Comparative Genomes Analysis of Aflatoxin B-1-Degrading Pseudomonas Strains with Different Degradation Abilities

Pseudomonas spp. had rich biological functions, including the degradation of mycotoxins. In this study, to reveal the reasons for the different AFB(1) degradation abilities, three pseudomonas strains with distinct AFB(1) degradation abilities were isolated and their genomes were sequenced and annotated. COG (Clusters of Orthologous Groups) and GO (Gene Ontology) annotations of the protein-coding genes show a conservation of genome-wide protein functions in genus Pseudomonas. However, the AFB(1)-degrading strains HAI2 and HT3 harbor much more genes belonged to the pathway of xenobiotics biodegradation and metabolism than non-degrading strain 48. Besides, the enzyme families potentially involved in the AFB(1) degradation of bacteria are more abundant in the two AFB(1)-degrading strains. A pan-genome profile was then formed by comparing the genomes against other reference genomes of the corresponding Pseudomonas species. Accordingly, a total of 1,528 genes were found to be specific in AFB(1)-degrading strains, and 65 genes of them are related to oxidoreductase activity. The two AFB(1)-degrading Pseudomonas strains HAI2 and HT3 harbor additional peroxidases compared to strain 48. However, none of these oxidoreductase activity-related genes is shared by all three AFB(1)-degrading strains. High AFB(1)-degrading strain HT3 is more diverse than those of strains 48 and HAI2 and harbored two cytochrome P450 genes, but homologous sequences could not be found in the other two strains. Moreover, the numbers of peroxidase in HT3 and strain HAI2 are higher than strain 48. These findings indicate that different Pseudomonas strains might earn the ability to degrade AFB(1) by independently acquiring different catalytic proteins rather than sharing some core proteins. Differences in some oxidoreductases, such as P450 and Peroxidase, may be responsible for this difference in degradation ability in Pseudomonas strains.