INITIAL IDENTIFICATION OF ISOLATES FROM BAMBARA NUT ROOT NODULES IN THE TROPICAL HUMID CLIMATE OF MALAYSIA

Variations in the conditions of the physical environment in different locations adversely affect crops production. An experiment was set up to isolate bacteria from the root nodules of bambara nut (Vigna subterranea L. Verdc) plants grown in the humid tropical climate of Malaysia. Bambara nut is a grain legume that is commonly being nodulated by the general Brady rhizobia bacteria but it is however known to adapt easily to the various strain of bacteria due to its flexibility. Nodule bacteria were obtained from nine (9) different bambara plants grown separately in a polythene bag (P) and in the open fields (F). The nine isolates that were randomly selected from the field (F) and polythene (P) are PA1, PB2, PC2, PD2, PE2, FA1, FB1, FC1, and FD1. Measurements were taken for nodule morphology [nodule fresh weight (g), nodule size (mm), nodules number per plant]. The nine isolates were then cultured on yeast mannitol agar medium (YMA) and pure cultures were obtained for identification and molecular evaluation which was done using 16S rRNA genes (27f and 1492R Primers- following the protocols in Genomic DNA mini kit manual (Yeast Biotech Co., Ltd) to distinguish between the isolates and obtain the DNA characteristics (purity and concentration) before gel electrophoresis and sequence blast analysis for comparison from previously isolated plant with NHK Bioscience Ltd. Results indicated that most of the isolates were legume nodulating bacterial endophytes (PB2- Klebsiella oxytoca; PC2- Pseudomonas aeruginosa; PD1- Paenibacillus spp; PE2- Bacillus spp; FA1- Bacillus aryabhattai; FB1- Bacillus spp; FC1- Bacillus megaterium and FD1- Bacillus altitudinis) with their rRNA sequence similarities ranges between 86% to 99%, except with PA1 which did not show any significant similarity to any bacterial organism. This result suggests that apart from rhizobia and bradyrhizobia, bambara nut root nodules could be inhibited and/or nodulated with other strains of bacteria which are not from rhizobiaceae.