Described herein is the isolation and identification of a number of sulfur oxidizing plant growth promoting rhizobacteria: RAY12, identified as Achromobacter piechaudii; RAY28, identified as Agrobacterium tumefaciens, RAY132, identified as Stenotrophomonas maltophilia; and RAY209, identified as Delftia acidovorans. The PGPR act to oxidize elemental sulfur which in turn provides sulfate for the plants. As a result of this arrangement, plants are able to grow more efficiently and effectively and have enhanced growth characteristics, for example, but by no means limited to, increased vigor, early emergence, increased emergence rate, increased biomass, increased plant leaf area, higher crop yield, increased pod number, increased pod weight, increased root biomass, increased seed weight, increased macro- and micro-nutrient uptake and the like. The sulfur-oxidizing PGPR may be applied to seeds, seed pieces, carrier materials, roots and planting soil.