Cow urine is a potent organic nitrogen source for microbial production of ethanol and β-carotene: an experimental proof

The improper disposal of cow urine (CU) cause significant environmental, social and health issues. The present study was aimed to develop a sustainable fermentation process using a fermentation medium having cellulosic sugars and cow urine as carbon and nitrogen source, respectively, for the production of β-carotenoids and ethanol. To achieve this, the concentration of CU was standardized along with other media components for the production carotenoids and ethanol using Rhodotorula glutinis CCT-2186 and Saccharomyces cerevisiae IR-2, respectively. Maximum recovery of total carotenoids (155.04 mg/L) and ethanol (54.32 g/L) were observed in a media supplemented with 1 and 0.5% (v/v) CU, respectively. This process allows for a partial reduction in the supplementation of commonly used nitrogen sources (such as yeast extract, peptone, ammonium sulfate, etc.), which represent a significant part of the industrial production cost. This yeast fermentation method in a medium supplemented with CU is a pioneering one, with no previous reports in the scientific literature.