Synergy between fungi and bacteria in fungi-bacteria augmented remediation of petroleum-contaminated soil

A new bioaugmentation technique for petroleum contaminated soil utilizing the synergistic function between bacteria and fungi in both growth and metabolism of petroleum was proposed and investigated using E. cloacae and Cun. echinulata, both of which were isolated from Zhongyuan Oil Field, Henan, China. The maximum biomass of E. cloacae and Cun. echinulata obtained in the mixed slurry culture were 3-and 20-fold as much as their respective counterpart obtained in the pure cultures. The decrease of cell activity was considerably postponed, as compared to the pure cultures. The removal of total petroleum hydrocarbon (TPH) by the mixture was higher than the sum of the individual removal obtained in the pure culture, which could be further enhanced by repeated inoculation of fresh fungal and bacterial inocula. The optimal parameters of the in situ bioremediation of crude oil-contaminated soil sampled in Zhongyuan Oil Field were determined as follows: 25% (m/m) soil humidity, 6% (m/m) of wood scraps, 2.5 × 10 CFU/g of E. cloacae and 2.5 × 10 CFU/g dry soil of Cun. echinulata. It was demonstrated that the growth behavior of the inocula and the degradation of TPH were not inhibited by the indigenous microorganisms. The in situ remediation via inoculating the fungal-bacterial consortia removed 65% of TPH in 40 days while the control experiment with the indigenous microorganisms removed 16%.