Wax esters synthesis as innovative application of microbial oil produced from food industry by-products

The food industry generates vast quantities of waste streams that could be further used as renewable resources for the production of biopolymers, fuels and chemicals. The present study proposes the fermentative production of microbial oil and its further conversion into wax esters through an integrated biorefinery concept. The oleaginous yeast strain Cryptococcus curvatus ATCC 20509 was employed for microbial oil accumulation using wine lees and cheese whey as the sole fermentation substrates. Wax esters synthesis via the chemical route encounters many disadvantages, such as requirements for corrosive acids and high energy consumption. Nonetheless, the lipase-catalyzed process in a solvent-free system constitutes a relatively simple and environmentally benign method. Wax esters can be used in cosmetic applications, as lubricants or as wood coatings. The effect of temperature and initial enzymatic activity on wax ester synthesis from palm oil was studied. Three different fatty alcohols and two commercial lipases were also evaluated during the optimization study. The maximum palm oil to ester conversion yield achieved was about 79 % at 70 ^οC using Novozyme 435 and behenyl alcohol. Subsequently, the optimized conditions using palm oil were assessed on wax esters synthesis implementing microbial oil. Experimental results demonstrated that microbial oil was effectively converted into wax esters with a conversion yield of 83 % after 6 h. This is the first study showing that microbial oil produced by oleaginous yeasts can be used for wax esters synthesis.