Feed Stu Production from Methanol by Methylotrophic Microorganisms

Abstract

Methanol has been of great interest as a substrate for production as a novel feed grade protein in Iran. Up to 160 methylotrophic strains were isolated at the Jahad-e Agriculture Research Engineering Center for Scienti c Research and various batch experiments were carried out at di erent pH, temperature, agitation, aeration rate and methanol concentrations. By these experiments, optimum production conditions were determined for one of the strains using the Taguchi method. The results showed optimum pH around 8 at temperatures of 26 to 30 C, aeration equal to 3 vvm and agitation about 800 rpm. The methanol was found to be optimum at concentration equal to 18 g.l????1 . In this condition, the biomass yield coe cient was 0.52 g/g methanol, biomass dry weight was 20-25 g/l and the crude protein content was about 70- 78%. A deep jet fermentor of 1 m3 capacity, with a working volume of 600 liters, was used for SCP production using isolated strains. In this continuous system, dilution rates ranging from 0.15 to 0.2 lit.h????1 were used to establish optimal condition for biomass production. Under this condition, 30 kg cell dry weight per day was obtained. These experiments showed that the selected methylotrophic strain has good potential for SCP production from methanol as a substrate.