Deoxynivalenol (DON) is a globally significant mycotoxin that can contaminate grains, representing a serious hazard to human and animal health. The current research identified a DON-degrading dehydrogenase from Devosia sp. 63-57 ( Ds DDH). A Ds DDH demonstrated noticeable activation in the presence of Ca 2+ , with electron acceptors including pyrroloquinoline quinone (PQQ), phenazine methosulfate (PMS), and 2,6-dichlorophenolindophenol (DCPIP). The Ds DDH effectively degraded over 82 % of DON (10 μg/mL) within 30 min using PMS or DCPIP as electron acceptors. Additionally, the Ds DDH retained 76 % of its activity after pre-incubating for 2 h at 45 °C. Moreover, the Ds DDH-mediated degradation product of DON was confirmed to be 3-keto-DON, which significantly showed lower toxicity than DON, as verified by zebrafish larvae assays. Furthermore, DON contents in corn and wheat flour decreased from 9.58 to 9.73 to 1.36 and 1.77 μg/g, resulting in degradation rates of 85.85 and 81.76 %, respectively. These findings provide valuable insights into developing a biological detoxification strategy for DON in cereal and feed applications, laying a promising foundation for safer and more effective mycotoxin control.
Introduction: Applying biochar (BC) to reduce toxic substance accumulation in soil, either through direct adsorption or modulation of the microbial community, has received considerable attention. However, a knowledge gap exists regarding how BC regulates microbial community structure and functions to mitigate toxic substance accumulation.Methods: We previously identified p-coumaric acid (p-CA) as a representative autotoxin in tobacco rhizosphere soil. On this basis, this study simulated a soil environment with p-CA accumulation to investigate the impacts of BC on p-CA, soil physicochemical properties, and microbial community structure and function.Results: The results showed that p-CA could be directly adsorbed onto BC, which followed the pseudo-second-order kinetic model (R2 = 0.996). A pot experiment revealed that BC significantly reduced soil p-CA, altered soil microbial composition, and enhanced bacterial community diversity. A weighted correlation network analysis showed a close association between taxon 1 in the microbial network and p-CA, suggesting a pivotal role for this taxon in reducing p-CA, with Devosia and Nocardioides identified as potential key contributors to this process. The prediction of possible keystone taxa functions showed that BC increased the relative abundances of aromatic compound degraders. Mantel tests indicated that soil organic matter exerted the greatest influence on keystone taxa functions and hub genera.Discussion: These findings suggest that BC may either directly chemisorb p-CA or indirectly facilitate p-CA degradation by regulating the functioning of keystone taxa. The results of this study provide a novel perspective for further investigation of the mechanisms through which BC reduces the accumulation of toxic substances in soil.
Bin Ma,Jiafeng Niu,Hao Zhu,Huibing Chi,Zhaoxin Lu,Fengxia Lu,Ping Zhu
The oxidative reaction of Fusarium mycotoxin deoxynivalenol (DON) using the dehydrogenase is a desirable strategy and environmentally friendly to mitigate its toxicity. However, a critical issue for these dehydrogenases shows widespread substrate promiscuity. In this study, we conducted pocket reshaping of Devosia strain A6-243 pyrroloquinoline quinone (PQQ)-dependent dehydrogenase (DADH) on the basis of protein structure and kinetic analysis of substrate libraries to improve preference for particular substrate DON (10a). The variant presented an increased preference for substrate 10a and enhanced catalytic efficiency. A 4.7-fold increase in preference for substrate 10a was observed. Kinetic profiling and molecular dynamics (MD) simulations provided insights into the enhanced substrate specificity and activity. Moreover, the variant exhibited stronger conversion of substrate 10a to 3-keto-DON compared to the wild DADH. Overall, this study provides a feasible protocol for the redesign of PQQ-dependent dehydrogenases with favourable substrate specificity and catalytic activity, which is desperately needed for DON antidote development.
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