Response of soil bacterial community to bioaugmentation with a plant residue-immobilized bacterial consortium for crude oil removal.

Both the crude oil removal efficiency of the Eichhornia crassipes dried straw-immobilized bacterial consortium and shifts in soil bacterial community in response to the bioaugmentation strategy were unmasked in this study. After 30 days of bioremediation, total petroleum hydrocarbon in soil was determined and immobilized consortium showed a removal percentage (51.7%) better than either Eichhornia crassipes dried powder (37.0%) or bacteria solution (36.0%) alone. Bacterial community and soil properties analyses demonstrated that the relative abundances of Cytophagales and Rhizobiales increased with increasing total organic carbon and total nitrogen contents because of the addition of Eichhornia crassipes dried powder. The genus Burkholderia which may play a key role in hydrocarbon degradation among the inoculated bacterial consortium proliferated when immobilized on the Eichhornia crassipes dried powder. Such a cell immobilization technology using plant residue materials as carriers helps to improve soil fertility and mitigate competition between indigenous and inoculated microorganisms for nutrients, which offers a promising way to enhance the removal of crude oil from contaminated soils.

Biodegradation of crude oil by a defined co-culture of indigenous bacterial consortium and exogenous Bacillus subtilis.

The aim of this work was to study biodegradation of crude oil by defined co-cultures of indigenous bacterial consortium and exogenous Bacillus subtilis. Through residual oil analysis, it is apparent that the defined co-culture displayed a degradation ratio (85.01%) superior to indigenous bacterial consortium (71.32%) after 7days of incubation when ratio of inoculation size of indigenous bacterial consortium and Bacillus subtilis was 2:1. Long-chain n-alkanes could be degraded markedly by Bacillus subtilis. Result analysis of the bacterial community showed that a decrease in bacterial diversity in the defined co-culture and the enrichment of Burkholderiales order (98.1%) degrading hydrocarbons. The research results revealed that the promising potential of the defined co-culture for application to degradation of crude oil.