Two aerobic sulfadiazine
(SDZ) degrading bacterial strains, D2
and D4, affiliated with the genus Arthrobacter, were isolated from SDZ-enriched activated sludge. The degradation
of SDZ by the two isolates followed first-order decay kinetics. The
half-life time of complete SDZ degradation was 11.3 h for strain D2
and 46.4 h for strain D4. Degradation kinetic changed from nongrowth
to growth-linked when glucose was introduced as the cosubstrate, and
accelerated biodegradation rate was observed after the adaption period.
Both isolates could degrade SDZ into 12 biodegradation products via
3 parallel pathways, of which 2-amino-4-hydroxypyrimidine was detected
as the principal intermediate product toward the pyrimidine ring cleavage.
Compared with five Arthrobacter strains
reported previously, D2 and D4 were the only Arthrobacter strains which could degrade SDZ as the sole carbon source. The draft
genomes of D2 and D4, with the same completeness of 99.7%, were compared
to other genomes of related species. Overall, these two isolates shared
high genomic similarities with the <i>s</i>-triazine-degrading Arthrobacter sp. AK-YN10 and the sulfonamide-degrading
bacteria Microbacterium sp. C448. In
addition, the two genomes contained a few significant regions of difference
which may carry the functional genes involved in sulfonamide degradation
