Bioethanol production from grass pea and wild oat hydrolysates using S. cerevisiae ETP53, K. marxianus ETP87, and P. fermentans ETP22

Abstract

AbstractConversion of lignocellulosic biomass into bioethanol is essential to reduce dependency on fossil fuels. After the grass pea and wild oat straws were characterized, they were hydrolyzed by live fungi (in situ), crude fungal enzymes, and chemical methods (sodium hydroxide and sulphuric acids at 0.5, 1, 2, and 3%). The fungi used for in situ degradation and crude lignocellulosic enzymes were Aspergillus niger JMC22344, Trichoderma reesei JMC22, Pleurotus ostreatus M2191, and Pleurotus sajor-caju M2145. Furfural content of hydrolysates was analyzed by GC–MS. The potential of activated charcoal, overliming, and sequential activated charcoal-overliming potential to reduce furfural in the acid hydrolysates were evaluated. The hydrolysates were fermented by S. cerevisiae ETP53, K. marxianus ETP87, and P. fermentans ETP22. Sulphuric acid hydrolyzed common wild oat (8.91 g/L) yielded higher sugars than NaOH (3.88 g/L) and NaOH treated wild oat (8.14 g/L) was superior in terms of sugars released than grass pea (4.21 g/L). P. ostreatus M2191 liberated the highest sugar (18.63 g/L) extracts than T. reesei JMC22676, A. niger ETP22344 and P. sajor-caju M2145. The 23–77% of the furfural in acid hydrolysates was reduced by overliming, activated charcoal, and the sequential activated charcoal-overliming. Yeasts produced optimal ethanol from straws hydrolyzed by crude enzymes from A. niger JMC22344. Generally, the ethanol titer was directly proportional to the amount of sugars released.