pH INFLUENCE ON SHELF LIFE OF LIQUID PGPR FORMULATIONS WITH Bacillus subtilis STRAINS

Authors : Sevgi İşlek, Kemal Karaca, Rengin Eltem

Pages : 14-24

Doi:10.18036/estubtdc.1413386

View : 53 | Download : 32

Publication Date : 2025-01-29

Article Type : Research Paper

Abstract :Plant Growth Promoting Rhizobacteria (PGPRs) are bacteria that promote plant growth through both direct and indirect mechanisms. The formulation of PGPR inoculants is crucial for the efficacy and commercial success of microbial fertilizers. Formulation aims to optimize the survival of microbial strains under specific environmental conditions and enhance their capacity to promote plant growth. This process ensures protection of bacterial cells against harsh conditions such as high temperatures, desiccation, and storage, thereby extending product shelf life. Proper formulation of PGPR inoculants is a critical component for sustainable agricultural practices, playing a significant role in improving both plant health and productivity. Among PGPR strains, Bacillus species are particularly produced and utilized as microbial fertilizers commercially due to their high efficacy potential and long shelf life. However, for large-scale production, strain-specific PGPR formulations need to be developed and optimized to produce PGPR inoculants with high efficacy potential and extended shelf life. In this study, acidic liquid formulations were prepared using acetic acid for B. subtilis EGE-B-36.5 strain, and alkaline liquid formulations were prepared using calcium acetate-calcium hydroxide for B. subtilis EGE-B-1.19 strain. The viable cell count in the liquid formulations was statistically compared with the control. In the acidic liquid formulation, statistically significant changes in viable cell count were observed for B. subtilis EGE-B-36.5 strain at pH 4.0 after 12 months and for B. subtilis EGE-B-1.19 strain at pH 4.0 after 12 months (p<0.05). In the alkaline liquid formulation at pH 9.5 there had been a statistically significant (p<0.05) difference between control group of the B. subtilis EGE-B-1.19.
Keywords : Bacillus subtilis, PGPRs, Microbial fertilizer, Liquid formulation, pH