4.4.1 Biological Features and Genotoxic 

 Properties of Microorganisms 



ALLA V. TSYBAN*. GENNADIY V. PANOV, VLADIMIR A. IVANITSA*. and GALINA V. KHUDCHENKO' 



Institute of Global Climate and Ecology. State Committee for Hydrometeorology and Academy of Sciences. Moscow, USSR 

 'Odessa State University', Odessa, USSR 



Introduction 



Local or regional increase in the concentration of some 

 natural components, such as heavy metals, oil, and nonnatural 

 components up to toxic levels, is a characteristic feature of the 

 present ecological situation in the World Ocean (Izrael et al., 

 1987). Therefore, a serious problem has arisen, concerning a 

 change in the metabolism of microorganisms as well as their 

 adaptation to new chemical conditions of the environment. 



It has been determined that adaptation of microorganisms 

 plays an important role in biodegradation of toxic organic 

 compounds. Adaptation can be defined as a change in the 

 microbial population which increases the rate of transformation 

 of toxic substances as a result of the preliminary contact with 

 these compounds. It is quite obvious that to predict the 

 biodegradation rate of organic pollutants in the marine 

 environment, it is necessary to gain an understanding of the 

 mechanisms of microbial transformation, such as genetic 

 transfer or mutation, enzyme induction, and changes in the 

 level of populations. It is also obvious that these mechanisms 

 play an important role in the process of adaptation of microbial 

 populations to new substances. 



Although mechanisms of microbial degradation may differ, 

 the process is under the genetic control of chromosome or extra 

 chromosomal (plasmid) material. Numerous forms of genetic 

 transmission with plasmids can occur and can offer strong 

 possibilities for genetic engineering in nature, including the 

 World Ocean. Evidence in support of this can be seen in the 

 distribution of benzo(a)pyrene- and PCB-transforming bacteria 

 in estuaries, the Baltic, Bering, and Chukchi Seas (see preceding 

 Subchapters). 



While studying the mechanisms of biodegradation. 

 controlled by plasmids, the traits providing selective advantages 

 to marine organisms become of primary importance. Such 

 traits are the resistance to bactericidal toxic compounds (for 

 instance, heavy metals) and the ability to utilize a number of 

 substances of a biogenic origin (Karasevich, 1 982; Izrael ei al. , 

 1987). Thus, protective functions determined by plasmid 

 genes can be acquired by a microbial cell under changing 

 environmental conditions. Although other traits should not be 

 disregarded, they are not related to direct selection. These traits 

 provide a cell with some advantages in the habitat and possibility 

 of transferring traits inside a bacterial population (Izrael & 

 Tsyban, 1989). 



The above account outlines the importance of studying the 

 signs of plasmid transmission in marine microorganisms. The 

 purpose was to assess and forecast the ecological state of the 

 environment, including protective properties of marine 



ecosystems. In addition, change in the genotypes of marine 

 microorganisms can be determined (Izrael & Tsyban, 1990). 

 New data on the biological properties of heterotrophic 

 microorganisms of the Bering Sea were recently obtained. 

 Investigations of the physiological, biochemical, and genetic 

 features of strains isolated from various components of marine 

 ecosystems were conducted by microbiologists of the Natural 

 Environment and Climate Monitoring Laboratory (Institute for 

 Global Climate and Ecology from 1991) of the USSR State 

 Committee for Hydrometeorology and USSR Academy of 

 Sciences. These materials have already been published in part 

 by Izrael f/(;/. (1987) and Izrael &T,syban( 1989, 1990). The 

 present paper describes research on the biological, biochemical, 

 and genetic features of strains isolated from the Bering and 

 Chukchi Seas in 1984 and 1988. 



Methods and Materials 



Investigations were conducted on 320 strains of 

 heterotrophic bacteria isolated from the Bering Sea in 1984, 

 and on 77 strains of bacteria isolated from the Chukchi Sea 

 water in summer 1 988. Selection of traits was determined by 

 plasmids, and methods of data processing were determined by 

 experimental procedures. 



The specific character of genetic investigations of a large 

 collection of microorganisms isolated from the marine 

 environment has necessitated the choice of the mass screening 

 method. The collection of the cultures was subdivided into 

 homogeneous groups based on traits that are easily identified 

 in mass screening (Izrael & Tsyban, 1990). Resistance of 

 cultures to antibiotics, organic pollutants, and heavy metals 

 (Hg, Cd, Co, Cu, Pb. and Ni) were investigated as signs of the 

 presence of plasmids. 



Ability to degrade petroleum hydrocarbons and paraffin 

 was determined from the presence of the zone where bacteria 

 grew on the compact nutritious medium prepared on seawater 

 (Tsyban, 1980) around sterile disks soaked with relevant 

 hydrocarbons. Minimum inhibiting concentrations (MIC) 

 were serially diluted in a solid medium. Eleven antibiotics of 

 the basic groups: ampicillin (Amp), benzylpenicillin (Ben), 

 and mcthicillin (Mtt) from the penicillin group: gentamicin 

 ( Gen ), kanamycin ( Kan ). monomycin ( Mon ), and streptomycin 

 (Str) from the group of aminoglycosides; chloramphenicol 

 (Clm) and tetracycline (Tet), broad-spectrum antibiotics; 

 polymicin (Pol) from the group of polypeptide antibiotics: and 

 nalidixic acid (Nal) in the range of concentrations from 0.06 to 

 4,000 |ig/ml. Due to high sensitivity of microorganisms to 

 gentamicin. the range of its concentration was 0.06 to 8 Hg/ml. 



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