SENSITIVITY TO UV-C OF GRAMNEGATIVE EPIPHYTIC BACTERIA FROM CHERNOBYL EXCLUSION ZONE

Abstract

Aim: to study the sensitivity to UV of the bacterial genera Pseudomonas and Pantoea from the epiphyte of plant samples from 10 km of Chernobyl Exclusion Zone (CEZ). Methods: The objects of the study were the strains of bacteria of the genera Pantoea and Pseudomonas isolated from plant epiphyte samples from 10 km of CEZ and the collection strains of P. aeruginosa UKM B-907 = ATCC 27853, P. putida UKM B- В-115т = ATCC 12633, P. agglomerans UKM B – В-1089т = ATCC 33248. UV irradiation of microorganisms was carried out using BUF-15 lamp, λ = 254 nm, exposure time from 1 to 15 min (0–600 J / m2). The dose of irradiation (J / m2) was determined using a DAU-81 dosimeter. Results: Indices of UV sensitivity at the dose of 40 J/m2 for investigated epiphytic strains Pantoea sp. H8 and Pantoea sp. pigment were over the range from [-0.41 lg%] tо [1.34 lg%]. LD50 for these microorganisms were 2.5 times lower than that for corresponding museum strain. Indices of UV sensitivity at the dose of 40 J/m2 for microorganisms from the strains Pantoea sp. H7 and Pseudomonas sp. P14 were over the range from [1.77 lg%] до [1.94 lg%]. LD50 for Pseudomonas sp. P14 was 3.8 times higher than that for reference bacteria P. putida ATCC 12633, and LD50 for Pantoea sp. H7 was 12.5% higher than that for corresponding reference strain. Irradiation over the dose range 85.5±15.8 J/m2 resulted in 99.99% cell death rate for all investigated strains. Conclusion: community of epiphytic bacteria of the genera Pseudomonas and Pantoea from 10 km of CEZ is heterogeneous in its sensitivity to UV. Bacteria of the genus Pantoea are characterized by the divergence of the sensitivity to this stressor, whereas epiphytic pseudomonads were represented by microorganisms that were tolerant to the UV radiation over the dose range 0–40 J/m2

Keywords

• епіфітні мікроорганізми
• ультрафіолет
• множинна стрес- толерантність