No abstract

No abstract

Biochemical mechanisms of pathogenic bacteria Yersinia pseudotuberculosis and Listeria monocytogenes ensuring their survival in the habitat were investigated. Low temperature and poor trophicity induce synthesis of cold isozymes in bacteria and accumulation of coenzymes of NAD and NADP-dependent dehydrogenases and intensify assimilation of hydrogen, oxygen, carbogen, and nitrogen maintaining energy and constructive metabolism under unfavorable environmental conditions.

Heavy metals are the major pollutants of the coastal waters of Primorye. This is associated with the natural geochemical features of the region, as well as with significant anthropogenic inputs. It is known that microorganisms are resistant actually to all heavy metals [15,20,24]. They are capable of rapid adaptation to specific habitat conditions and can thus provide an indicator of environmental changes [2,11,19]. The diversity of individual bacterial responses to toxic effects supports the plasticity of communities and, in some cases, ensures the possibility of melioration of the environment [12,15]. However, it has been experimentally demonstrated that in the marine environment bacterial adaptation to pollution, including heavy metals, can be accompanied by processes hazardous to human and animals [5]. Within the microbiocenoses of polluted waters, plasmid-bearing genes of biodegradation and resistance to toxicants are becoming increasingly more frequent. These genes may be linked with genes of antibiotic resistance and genes responsible for pathogenic properties [13,23]. Thus, individual bacterial strains have developed the capability of surviving under toxicological stress and dominate microbiocenoses. This is essential to the study of metal resistant microbiocenoses, which are being formed in response to selective anthropogenic pressure.This work is focused on study of the diversity and heavy metal resistance of bacterial strains isolated from coastal waters of Primorye with different extents and natures of heavy metal pollution, identification of highly resistant strains, and analysis of the range of their antibacterial resistance and plasmid number and size. MATERIALS AND METHODSTwo hundred twenty bacterial strains were aseptically isolated from the water or from the thallus of brown algae collected from several locations in Primorye: Rudnaya Bay (northern Primorye), which is situated in the area of mining and processing of complex ores; a reference station located far from pollution sources; and Zolotoi Rog Bay, which receives combined anthropogenic and technogenic inputs. Pure cultures of bacteria were isolated from selective metalcontaining media [4] according to the standard method [8]. The formula of the basic medium was as follows (g/liter): peptone, 5.0; yeast extract, 5.0; glucose, 1.0; K 2 HPO 4 , 0.2, MgSO 4 , 1.0; CaCO 3 , 1.0, distilled water, 500 ml, sea water, 500 ml; pH, 7.8. To it were added chlorides of Cd, Cu, Zn, Ni, and Co or nitrate of Pb. The individual metal resistance of bacterial strains was assessed by determining the minimum inhibitory concentration (MIC) of the salt of each metal [18]. Pure cultures were inoculated (in three replicates) by the imprint method in the above medium supplemented with metal salts in increasing concentrations.The morphological, cultural, and biochemical properties of bacterial strains were tested using widely adopted methods [8]. Bacteria were identified according to Berge's manual [9] and using standard tests API-20E and API-20NE (BioMerieux, France...

It was found that at low temperature (6-8 degrees C) in the absence of nitrogen supply and at the presence of phosphate ions in the medium, Yersinia pseudotuberculosis and Listeria monocytogenes are able to actively synthesize reserve substances as polyphosphates. Most of the bacterial polyphosphates are alkali-soluble, especially at the preliminary stage of cell growth (lag-phase). This is proved by electron microscopic studies of ultrastructure of model microorganisms. During a long starvation period under conditions of carbon and energy source deficit, L. monocytogenes and Y. pseudotuberculosis consume this biopolymer for biosynthetic and bioenergetic processes.

No abstract

No abstract

The influence of culture method (free-floating cells in liquid nutrient broth or bacteria attached to agar surface on solid agarized medium of the same formulation) and bacterial age on the composition of free lipids in Yersinia pseudotuberculosis (O:Ib serovar, strain KS 3058) grown in the cold (5 degrees C) has been investigated. The specific growth rate of the bacteria on solid medium was about threefold less than that in liquid medium. The qualitative composition of phospholipids and fatty acids only slightly depended on the bacterial culture method. At the same time, the colonially growing cultures contained somewhat more total lipids, they synthesized more phospholipids, in the linear growth phase they contained more lysophosphatides, and they had higher fatty acid unsaturation index and higher pathogenic potential than their "planktonic" counterparts grown in otherwise identical conditions. The bacterial growth phase influenced the amount of 3-hydroxytetradecanoic acid and, indirectly, that of lipopolysaccharide. The dynamics of changes in the amount of this acid with bacterial age was opposite in the surface and broth cultures.