Highlights
•
Knowledge on biological remediation of co-contaminated soils is not sufficient.
•
Bioremediation strategies were compared through a pot experiment in growth-chamber.
•
Alfalfa was able to tolerate and grow in a moderately co-contaminated soil.
•
Pseudomonas aeruginosa promoted plant growth and alleviated plant stress.
•
Alfalfa-Pseudomonas aeruginosa association enhanced petroleum hydrocarbon removal.