Metal-Resistant Heterotrophic Bacteria in Coastal Waters of Primorye

Abstract

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...

Levels of some toxic elements and frequency of bacterial heavy metal resistance in sediment and sea water

“…Statistically significant differences in the minimum inhibitory concentrations of some metals were found for bacteria isolated from environments with different levels of pollution. Bacteria of the family Enterobacteriaceae and the genus Pseudomonas were the dominant metal-resistant bacterial forms in the polluted coastal wasters of Primorye (Bezverbnaya et al 2005). Positive correlations between tolerance to high levels of Cu 2+ , Pb 2+ , Zn 2+ and multi-resistant bacteria isolated from drinking water have previously been reported (Calomiris et al 1994).…”

“…Jana and Bhattacharya (1988) reported that several strains of members of E. coli, K. aerogene, and S. marcescens were screened for Cd resistance and sensitivity, and only one strain of each of these microorganisms was resistant to CdCl 2 . Bezverbnaya et al (2005) explained that colony-forming heterotrophic bacteria were isolated from several locations that differed in extent and character of heavy metal pollution in the coastal waters of Primorye. Statistically significant differences in the minimum inhibitory concentrations of some metals were found for bacteria isolated from environments with different levels of pollution.…”

Isolation, characterization of heavy metal resistant strain of Pseudomonas aeruginosa isolated from polluted sites in Assiut city, Egypt

“…Microorganisms resistant to antibiotics and tolerant to metals appear to be the result of exposure to metalcontaminated environments that cause coincidental selection for resistance factors for both [37]. Many investigators have reported that metal tolerant environmental isolates are resistant to a wide array of antibiotics and there are correlation between heavy metal resistance and antibiotic resistance [21,32,[38][39][40][41]. Metal-tolerant bacteria have evolved various resistance and detoxification mechanisms [15].…”

BIOSORPTION OF CD, CR, MN, AND PB FROM AQUEOUS SOLUTIONS BY Bacillus SP STRAINS ISOLATED FROM INDUSTRIAL WASTE ACTIVATE SLUDGE

“…of adsorbent, solubility of the metals ions and the degree of ionization and speciation of adsorbate [24,25] . Cd, Cr, Mn and Pb adsorption increases linearly with in solution pH in the range of 7 to 10 as shown in Figure 4 for the isolated strain Bacillus sp.…”

“…The results obtained in this study showed that the alkaline treatment is more effective in removing metals, as after 5 minutes the biosorption process removed 90% of the metals [27] . The possible reasons for this is that at pH less than 3, polymers are protonated and restrict entry of metallic ions, and at higher pH, the groups responsible for the retention of metals are negatively charged facilitating the binding of the metals ions [24,[28][29][30][31] . This resulted in a more favorable electrostatic attraction capacity of Cd, Cr, Mn and Pb: a concentration of 50 mg L -1 of metal forces, and so enhances, cationic metal ion adsorption at a temperature of 27 ± 1°C.…”