Abstract

Chromobacterium violaceum is a human opportunistic pathogen which appears in soil and water environments. It produces a purple-colored bactericide named violacein. The aim of this study was to investigate the correlation between violacein production and the competitive ability of C. violaceum in co-culture with other soil bacteria. The C. violaceum (3), Chryseobacterium indologenes (1), Serratia marcescens (2), Pantoea agglomerans (4 and 5), Enterobacter asburiae (6) andBacillus megaterium (7), were isolated together from a nest of Crematogaster biroi. In the duel species competition experiments, C. violaceum (3) inhibited the growth of C. indologenes (1), while being dramatically inhibited by S. marcescens (2). The growth of C. violaceum (3) was unaffected by P. agglomerans (4 and 5) and E. asburiae (6), but it was slightly reduced by B. megaterium (7) (after 48 h of incubation). In the multiple competition experiments, the survival of C. violaceum (3) was increased in the presence of C. indologenes (1). The production of violacein was reduced in co-culture with all the examined bacterial strains, except C. indologenes (1). The violacein degradation assay demonstrated that, S. marcescens (2), P. agglomerans (4 and 5) and E. asburiae (6) were capable of decolorizing violacein, while C. indologenes (1) and B. megaterium (7) had no effect on violacein stability in 24 h of incubation. Taken together, these results might be useful for industrial violacein production.

Key words: Chromobacterium violaceum, Chryseobacterium indologenes, growth competition, violacein.