Fodder yeast development optimisation using as main carbon source barley husks hydrolysed

Assessing the possibility of using the hydrolysed husks as carbon source for the production of fodder yeasts useful as supplements in animal nutrition was the aim of this work. The appropriate hydrolysis of barley husks lignocellulosic content can lead to high amounts of fermentable sugar useful for the growth of two different yeast strains (Candida utilis and Candida arboreea) which were chosen for their ability to utilize a wide variety of carbon sources and to conduct to high protein yield. A particular interest was directed to the optimization of three different parameters: sugar content from hydrolysed barley husks, ammonium sulphate and magnesium sulphate contents, known as affecting the biomass development, using the response surface methodology (RSM). Based on the proposed models, the optimum conditions for Candida utilis production were found to be at 18.81 g/L for sugar concentration, 8.71 g/L for ammonium sulphate and 0.69 g/L for magnesium sulphate. Under these conditions, the estimated biomass content was 6.69 g/L and protein content at 51.15% (w/w dry matter). For Candida arboreea strain the analysis revealed as optimum the following conditions: 18.42 g/L sugar concentration, 8.95 g/L ammonium sulphate and 0.66 g/L magnesium sulphate for biomass and protein contents of 6.74 g/L and 49.37% (w/w dry matter).