Isolation and characterization of yeast from traditionally fermented cow milk and their application in the production of biosurfactant

Abstract

Yeast are chemoorganotrophs that obtain carbon mostly from hexose sugars, such as glucose and fructose or disaccharides such as sucrose and maltose and these carbon sources are frequently present in yoghurt, cow milk and other fermentable products. Three fungal isolates were isolated from traditionally fermented cow milk which are saccharomyces cerevisiae, Saccaharomyces pombae and Pichia anomala. Isolation was carried out by serially diluting the samples in the laboratory, which were fermented at room temperature for 24 hours. All of the yeast isolated are glucose and sucrose fermentors. Biosurfactant was also produced after growing the yeast in a prepared Sabouraud Dextrose Agar (SDA) containing 1.0 ml of crude oil at the temperature range between 27-30 ⁰C for 72 hours. After incubation oil displacement test was carried out to determine if biosurfactant can be produced from the yeast, from the result Saccharomyces cerevisiae and saccohromyes pombae showed clear zones with diameter 96.0 mm/cm³ and 40.4 mm/cm³ respectively. Conclusively, biosurfactant was extracted from Saccharomyces cerevisiae which was measured with amount of 220 mg/ml while Saccharomyces pombae do not produced biosurfactant when grown in Sabouraud Dextrose agar (SDA) containing 1.0 ml of crude oil at a room temperature for 24 hours.