Biogenic synthesis of selenium and tellurium nanoparticles by marine bacteria and their biological activity.

Selenium (SeNPs) and tellurium nanoparticles (TeNPs) were synthesized by green technology using the three new bacterial marine isolates (strains PL 2476, AF 2469 and G 2451). Isolates were classified as Pseudoalteromonas shioyasakiensis according to 16S rRNA sequence analysis, morphological characteristics, and biochemical reactions. The bioreduction processes of isolates were studied in comparison with the previously described Alteromonas macleodii (strain 2328). All strains exhibited significant tolerance to selenite and tellurite up to 1000 µg/mL. A comparative analysis of the bioreduction processes of the isolates demonstrated that the strains have a high rate of reduction processes. Characterization of biogenic red SeNPs and black TeNPs using scanning electron microscopy (SEM), EDX analysis, Dynamic Light Scattering, and micro-Raman Spectroscopy revealed that all the isolates form stable spherical selenium and tellurium nanoparticles whose size as well as elemental composition depend on the producer strain. Nanoparticles of the smallest size (up to 100 nm) were observed only for strain PL 2476. Biogenic SeNPs and TeNPs were also characterized and tested for their antimicrobial, antifouling and cytotoxic activities. Significant antimicrobial activity was shown for nanoparticles at relatively high concentrations (500 and 1000 µg/mL), with the antimicrobial activity of TeNPs being more significant than SeNPs. In contrast, against cell cultures (breast cancer cells (SkBr3) and human dermal fibroblasts (HDF) SeNPs showed greater toxicity than tellurium nanoparticles. Studies have demonstrated the high antifouling effectiveness of selenium and tellurium nanoparticles when introduced into self-polishing coatings. According to the results obtained, the use of SeNPs and TeNPs as antifouling additives can reduce the concentration of leachable biocides used in coatings, reducing the pressure on the environment.

Assessment of the toxic effect exerted by fluorescent pseudomonads on embryos and larvae of the sea urchin Strongylocentrotus nudus.

Strains of bacteria capable of growing on artificial culture media were isolated from the fouling of brass plates submerged in Nha Trang Bay, South China Sea, and from tissues of the seastar Distolasterias nipon, caught in Peter the Great Bay, Sea of Japan. According to the complex of data of genetic and physiological/biochemical analyzes, two strains of cultivated bacteria were identified by us as the species Pseudomonas aeruginosa, two strains as Pseudomonas fluorescens, and one strain as Ruegeria sp. It was shown that the cultivated strains of P. aeruginosa released exotoxins, particularly phenazine pigments, into the environment. Production of the toxins did not depend on presence of a target organism in the system and was aimed at regulation of interactions in the microbial community. The toxicity of the studied natural isolates of fluorescent pseudomonads was analyzed by using embryos and larvae of the sea urchin Strongylocentrotus nudus, which are the sensitive and dynamic toxicological sea-urchin embryo test (SET) system. As was established, exotoxins produced by the strains of P. aeruginosa inhibit activity of cilia in sea urchin larvae, as well as disturb processes of cell differentiation in embryos and larvae. Their toxic influence is accompanied by disturbances of protein synthesis and the disruptions of cytoskeleton in the course of zygote cleavage and larval development. Unlike P. aeruginosa, the strains of P. fluorescens and Ruegeria sp. did not exert the toxic effect on SET. The obtained data allow considering objects of the environment as the natural reservoir of opportunistic microorganisms posing a potential threat to human, whereas the use of SET for determination of toxicity of isolated bacteria provides an opportunity to study the mechanisms of their interactions with organisms in marine ecosystems.

[Characterization, identification, and screening for tetrodotoxin production by bacteria associated with the Cephalotrix simula (Ivata, 1952) proboscis worm].

The taxonomic composition of bacteria associated with the Cephalotrix simula proboscis worm was studied and screening of the tetrodotoxin (TTX)-producing bacteria was carried out using confocal laser scanning microscopy and polyclonal antibodies. Bacterial isolates were identified using the 16S rRNA gene sequencing and phenotypic characteristics. A Bacillus species was found to be responsible for tetrodotoxin production in C. simula proboscis worms. Vibrio spp. predominated in the associated microflora (68.18% of the total number of isolates). Analysis of the sensitivity of 16 strains to antibiotics of various classes revealed multiple resistance to three or more antibiotics in all studied isolates. Poor growth of most of the isolates on all laboratory media was an indirect confirmation of the symbiotic relationships between the micro- and macroorganisms.

[Distribution and characteristics of Bacillus bacteria associated with hydrobionts and the waters of the Peter the Great Bay, Sea of Japan].

Bacilli of the species Bacillus subtilis, B. pumilus, B. mycoides, B. marinus and B. licheniformis (a total of 53 strains) were isolated from 15 invertebrate species and the water of the Vostok Bay, Peter the Great Bay, Sea of Japan. Bacilli were most often isolated from bivalves (22.7%) and sea cucumbers (18.9%); they occurred less frequently in sea urchins and starfish (13.2 and 7.5%, respectively). Most of bacilli strains were isolated from invertebrates inhabiting silted sediments. No Bacillus spp. strains were isolated from invertebrates inhabiting stony and sandy environments. The species diversity of bacilli isolated from marine objects under study was low. Almost all bacterial isolates were resistant to lincomycin. Unlike B. pumilus, B. subtilis isolates were mostly resistant to benzylpenicillin and ampicillin. Antibiotic sensitivity of B. licheniformis strains was variable (two strains were resistant to benzylpenicillin and oxacillin, while one was sensitive). A significant fraction of isolated bacilli contained pigments. Pigmented strains were more often isolated from seawater samples, while colorless ones predominated within hydrobionts. B. subtilis colonies had the broadest range of colors. In the Bacillus strains obtained, DNase, RNase, phosphatase, elastolytic, chitinase, and agarolytic activity was detected. Bacilli strains with hydrolytic activity occurred in invertebrates more often than in seawater.

[Taxonomic composition of bacteria associated with cultivated mollusks Crassostrea lugubris and Perna viridis and with the water of the Gulf of Nha Trang Lagoon, Vietnam].

One hundred and four strains of heterotrophic bacteria have been isolated and characterized from two species of bivalve mollusks cultivated in the Gulf of Nha Trang (Vietnam) and from the water of a mariculture farm. The isolates have been identified on the basis of morphological, physiological, biochemical, and chemotaxonomic properties, as well as by the content of G+C bases in DNA. In the microflora of mollusks, Vibrio alginolyticus was predominant; the pathogenic species V. harveyi and V. splendidus were found as well. Staphylococci and bacilli occupied the second place in abundance after vibrios. In addition, coryneforms and enterobacteria, as well as Pseudomonas spp. and Pseudoalteromonas spp., were revealed. The composition of the water microflora was more diverse as compared with the microflora of mollusks. In the water, Bacillus spp., Vibrio spp., and Pseudomonas spp. were predominant. Brevibacterium spp. and other coryneform bacteria, as well as enterobacteria, occurred in significant amounts. In addition, Pseudoalteromonas spp., Marinococcus sp., Halobacillus sp., Shewanella sp., Sulfitobacter sp., and bacteria of the CFB cluster were noticed. The presence of pathogenic and conditionally pathogenic bacterial species in the water and mollusks is probably the reason for the high death rate of cultivated animals at the mariculture farm.

[Bacterial communities of brown and red algae from Peter the Great Bay, the Sea of Japan].

The structure of microbial communities of brown algae, red algae, and of the red alga Gracilaria verrucosa, healthy and affected with rotten thallus, were comparatively investigated; 61 strains of heterotrophic bacteria were isolated and characterized. Most of them were identified to the genus level, some Vibrio spp., to the species level according to their phenotypic properties and the fatty acid composition of cellular lipids. The composition of the microflora of two species of brown algae was different. In Chordaria flagelliformis, Pseudomonas spp. prevailed, and in Desmarestia viridis, Bacillus spp. The composition of the microflora of two red algae, G. verrucosa and Camphylaephora hyphaeoides, differed mainly in the ratio of prevailing groups of bacteria. The most abundant were bacteria of the CFB cluster and pseudoalteromonads. In addition, the following bacteria were found on the surface of the algae: Sulfitobacter spp., Halomonas spp., Acinetobacter sp., Planococcus sp., Arthrobacter sp., and Agromyces sp. From tissues of the affected G. verrucosa, only vibrios were isolated, both agarolytic and nonagarolytic. The existence of specific bacterial communities characteristic of different species of algae is suggested and the relation of Vibrio sp. to the pathological process in the tissues of G. verrucosa is supposed.

[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.

[Hydrolytic activity of marine bacteria associated with the mussel Mytilus trossulus].

The ability to produce hydrolytic enzymes--DNAses, RNAses, alkaline phosphatases, chitinases has been studied in 316 strains of bacteria isolated from mussel Mytilus trossulus. Strains of Vibrio spp. produced all the spectrum of examined enzymes, bacteria of Pseudoalteromonas genus produced alkaline phosphatase and DNAse. Chitin-degrading enzymes were found in Vibrio and Cytophaga--Flavobacterium--Bacteroides group. Bacillus and Vibrio spp. strains produced most actively RNAses. The presence of proteinases, amylases and lipases has been found in all tested groups of bacteria. The antagonistic activity of a number of isolated strains against Candida albicans, Proteus vulgaris and Escherichia coli has been studied.

[Spread of bacteria of the genus Acinetobacter in the hydrobios of the Bay of Peter the Great, the Sea of Japan]. / Rasprostranenie bakterii roda Acinetobacter v gidrobiontakh zaliva Petra Velikogo, Iaponskoe more.

The analysis of the spread of bacteria of the genus Acinetobacter among the invertebrate animals of the Bay of Peter the Great (the Sea of Japan): in bivalved mollusks, sea cucumbers and sea urchins Acinetobacter bacteria were detected more often than in cushion stars and crustaceous animals. The biological properties of 45 isolated bacteria were studied with the use of a wide variety of tests. The study revealed that 9% of Acinetobacter cultures isolated from marine animals had pronounced beta-hemolysis.

[Comparative study of microbial communities from cultured and natural population of the mussel Mytilus trossulus in Peter the Great bay]. / Sravnitel'noe izuchenie struktury mikrobnykh soobshchestv midii Mytilus trossulus iz kul'tiviruemoi i prirodnoi populiatsii zaliva Petra Belikogo.

The 525 strains of heterotrophic bacteria isolated from natural and cultured populations of the mussel Mytilus trossulus and the surrounding seawater were identified to a genus level on the basis of phenotypic analysis and the fatty acid composition of cell lipids. Gram-negative isolates were dominated by six genera of the family Enterobacteriaceae and by the genera Pseudoalteromonas, Vibrio, Photobacterium, Cytophaga/Flavobacterium/Bacteroides, Pseudomonas, and Moraxella, Gram-positive isolates were mainly represented by the genus Streptomyces. The taxonomic compositions of natural and cultured populations of the mussel M. trossulus in Peter the Great Bay were similar.

[Opportunistic bacteria detected in cultivated mussels]. / Uslovnopatogennye bakterii,obnaruzhivaemye v kul'tiviruemykh midiiakh.

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.

[The ecological aspects of listeriosis in the Maritime Territory]. / Ekologicheskie aspekty listerioza v Primorskom krae.

In the process of batch cultivation the strains under study are capable of prolonged growth at low temperature in rich and poor nutrient media (with the term of observation equal to 4 months), while at a temperature of 37 degrees C microbial populations quickly die (in 8-35 days). In the absence of compounds containing carbon, hydrogen and nitrogen in the nutrient medium, Listeria can proliferate under such conditions. As established with the use of gas chromatography and the radioisotopic method, they can uptake carbon dioxide, hydrogen and nitrogen from the air gas mixture, using carbon of the first gas for the synthesis of the main biopolymers (proteins, lipids, carbohydrates, DNA and RNA) and the second one as the source of energy. During the cultivation of Listeria at low temperature in poor nutrient media (soil microecosystems, synthetic mineral media) they are capable of preserving and under favorable conditions also increasing their virulence. Its increase is facilitated by capsule formation, mobility, chemotaxis, adhesion and invasion enhancing under such conditions.