis, grown on special installations in the Trinity Bay of the Gulf of Peter the Great, the Sea of Japan. The isolated cultures proved to be highly resistant to a number of antibiotics. Many strains displayed DNAase and haemolytic activity. The cultures of L. monocytogenes, S. aureus and P. aeruginosa also had high lipase, protease and lecithinase activity. The organism of the mussels seems to be a confinement for these bacteria under study.     

Biochemical and pathogenic properties of the natural isolate of Shewanella algae from Peter the Great Bay, Sea of Japan

Pathogenic properties of the natural isolate of Shewanella algae from the coelomic fluid of the sea cucumber Apostichopus japonicus (Peter the Great Bay, Sea of Japan) were investigated. The isolate had oxydative metabolism, was positive for ornithine decarboxylase, cytochrome oxidase, catalase, DNase and gelatinase, hemolytically active, did not produce acid from carbohydrates, and did not hydrolyze urea and esculin. The strain was resistant to penicillin, amoxicillin, and ampicillin and susceptible to tetracycline and carbenicillin. Among cellular fatty acids, 13:0-i, 15:0-i, 16:0, 16:1(n-7), 17:0-i, and 17:0-ai dominated. These biochemical properties made it possible to attribute the isolated bacteria to the genus Shewanella and identified as S. algae. The cells of this bacterium were introduced into the coelomic cavity of another echinoderm, the sea urchin Strongylocentrotus nudus. As a result, in about 24 h the animals became slow and 3-8 days after the inoculation died. Dividing bacteria were being found during the experiment in the coelomic fluid as well as in the phagosomes of amoebocytes, i.e. cells acting as phagocytes in the coelomic fluid. The studies of the invasive properties of strain 156 showed that bacterial cells entered the subcuticular space of S. nudus and A. japonicus through the cuticle and stayed there for a long time without penetrating epithelium and exerting toxic effect upon the organisms of the laboratory animals. Pathogenic effect of S. algae can be manifested only if the cutaneous epithelium is destroyed permitting it to penetrate the lower tissue layers. The toxicity of S. algae is confirmed by in vitro experiments. The inoculation of the embryonic cells of S. nudus with samples of this bacterium caused the death of 10% of cells within an hour and 100% of cells within 12 h after inoculation. The results of the investigations demonstrate that S. algae could produce opportunistic infection in the sea cucumber A. japonicus and the sea urchin S. nudus, which may be natural reservoirs of this human pathogen.     

Enzymatic indication of heavy metal toxicity to marine heterotrophic bacteria

The ecotoxicological effect of heavy metals on the dehydrogenase and catalase activities of marine heterotrophic bacteria was assessed in pure strains and in associations. The microorganisms from the surfaces of copper-containing materials had higher levels of enzyme activities and were inhibited by trace metals to a lesser degree. The data from the field and laboratory experiments suggest that catalase activity can provide an ecological indicator of the effects of heavy metals on the aquatic environment.     

Characterization of communities of heterotrophic bacteria associated with healthy and diseased corals in Nha Trang Bay (Vietnam)

A comparative investigation of the heterotrophic microflora of 11 species of healthy corals and of white-band-diseased and yellow-band-diseased corals inhabiting the reefs of Nha Trang Bay (Vietnam), which has been exposed to anthropogenic impact, was performed. Fifty-nine strains of heterotrophic bacteria isolated on Y/K and Endo media were investigated and characterized. All the isolates were identified at the genus level by consideration of the results of analysis of their phenotypic properties, determination of the molar percent of G+C bases in their DNA, and the composition of fatty acids of their lipids. In the composition of the microflora of tissues of healthy corals, gamma-proteobacteria prevailed, with halomonads being dominant among them. In addition, the gram-negative bacteria included Pseudomonas and Vibrio spp., members of the Cytophaga-Flavobacterium-Bacteroides (CFB) phylogenetic cluster, and Moraxella sp. The gram-positive bacteria revealed included Bacillus, Staphylococcus, Halococcus, and Micrococcus spp., and coryneform bacteria. In the composition of the microflora of the tissues of affected corals, bacteria of the family Enterobacteriaceae and of the genera Planococcus and Arthrobacter, which were not revealed in healthy hydrobionts, were found. The anthropogenic impact is not the sole factor determining the infection of corals.