Ethanol production by Saccharomyces cerevisiae immobilized on stem ground tissue of different maize hybrids

Abstract

The maize stem is a low in cost, environmentally friendly, sustainable and abundantly available lignocellulosic raw material in many regions of the world. The maize stem ground tissue is a highly porous biomaterial, consisted of parenchyma cells, with honeycomb microstructure, enabling efficient yeast cells immobilization and alcoholic fermentation without significant mass transfer limitation. The aim of this paper was to study the influence of the addition of stem ground tissue from six maize hybrids as Saccharomyces cerevisiae cells support: NS 444, NS 3014, NS 5043, NS 6010, NS 6030, NS 7016 on the dynamic of alcoholic fermentation, ethanol yield, ethanol productivity, and molasses sugar conversion rate. Acid or alkaline nature and hydrophilicity of stem ground tissue is different for each hybrid. Depending on the maize hybrid, addition of 10 g/dm3 of stem ground tissue led to an increase in ethanol yield by 4.89-9.94 g/dm3, and increase of sugar conversion by 7.65-15.56%. Addition of 10 g of maize stem ground tissue decreased the total fermentation time by 10 h, regardless of the hybrid. Among all hybrids tested, the most efficient in improving the ethanol productivity was NS 3014. .

Parenhimsko tkivo stabla kukuruza je jeftin, široko rasprostranjen, ponovno upotrebljiv, stabilan i netoksičan biomaterijal koji zbog visokog stepena poroznosti i specifične mikrostrukture pčeljinjeg saća omogućava efikasnu imobilizaciju ćelija kvasca sa minimalnim ograničenjima internog prenosa mase. U radu je ispitivan uticaj dodatka parenhimskog tkiva stabla šest hibrida kukuruza (NS 444, NS 3014, NS 5043, NS 6010, NS 6030, NS 7016) u podlogu za fermentaciju, kao nosača za imobilizaciju ćelija Saccharomyces cerevisiae, na dinamiku alkoholne fermentacije. Određen je stepen konverzije šećera iz melase, prinos i proizvodnost etanola. Alkalna ili kisela priroda, kao i hidrofilnost parenhimskog tkiva stabla kukuruza bila je različita za svaki ispitivani hibrid. U zavisnosti od hibrida, dodatkom 10g/dm3 nosača postižu se za 4.89-9.94 g/dm3 viši prinosi etanola i za 7.65-15.56 % viši stepen konverzije šećera u etanol. Fermentacija melase uz dodatak 10 g/dm3 parenhimskog tkiva stabla kukuruza trajala je 10 h kraće, u poređenju sa fermentacijom bez dodataka. Prilikom alkoholne fermentacije melase najviši prinosi etanola ostvareni su u postupku uz dodatak parenhimskog tkiva stabla kukuruza hibrida NS 3014. .