Influences of Culture Media, Temperature and Light/Dark Conditions on Growth and Antifungal Activity of Streptomyces spp. Against Botrytis cinerea, in vitro and on Tomato Leaf

Abstract

The influences of culture media, temperature, and light/dark conditions on growth and antifungal activity of the three strains Streptomyces spp. against Botrytis cinerea was studied. Results of in vitro study indicated that the GYM agar and incubated at 28°C exhibited good mycelial growth and a spore mass production of the three strains of Streptomyces spp. On the other hand, the PDA and incubation at 21°C were suitable for the mycelial growth of B. cinerea . Moreover, light/dark conditions had an effect on the growth of the two strains of S. philanthi . The strains RL-1-178 and RM-1-138 of S. philanthi grown in all media and incubation temperatures tested possessed antifungal activity against B. cinerea (100% inhibition) while S. mycarofaciens showed different results on PDA (83% inhibition) and GYM (88% inhibition) with the optimum incubation temperature at 21°C. Then, the antifungal compounds in culture filtrates produced by the three antagonistic strains against B. cinerea were tested on tomato leaf. They showed a significantly higher inhibitory effect on the symptoms of blight disease on tomato leaf compared with the control. The better protection efficacy against B. cinerea on tomato leaf was observed with the culture filtrates of S. philanthi RM-1-138 (82.89% and 0.33 cm 2 lesion areas symptoms). Moreover, the antifungal compounds in the culture filtrate of S. philanthi RM-1-138, identified by GC-MS, were greatly altered relative to concentration components under different temperatures and light/dark conditions tested. Our results clearly demonstrated that the environmental factors have an influence on antifungal activity of the three strains of Streptomyces spp.

The Potential Use of Actinomycetes as Microbial Inoculants and Biopesticides in Agriculture

“…In vivo performance of actinomycetes against fungal phytopathogens are often associated with positive results, demonstrating inhibiting effects that consolidate its possible application as constituents of biopesticides for plant defense (166)(167)(168). However, the in vitro behavior may not always be reflected when evaluating the antagonistic effect in vivo.…”