Bioethanol production by Saccharomyces cerevisiae, Pichia stipitis and Zymomonas mobilis from delignified coconut fibre mature and lignin extraction according to biorefinery concept

Abstract

In search to increase the offer of liquid, clean, renewable and sustainable energy in the world energy matrix, the use of lignocellulosic materials (LCMs) for bioethanol production arises as a valuable alternative. The objective of this work was to analyze and compare the performance of Saccharomyces cerevisiae, Pichia stipitis and Zymomonas mobilis in the production of bioethanol from coconut fibre mature (CFM) using different strategies: simultaneous saccharification and fermentation (SSF) and semisimultaneous saccharification and fermentation (SSSF). The CFM was pretreated by hydrothermal pretreatment catalyzed with sodium hydroxide (HPCSH). The pretreated CFM was characterized by X-ray diffractometry and SEM, and the lignin recovered in the liquid phase by FTIR and TGA. After the HPCSH pretreatment (2.5% (v/v) sodium hydroxide at 180 C for 30 min), the cellulose content was 56.44%, while the hemicellulose and lignin were reduced 69.04% and 89.13%, respectively. Following pretreatment, the obtained cellulosic fraction was submitted to SSF and SSSF. Pichia stipitis allowed for the highest ethanol yield e 90.18% e in SSSF, 91.17% and 91.03% were obtained with Saccharomyces cerevisiae and Zymomonas mobilis, respectively. It may be concluded that the selection of the most efficient microorganism for the obtention of high bioethanol production yields from cellulose pretreated by HPCSH depends on the operational strategy used and this pretreatment is an interesting alternative for add value of coconut fibre mature compounds (lignin, phenolics) being in accordance with the biorefinery concept.

Lignocellulosic bioethanol production: prospects of emerging membrane technologies to improve the process – a critical review

“…Gonçalves et al (2014) showed that a short presaccharification step at 50°C for 8 h in the SSSF process with three microorganisms (S. cerevisiae, P. stipitis, and Z. mobilis) had a positive effect to increase the overall yield of bioethanol from 79.27-84.64% to 85.04-89.15%. In a similar study with coconut fiber, Gonçalves et al (2016) showed the hydrothermal pretreatment catalyzed with NaOH (HPCSH) followed by SSF (SSSF) process using S. cerevisiae, P. stipitis, and Z. mobilis microbes was useful to achieve high yields of bioethanol of 91.17% and 91.03%. Among the existing process of the modified SSF approach, simultaneous saccharification and cofermentation (SSCF) has been most feasible approach to convert both hexose and pentose sugars to increased concentration of lignocellulosic bioethanol.…”

Valorization, Comparison and Characterization of Coconuts Waste and Cactus in a Biorefinery Context Using NaClO2–C2H4O2 and Sequential NaClO2–C2H4O2/Autohydrolysis Pretreatment

“…Theoretical solubilized lignin (TSL) was calculated by the Eq. 2, modified from Gonçalves et al [20]:…”

Pretreated of banana pseudo-stem as raw material for enzymatic hydrolysis and bioethanol production

“…cerevisiae was cultivated on agar slant containing 10 g/L glucose, 5 g/L peptone, 3 g/L yeast extract, 20 g/L agar at 28 °C [7]. The inoculum of S. cerevisiae was cultivated on culture medium containing 50 g/L glucose, 1 g/L (NH4)2HPO4, 0.5 g/L KH2PO4, 0.25 g/L MgSO4.7H2O, 10 g/L peptone, 10 g/L yeast extract, at 30 °C for 24 hours [8].…”