CHEMOTAXONOMIC FEATURES AND PLASMID PROFILES OF AEROBIC AND FACULTATIVE ANAEROBIC SPORE-FORMING BACTERIA FROM VEGETABLES

Abstract

Aim. To set the systematic position and some molecular genetic characteristics of potential agents of food poisoning and spoilage microorganisms residual vegetable products – aerobic and facultative anaerobic spore-forming bacteria in their hemotaxonomic and plasmid profiles. Methods. The fatty acid analysis of the investigated strains was carried out by gas chromatography using the system identification of microorganisms MIDI Sherlock (MIDI, USA). The species belonging of bacilli strains that according to chromatography of fatty acids had high, but close similarity indices by types of Bacillus cereus and B. thuringiensis, was confirmed by conducting PCR with specific primers. Plasmid DNA isolation was performed by the modified Jensen’s method. Results. The analysis of the results of gas chromatography showed that content of branched fatty acids in the investigated strains was from 54 to 85% of the total fatty acid cell pool, including saturated and unsaturated fatty acids and their branched structural isomers with a predominance of iso-C15:0 and antеizo -C15:0 fatty acids. It was also characterized for them a high content of antеizo-C17:0 and iso-C17:0 fatty acids. Mostly strains of Bacillus cereus, Lysinibacillus sphaericus and B. pumilus contained plasmids of different sizes, which fell into two groups: the small plasmids from 2000 to 12000 bp and megaplazmids to 200000 bp. Conclusion. The investigated strains of bacteria due their chemotaxonomic features have belonged to 4 genera of Bacillales order: Bacillus, Lysinibacillus, Paenibacillus, Brevibacillus with the predominance of the first group of rRNA representatives and the dominance of B.subtilis strains. The results of the fatty acid biomarking of Bacillus cereus strains have been confirmed by PCR with the group- and species-specific primers for the samples that according to fatty acids chromatography had high but similar indices of similarity between B. cereus and B. thuringiensis species. The peculiarities of fatty acid and plasmid profiles of investigated microorganisms can be used as an auxiliary key for taxonomic differentiation of bacillary contaminants – potential pathogens of foodborne diseases, damage and residual microbiota of vegetable production in the South of Ukraine.