This study aimed to investigate the production of pigment, lipid, and fatty acid using Rhodosporidium babjevaee yeast. The primary focus was on enhancing the production levels through different approaches. Initially, key factors like initial pH, carbon-nitrogen ratio (C/N), and the influence of various metal ions (such as calcium, zinc, iron, copper, magnesium, and nickel) in the culture medium were examined. Optimal conditions were determined, pH 6.2 and carbon-nitrogen ratio 100 yielding the most efficient results. The presence of magnesium ions in the culture medium had a substantial positive impact on biomass and pigment production. The presence of zinc ions, when combined with magnesium ions, improved pigment, and lipid production. However, zinc ions did not exhibit any noticeable effect on enhancing biomass production. The study further examined the variations in growth, pigment, and lipid production over time. After a cultivation period of 144 h, the most notable levels of biomass, pigment, and lipid were achieved, measuring 11.9 g/L, 3400 μg/L, and 6.6 g/l, respectively. Furthermore, the impact of various glucose concentrations (from 10 to 150 g/l) was assessed. When the yeast was exposed to glucose concentration of 60 g/l, it displayed the capability to yield 16.9 g/l of biomass and 10.5 g/l of lipid, while the highest pigment concentration (312.0 µg/g) was observed at glucose concentration of 10 g/l. Sugarcane bagasse and corn steep liquor were employed as the carbon and nitrogen sources, respectively, for the investigation of growth, pigment, and lipid production. Several pre-treatment methods, including organosolv (ethanol 60% w/w), alkali (sodium hydroxide 2%(w/v)), and alkaline organosolv (ethanol 60% w/w and sodium hydroxide 2%(w/v)), were applied to the sugarcane bagasse. Among these methods, alkaline organosolv pre-treatment exhibited the most effective lignin removal at 81.9%, releasing 58.4 g/l of sugar during the hydrolysis process. Yeast cultivation on the sugars derived from each pre-treatment route resulted in the highest biomass and lipid yields, reaching 9.6 g/l and 5.0 g/l, respectively, when using the culture medium associated with alkaline organosolv pre-treatment. Regarding pigment synthesis, the most significant amount was achieved through organosolv pre-treatment at 280.0 µg/g. Furthermore, with the production of 11.3 g/l of biomass, 204.4 µg/g pigment, and 6.7 g/l of lipid, comparable to the concentration values observed in the control medium when yeast extract was present, it was established that corn steep liquor holds potential as a viable alternative to yeast extract as a nitrogen source. Furthermore, a comprehensive analysis of the yeast's fatty acid composition was undertaken. The analysis revealed the preva‎lence of certain compounds, namely linoleic acid, oleic acid, palmitic acid, palmitoleic acid, and stearic acid, as dominant components.

حميد زيلوئي

محمد هادي جزيني , هاجر شكرچي زاده