Endophytic microbe in stem tissue of oil palm colonized by Ganoderma sp.

Abstract

Infection with Ganoderma sp. results in pseudoschlerotium, a distinctive feature of oil palm tissue trunks. The goal of this study was to study the microbial communities in Ganoderma sp. colonized oil palm trunk tissue. Endophytic bacteria are isolated from oil palm trunk tissue using selective media such as Ashby, Pikovskaya, King’s B, and a half-NA media to isolate N2 fixing bacteria, P solubilizing bacteria, Pseudomonas sp., and endophytic microbes, respectively. To prepare the sample, two methods were tested: 1) sterilizing the surface of the sample and then directly planting the stem tissue in a medium, and 2) sterilizing the surface of the tissue, crushing the tissue with a sterilizer mortar, and centrifuge for further seeding the supernatant in the selected medium. The first procedure was found to be effective in isolating N2-fixing bacteria from the top, middle, and bottom of the stem. We also recovered P solubilizing bacterium, which was yellow in colour and only located in the centre part of the stem, whereas the Pseudomonas sp. isolate was white in colour and found throughout the stem except at the bottom in the left side of the pseudosclerotium. We were able to isolate endophytic bacteria with a white hue using a half-NA medium. Method 2 did not succeed in isolating Azotobacter sp., but it can still isolate P solubilizing, Pseudomonas sp., and endophytic bacteria in all sections of the stem. The number of bacteria successfully isolated using the culture approach was low, particularly in the pseudosclerotium area. However, the larger quantity of Pseudomonas bacteria found in infected Ganoderma sp. tissue should be investigated further to establish the role of these bacteria, particularly in plant defence against Ganoderma sp.