Antifungal activity of chitinases produced by some fluorescent pseudomonads against Colletotrichum falcatum Went causing red rot disease in sugarcane

Chitinase production and growth of certain fluorescent pseudomonads isolate d from sugarcane rhizosphere on different subtrates were studied. When chit in was substituted for glycerol in King's B medium, 3 of the 4 strains show ed enhanced bacterial multiplication. Bacterial cells grown on chitin-conta ining medium showed enhanced antifungal activity against Colletotrichum fal catum Went causing red rot disease in sugarcane. Chitinase production was s ignificantly higher when chitin was amended to King's B medium. Higher chit inase production was also recorded when fluorescent pseudomonad strains wer e grown in the medium containing crab-shell chitin. Cell-free bacterial cul ture filtrate from chitin-containing medium significantly inhibited mycelia l growth of the pathogen. These cell-free conditioned media contained 3 to 7 polypeptides. Western blot analysis revealed five isoforms of chitinase w ith molecular masses of 47, 36, 32, 20 and 18.5 kDa. A possible role of chi tinases in red rot disease management is discussed.