Application of Industrial Wastes for the Production of Microbial Single-Cell Protein by Fodder Yeast Candida utilis

Abstract

Purpose: The aim of this study was to determine the use of glycerol as a source of carbon and the use of deproteinized potato wastewater as a source of nitrogen and mineral components for the production of biomass by fodder yeast Candida utilis. Methods: The yeast strain Candida utilis ATCC 9950 was used in this study. Experimental media contained potato wastewater and glycerol at concentrations of 5, 10, 15, 20, and 25% (w/v). Control medium was YPD and potato wastewater. During the 72 h of cultivation (200 rpm, 28 °C), the optical density (spectrophotometric method), biomass yield (weight method), glycerol (chemical method), and protein (Kjeldahl’s method) concentration in the experimental media, protein content in the biomass (Kjeldahl’s method) and chemical-oxygen demand index (dichromate method) in selected culture media were determined. Results: Candida utilis was able to grow in the medium composed of potato wastewater and glycerol. Addition of 5% of glycerol gave a biomass yield above 30 gd.w./L and the efficiency of protein biosynthesis was 12.2 g/L. The results showed that the cultivation C. utilis in this medium caused a significant reduction of glycerol (83%), nitrogen present in potato wastewater (51%), and a high degree of COD index reduction (91%). Conclusions: The study demonstrated that potato wastewater supplemented with glycerol may be successfully used as a carbon source in the production of fodder yeast C. utilis ATCC 9950 biomass. In addition, the results show that these two troublesome industrial wastes could be efficiently used in such processes.