POTENTIAL ACTINOMYCETES FROM BANG KRAJCHAO SOIL FOR THE PRODUCTION OF PLANT GROWTH-PROMOTING BIOPRODUCTS

Abstract

This research aimed to isolate potent plant growth-promoting actinomycetes (PGPA) from the saline soil of the Bang Krachao agroforestry area in Samut Prakan Province. Soil samples were collected from 11 distinct locations. A total of 219 actinomycete isolates were successfully recovered. A Screening for phosphate-solubilizing ability revealed 20 isolates capable of solubilizing phosphate on three different test media: PKV agar, LB agar, and NBRIP agar, using the spot test method at 28 °C for 7 days. The results indicated that phosphate degradation was most effective on PKV agar. The phosphate solubilization index (PSI) was measured, and only 3 isolates out of the 20 exhibited a PSI value greater than 3.50. These isolates coded BJ01-4, BJ09-4, and BJ01-2 yielded PSI values of 5.02±0.07, 4.30±0.50 and 3.90±0.09, respectively. 16S rRNA gene sequencing of isolate BJ01-4 showed high sequence similarity to Streptomyces sennicomposti. The promising isolate, BJ01-4, was subsequently tested as an inoculant for the production of a biofertilizer powder. Four different biofertilizer formulations were compared in growth trials with chili and tomato plants for 30 days. The results demonstrated that the BJ01-4 isolate maximized the growth promotion of chili plants when incorporated into Formulation 4, which consisted of a rice flour and rice bran mixture (80:20 w/w) with 30 mL of water. This actinomycete isolate presents a promising opportunity for developing a cost-effective biofertilizer to potentially reduce the reliance on chemical fertilizers in agricultural practices in the future.