Epsilon Open Archive

Abstract

The species Arthrobacter chlorophenolicus was isolated from soil because of its ability to degrade high concentrations of 4-chlorophenol and other toxic aromatic compounds. It is also able to grow on and degrade phenolic compounds at low temperatures as well as during extreme temperature fluctuations. In this thesis the degradation pathway through which 4-chlorophenol is degraded by this organism is described. It is an efficient and very unusual 4-chlorophenol catabolic pathway for aerobic bacteria, with hydroxyquinol as the ring-cleavage substrate. In addition, A. chlorophenolicus was studied during growth on mixtures of phenolic compounds, giving new insights into substrate preferences and mechanisms behind the sequential degradation of similar compounds. Changes in cell membrane fatty acid composition at two different temperatures when phenolic compounds were added in increasing concentrations were also studied. The results have provided more information about this adaptive response in Gram positive bacteria. In addition, the proteins expressed during the same growth conditions mentioned above were identified by shotgun proteomics, confirming the catabolic routes used by this organism during growth on phenolic compounds as well as some of its stress response mechanisms. The genome sequence of A. chlorophenolicus was sequenced and annotated, revealing secrets of adaptation and stress mechanisms as well as new findings on the genome structure and catabolic activities of A. chlorophenolicus.