Dechlorination of Chloral Hydrate by Pseudomonas putida LF54 which Possesses Biofilm Adhesin Protein LapA

Because of the lack of enzymes in critical steps of catabolic pathways, low-molecularweight halogenated compounds are often recalcitrant to biodegradation. In our previous study, we isolated Pseudomonas sp. LF54 (LF54), the first bacterium that has been shown to use chloral hydrate (CH) as sole carbon source by an assimilation pathway in which dechlorination is the critical step. In this study, we identified a transposon (Tn) mutant that can render LF54 defective in CH dechlorination. The molecular characterization of Tn mutants revealed that the transposon insertion sites map to lapA. Sequence analyses verified the existence of lapA in LF54. Additionally, induced expression of lapA in the conditional lapA mutant of LF54 further verified that defective lapA expression renders LF54 defective in dechlorination. Recent studies have revealed that the largest cell-surface-associated protein LapA, a biofilm adhesin, is able to initiate biofilm formation. This function was also verified in the induced conditional lapA mutant and in LF54. Furthermore, we also found out that the defective lapA mutant rendered the variation of bacterial motility. LapA, the largest biofilm adhesin protein of P. putida, which influences CH dechlorination and flagella motility, is a novel discovery not previously reported.