SCREENING OF ACTINOMYCETES – POTENTIAL BIOCONTROL AGENTS OF THE TYPICAL TREES INFECTIONS

Abstract

From the main ridge of Crimean mountains were isolated 564 strains of soil non-rhizospheric actinomycetes and 640 isolates from rhizosphere medicinal and endemic plants Thymus roegneri K. Koch aggr., Jurinea sordida Stev., Helianthemum stevenii Rupr. ex Juz. & Pozd., Orchis purpurea Huds., Trinia bibershteinii Fedoronch., Potentilla depressa Willd. ex D. F. K. Schltdl. Their antimicrobial properties were studied against phytopathogenic bacteria Pseudomonas syringae IMV 8511, Xantomonas campestris pv. campestris IMV 8003, Agrobacterium tumifaciens IMV 8628 і Erwinia amylovora Mi2 and fungi Fusarium oxysporum IMV 54201, Aspergillus niger IMV 16706, which are typical infectious diseases wide range of plants, including trees. Isolates with antibacterial and antifungal properties are more represented in the rhizosphere of plants. Overall, about half non-rhizospheric or rhizospheric isolates inhibited growth of at least one test-culture. Most antagonists were found in the rhizosphere Thymus roegneri K. Koch aggr. (67.4 %). least – in the rhizosphere Helianthemum stevenii Rupr. ex Juz. & Pozd. (39.8 %), there were 50.6 % among non-rhizospheric strains. Most isolates inhibited growth of X. campestris pv. сampestris (almost 30 %), least – P. syringae (about 5 %) and fungi (not more 3 %). We isolated 18 strains, which are capable of inhibiting all used phytopathogenic bacteria (10 non-rhizospheric and 8 with rhizosphere of plants), 35 isolates inhibited growth Fusarium oxysporum and Fusarium oxysporum , of which 27 were non-rhizospheric. Also we isolated 4 strains of non-rhizospheric actinomycetes which showed activity against all used test-cultures. At the same time in non-rhizosphere soil more isolates were found that supressed the growth of pathogenic bacteria or fungi, and 4 actinomycete strains have antimicrobial activity against all teststrains. We selected 57 isolates for further research that could be potential biocontrol agents of infectious diseases of trees.