Relationship between Extracellular Polysaccharide and Benzene Tolerance of Rhodococcus sp. 33

Abstract

Benzene is one of the most toxic and prevailing environmental pollutants. Rhodococcus sp. 33 can tolerate and efficiently degrade various concentrations of benzene. Under either resting or growth conditions, rough mutant strains derived from strain 33 were more sensitive to benzene than the mucoidal parent strain. The rough strains did not produce extracellular polysaccharides (EPS), whereas the parental strain 33 did so in large quantity (33 EPS). By the addition of 33 EPS to the rough strains, both the survival and growth of the rough strains in media containing benzene were improved. The 33 EPS was found to be an acidic polysaccharide containing D-galactose, D-glucose, D-mannose, D-glucuronic acid, and pyruvic acid at a molar ratio of 1: 1: 1: 1: 1. These data suggest that the 33 EPS plays an important role in the benzene tolerance in Rhodococcus sp. 33, especially helping the cells to survive an initial challenge with benzene.