Bioremediation of n-alkanes and the formation of biofloccules by Rhodococcus erythropolis NTU-1 under various saline conditions and sea water

From our previous report, the speedy removal of some n-alkanes or branched-alkanes by Rhodococcus erythropolis NTU-1 was already demonstrated in aqueous MS medium. Therefore, this strain was further tested under saline conditions, as well as in pure sea water. Hexadecane of 2000 ppmv was used as a model carbon source in this report. Under saline conditions, the biodegradation was again confirmed with the cell aggregates formation during the cultivation. The formation of biofloccules, trapping significant amount of alkane, provides an easy physical removal of alkane, in addition to biodegradation. At an initial NaCl concentration 1.2% and 2.4%, 80-90% removal of alkane was achieved within 56 h and 65% removal at 3.6% NaCl concentration within 68 h. Addition of 0.24 g/L nutrient broth (NB) in the medium would further promote the biodegradation rate and cell aggregation phenomenon during the process and more than 80-95% removal of alkane was achieved within 56-68 h. In the case of sea water, alkane removal was about 50% after 140 h and 65% with NB addition. The results suggest that strain NTU-1 has considerable ability for the bioremediation processes of n-hexaclecane in a marine environment. (c) 2009 Elsevier B.V. All rights reserved.