A novel biological function of alginate inPseudomonas aeruginosaand its mucoid mutants: stimulation of exolipase

Treatment of Pseudomonas aeruginosa ATCC9027 with various commercial alginates from brown algae enhanced extracellular lipase activities in a time- and concentration-dependent manner (“exolipase stimulation”). Alginate isolated from Azotobacter vinelandii and mucoid mutants of P. aeruginosa was similarly effective. Several independently isolated mucoid (alginate-producing) mutants of P. aeruginosa showed higher spontaneous exolipase activities than the nonmucoid wild type. Alginate was chemically modified by (i) reduction of carboxyl groups (removal of charge), (ii) oxidation of pyranoid rings (destruction of tertiary structure), and (iii) reduction of reducing end groups. None of the chemical modifications resulted in total loss of the exolipase-stimulating ability of the alginate derivatives.