ABSTRACT
Two strains, Afipia sp. 624S and Diaphorobacter sp. 624L, were isolated from an enrichment culture with 4-aminobenzenesulfonate (4-ABS) as the only carbon source. Strain 624S utilized 4-ABS as the only source of carbon and energy and degraded 3.8 mM 4-ABS in 2 weeks, releasing a small amount of sulfate ions. On the other hand, strain 624L did not utilize 4-ABS. Additionally, a co-culture of strains 624S and 624L resulted in the enhanced degradation of 4-ABS, and no sulfite was accumulated in the degradation of 4-ABS. When incubated in 50 mM Tris-HCl buffer (pH 8.0) containing 2.2 mM sodium sulfite, strain 624S exhibited no sulfite oxidation; however, strain 624L completely oxidized the sulfite after 2 days. Furthermore, when manganase, which has the ability to oxidize sulfite, was added to the medium, the degradation rate of 4-ABS was increased in comparison with the non-addition control. These results indicate that the sulfite oxidation might stimulate the degradation of 4-ABS by strain 624S, suggesting syntrophic interaction between strains 624S and 624L based on sulfite oxidation.
