In Vitro Antagonistic Effects of Some Bacillus Spp. On the Growth and Mycotoxin Production of Toxigenic Aspergilli

Abstract

This study aimed to investigate the antagonistic effect of three strains of the genus Bacillus on toxigenic fungi contaminating food commodities, with emphasis on two ochratoxigenic isolates (A. ochraceus, A. westerdijkiae) and two aflatoxigenic isolates (A. flavus and A. parasiticus). In vitro studies were carried out using two different methods for cultivation tested bacilli with fungal isolatescoincubation and dual culture method. The most sensitive isolate was A. ochraceus by both used methods. B. mycoides (5.72 ± 6.4 mm) and B. subtilis (5.08 ± 2.84 mm) were able to inhibit its growth and sporulation during ten days of cultivation (both inhibited the sporulation of A. ochraceus 100%) in coincubation. The most effective in the dual culture method were B. subtilis and B. thuringiensis against A. ochraceus (growth inhibition rate 84.40%; 90.55%) and A. flavus (growth inhibition rate 91.54%; 92.43%). The most effective sporulation inhibitors were B. subtilis and B. thuringiensis, which completely inhibited the sporulation of A. ochraceus and A. parasiticus after ten days of coincubation. Likewise, all tested bacterial strains showed complete inhibition of ochratoxin A synthesis in A. ochraceus and A. westerdijkiae exposure to bacterial volatiles. So, the current study illustrated that strains of the genus Bacillus could significantly inhibit the growth, sporulation, and mycotoxin production of toxigenic aspergilli and showing the great potential as a biocontrol agent of preand post-harvest food diseases caused by microscopic filamentous fungi. ARTICLE INFO

Bacillus VOCs in the Context of Biological Control

“…Inhibition of mycotoxigenic fungi was also observed by the VOCs produced by B. megaterium KU143 and Pseudomonas protegens AS15 in the case of Aspergillus flavus , where the total aflatoxin production in rice grains was reduced by 90.4%, besides the reduced fungal population [ 52 ]. Hlebová et al [ 53 ] have shown complete inhibition of ochratoxin synthesis in Aspergillus ochraceus and Aspergillus westerdijkiae by VOCs produced by B. mycoides, B. subtilis, and B. thuringiensis . Acetoin was found to be the major VOC produced by B. velezensis G341, inhibiting mycelial growth of Sclerotinia sclerotiorum (cucumber Sclerotinia rot ), Rhizoctonia solani (rice sheath blight), and Botrytis cinerea (tomato grey mold) [ 54 ].…”