Transformation of methylthio-s-triazines via sulfur oxidation by strain JUN7, a Bacillus cereus species

It is known that methylthio-s-triazines can be transformed to the corresponding 2-hydroxy derivatives through sulfoxides and sulfones in aerobic and flooded soil; however, production of sulfoxides and/or sulfones from methylthio-s-triazines by isolated s-triazine-degrading bacteria has not been reported yet. In the present study, a new bacterial strain, JUN7, was obtained from Japanese soil; the bacterium is capable of transforming simetryn to 2-methylsulfinyl 4,6-bis(ethylamino)-s-triazine (sulfoxide simetryn) and 2-hydroxy-4,6-bis(ethylamino)-s-triazine (2-hydroxy simetryn) in a Luria-Bertani (LB) medium. This is the first isolation of the specific microorganism that mediates sulfur oxidation of methylthio-s-triazines, as far as we know. Strain JUN7 could decrease other methylthio-s-triazines such as dimethametryn and prometryn, but not chlorinated s-triazines (atrazine, simazine, and terbuthylazine) and methoxy-s-triazine (atraton) in 1/10 LB medium. Strain JUN7 did not possessed gene atzA or trzN encoding triazine-degrading enzymes, suggesting that the strain may have another metabolic system. Characterizations of strain JUN7 based on comparative morphology, physiological classification, and comparison of the partial 16S rRNA sequence indicated that it is assigned as a Bacillus cereus species.