Tuesday, April 30, 2013
Exhibit Hall
Current biodiesel feedstocks account for 60-75 % of total biodiesel production costs, creating a need for cheaper alternatives. Alternative feedstocks would help to displace the dependence on crops for biodiesel. Using waste to make biodiesel can be applied in conjunction with bioremediation, assuming the proper organism is employed. Rhodococcus rhodochrous is a gram-positive bacterium capable of degrading hydrocarbons and a range of other environmental contaminants. Phenol is widely used in the pulp and paper industry and, as a result, is often found in industrial effluents and nearby streams. The purpose of this study was to evaluate phenol as a carbon source for R. rhodochrous and to determine any associated lipid accumulation. A shake-flask experiment was designed to culture R. rhodochrous in minimal salts medium containing glucose or 1g/L of phenol and varying reductions of nitrogen to promote lipid accumulation. Phenol was analyzed using solid-phase microextraction (SPME) daily until the levels of phenol were below detection of gas chromatography. Cells from both treatments were harvested daily and lipids were extracted from total cell dry weight. R. rhodochrous accumulated 24% of cell dry weight as lipids when grown in a 45:1 phenol to nitrogen medium. When grown in 30g/L of glucose with reduced nitrogen, R. rhodochrous accumulated 27% of its mass as lipid. These results suggest that phenol served as a comparable carbon source to glucose in regard to total lipid accumulation. Future research will identify other phenolic waste sources that can be used for lipid accumulation by R. rhodochrous.