Potential of Pseudomonas sp. (UniSZA-MKB10) and Bacillus spp. (UniSZA-BK3, UniSZA-BK4 and UniSZA-DA) as Biological Control Agent for Controlling Anthracnose Disease of Carica papaya L.

Colletotrichum gleosporioides is known as the causal agent of anthracnose disease of Carica papaya in Malaysia. Economic losses are mostly reported during postharvest where the disease incidence and severity was recorded as 90-98 % and 25-38 % respectively. Colletotrichum sp. were isolated from lesions of infected C. papay that showing the typical anthracnose disease symptoms. Three types of fungal cultures were obtained and identified as Colletotrichum sp., Fusarium sp. and Rhizoctonia sp. One of the fungal obtained that was confirmed to be C. gleosporioides is based on morphological characteristics on PDA and Koch’s Postulate has confirmed C. gleosporioides as causal agent of papaya antracnose disease. The pathogen under study varied in its ability to grow under different environmental conditions. However, isolate preferred temperature range of 20°C to 30°C for the growth on PDA media. C. gloeosporioides isolates grew well at pH values within range of pH 6 to pH 7. Four bacterial strains, UniSZA-MKB10, UniZA-BK4, UniSZA-BK3 and UniSZA-DA, were tested in this study and proved to have antifungal properties against C. gloeosporioides. Dual culture assay, double layer and double plate method were conducted to test their metabolites as well as diffusible and volatiles antibiotic compound of bacteria. Out of four, three bacterial were found to show inhibition ability with MKB10 showed highest percentage of inhibition on radial growth with 62.08 ± 3.64% PIRG as well as produced greater diffusible and volatiles substances that significantly (P<0.05) inhibited the mycelial growth of C. gloeosporioides with PIRG of 85.48 ± 1.53 % and 31.03 ± 2.56 % respectively, and followed by UniSZA-DA. Culture filtrate of BK4 also showed highest significance effect towards inhibition of spore germination where the germ tube produced is the shortest (0.9055 µm)