Lack of Capsular Exopolymer Effects on the Biodegradation of Organic Compounds by Pseudomonas sp. Strains JS1 and JS150

Abstract

Due to the increasing interest in the effects of exopolymers on microbial activities, two Pseudomonas sp. strains, JS1 (possesses capsular exopolymer) and JS150 (unencapsulated), were compared for their ability to degrade a variety of organic compounds under a number of different conditions. Degradation kinetics for citrate, salicylate, phenol, toluene, and 2,4,6-trinitrotoluene were identical for both strains in liquid media, regardless of cell density. JS1 and JS150 grew on citrate at the same rate in sand, sterile surface soil, and sterile subsurface sediments. The biodegradation curves for toluene by cells pregrown on citrate in any of the above matrices were indistinguishable. Twofold differences in water content and carbon-to-nitrogen ratios of 0.032 or 320 did not result in any apparent differences in phenol degradation by either encapsulated or unencapsulated cells in sand. These results indicate that generalizations about the effects of exopolymers on microbial processes may not be possible without further research.