2.5 Microbial and plant growth assay
This study determined the degradation efficiency of petroleum hydrocarbons by three bacterial strains isolated from long-term petroleum-contaminated soil. In addition, the effects of three bacteria strains and their synthetic communities on the growth of maize seedlings under petroleum hydrocarbon stress were investigated. Briefly, the crude oil was evenly mixed with sterilized oilfield control soil at a proportion of 0.5% and stored for four weeks. Maize seeds were surface-sterilized with 70% ethanol and 50% bleach before germination in the hydroponics platform. All SynCom strains were grown to saturation in quarter-strength tryptic soy broth and washed using phosphate-buffered saline before root inoculation.