ALTERNATIVE SUBSTRATE MEDIA FOR Bacillus subtilis AGAINST FUSARIUM WILT (Fusarium oxysporum)

Catherine Anne Porter and May V. Tampus

Abstract

The Philippines is one the major banana producers in Asia. Banana is known to be susceptible to diseases. The most common among these diseases is fusarium wilt (Fusarium oxysporum), a soil-borne fungus that is difficult to control. With the shift of consumer to organic products, there is a need to search for biocontrol methods as an alternative strategy in managing the wilt disease.

Bacillus subtilis is known producer of antifungal compounds. In this work, B. subtilis is investigated as a biocontrol agent for F. oxysporum. The B. subtilis is grown on molasses and marine products processing wastes. These are cheap raw materials which make the production of antifungal compounds economically feasible. The antifungal activity of B. subtilis against F. oxysporum is determined by well agar diffusion method where zones of inhibition are measured.

Results show that B. subtilis can be grown in molasses and marine waste media. Through Kheldal analysis shrimp hydrolysate gave 2.12& N while the fish hydrolysate was 1.98%. The B. subtilis grown in shrimp hydrolysate was effective against F. oxysporum with 26.6 mm inhibition zone and is comparable to the nutrient broth media with 25.2 mm inhibition zone. The shrimp hydrolysate is also effective at different dilutions with distilled water. At 3:1 dilution, the inhibition zone is 24.1 mm; at higher dilution (1:3), the inhibition zone is 26.7 mm.

The shrimp hydrolysate has a potential in the mass production of B. subtilis F. oxysporum. Further study has to be conducted to verify the laboratory result, evaluate the efficacy under field condition, and develop mass production technique of B. bacillus as a biocontrol agent.

Key words: fusarium wilt, Bacillus subtilis, molasses, marine wastes