Lawrence Berkeley National Laboratory

The goal of this study was to establish a plant growth promoting bacterial consortium, using strains previously isolated from a solid waste management unit (SWMU), and determine its effectiveness with respect to enhancing saltgrass colonization of contaminated soil from the SWMU. Bacterial strains were identified exhibit certain growth promoting characteristics and were tolerant to site relevant levels of petroleum hydrocarbons, salinity and pH. Five best performing strains including Pseudomonas sp. strain PFS1 and BSS3B2, Serratia proteamaculans strain S1BD1, Alcaligenes sp. strain PKS1 and Bacillus sp. strain PSS2 were selected to establish a plant growth promoting bacterial consortium named PGPBc, which was then tested to determine its effectiveness in facilitating saltgrass seed germination and growth both in vitro and in contaminated soil. The results showed that PGPBc inoculation had no significant effect on the germination of saltgrass seeds, but had significantly positive effect on plant biomass production in contaminated soil covered with a surface layer of potting soil. PGPBc inoculation increased plant biomass in sterilized soil by 4-fold and in unsterilized soil by 6.6-fold. In this study, we reported the phosphate solubilization ability of Serratia proteamaculans, and demonstrated the use of PGPBc for promoting saltgrass growth in hydrocarbon contaminated soil.