Biodegradation of animal fats and vegetable oils by Rhodococcus erythropolis PR4

• Rhodococcus eryhtropolis PR4 strain has numerous lipase genes and remarkable extracellular lipase activities.
• The strain could efficiently decompose poultry fats, pig lards, vegetable oils, butter and margarine within a short period.
• The biodegradation yields are dramatically improved by buffering agents, such as carbonate.
• Fats with saturated or unsaturated fatty acids are equally utilized.
• In spite of the high bioconversion yields, the degradation kinetics of various substrates apparently vary.

The alkane (pristane) degradation capacity of Rhodococcus erythropolis PR4 (NBRC 100887), isolated from marine environment, was previously observed. In this study, the ability of this strain for biodegradation of various animal fats, such as pig lards and poultry fats as well as butter, margarine and sunflower cooking oil was studied. Bioconversion of fats and oil was determined as methyl-ester (FAME) derivatives by GC–MS. R. erythropolis PR4 strain could utilize all substrates tested but the bioconversion rate and efficacies varied. The optimum pH for decomposition of pig lard and poultry fat was 8.5, respectively. Addition of carbonate to the media dramatically improved the efficiency of the process via stabilization of pH of the fermentation. Biotransformation of poultry fat was complete in four days and around 80% conversion was reached in the case of pig lard in media containing carbonate. The extracellular lipase activity of the R. erythropolis PR4 strain was also demonstrated by various techniques. The results suggest the R. erythropolis PR4 strain studied is a promising candidate in bioremediation/bioconversion of fat-containing wastes within a relatively short time.