جداسازی و ارزیابی فعالیت آنتاگونیستی یک استرین باکتری و اکتینومیست اپیفیت برعلیه باکتری عامل هسته یخ در گیاه پسته.

One of the aggravating factors in the amount of frost damage, is the presence of epiphytic ice nucleation bacteria on plant philosopher. Biological control of ice nucleation bacteria seems to be a promising option to reduce this type of frost damage. In this study, the antimicrobial capacity of epiphytic bacteria and actinomycetes was evaluated through growth inhibition of ice nucleation active bacteria (Pseudomonas fragi raf₃) on pistachio in Rafsanjan. For this purpose, samples were collected from healthy pistachio leaves in Rafsanjan. Among the isolated bacteria and actinomycetes, two isolates (A₄ and B₅₂) with the highest inhibitory zone were subject to different biochemical and physiological tests. Results showed that the zone of inhibition growth of ice nucleation bacterium on Petri dish, was 20 mm and 14 mm for isolates A₄ and B₅₂ respectively. Analysis of morphological and biochemical characteristics showed that isolate A4 was noted to be Gram-positive and to form white, dry colonies similar to actinomycetes. It was able to degrade glucose and sucrose as a carbon source and able to produce lipase, protease and catalase enzymes. This isolate was able to grow in conditions with pH 5 and 7, as well as, showed 2, 5,7 and 10% (w/v) salt-salt (sodium chloride) tolerance. It was tetracycline-sensitive and penicillin-resistance. The other antagonist isolate, B₅₂, had yellow colonies on nutrient agar media Gram-negative bacterium, catalase positive, oxidase negative, facultative anaerobic and lactose fermenting. [ABSTRACT FROM AUTHOR]