DEGRADATION OF 4-AMINOBENZENESULFONATE BY A 2-SPECIES BACTERIAL COCULTURE - PHYSIOLOGICAL INTERACTIONS BETWEEN HYDROGENOPHAGA-PALLERONII S1AND AGROBACTERIUM-RADIOBACTER S2

The mutualistic interactions in a 4-aminobenzenesulfonate (sulfanilate ) degrading mixed bacterial culture were studied. This coculture consi sted of Hydrogenophaga palleronii strain S1 and Agrobacterium radiobac ter strain S2. In this coculture only strain S1 desaminated sulfanilat e to catechol-4-sulfonate, which did not accumulate in the medium but served as growth substrate for strain S2. During growth in batch cultu re with sulfanilate as sole source of carbon, energy, nitrogen and sul fur, the relative cell numbers (colony forming units) of both strains were almost constant. None of the strains reached a cell number which was more than threefold higher than the cell number of the second stra in. A mineral medium with sulfanilate was inoculated with different re lative cell numbers of both strains (relative number of colony forming units S1:S2 2200:1 to 1:500). In all cases, growth was found and the proportion of both strains moved towards an about equal value of about 3:1 (strain S1:strain S2). In contrast to the coculture, strain S1 di d not grow in a mineral medium in axenic culture with 4-aminobenzenesu lfonate or any other simple organic compound tested. A sterile culture supernatant from strain S2 enabled strain S1 to grow with 4-aminobenz enesulfonate. The same growth promoting effect was found after the add ition of a combination of 4-aminobenzoate, biotin and vitamin B-12. St rain S1 grew with 4-aminobenzenesulfonate plus the three vitamins with about the same growth rate as the mixed culture in a mineral medium. When (resting) cells of strain S1 were incubated in a pure mineral med ium with sulfanilate, up to 30% of the oxidized sulfanilate accumulate d as catechol-4-sulfonate in the culture medium. In contrast, only min or amounts of catechol-4-sulfonate accumulated when strain S1 was grow n with 4ABS in the presence of the vitamins.