Tolerance of Pseudomonas pseudoalcaligenes KF707 to metals, polychlorobiphenyls and chlorobenzoates: effects on chemotaxis-, biofilm- and planktonic-grown cells

Pseudomonas pseudoalcaligenes KF707 is a polychlorinated biphenyls (PCBs) degrader, also tolerant to several toxic metals and metalloids. The work presented here examines for the first time the chemotactic response of P. pseudoalcaligenes KF707 to biphenyl and intermediates of the PCB biodegradation pathway in the presence and absence of metals. Chemotaxis analyses showed that biphenyl, benzoic acid and chlorobenzoic acids acted as chemoattractants for KF707 cells and that metal cations such as Ni2+ and Cu2+ strongly affected the chemotactic response. Toxicity profiles of various metals on KF707 cells grown on succinate or biphenyl as planktonic and biofilm were determined both in the presence and in the absence of PCBs. Notably, KF707 cells from both biofilms and planktonic cultures were tolerant to high amounts (up to 0.5 g L-1) of Aroclor 1242, a commercial mixture of PCBs. Together, the data show that KF707 cells are chemotactic and can form a biofilm in the presence of Aroclor 1242 and specific metals. These findings provide new perspectives on the effectiveness of using PCB-degrading bacterial strains in bioremediation strategies of metal-co-contaminated sites.