Isolation and characterization of linear alkylbenzene sulfonate mineralizing bacterial consortia

Author

Alexander W. Breen

Date of Award

8-1992

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Life Sciences

Major Professor

Gary S. Sayler

Committee Members

Walter Farkas, Gerald Strandberg, Barbara Walton, David White

Abstract

Linear alkylbenzene sulfonate (LAS), an anionic surfactant widely used in the detergent industry, is in most circumstances a readily degradable compound. It is of environmental concern because of its widespread and high volume usage. Though much effort has been expended studying the fate and effects of LAS in the environment not much is known about the specific bacteria responsible for its removal. The initial phase of this study focused on a field study which compared LAS impacted and pristine freshwater ponds. The objectives of this research were to: i) compare bacterial populations in two ponds; ii) determine frequency of plasmids in bacteria from these sites; iii) compare frequency of DNA sequences coding for catabolism of aromatic compounds in isolates from these two sites. Plate counts indicated that exposure to LAS resulted in higher levels of heterotrophic bacteria and of bacteria capable of growing on LAS containing medium. Mineralization of LAS in any habitat within the pond system directly correlated with the presence of bacteria able to grow in the presence of LAS. No pond isolate was capable of complete LAS mineralization. Though a higher incidence of plasmids was found in bacteria from the LAS impacted site and among bacteria able to grow on LAS containing medium, the presence of a plasmid did not necessarily confer the ability to degrade LAS nor was ability to degrade LAS dependent on plasmid occurrence. The incidence of the selected genotypes for aromatic catabolism was similar at both sites suggesting that LAS catabolism was encoded by alternative sequences. This second phase of this study characterizes and compares two consortia, designated KJB and PG, capable of complete LAS mineralization. Both consortia are derived from activated sludge and contain four members. There is an absolute requirement for the presence of all four members to observe ¹⁴CO₂ from U-ring labeled LAS. In pure culture only one member of each consortium was capable of transforming LAS to polar products. No member of either consortium grew on LAS as a sole carbon source or was capable of LAS mineralization as a pure culture. Consortium PG is a more proficient culture for LAS oxidation than KJB. While KJB requires greater than 10 days for 25% conversion of LAS to CO₂. PG can convert 30% of added LAS to CO₂ in 2 days. Gene probe analysis of consortium KJB with xyIE, nahA, alkB and astA (two dioxygenases, an alkane hydroxylase and an arylsulfatase gene probes) showed no homology with these genes.

Recommended Citation

Breen, Alexander W., "Isolation and characterization of linear alkylbenzene sulfonate mineralizing bacterial consortia. " PhD diss., University of Tennessee, 1992.
https://trace.tennessee.edu/utk_graddiss/10846