In vitro growth inhibition of Curvularia gudauskasii by Bacillus subtilis

Abstract

Five rhizosphere Bacillus subtilis isolates were tested for in vitro antagonism against a sugarcane seedling pathogen strain of Curvularia gudauskasii. The isolate B. subtilis SR/B-16 was selected because it permanently inhibits 71% of fungal growth. Microscopic analysis of the antagonistic bacteria effects on C. gudauskasii revealed swelling and bulbous hyphae, vacuolated cytoplasm and no spore formation. The analysis of culture filtrates of SR/B-16 collected from stationary phase showed that they are responsible for the antifungal effects and for the abnormal shapes observed. However, bacterial culture efficiency is higher. The organic concentrated fraction of the extracts caused the same morphological changes as those caused by antifungal lipopeptides secreted by Bacillus species. The strain SR/B-16 can be used for the formulation of bioactive compounds for the treatment of C. gudauskasii diseases on sugarcane seedlings.

Activity of Fengycin and Iturin A Isolated From Bacillus subtilis Z-14 on Gaeumannomyces graminis Var. tritici and Soil Microbial Diversity

“…Bacillus-secreted lipopeptides, such as iturins and fengycins, strongly antagonize a broad spectrum of plant pathogenic fungi, but rarely inhibit bacteria (Cawoy et al, 2015;Chen et al, 2019). These Bacillus-secreted antifungal lipopeptides cause hyphal deformity, fracture, condensation of protoplasm, and inhibition of spore germination of plant pathogenic fungi (Ratón et al, 2012). However, the differences between these two lipopeptides in terms of their inhibitory mechanisms against pathogenic fungi and their effect on soil microbial diversity remain unclear.…”