Searching usability of waste material of rose oil for microbial oil production

Our country is one of the leading countries in rose production and the pulp that is left over after extraction of rose oil and rose water is released to environment and is not utilized economically. This study aims to produce microbial oil with the help of yeasts in waste rose pulp-containing media as a carbon source so that rose pulp, which emerge in large quantities, may cease to be an environmental pollutant but may also contribute to production of biodiesel, an environment-friendly oil that is cost-effective for the national economy. The study investigated whether 162 tested yeast isolates propagated in the yeast extract peptone dextrose agar, and lipid buildup developing in this setting was assayed using Sudan Black B staining method. The selected isolates were identified with sequence analysis using the primers NL1 and NL2 of 26S rDNA D1/D2 domain. The six yeast isolates with percent lipid ratio of above 3.5 in the nutrient media containing waste rose pulp (W. subpelliculosus-6, C. albicans-7, Y. lipolytica-18, Y. lipolytica-48, P. anomola-141 and K. marxianus-155) were chosen, followed by optimization work. First, the effect of pretreatment of waste rose pulp with water and acid on lipid yield % was determined. Then temperature, inoculum age and inoculum volume optimization was undertaken using the Box Behnken experimental design. Following validation work, fatty acid analyses of the obtained lipid were carried out with the GC-MS. In this study which used waste rose pulp, the highest oil yield was 45% from the waste rose pulp following a 38-hour culture at 35ºC with W. subpelliculosus-6 and treatment with acid at 25% inoculum volume. Lipid was obtained with W. subpelliculosus-6 for the first time in this study. The obtained fatty acid profile included 45% palmitic acid, 42.62% stearic acid and 7.38% oleic acid, with a fatty acid composition that is similar to vegetable oil acids. It can therefore be considered as a suitable material for biodiesel production.