Managing Gene Expression in Pseudomonas Simiae EGD-AQ6 for Chloroaromatic Compound Degradation

Abstract

Pseudomonas simiae EGD-AQ6 showed utilization of chloroaromatic compound, 2-4-dichlorophenoxyacetic acid (2,4-D) efficiently in its biofilm phenotype. The differential rates of accumulation of intermediate metabolite 4-chlorocatechol (4-CCA) were significant in both planktonic and biofilm phenotypes; also increased number of biofilm cells were observed during 2,4-D utilization. Interestingly, response surface analysis demonstrated the combined positive effects of 2,4-D degradation and 4-CCA accumulations. Also, gene expression profiles showed significant up-regulation of degradative and biofilm genes (particularly pellicle forming genes) in the biofilm phenotypes than their planktonic counterparts, thereby confirming occurrence of phenotype variations of Pseudomonas simiae EGD-AQ6 during chloroaromatic degradation. Furthermore, the sequence similarity of the 2-4-D catabolic genes and biofilm forming proteins (pel ABCDEFG and pga ABCD) which are responsible for building carbohydrate rich extracellular matrix, were significant with the respective organisms as revealed through genome analysis. This is the first report, which endorses this Pseudomonas simiae species to be unique in chloro-aromatic degradation through phenotype variation, thereby proving as a potential candidate in the improvement of bioremediation technologies.