Aflatoxin M1 [KLH]

The objective of this study was to determine the effects of a high salt culture medium (fish sauce and salted fish) on the detoxification capacity of Lactobacillus acidophilus (L.a), L. bulgaricus (L.b), and L. casei (L.c). These lactic acid bacteria (LAB) strains were mixed with dried fish and fish sauce containing aflatoxin B-1 (AFB(1)) and T-2 toxin (T-2) and cultured at room temperature for 24 h. The toxin concentrations in the media were quantified using LC-MS/MS following the incubation. Compared with the MRS broth, the growths of L.a, L.b, and L.c were inhibited in the salted fish and fish sauce media. As the toxin concentration in the MRS broth increased, the toxin removal rates for L.a, L.b, and L.c increased, especially those for the mixed L.a, L.b, and L.c (L.abc). Moreover, the abilities of L.a, L.b, and L.c to remove AFB(1) in the MRS broth was significantly stronger than that for T-2, indicating the mycotoxin toxicity enhanced the detoxification ability of LAB. Unlike the MRS broth, salted fish and fish sauce can enhance the removal rates of T-2 for L.a, L.b, and L.c. This indicates that high-salt stress could promote the synthesis of a detoxification factor in LAB.

The efficacy of eleven essential oils (EOs) against Aspergillus flavus NRRL 3357 was investigated. The highest antifungal activity against this aflatoxigenic fungus was exhibited by cinnamon, oregano and lemongrass, which showed low minimum inhibitory concentration (MIC) values under vapor conditions. Interactions of the three EOs were evaluated by the fractional inhibition concentration index (FICI), and the composite essential oils (CEO) showed synergistic inhibitory activities. Chemical analysis of the composite essential oils of cinnamon, oregano, and lemongrass (COL-CEO) revealed that (Z)-citral (33.44%), (E)-citral (32.88%) and carvacrol (19.84%) were the dominant components, followed by limonene (4.29%) and cinnamaldehyde (3.76%). COL-CEO not only inhibited fungal growth but also decreased aflatoxin B1 production by A. flavus. Downregulation of the relative expression of aflatoxin genes in the aflatoxin biosynthetic pathway by COL-CEO revealed its anti-aflatoxigenic mechanism. COL-CEO could also affect the colonization of A. flavus on maize grains. Therefore, COL-CEO may be considered as a potential natural antifungal agent, which could be used for the storage of maize and other grains.