Production and stability of pigments by <i>Talaromyces purpurogenus</i> LC128689 in an alternating air phase–liquid phase cultivation system
Cosmas T. Ugwu, Christiana N. Ogbonna, James C. Ogbonna, Hideki Aoyagi
Abstract
Abstract Effects of carbon source, nitrogen source, and alternatingly submerging the cells and exposing to gaseous oxygen on pigment production by Talaromyces purpurogenus LC128689, as well as pH, temperature, and UV stability of the pigments were investigated. Although fructose supported higher cell growth, a mixture of glucose and glycerol resulted in higher pigment production. Out of the organic and inorganic nitrogen sources investigated, peptone gave the highest cell concentration (7.2 ± 1.1 g/L) and pigment production ( p ≤ 0 .05). The cells were then immobilized in loofa sponge and cultivated under alternating liquid phase–air phase (ALAP) system whereby the cells were alternatingly submerged and exposed to gaseous oxygen. After 20 days of cultivation, the concentrations of the red, orange, and yellow pigments were 30.15 AU 500 nm , 15 AU 460 nm , and 6.25 AU 400 nm , respectively. In comparison with submerged culture in flasks, the red and orange pigments were 100% and 50% higher ( p ≤ 0.05) in ALAP system. On the other hand, the yellow pigment was 100% higher in flask cultures than in ALAP. The three pigments were stable within a pH range of 2–12, retained more than 80% of their color intensity after autoclaving at (121°C and 1.0 atm) for 15 min and exposure to UV (3 uW/cm 2 ) for 24 h.