Microbial lipid production by Debaryomyces hansenii using industrial wastes

It was aimed to produce lipids from Debaryomyces hansenii by using olive mill wastewater (OMW) and whey as substrate separately. In order to increase the lipid production, parameters such as medium composition, nitrogen and carbon sources, initial pH, NaCl, temperature, time and waste concentration in the mixture were investigated. The effects of these parameters on the cell concentration, lipid content and lipid composition were determined. OMW and whey were obtained from industry. The total amount of lipids in the yeast was analyzed gravimetrically following extraction, the lipid composition was analyzed by GC and the reducing sugar, total phenol and protein determinations were made by spectrophotometric analyzes. Addition of nitrogen source into medium increased cell concentration but decreased lipid content; the addition of carbon source increased both the cell concentration and lipid production. While the increase in the initial pH had a positive effect on cell growth, the highest lipid content was reached in OMW at pH=6.00 and in whey at pH=5.80. NaCl provided an increase in lipid synthesis. Increasing the temperature decreased the cell concentration and had a positive effect on the lipid content in the cell. The highest lipid content was reached at 25ºC in whey and at 30ºC in OMW. While the long growth period supported the lipid production of the cells until the stationary phase, a decrease was observed in the death phase in whey medium. As a result, while the highest cell concentration was 9.22 g/L (C/N=260, 30 g/L NaCl, 9 day, 25ºC, 150 rpm) and the highest lipid was 15.50% (w/w) (C/N=260, 30ºC, 150 rpm) in whey; the highest cell concentration was 6.70 g/L (60 g/L glycerol, 25ºC, 150 rpm), the highest lipid content was 14.33% (w/w) (60 g/L glycerol, 30ºC, 150 rpm) in OMW medium. The most synthesized fatty acid in both medium was oleic acid.