The OTA-degrading phenotype in the Lysobacter and Stenotrophomonas genera is conferred by the hydrolytic activity of subtype I amidohydrolases

The ochratoxin A (OTA)-degrading phenotype was examined in Stenotrophomonas and Lysobacter genera. Seven Stenotrophomonas type strains and 20 Lysobacter species were studied for OTA detoxification potential. OTA hydrolysis was found in Stenotrophomonas species S. acidaminiphila and S. nitritireducens, while 18 of 20 Lysobacter strains showed OTA-degrading activity. Genomic analysis indicated that the OTA-degrading phenotype is associated with subtype I amidohydrolase-encoding genes, such as ADH3- or ADH2-like amidohydrolases in Stenotrophomonas and Lysobacter, respectively, but it was not linked to other known OTA-degrading enzymes. The limited distribution of these enzymes in Stenotrophomonas suggests horizontal gene transfer events from Lysobacter strains. Biochemical and structural analyses confirmed that subtype I amidohydrolases, particularly SaOTA, LcOTA, and LaOTA from S. acidaminiphila, L. concretionis, and L. antibioticus respectively, play a key role in OTA degradation, affirming the correlation between this phenotype and amidohydrolase enzyme activity in OTA detoxification.