The fungal secondary metabolite patulin is a mycotoxin widespread in foods and beverages which poses a serious threat to human health. However, no enzyme was known to be able to degrade this mycotoxin. For the first time, we discovered that a manganese peroxidase (MrMnP) from Moniliophthora roreri can efficiently degrade patulin. The MrMnP gene was cloned into pPICZα(A) and then the recombinant plasmid was transformed into Pichia pastoris X-33. The recombinant strain produced extracellular manganese peroxidase with an activity of up to 3659.5 U/L. The manganese peroxidase MrMnP was able to rapidly degrade patulin, with hydroascladiol appearing as a main degradation product. Five mg/L of pure patulin were completely degraded within 5 h. Moreover, up to 95% of the toxin was eliminated in a simulated patulin-contaminated apple juice after 24 h. Using Escherichia coli as a model, it was demonstrated that the deconstruction of patulin led to detoxification. Collectively, these traits make MrMnP an intriguing candidate useful in enzymatic detoxification of patulin in foods and beverages.

Citrinin (CIT) is a mycotoxin found in foods and feeds and most commonly discovered in red yeast rice, a food additive made from ordinary rice by fermentation with Monascus. Currently, no enzyme is known to be able to degrade CIT effectively. In this study, it was discovered that manganese peroxidase (MrMnP) from Moniliophthora roreri could degrade CIT. The degradation appeared to be fulfilled by a combination of direct and indirect actions of the MrMnP with the CIT. Pure CIT, at a final concentration of 10 mg/L, was completely degraded by MrMnP within 72 h. One degradation product was identified to be dihydrocitrinone. The toxicity of the CIT-degradation product decreased, as monitored by the increased survival rate of the Caco-2 cells incubated with MrMnP-treated CIT. In addition, MrMnP could degrade CIT (with a starting concentration of up to 4.6 mg/L) completely contaminated in red yeast rice. MrMnP serves as an excellent candidate enzyme for CIT detoxification.

Clostridium perfringens infection can induce necrotic enteritis and lead to significant economic loss to the chicken industry. In this study, a xylanase (CbXyn10C), which effectively promotes the growth of probiotics, and a protease, which degrades the biofilm of C. perfringens, were analyzed for their ability to alleviate C. perfringens-induced necrotic enteritis in broiler chickens. A total of 300 male AA chickens were divided into five treatment groups (control, no enzyme and no C. perfringens challenge; Cp, no enzyme, C. perfringens challenge; Xyn, CbXyn10C plus C. perfringens challenge; Xyn+Am, CbXyn10C+Amylase plus C. perfringens challenge; Xyn+Ap, CbXyn10C+Alkaline protease plus C. perfringens challenge). The C. perfringens CVCC 60102 was administered orally on a daily basis to the chickens from 14 to 20 days. In comparison with Cp, Xyn+Ap significantly reduced intestinal damage in the duodenum, jejunum, and ileum of chickens challenged with C. perfringens (p < 0.05). The enzymes, and particularly Xyn+Ap, notably enhanced the expression of key intestinal barrier genes, reduced the IL-6 level, and decreased the DAO (diamine oxidase) level. Not unexpectedly, feeding enzymes influenced the abundance of Lactobacillus and Butyricicoccus bacteria in the intestine. These results indicated that CbXyn10C and protease can be used to alleviate intestinal damage caused by C. perfringens infection.