Fermentation technologies have been developed to improve the production of ethanol and an alternative is the immobilization technology, which offers the possibility of efficiently incorporating symbiotic bacteria in the same matrix. This study analyzes the potential use of immobilized and coinmobilized systems on beads of calcium alginate for ethanol production used mango waste (Mangifera indica) by Zymomonas mobilis and Saccharomyces cerevisiae compared with free cells culture and evaluate the effect of glucose concentration on productivity in coimmobilized system using a Chemostat reactor Ommi Culture Plus. For free cell culture, the productivity was higher for Z. mobilis (5.76 g L-1 h-1) than for S. cerevisiae (5.29 g L-1 h-1); while in coimmobilized culture, a higher productivity was obtained (8.80 g L-1 h-1) with respect to immobilized cultures (8.45 g L-1 h-1 - 8.70 g L-1 h-1). The conversion of glucose to ethanol for coimmobilized system was higher (6.91 mol ethanol) with 50 g L-1 of glucose compared to 200 g L-1 of glucose (5.82 mol ethanol); suggesting the immobilized and coimmobilized cultures compared with free cells offer an opportunity for the reuse of organic residues and high alcohol production.
Part of the book: Yeast
This research presents the effect of hydrodynamic conditions at different rates of aeration (1.4, 1.8, and 2.3 vvm) and the geometry of two photobioreactors with internal lighting on lipid productivity and other parameters of Chlorella vulgaris. A two-step nitrogen-reduction cultivation mode was applied for promoting lipid accumulation. The inoculum was cultivated initially at 90 mg L−1 N-NH4+, and at the end of the exponential phase, it was fed to 11 L photobioreactor at 20 mg L−1 of N-NH4+. The results showed that with similar aeration rates, the hydrodynamic regime in both photobioreactors was different. However, the increase in shear rate and agitation did not cause cell damage or photoinhibition. The maximum cell growth was 12 × 106 cells mL−1. The highest consumption of nitrogen was 19% and shear rates were of 120-340 s−1. The highest lipid productivity was reached in bubble column at 1.8 vvm with 0.650 mg·L−1 d−1.
Part of the book: Microalgal Biotechnology