ISOLATION OF PHOSPHATE SOLUBILIZING BACTERIA CAPABLE OF PRODUCING ACC DEAMINASE FROM SOIL OF DROUGHT AREA IN THE NORTHEASTERN THAILAND

Abstract

This research was to study the isolation of phosphate solubilizing bacteria capable of producing ACC deaminase from the soil of drought areas in the northeastern Thailand. Soil samples were collected from sugarcane fields and public forest areas in Chaiyaphum, Khon Kaen, Nong Bua Lam Phu, Maha Sarakham, and Roi Et provinces. Phosphate solubilizing bacteria (PSB) were isolated using spread plate technique on Pikovskaya agar. Subsequently, PSB isolates were tested for growth in Tryptic soy broth (TSB) with polyethylene glycol-6000 (PEG6000) at a concentration of 260 g/L to simulate drought condition and for their ability to produce the ACC deaminase enzyme. From the experiments, a total of 34 isolates of phosphate solubilizing and ACC deaminase producing bacteria were obtained. All isolates were identified by 16S rRNA sequencing. Sequencing analysis revealed that belonged to the following genera: Klebsiella (11 isolates), Burkholderia (9 isolates), Pantoea (7 isolates), Enterobacter
(5 isolates) and Bacillus (2 isolates). The activity of ACC deaminase ranged from 3.78×10^-4 to 3.52×10^-2 Unit/mL, and the specific activity of ACC deaminase ranged from 2.18×10^-6 to 9.84×10^-5 Unit/µg-Protein. Among the PSB, isolate S15-U4 exhibited the highest enzyme activity and specific enzyme activity for ACC deaminase The strain S15-U4 is suitable for further development as a phosphate solubilizing biofertilizer that can be effectively used in crop production in drought prone areas.