killed cells in 38% of the strains. On the E. coli Rec- niodel. 

 the above figures were 50, 50. and 67'7f , respectively ( Table 9 ). 

 Twenty-eight percent of the strains of Bering Sea 

 Pseudomonades produce compounds possessing DNA- 

 damaging effect upon both mutant strains. This suggests 

 carcinogenic activity. 



TABLE 9 



Toxic and DNA-damaging effects of metabolites of 

 Psfuddimmadi's from the Bering Sea. 



Number of strains (%) 

 with positive effect 

 Test-object Exometa- Endometa- Killed 



bolites bolites cells 



E. coli WP-2 

 E. coli Pol A- 

 E. coli Rec- 



75 50 60 



69 54 38 



50 50 67 



In representatives of the F/(n'()/«(rr('/7H/;;-Cv/( '/'/;«,!,'(/ group, 

 DNA-damaging effect appears considerably lower than the 

 Pseudomonas. Only one of the seven strains gave a positive 

 effect in the model E. coli Pol A-. 



From the comparison of the results on toxic and genotoxic 

 properties of the metabolites of the genus Pseudomonas isolated 

 from the Bering and Chukchi Seas, it was found that the 

 Chukchi Sea occupies an intermediate position between the 

 Baltic and Bering Seas. With respect to an increase in the 

 number of strains possessing the genotoxic activity, the seas 

 are listed in the order of the Bering Sea, the Chukchi Sea, and 

 the Baltic Sea. 



Thus, investigations showed that an ability to produce 

 metabolites with a genotoxic effect is a marginal characteristic 

 of marine bacteria, such as Pseudomonas, Alcaligenes, 

 Xaiitomoiias. Arthrohaclcr, Bacillus, and Flavnhactehum- 

 Cytopliaga. However, the ability of marine bacteria to produce 

 substances possessing genotoxic activity, which was determined 

 under laboratory conditions, does not affirm if these properties 

 are dangerous under natural conditions. It remains unknown 

 whether bacteria produce a genotoxic effect in the marine 

 environment. 



To determine the minimum concentrations of bacteria, 

 sufficient to elicit DNA-damaging effect, three strains of the 

 Elavi)hacterium-Cytf>pha,i>a group, which manifested a 

 genotoxic effect, were used. It was detennined that the maximum 

 dilution of exometabolites, at which the DNA-damaging action 

 was preserved, was 1:125. This corresponds to a bacterial 

 density in seawater on the order of 1 x 10' cells/ml under 

 experimental conditions. The active dilution for two other 

 strains ranged from 1 :25 to 1 :5. This corresponds to a bacterial 

 density to 1 x 10' to 1 x 10'' cells/ml. 



Exo- and endometabolites of four strains (including the 

 above strains) with genotoxic and DNA-damaging effects 

 were analyzed by means of the standard Ames test. The 

 purpose is to elucidate questions about mutagenic activity. 



As test strains, the specialized strains Salmonella typhimurium 

 TA-98 and TA- 100. when used, revert to prototrophicity with 

 respect to histidine due to mutation of a reading frame shift and 

 replacement of base pairs. 



The results from this test suggest that one of the four strains 

 produced metabolites with mutagenic activity. Exometabolites 

 of this strain, in a volume of 0. 1 ml per Petri cap, induced 

 genetic mutations of the frame shift type. The frequency of 

 occurrence was more than 40 times higher than spontaneous 

 mutation (82.6 x 10*% as compared to the control value of 

 2.0 X 10"%). 



Of great importance seems to be the DNA-damaging 

 effect clearly marked in the genus Pseudomonas. This genus 

 has gained an advantage in conditions of marine pollution and 

 develop in waters subjected to heavy anthropogenic inputs. So 

 we speculate that the development of indicator microfiora, 

 which includes bacterial decomposers in impact regions of the 

 World Ocean, is secondary pollution of the marine environment 

 (i.e., intensifying the potential response of chemical pollution 

 and threatening the genotype of marine ecosystems). 



The ability of certain forms of microorganisms to change 

 under the effect of chemical pollution can be far from safe for 

 other marine organisms and man. There is a risk of possible 

 genetic transformation of harmless bacteria under the pressure 

 of the environmental mutagens and selection towards aggressive 

 pathogenic forms of microorganisms. The risk increases if the 

 protective mechanisms of animals and man have not yet 

 adapted. In this case, transformation of the microorganisms 

 can mutate from the nonpathogenic to quasi-pathogenic group 

 and from the latter into the pathogenic group. 



Two main models are used to determine pathogenicity of 

 microorganisms. One is classical and is based on the 

 reproduction of an infection process in laboratory animals. The 

 other examines the effect of bacteria on man and animal cell 

 cultures as a model. Cell cultures provide a less expensive, 

 rapid answer, with a more stable assay with higher sensitivity 

 and reliability than results with experimental animals. 



Pathogenic properties of 1 4 strains from the Bering Sea, 1 8 

 strains from the Chukchi Sea, and 27 strains from the Baltic Sea 

 were studied with the use of white mice and the reinoculated 

 kidney cells of a human embryo (RH) and fish skin cells (EPC) 

 (Tsybanf/«/.. 1988). 



The study included 26 strains of two groups of bacterial 

 populations. These groups were Pseudomonas and 

 Flavobacterium-Cytophaga, isolated from the Bering Sea and 

 other regions of the World Ocean. With the use of the model 

 of intraperitoneal infection, white mice did not reveal pathogenic 

 properties. However, the use of cell cultures revealed a 

 differentiation of strains by the level of potential pathogenic 

 activity of bacteria cells. 



The cytopathic effects cause morphological changes of 

 cells and disruption of the monolayer. For pathogenic strains, 

 cytopathic response occurred in 50-100% of the tests, quasi- 

 pathogenic (potentially pathogenic) strains — 25-50%, and 

 nonpathogenic strains — less than 25%. Changes observed 

 included vacuolization of cytoplasm, rounding-off of some 

 cells, and acidification of the medium. For controls, two 

 species were used: Pseudomonas fluorescence BKM-894(H) 



109 



