Antifungal and antiaflatoxigenic mechanism activity of freeze-dried culture filtrate ofStreptomyces philanthiRL-1-178 on the two aflatoxigenic fungi and identification of its active component

Abstract

Aims The study reports the antifungal and antiaflatoxigenic mechanism activity of freeze-dried culture filtrate of Streptomyces philanthi RL-1-178 (DCF RL-1-178) against two aflatoxigenic strains (Aspergillus parasiticus and A. flavus) and identification of its active component. Methods and Results Significant inhibition in ergosterol biosynthesis by the DCF RL-1-178 appeared on the plasma membrane. Moreover, the DCF RL-1-178 showed dose-dependent inhibition of methylglyoxal (MG) (an aflatoxin inducer) biosynthesis and exhibited a novel antiaflatoxigenic action mechanism. Significant impairments in enzymatic [superoxide dismutase (SOD) and catalase (CAT)] and nonenzymatic [oxidized and reduced glutathione (GSH) and ratio of oxidized and reduced glutathione (GSSG)] anti-oxidative defense molecules were observed in the two aflatoxigenic cells. The active component of the DCF RL-1-178 was identified as natamycin. The natamycin exhibited against A. parasiticus and A. flavus with the minimum inhibitory concentration (MIC) values of 0.5 and 1.0 µg ml−1, respectively, while the minimum fungicidal concentration values were the same (4.0 µg ml−1). Conclusions The DCF RL-1-178 containing natamycin exhibited the following effects: (1) inhibition of cellular ergosterol biosynthesis on plasma membrane, (2) reduction in MG (aflatoxin inducer) confirmed novel antiaflatoxigenic mechanism of action, and (3) caused remarkable debasement in antioxidant defense enzymes (SOD and CAT) and nonenzymatic defense molecules (GSH and GSSG) revealing biochemical mechanism of action.

Antifungal mechanism of cell-free supernatant produced by Trichoderma virens and its efficacy for the control of pear Valsa canker

“…Thus, this pathogen-beneficial ROS suppression effect may be driven by the pathogens themselves to scavenge ROS. It was supported by Boukaew et al, who reported that Aspergillus parasiticus and A. flavus increased tolerance to biotic stress through enhanced activities of antioxidant enzymes activities, such as POD, SOD, and CAT (Boukaew et al, 2023). However, it remains unclear how WJ561 CFS balances its ROS-mediated responses to inhibit V. pyri during infection.…”