Microbial degradation of polycyclic aromatic hydrocarbons in soil by bacterium-fungus co-cultures

Two fungi and the phenanthrene-degrading bacterial strain Rhodococcus sp. IC10 were used as inocula for the bioremediation of petroleum hydrocarbon-contaminated soil from a manufactured gas plant area. The two fungi, which were previously isolated from different hydrocarbon-contaminated soil samples, were identified as Aspergillus terreus and Penicillium sp. In addition, two types of co-cultures which consist of fungal species including A. terreus or Penicillium sp. with Rhodococcus sp. IC10 were applied. After a 10-week incubation period, the concentrations of anthracene, phenanthrene, and pyrene were totally biodegraded by days 68, 54, and 64, for the 16 polycyclic aromatic hydrocarbons (PAH's) tested. The ecotoxicity of the soil after bioremediation did not show any effect on the survival of Daphnia magna (24 h-old-daphnids). However, the toxicity on seed germination of Brassica alba and the oxidoreductase activity of Bacillus cereus declined after 5- and 10-weeks of incubation, respectively. Co-cultures of Penicillium sp. and Rhodococcus sp. IC10 revealed the best efficiency at reducing ecotoxicity. (c) KSBB.