Antibiotic Resistance of Heterotrophic Bacteria Isolated from Various Habitats of the Litoral Area of Lake Baikal

This is the first time the data on the antibiotic resistance of heterotrophic bacteria were obtained. These bacteria were isolated from fouling of stone substrates and also from «healthy» and «diseased» sponges of Lake Baikal. We have analysed 377 strains for the resistance to 11 antimicrobial agents. 133 of them were isolated from the water column, 277 from stone fouling, 17 from «healthy» sponges, and 20 from «diseased» sponges of Lake Baikal. We have revealed 9 sensitive strains and 36 strains resistant to all antibiotics. A high percentage of bacterial strains from both plankton (34–82 %) and periphyton (23–94 %) are resistant to a number of broad-spectrum antibiotics. At the same time, they have different sensitivity to azithromycin, vancomycin, tetracycline, and meropenem. The strains isolated from periphyton showed the most effective antimicrobial activity to azithromycin, tetracycline and meroperem; those isolated from water showed the most effective antimicrobial activity to meroperem. The strains sensitive to antibiotics (18–71 %) prevail in the microbial community of «healthy» sponges. At the same time, the microbial community of «diseased» sponges has a larger share of sensitive strains, which accounts for 30–75 %. The proportion of resistant strains with gram-negative cell wall is higher for most antibiotics compared to the gram-positive bacteria.