Abstract

ISOLATION AND CHARACTERIZATION OF RICE ENDOPHYTIC BACTERIA IN ACID SULPHATE SOIL OF MEKONG DELTA, VIETNAM

Ly Ngoc Thanh Xuan*, Dr. Tran Van Dung, Prof. Dr. Ngo Ngoc Hung and
Prof. Dr. Cao Ngoc Diep

ABSTRACT

Endophytic bacterial diversity in rice plant cultivated on acid sulphate soil of the Mekong Delta, Vietnam was studied. Rice plant samples were taken in four regions (Trung Song Hau, Tu Giac Long Xuyen, Dong Thap Muoi and Ban dao Ca Mau). Endophytic bacteria were isolated in two kinds of medium (LGI, NFb) together with 16S rRNA gene fragments amplified from DNA using eubacterial universal primers (p515FPL, p13B and PCR-1). A total of 160 isolates were isolated on two media and all of them have ability of nitrogen fixation and phosphate solubilization together with IAA biosynthesis but there were 60 isolates having the best characteristics and they were identified as rice endophytes. The sequences from selected endophytic bacteria (15/60 isolates) showed high degrees of similarity to those of the GenBank references strains (between 98% and 100%). From 15 isolates, 3 isolates belonged to genus Bacillus (20%), 12 isolates were Proteobacteria (80%) with Beta and Gammaproteobacteria were 5 isolates (33%) and 7 isolates (47%), respectively. From these results showed that 4 Burkholderia vietnamiensis strains (Burkholderia vietnamiensis HG6-21b, KG2-21, BL1-21b and LA5-22b) from 4 regions (Trung Song Hau, Tu Giac Long Xuyen, Ban dao Ca Mau and Dong Thap Muoi) revealed promising candidates with multiple beneficial characteristics and they have the potential for application as inoculants or bio-fertilizer adapted to acid sulphate soil and high-yielding rice because they are not only famous strains but also are safety strains for agricultural sustainable.

Keywords: 16S rRNA Gene Sequence, Acid sulphate soil, Endophytic Bacteria, Mekong Delta, Rice Growth Promoting.