Effect of immobilized cells in calcium alginate beads in alcoholic fermentation

Abstract

Saccharomyces cerevisiae cells were immobilized in calcium alginate and chitosan-covered calcium alginate beads and studied in the fermentation of glucose and sucrose for ethanol production. The batch fermentations were carried out in an orbital shaker and assessed by monitoring the concentration of substrate and product with HPLC. Cell immobilization in calcium alginate beads and chitosan-covered calcium alginate beads allowed reuse of the beads in eight sequential fermentation cycles of 10 h each. The final concentration of ethanol using free cells was 40 g L-1 and the yields using glucose and sucrose as carbon sources were 78% and 74.3%, respectively. For immobilized cells in calcium alginate beads, the final ethanol concentration from glucose was 32.9 ± 1.7 g L-1 with a 64.5 ± 3.4% yield, while the final ethanol concentration from sucrose was 33.5 ± 4.6 g L-1 with a 64.5 ± 8.6% yield. For immobilized cells in chitosan-covered calcium alginate beads, the ethanol concentration from glucose was 30.7 ± 1.4 g L-1 with a 61.1 ± 2.8% yield, while the final ethanol concentration from sucrose was 31.8 ± 6.9 g L-1 with a 62.1 ± 12.8% yield. The immobilized cells allowed eight 10 h sequential reuse cycles to be carried out with stable final ethanol concentrations. In addition, there was no need to use antibiotics and no contamination was observed. After the eighth cycle, there was a significant rupture of the beads making them inappropriate for reuse.

Immobilization and association of microorganisms to improve fermentation performance for ethanol production

“…Under the same conditions, S. cerevisiae reached 42.80 and 39.87 g/L, representing 79 and 77% of theoretical yield, respectively (Figure 2). Fermentation yield for S. cerevisiae came close to yields described by Shafaghat et al (2011) and Duarte et al (2013). In mixed culture, the indexes were 44.13 and 40.93 g/L, representing 81 and 79% of theoretical yield, respectively (Figure 3).…”

“…In the fermentation process, there was an adaptation of pure and mixed cultures to the condition of immobilized cells within the first 48 h. In this first stage of the experiment, there was a lag phase followed by cell growth inside the beads, an observation also reported by Duarte et al (2013). Thus, part of sugar consumption and consequent energy production was reversed for cell reproduction.…”

Impact of Immobilization Techniques of Brewing Strain Saccharomyces carlsbergensis on Fermentation Kinetics

“…Entrapment Immobilization: Yeast cells were mixed with the Na-alginate 6% and poured drop by drop in the calcium chloride solution 0.1 M and left for 30 minutes in order to increase their stability ( Figure 1B), (Duarte et al, 2013 and http://www.fao.org/docrep/w7241e/ w7241e0a.htm).…”

Biotransformation of C-5 and C-6 Sugars of Cellulosic Cotton Wastes to Bioethanol Through Physical and Enzymatic Modes

“…The beads were stored at 4°C after washing with distilled H 2 O. The viability of the immobilized S. cerevisiae cells was verified as per standard procedure (Duarte et al, 2013).…”