Screening of plant growth-promoting rhizobacterial strains for the degradation and utilization of exogenous pectin as a sole carbon source

Abstract

Universal primers for gyrB were used to screen 79 strains of Bacillus species. The genomic DNA from each strain was extracted, and the PCR product of gyrB was amplified and purified for gene sequencing. Gene sequences were edited, and aligned, and Bacillus amyloliquefaciens subsp. plantarum (Bap) strains identified based on the gyrB phylogenetic tree. Two primers (exuT and uxuB) were designed to detect pectin-associated transporter gene exuT and D-mannonate oxidoreductase gene uxuB. The Bap strains were then screened for the presence of the exuT and uxuB genes. These two pectin-utilizing genes were confirmed in 57 and 54 Bap strains by PCR amplification. Second, an in vitro tests were conducted to screen 59 Bap strains using pectin as a sole carbon source to confirm the pectate lyase and utilizing activity. Pectate Agar (PA) and Tris-Spizizen Salts (TSS) medium were used for the in vitro pectate lyase and degradation assays.