The production of biodiesel has notably increased over the past decade. Currently, plant oil is the main feedstock for biodiesel production,\r\nbut, due to concerns related to the competition with food production, alternative oil feedstocks have to be found. Oleaginous\r\nyeasts are known to produce high amounts of lipids, but no integrated process from microbial fermentation to final biodiesel\r\nproduction has reached commercial realization yet due to economic constraints. Therefore, growth and lipid production of\r\nred yeast Rhodotorula glutinis was tested on low-cost substrates, namely, wastewaters from potato, fruit juice, and lettuce processing.\r\nAdditionally, the production of carotenoids as high-value by-products was examined. All evaluated wastewaters met the\r\ngeneral criteria for microbial lipid production. However, no significant increase in lipid content was observed, probably due to lack\r\nof available carbon in wastewaters from fruit juice and lettuce processing, and excess of available nitrogen in potato processing\r\nwastewater, respectively. During growth on wastewaters from fruit juice and lettuce processing the carotenoid content increased significantly\r\nin the first 48 hours. The relations between carbon content, nitrogen content, and carotenoid production need to be further\r\nassessed. For economic viability, lipid and carotenoid production needs to be increased significantly. The screening of feedstocks\r\nshould be extended to other wastewaters.
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