Inhibition of Growth and Aflatoxin Production of Aspergillus flavus by Lactobacillus Species

Abstract

A mixture of Lactobacillus species from a commercial silage inoculum reduced mold growth and inhibited aflatoxin production by Aspergillus flavus subsp. parasiticus. Actively growing Lactobacillus spp. cells totally inhibited germination of mold spores. Culture supernatant broth from the mixture of strains inhibited mold growth but did not destroy mold spore viability. Some mold spores were observed microscopically to have germinated and produced short nonbranching germ tubes; then growth ceased. While the pH of the culture broth and supernatant were about 4.0, acidification of nonfermented broth to pH 4.0 with HCl and lactic acid did not cause a similar inhibition of spore germination. The mixture of Lactobacillus species growing in a dialysis sack inhibited aflatoxin production by the A. flavus culture growing outside of the sack in broth, whereas mold growth was not affected. The pH values outside of the dialysis sack in the control and the treatments were similar (6 to 7) throughout the incubation period. When a dialysis sack with a molecular weight cutoff (MWCO) of 1,000 was used, there was little inhibition of aflatoxin B1 production, but with MWCOs of 6,000 to 8,000 and 12,000 to 14,000 aflatoxin production was greatly inhibited. In mixed culture experiments, levels of aflatoxin B1 and G1 were depressed compared to the control (monoculture). Mold growth in this case was also reduced compared to the monoculture system. Purified isolates of Lactobacillus from the commercial mixture had a slight effect on mold growth and aflatoxin production, but supernatant liquid of one isolate was quite inhibitory to production of aflatoxins B1 and G1, without affecting mold growth.

Enhancing the Microbiological Stability of Malt and Beer - A Review

“…Some LAB can inhibit mould growth and /or reduce mycotoxin production. Several investigations have demonstrated that LAB from dairy, meat, silage and gut environments either suppressed mycotoxin biosynthesis or effectively removed preformed mycotoxins 31,49,63,64,78,120 .…”

Biological Control of Molds and Mycotoxins in Foods

“…The effect of small molecular weight metabolites produced by Lactobacillus species in the inhibition of aflatoxin production was demonstrated by Gourama & Bullerman (21). In their experiments a mixture of Lactobacillus species from a silage inoculant was cultivated inside of a dialysis sack, while A. parasiticus was cultivated on the outside.…”

“…Foodborne and food grade LAB have been studied much more than Bacillus species or propionic bacteria and their antifungal activities have been reported by several authors throughout the years (20,21,22,23,24,25,26,27). Table 1 shows some of the publications that have demonstrated the antifungal activity of LAB, which vary from broad to very specific among and within species.…”

Anti-aflatoxigenic Effect of Some Lactobacillus Species on Aspergillus flavus by Using Real – Time - q PCR

“…However, to date, there are few practical methods for preventing aflatoxin contamination, and it is therefore critical to develop effective methods for prevention. A limited number of reports have shown that a good selection of Lactic Acid Bacteria (LAB) could allow the control of mould growth and improve the shelf life of many fermented products and, therefore, reduce health risks due to exposure to mycotoxins (Gourama &Bullerman, 1995b andDal Bello et al, 2007). El-Nezami et al (1998a) and Gratz et al (2006) demonstrated that the probiotic Lactobacillus rhamnosus (L. rhamnosus) strain GG is able to bind the potent hepatocarcinogenic aflatoxin B 1 (AFB 1 ).…”