Influence of Bacillus spp. isolated from maize agroecosystem on growth and aflatoxin B₁ production by Aspergillus section Flavi

Abstract

A total of 59 bacteria of the Bacillus genus were isolated from different components of a maize agroecosystem and their antifungal activity against Aspergillus section Flavi was evaluated. Thirty-three and 46% of these bacteria were able to inhibit Aspergillus flavus Link and A. parasiticus Speare respectively at water activity (a(w)) 0.982; however, when a(w) was 0.955, these percentages were decreased and only three isolates were able to inhibit Aspergillus section Flavi. The majority of bacilli acted as contact antagonists, while a small number of isolates were able to form inhibition zones. In maize meal extract agar, Aspergillus section Flavi growth rate and aflatoxin B(1) (AFB(1)) production were significantly reduced when these strains were paired at a(w) 0.982 with bacilli at all inoculum levels studied. However, two bacilli isolated were able to reduce growth rate and aflatoxin production when a(w) was 0.955. Lag phase increase followed the same general pattern as growth rate reduction. When Aspergillus section Flavi was grown in sterile maize in the presence of three Bacillus strains at a(w) 0.982, the reduction in count (colony-forming units (cfu) g(-1) maize) was less than 30%, except when Aspergillus section Flavi grew with Bacillus amyloliquefaciens UNRCLR. However, levels of detectable AFB(1) were significantly reduced in these interactions at a(w) 0.982.

Antifungal compounds from Bacillus subtilis B-FS06 inhibiting the growth of Aspergillus flavus

“…The results indicated that L. casei CRL 431 and L. rhamnosus CRL 1224 might be utilized as potential biocontrol agents against A. flavus. Some other bacterial species had been found to be able to reduce A. flavus growth and/or aflatoxin production significantly (Mickler et al 1995;Misaghi et al 1995;Bluma and Etcheverry 2006;Palumbo et al 2006).…”

In Vivo Effect of Mint (Mentha Viridis) Essential Oil on Growth and Aflatoxin Production by Aspergillus Flavus Isolated From Stored Corn

“…P. expansum was incapable of growth during the trial on apple-based agar plates inoculated with the antifungal producing culture, whereas the mold did grow on apple plates inoculated with a LAB possessing no antifungal activity (Rouse et al 2008). Bluma and Etcheverry (2006) found that the reduction in colony size (cfu/g maize) of Aspergillus section Flavi, which grew in sterile maize in the presence of three Bacillus strains at water activity 0.982, did not reach 30%, except when Aspergillus section Flavi grew with Bacillus amyloliquefaciens UNRCLR. Kim and Hwang (2007) reported that microbial metabolites with antifungal activity have an impact on crop protection as microbial fungicides.…”

“…Bluma and Etcheverry (2006) found that the reduction in colony size (cfu/g maize) of Aspergillus section Flavi , which grew in sterile maize in the presence of three Bacillus strains at water activity 0.982, did not reach 30%, except when Aspergillus section Flavi grew with Bacillus amyloliquefaciens UNRCLR.…”

Effect of Bacillus spp. on Aspergillus westerdijkiae growth, sporulation and ochratoxin A production in green-coffee medium

“…isolates on A. westerdijkiae's mycelium growth rate, we used the method proposed by Bluma & Etcheverry (2006). Briefly, aliquots (1 mL) of bacterial suspensions were inoculated on Petri plates (final concentration of 10 9 cells mL -1…”

“…This assay was repeated three times. Fungal growth in diameter, was evaluated daily by measuring two radii at right angles one to another with a ruler (Cavaglieri et al, 2005;Bluma & Etcheverry, 2006). The radial growth rate (cm day -1 ) was calculated by linear regression.…”