Use of wool protein hydrolysate as nitrogen source in production of microbial pigments

This study investigated the usability of sheep wool peptone (SWP) as an organic nitrogen source in production of pigments from the bacterium Serratia marcescens and the yeast Rhodotorula glutinis. SWP was prepared from sheep wool by KOH hydrolysis and H3PO4 neutralization. The potantial of SWP on pigment synthesis was compared with commercial tryptone peptone (TP) and proteose peptone (PP). The effectiveness of peptones on pigment synthesis was tested at different culture pHs and peptone concentrations in shaking flask culture. An initial medium pH of 7.0 and a peptone concentration of 6 g/L were found to be optimal for carotenoid synthesis in R. glutinis, but an initial culture pH of 8.0 and a peptone concentration of 8 g/L for prodigiosin synthesis in S. marcescens. In SWP, TP and PP-based cultures; prodigiosin concentrations of 341, 175, and 302 mg/L; and carotenoid concentration of 94, 88, and 80 mg/L were reached. Novelty impact statement Commercial peptones or protein hydrolysates are extensively used as organic nitrogen source in production of microbial pigments; however, high price of peptones restricts their use for this purpose. The present study revealed that protein hydrolysate prepared from sheep wool could be used as a peptone source in production of pigments from the yeast Rhodotorula glutinis and the bacterium Serratia marcescens. SWP was found to be superior to commercial peptones for production of both R. glutinis and S. marcescens pigments. Usability of wool protein hydrolyzate as an organic nitrogen source or peptone in production of microbial pigments was tested for the first time in the present study.