Comparative Genomic Analysis of Pseudoxanthomonas sp. X-1, a Bromoxynil Octanoate-Degrading Bacterium, and Its Related Type Strains

Most Pseudoxanthomonas species described have been derived from water, plants, or contaminated soils. Here, a strain Pseudoxanthomonas sp. X-1 isolated from bromoxynil octanoate (BO)-contaminated soil is presented. Strain X-1 could degrade BO and produce bromoxynil. The optimal conditions for degradation of BO by strain X-1 were an initial BO concentration of 0.1 mM, 30 °C, pH 7, and Mn 2+ concentration of 1.0 mM. The bacterial morphological, physiological, and biochemical characteristics of strain X-1 were described, which showed differences comparing with other related type strains. The genome of strain X-1 was sequenced, and a comparative genomic analysis of X-1 and other Pseudoxanthomonas species was conducted to explore the mechanisms underlying the differences among these strains. The genome of strain X-1 encodes 4160 genes, 4078 of which are protein-coding genes and 68 are RNA coding genes. Specifically, strain X-1 encodes enzymes belonging to 778 Enzyme Commission (EC) numbers, much more than those of other related strains, and 62 of them are unique. Eight genes coding esterase are detected in strain X-1 which leads to the ability of BO degradation. This study provides strain, enzyme, and genome resources for the microbial remediation of environments polluted by herbicide BO.