Title

Sulfonate metabolism by bacteria

Date of Completion

January 1997

Keywords

Biology, Microbiology|Biogeochemistry|Chemistry, Biochemistry

Degree

Ph.D.

Abstract

Bacterial assimilation of sulfonate-sulfur under anaerobic conditions has been demonstrated. Two different bacteria able to grow fermentatively using sulfonate-sulfur as sole sulfur source were isolated by enrichment culture; neither were able to utilize sulfonate as sole source of carbon and energy for growth. An isolate of Clostridium pasteurianum assimilated the sulfur of isethionate (2-hydroxyethanesulfonate), taurine (2-aminoethanesulfonate), or p-toluenesulfonate, A facultative fermentative Klebsiella strain did not utilize the sulfur of any of these sulfonates but assimilated cysteate-sulfur, in contrast, when growing by aerobic respiration, the range of sulfonates able to serve as sulfur source was greater. Both bacteria displayed a preferential utilization of sulfate-sulfur to that of the sulfonates tested. Thus, bacterial assimilation of sulfonate-sulfur during anaerobic growth has direct parallels with features until now recognized only for the aerobic assimilatory process.^ A novel taurine-pyruvate aminotransferase activity was detected in cell extracts of Clostridium pasteurianum when grown with taurine as sole sulfur source but was absent when cells had been grown with sulfate or sulfite as sole sulfur source. This aminotransferase activity was not detected in cell extracts of other bacteria examined. The characterization of taurine-pyruvate aminotransferase shows that the enzyme activity is inducible and has temperature optimum of 37$\sp\circ$C and pH optimum between 8.5 to 9.5.^ The diverse pattern of sulfonate utilization in the aerobic bacterial world has also been studied. Taurine could be utilized as sole source of carbon, energy, nitrogen and sulfur by Arthrobacter crystallopoietes and a Rhodococcus sp. isolated as a chance contaminant. None of the other sulfonates tested (isethionate, ethanesulfonate, sulfoacetaldehyde etc.) served as sole source of carbon and energy source. However, the Rhodococcus sp. could utilize a wide range of sulfonates as sole source of sulfur, even those sulfonates that could not serve as sole carbon source for the bacterium.^ Overall, my research showed the diversity of microorganisms which can metabolize sulfonates as well as the diverse patterns of sulfonate utilization in the bacterial world, extended to the biochemical and physiological aspects of utilization of sulfonates by these microorganisms. ^