Detoxication and bioconversion of aflatoxin B1 by yellow mealworms (Tenebrio molitor): A sustainable approach for valuable larval protein production from contaminated grain

Bioremediation of Aflatoxin B1 by Meyerozyma guilliermondii AF01 in Peanut Meal via Solid-State Fermentation

The use of microorganisms to manage aflatoxin contamination is a gentle and effective approach. The aim of this study was to test the removal of AFB1 from AFB1-contaminated peanut meal by a strain of Meyerozyma guilliermondii AF01 screened by the authors and to optimize the conditions of the biocontrol. A regression model with the removal ratio of AFB1 as the response value was established by means of single-factor and response surface experiments. It was determined that the optimal conditions for the removal of AFB1 from peanut meal by AF01 were 75 h at 29 °C under the natural pH, with an inoculum of 5.5%; the removal ratio of AFB1 reached 69.31%. The results of simulating solid-state fermentation in production using shallow pans and fermentation bags showed that the removal ratio of AFB1 was 68.85% and 70.31% in the scaled-up experiments, respectively. This indicated that AF01 had strong adaptability to the environment with facultative anaerobic fermentation detoxification ability. The removal ratio of AFB1 showed a positive correlation with the growth of AF01, and there were no significant changes in the appearance and quality of the peanut meal after fermentation. This indicated that AF01 had the potential to be used in practical production.

Biotransformation of Deoxynivalenol by a Dual-Member Bacterial Consortium Isolated from Tenebrio molitor Larval Feces

In this study, a dual-member bacterial consortium with the ability to oxidize deoxynivalenol (DON) to 3-keto-DON, designated SD, was first screened from the feces of Tenebrio molitor larvae. This consortium consisted of Pseudomonas sp. SD17-1 and Devosia sp. SD17-2, as determined by 16S rRNA-based phylogenetic analysis. A temperature of 30 °C, a pH of 8.0-9.0, and an initial inoculum concentration ratio of Devosia to Pseudomonas of 0.1 were optimal single-factor parameters for the DON oxidation activity of the bacterial consortium SD. Genome-based bioinformatics analysis revealed the presence of an intact PQQ biosynthesis operon (pqqFABCDEG) and four putative pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) genes in the genomes of Pseudomonas strain SD17-1 and Devosia strain SD17-2, respectively. Biochemical analyses further confirmed the PQQ-producing phenotype of Pseudomonas and the DON-oxidizing enzymatic activities of two of four PQQ-dependent ADHs in Devosia. The addition of PQQ-containing a cell-free fermentation supernatant from Pseudomonas activated DON-oxidizing activity of Devosia. In summary, as members of the bacterial consortium SD, Pseudomonas and Devosia play indispensable and complementary roles in SD's oxidation of DON. Specifically, Pseudomonas is responsible for producing the necessary PQQ cofactor, whereas Devosia expresses the PQQ-dependent DON dehydrogenase, together facilitating the oxidation of DON.

Characteristics of Aflatoxin B1 Degradation by Stenotrophomonas acidaminiphila and It's Combination with Black Soldier Fly Larvae

Aflatoxin B₁ (AFB₁) is a common mycotoxin contaminant in cereals that causes severe economic losses and serious risks to the health of humans and animals. In this paper, we investigated the characteristics of AFB₁ degradation by black soldier fly larvae (BSFL) combined with commensal intestinal microorganisms. Germ-free BSFL and non-sterile BSFL were reared on peanut meal spiked with AFB₁ for 10 days. The result showed that germ-free BSFL and non-sterile BSFL could achieve 31.71% and 88.72% AFB₁ degradation, respectively, which indicated the important role of larvae gut microbiota in AFB₁ degradation. Furthermore, twenty-five AFB₁-degrading bacteria were isolated from BSFL gut, and S. acidaminiphila A2 achieved the highest AFB₁ degradation, by 94%. When S. acidaminiphila A2 was re-inoculated to BSFL, the detrimental effect of AFB₁ on the growth performance of BSFL was alleviated, and complete AFB₁ degradation in peanut meal was obtained. In conclusion, the present study may provide a strategy to degrade AFB₁ in feedstuff through bioconversion with BSFL in combination with gut-originated AFB₁-degrading bacteria, while providing a sustainable insect protein and fat source to animals.