Background: Rhodotorula glutinis yeast is capable of the synthesis of numerous valuable metabolites with extensive potential industrial usage. This paper reports the study on determination of the effect of initial culture medium pH on growth and protein, lipid and carotenoid biosynthesis by R. glutinis yeast.

Results: The highest biomass yield was obtained in media at pH 4.0-7.0, and the value after 72 h was 17.2-19.4 g_d.w./L. An initial pH of the medium in the range 4.0-7.0 have no significant effect on the protein (38.5-41.3 g/100 g_d.w.), lipid (10.2-12.7 g/100 g_d.w.), or carotenoid (191.7-202.9 μg/g_d.w.) content in the biomass, or on the profile of synthesized fatty acids and carotenoids. The whole pool of fatty acids was dominated by oleic (48.1-53.4%), linoleic (21.4-25.1%) and palmitic acids (13.0-15.8%). In these conditions, the yeast mainly synthesized torulene (43.5-47.7%) and β-carotene (34.7-38.6%), whereas the torularhodin contribution was only 12.1-16.8%. Cultivation in medium at initial pH of 3.0 resulted in a growth reduction (13.0 g_d.w./L) and total carotenoid (115.8 µg/g_d.w.), linoleic acid (11.5%) and torularhodin (4.5%) biosynthesis.

Conclusion: The different values of initial pH of the culture medium with glycerol and deproteinized potato wastewater had a significant effect on the growth and on protein, lipid and carotenoid biosynthesis by R. glutinis yeast.