Effect of Time, C/N Ratio and Molasses Concentration on Saccharomyces Cerevisiae Biomass Production

Yeast is one of the potential microorganisms to be utilized as a feed supplement for animals due to its high nutritional value, mainly protein and organic matter content. It could be used for varieties of substrates of agricultural and industrial byproducts. Yeast utilization into animal diet would improve the intestinal environment, especially on digestibility tract, prevent colonization of pathogenic bacteria in small intestine, and also systemic immune functions. To be more proof, this experiment was to introduce and to promote the yeast biomass of Saccharomyces cerevisiae as growth promotor to improve the animal feed nutrition. The experiment was conducted by nested model with 3 replicates to determine the effects of time, carbon and nitrogen ratio (C/N) and molasses concentration within C/N ratio of the growth medium on yeast biomass. The molasses concentrations could be used from lowest to highest, while different levels of urea levels of 0.5, 1.0, 1.5 and 2.0% were used to calibrate the ratio of C/N in the medium for the grow of yeast. Abstract Keywords: Biomass of Saccharomyces Cerevisiae Yeast; Molasses; Urea Levels Use of Saccharomyces cerevisiae to the diet of pigs affected the intestinal environment, improved growth rate and digestibility, prevented colonization of pathogenic bacteria in small intestine, and increased systemic immune functions [4-6]. There have been several studies on the use of Saccharomyces cerevisiae to ferment cassava pulp and root for animal feed [7-9]. The result of those studies suggests that cassava root and cassava by-product can be nutritionally improved with Saccharomyces cerevisiae for animal feeding. Tefera T, et al. (2014) also reported that fermentation of cassava root meal with starter cultures of yeast of Saccharomyces Cerevisiea resulted in elevation of crude protein (CP) and decreased pH, free cyanide (FC) and moisture contents. However, in order to increase biomass of Saccharomyces cerevisiae, the substrate must have enough soluble carbohydrate and nitrogen for the growth of yeast cells [10]. Danesi, et al. (2006) reported that the type and concentration of carbon and nitrogen sources, as well as the C and N ratio of the medium for Saccharomyces cerevisiae cultivation influence cellular growth [11]. The results for cell concentration demonstrated that the use of sugarcane blackstrap molasses and yeast extract at a C and N ratio of 10 gave the highest biomass of yeast. Yeasts of saccharomyces cerevisiae usually can use some of the amino acids in molasses, but addition of nitrogen sources from urea is required. Pretreatment of yeast with urea solution enhanced the ability of yeast cell to use urea and elevated As the result, variations in fermentation time had the greatest impact on the biomass of Saccharomyces cerevisiae. The best fermentation time for obtaining optimum production of yeast biomass to be at 24 h. Biomass of yeast was highest at C/N ratio of 10/1 reached 6.68 g L-1. At a concentration of molasses at 35.00 g within C/N ratio of 10/1 gave highest biomass of yeast, reached 7.57 g L-1.