A Study of Endophytic Bacteria to Understand Their Inhibition of the Growth of Ganoderma Boninense

Lim, Chen Yee (2022) A Study of Endophytic Bacteria to Understand Their Inhibition of the Growth of Ganoderma Boninense. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Ganoderma boninense, a wood rot fungi that act as the pathogen of the fatal basal stem rot (BSR) disease in oil palm trees, resulting in the reduction of oil palm yield. This project aims to understand how four previously isolated endophytic bacteria, namely SL14(1), SL14(2), SL22(LLT) and SL22(YC) inhibit G. boninense. Dual culture assay shows that all the bacteria have the ability to inhibit the growth of the G. boninense. Interestingly, three of the bacteria, SL14(2), SL22(LLT) and SL22(YC), inhibited Fungi A by the bacteria filtrate assay at percentage of inhibition radial growth (PIRG) of 90.28%, 91.67% and 91.67% respectively, but not filtrate from SL14(1), which yielded only PIRG of 5.56% while the PIRG of Fungi C with SL14(1), SL14(2), SL22(LLT) and SL22(YC) were 0%, 92.94%, 91.76% and 61.18% respectively. Purple hydrolysis zone was visible on colloidal chitin bromocresol purple agar cultured with SL22(LLT) but not SL14 (1), SL14(2), and SL22(YC), demonstrating chitinase activity from SL22(LLT). In addition, results from 3,5-dinitrosalicylic acid (DNS) assay showed glucose detected from SL22(LLT) culture, but not SL14 (1), SL14(2), and SL22(YC), suggesting SL22(LLT) was chinolytic but not the other three strains of bacteria. Glucanase activity of these bacteria was examined by using glucan or carboxymethyl cellulose (CMC). Hydrolysis zones were observed in SL14(1), SL14(2), SL22(LLT) and SL22(YC) as 1.5 cm, 1.7 cm, 1.3 cm and 1.5 cm when glucan used as a substrate while 1.3 cm, 1.6 cm, 1.8 cm and 1.5 cm respectively when carboxymethyl cellulose (CMC) was used as the substrate. These results suggest that SL14(1), SL14(2), SL22(LLT) and SL22(YC) could utilize their glucanase activity for the inhibition of G. boninense