Nutritional content analysis of plant growth-promoting rhizobacteria species

Agricultural production requires the continuous application of mineral fertilizers, which not only disrupt the natural balance but also reduce economic efficiency. The objective of this study was to understand the effects of plant growth-promoting rhizobacteria (PGPR) species (Bacillus megaterium M3, Bacillus subtilis OSU142, Bacillus pumilus C26, Paenibacillus polymyxa RC05, Azospirillum brasilense sp245, Burkholderia cepacia OSU7, B. cepacia OSU7 AMP Res and Raoultella terrigena TFi08) on their host plants. The maximum levels of arginine, histidine, tartaric acid, citric acid, and gibberellic acid were observed in B. megaterium M3 with maximum levels of glycine and threonine in B. subtilis OSU142, maximum lysine and lactic acid levels in R. terrigena TFi08 and maximum asparagine, serine, and abscisic acid levels in A. brasilense sp245. The highest Ca and P concentrations were observed in B. megaterium M3, while high concentrations of K, S, Na, Mn, Cd, and Ni were obtained from A. brasilense sp245. These data suggest that the B. megaterium M3, A. brasilense sp245, and R. terrigena TFi08 strains have the potential to be used as organic fertilizers to facilitate plant growth in sustainable and organic farming.