Abstract
On industrial acetone-butanol fermentation of Blackstrap molasses, authors had experienced three types of abnormal fermentation. Among them the B type (Fig. 1) was the one of the extremly prolonged acidity peak and was very sluggish, resulting poor yields of solvents.
To overcome this sluggishness, experiments were carried out to search out some symbiotic organisms among various aerobic bacteria and yeasts for several strains of Cl. acetobulylicum.
Among tested organisms (Table 1) Torula utilis showed an outstanding effectiveness for a rapid completion of the fermentation and the solvents yields were much increased. (Table 2).
The effective factor was thermolabile and was filtrable. A strong invertase activity was demonstrated in the filtrate and a close relation between high yield of solvents and degree of inversion of the molasses medium was revealed. (Table 5, Fig. 3).
Thus the effective factor of T. utilrs against sluggishness was positively ascribable to the invertase activity of the yeast.
The sluggish factor of solvents fermentation of molasses has hitherto been unknown. However the above experiments in this paper suggested that some inhibiting factors of the invertase activity of Cl. acetobutylicum which were contained in molasses should be the principal cause of sluggishness.
