The horizontal gene transfer of perchlorate reduction genomic island in three bacteria from an ecological niche

AbstractThree new strains of dissimilatory perchlorate-reducing bacteria (DPRB), QD19-16, QD1-5, and P3-1, were isolated from an active sludge. Phylogenetic trees based on 16S rRNA genes indicated that QD19-16, QD1-5, and P3-1 belonged toBrucella,Acidovorax, andCitrobacter, respectively, expanding the distribution of DPRB in theProteobacteria. The three strains were gram-negative and facultative anaerobes with rod-shaped cells without flagella, which were 1.0 –1.6 μm long and 0.5–0.6 μm wide. The three DPRB strains utilized similar broad spectrum of electron donors and acceptors and demonstrated a similar capability to reduce perchlorate within 6 days. The enzyme activity of perchlorate reductase in QD19-16 toward chlorate was higher than that t oward perchlorate. The high sequence similarity of the perchlorate reductase operon and chlorite dismutase genes in the perchlorate reduction genomic islands (PRI) of the three strains implied that they were monophyletic origin from a common ancestral PRI. Two transposase genes (tnp1 andtnp2) were found in the PRIs of strain QD19-16 and QD1-5, but were absent in the strain P3-1 PRI. The presence of fragments of IR sequences in the P3-1 PRI suggested that P3-1 PRI had previously contained these twotnp genes. Therefore, it is plausible to suggest that a common ancestral PRI transferred across the strainsBrucella sp. QD19-16,Acidovorax sp. QD1-5, andCitrobacter sp. P3-1 through horizontal gene transfer, facilitated by transposas...

Source: European Journal of Applied Physiology - December 30, 2023 Category: Physiology Source Type: research