Isolation, characterization and identification of endophytic bacteria in maize (Zea mays L.) cultivated on Acrisols of the Southeast of Vietnam

Abstract

Endophytic bacterial diversity in Maize plant cultivated on Acrisols of the Eastern of South Vietnam was studied. Maize material was collected from five sites (provinces/cities) of this region. 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 and p13B). A total of 301 isolates were isolated and all of them have ability of nitrogen fixation and phosphate solubilization together with IAA biosynthesis but there were 30 isolates having the best characteristics and they were identified as maize endophytes and nifH gene owners. The sequences from selected endophytic bacteria (30 isolates) showed high degrees of similarity to those of the GenBank references strains (between 97% and 100%). Among the selected isolates were 6 isolates belong to Bacillus (20.00%) and 24 isolates belong to Proteobacteria (80.00%) including 2 alpha-proteobacteria (7%), 6 beta-proteobacteria (20%), and 16 gamma-proteobacteria (53%). Based on Pi value (nucleotide diversity), Proteobacteria group had the highest Theta values and Theta values (per sequence) from S of SNP for DNA polymorphism were calculated for each group and Proteobacteria group had the highest values in comparison of two groups. From these results showed that 3 isolates including DTN1b (Azotobacter vinelandii), VTN2b (Bacillus subtilis) and VTN7 (Enterobacter cloacae) proposed as potential microbial inoculants or biofertilizers for sustainable corn production in poor Acrisols in Vietnam because of their benefit and biosafety.