Optimization of C/N ratio for preparation of protein-rich and multi-enzymes feed thallus through synergic fermentation of mixed distillers' grains

Article type: Research Article

Authors: Li, Zheng-yi | Zhou, Ding

Affiliations: Harbin Institute of Technology, Department of Environmental Sciences and Engineering, Harbin 150006, China. E-mail: [email protected] | Institute of Chemical Engineering, Beijing Technology and Business University, Beijing 100037, China

Abstract: A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N , their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven-dried thallus The conditions of fermentation are: inoculum size 10%, temperature 30.0°C, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14.693g in a liter liquid medium, maximum utilization rate of carbon source is 98.13% and maximum utilization rate of nitrogen is 78.14%. Optimal C/N is 5.1.

Keywords: optimal C/N, fermentation distillers' grains, utilization rate of carbon source, transformation rate of nitrogen source

Journal: Journal of Environmental Sciences, vol. 14, no. 1, pp. 141-144, 2002