Functional and molecular characterization of plant growth promoting bacteria associated with sugarcane cultivated in Tay Ninh Province, Vietnam

Bacteria associated with sugarcane were investigated characteristics of plant growth promotion and identified base on molecular characteristics. Nitrogen fixation bacteria were isolated by using N-free Burk’s and LGI media. Pure colonies were then streaked on NBRIP medium to select phosphate solubilizing bacteria. The ability of producing IAA was screened by dropping Salkowski reagent into the bacterial suspension. There were 140 isolates of nitrogen-fixing and phosphate-solubilizing bacteria, and 41 isolates among them showed IAA producing. The abilities of producing IAA, fixing nitrogen, and solubilizing phosphate of these 41 isolates ranged from 1.9 to 12.8 mg L^-1 IAA, 0.1 to 2.5 mg L^-1 NH₄+, and 32.4 - 286.5 mg L^-1 P₂O₅, respectively. Thirteen selected isolates were preliminary tested biological control ability and identified base on 16S rDNA sequencing. There were 4 isolates capable of producing siderophore, 8 isolates inhibit Fusarium sp., 4 isolates inhibit Aspergillus niger, and one isolate capable of resisting both Escherichia coli and Staphylococcus aureus. The identification result showed these isolates belong to genera Stenotrophomonas, Bacillus, Chitinophaga, Burkholderia, Serratia, and Acinetobacter. These outstanding isolates were proposed to test the ability to promote sugarcane growth.