The present invention includes a contaminant-degrading composition for use in remediation of contaminated soil having a selected contaminant. Such a composition can include a seed for a plant capable of growing in the presence of the selected contaminant, and a contaminant-degrading mycobacteria on the seed. Additionally, the present invention includes a contaminant-degrading system for use in remediation of contaminated soil having a selected contaminant. Such a system can include a plant growing in the contaminated soil, and contaminant-degrading mycobacteria colonized on a root of the plant, wherein the mycobacteria is capable of degrading the selected contaminant. The mycobacteria can be capable of degrading the selected contaminant, such as PAHs, PCPs, MTBEs, and the like. Additionally, the contaminant-degrading mycobacteria can be at least one of M. KMS, M. JLS, or M MCS. Also, the contaminant-degrading mycobacteria can have nid dioxygenase genes, which can further include a nidB-nidA sequence motif.
