Abstract

INVERTASE ACTIVITY OF INTACT SACCHAROMYCES CEREVISIAE CELLS CULTURED IN SUGARCANE MOLASSES BY BATCH FERMENTATION PROCESS

*Prof. Dr. Michele Vitolo

ABSTRACT

Saccharomyces cerevisiae was cultured by batch fermentation in 2.6L of sugar cane molasses (supplemented with (NH4)2SO4, (5.1g/L), MgSO4.7H2O (75mg/L) and Na2HPO4.12H2O (2.4g/L); concentration of reducing sugars (RS) and total reducing sugars (TRS) 7g/L and 30g/L, respectively) inoculated with 0.6L of yeast suspension at agitation of 500 min-1 for 9h. The temperature (30oC, 35oC and 40oC), pH (4.0, 4.5, 5.0, 5.5, 6.0 and 6.5), and aeration (min-1): (0, 0.5, 1.0, 2.0 and 3.0) were changed. Invertase was subjected to catabolite repression at RS concentration in the mash (expressed as glucose) over 4g/L. During fermentation the specific invertase activity of intact cells was enough for guaranteeing the amount of RS (the unique carbon source in the mash) needed for maintaining the yeast metabolism. The high invertase productivity (494gTRS/L.h) occurred at pH 5.5, aeration of 2.0 min-1 and 30oC.

Keywords: Yeast, invertase, molasses, Saccharomyces cerevisiae, batch fermentation.