Production of fatty acids from distilled aromatic waste biomass using oleaginous yeast

Microbial lipids are feasible alternatives to vegetable oils and fats in the production of biodiesel and other industrially significant compounds. To achieve the main goals of the circular economy, waste materials go under microbiological processes, it reduces wastes through recycling. To show the effectiveness of the suggested strategy, four fungi, and four oleaginous yeasts were used in the present investigation. Along with this, distilled biomasses from different aromatic crops (lemongrass, mentha, citronella, geranium, ocimum, palmarosa) were used for microbial growth and lipid production. The distillation process acts as a pretreatment step for the fermentation of lignocellulosic biomass. The heat results in the breakdown of some bonds to easily release monomers and increase the available surface for the action of hydrolytic enzymes produced by fermenting microbes to release monomers which may be used further for lipid production. The lipid content obtained by Trichoderma harzianum, Rhodotorula glutinosa, Rhodotorula mucilaginosa, Aspergillus awamori, and Fusarium solani under optimized growth conditions were found significant in comparison to other strains, control 1 and 2. Lemongrass, citronella, ocimum, and palmarosa showed a promising lipid accumulation in comparison to other distilled biomasses. The major fatty acids produced by Rhodotorula glutinosa, R. mucilaginosa, Trichosporon cutaneous, Aspergillus awamori and Trichoderma harzianum were oleic, linoleic, linolenic and lignoceric acid from after distilled biomass of mentha, citronella and ocimum. Principal component analysis was performed to observe the variability within the dataset and provide evidence that the results are matching with the observations. Scanning electron microscopy and confocal fluorescence microscopy were also performed to confirm the lipid production by R. mucilaginosa and Aspergillus awamori. The oil obtained from R. mucilaginosa was further transesterified and assessed for their physical properties as biodiesel. It is found suitable to be used as bio-based fuel with the EN 14214 as well as ASTM D6751 standards. As a result, the distilled biomasses will provide a low-cost alternative for yeast growth that leads to accumulation of lipids and subsequently biodiesel generation. In order to integrate biotechnological processes in a circular economy challenge, this study offers convincing evidence that the valorization of distilled biomasses to lipid production using oleaginous yeasts is promising.