A Hydrolase Produced by Rhodococcus erythropolis HQ Is Responsible for the Detoxification of Zearalenone

Abstract

Zearalenone (ZEN), an estrogenic mycotoxin, is one of the prevalent contaminants found in food and feed, posing risks to human and animal health. In this study, we isolated a ZEN-degrading strain from soil and identified it as Rhodococcus erythropolis HQ. Analysis of degradation products clarified the mechanism by which R. erythropolis HQ degrades ZEN. The gene zenR responsible for degrading ZEN was identified from strain HQ, in which zenR is the key gene for R. erythropolis HQ to degrade ZEN, and its expression product is a hydrolase named ZenR. ZenR shared 58% sequence identity with the hydrolase ZenH from Aeromicrobium sp. HA, but their enzymatic properties were significantly different. ZenR exhibited maximal enzymatic activity at pH 8.0–9.0 and 55 °C, with a Michaelis constant of 21.14 μM, and its enzymatic activity is 2.8 times that of ZenH. The catalytic triad was identified as S132-D157-H307 via molecular docking and site-directed mutagenesis. Furthermore, the fermentation broth of recombinant Bacillus containing ZenR can be effectively applied to liquefied corn samples, with the residual amount of ZEN decreased to 0.21 μg/g, resulting in a remarkable ZEN removal rate of 93%. Thus, ZenR may serve as a new template for the modification of ZEN hydrolases and a new resource for the industrial application of biological detoxification. Consequently, ZenR could potentially be regarded as a novel blueprint for modifying ZEN hydrolases and as a fresh resource for the industrial implementation of biological detoxification.

Effectiveness of Rhodococcus erythropolis strain OPI-01 on the fungal development in winter wheat

“…was associated with archetypal salicylic acid and jasmonic acid defense pathways (Tan et al 2021). Hu et al 2023 also observed that R. erythropolis could also reduce zearalenone through the expression of the zenR gene (Hu et al 2023). According to McLeod et al 2006 the metabolic diversity of Rhodococcus species was also due to the presence and mobilization of large linear plasmids and multiple enzymatic homologs in catabolic pathways (McLeod et al 2006).…”

Actinobacteria as Promising Biocontrol Agents for In Vitro and In Planta Degradation and Detoxification of Zearalenone

“…Given the substantial differences between field conditions and those used in in vitro studies, it is not unlikely that good degrading organisms in vitro would fail to deliver under field conditions. In spite of that, state-of-the-art research regarding the microbiological degradation of ZEN still often only focuses on the degradation in vitro [ 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. We want to emphasise the pivotal role of in planta validation in order to present strains that have a higher potential to be successful in a field application.…”

“…In 2018, Risa et al studied the degradation and detoxification potential of 42 type strains of the genus Rhodococcus and concluded that one strain, namely R. percolatus JCM 10087 T , was able to degrade 95% of 1 mg/L ZEN and decreased oestrogenicity by 70% [39]. Lastly, Hu et al (2023) identified the key degradation enzyme ZenR that is responsible for the degradation of ZEN by R. erythropolis HQ [40]. All these studies were performed in vitro in liquid growth medium, which bears little resemblance to the plant environment in which ZEN is actually to be remediated.…”