PHYSIOLOGICAL-CHANGES AND ALK GENE INSTABILITY IN PSEUDOMONAS-OLEOVORANS DURING INDUCTION AND EXPRESSION OF ALK GENES

The alk genes of Pseudomonas oleovorans, which is able to metabolize a lkanes and alkenes, are organized in alkST and alkBFGHJKL clusters, in which the expression of alkBFGHJKL is positively regulated by AILS, G rowth of the wild-type strain GPo1 and P. oleovorans GPo12 alk recombi nants on octane resulted in changes of cellular physiology and morphol ogy. These changes, which included lower growth rates and a reduction of the number of CFU due to filamentation, were also seen when the cel ls were grown on aqueous medium, and the alk genes were induced with d icycloproplketone, a gratuitous inducer of the alk genes, These effect s were seen only for recombinants carrying both alkST and alkBFGHJKL o perons, Deletion of parts of either alkB or alkJ, which encode two maj or Alk proteins located in the cytoplasmic membrane, modified but did not eliminate the effects described above, suggesting that they were d ue to induction and expression of several alk genes, Continuous growth of the cells in the presence of dicyclopropylketone for about 10 gene rations led to inactivation, but not elimination, of the alk genes, Th is resulted in a return of the recombinants to normal physiology and g rowth.