Biotechnology process for microbial lipid synthesis from enzymatic hydrolysate of pre-treated sugarcane bagasse for potential bio-oil production

Abstract

Sugarcane bagasse is a lignocellulosic biomass waste produced from sugar and alcohol production. The aim of this study was to produce cellular lipids from sugarcane bagasse with a biotechnology process using microbial enzymes and lipid-accumulating yeast. Sugarcane bagasse, pre-treated with a steam explosion method, was subjected to enzymatic hydrolysis by a separate hydrolysis and fermentation (SHF) system, using crude enzymes from a new strain of Trichoderma SG2 (T. SG2) with or without supplementation with a commercial enzyme (Cellic CTec2). The mixture of both enzymes produced substantial amounts of sugar from pretreated sugarcane bagasse. In a multistage SHF process, in the second stage (21 + 21 h), a total of 26.92 g L−1 of sugar was converted. In another stage-wise process (21 + 21+21 h) of hydrolysis of residual biomass, 26.23 g L−1 of sugar was recorded; thus maximizing the production of fermentable sugars from bagasse. The cultivation of Rhodotorula sp. R1 in sugarcane bagasse enzymatic hydrolysate (BH) for lipid production was evaluated. The enrichment of the hydrolysate with d-glucose, Y-yeast extract, and P-peptone (BH + P20D20/N0.93) and (BH + Y10D20/N0.2) produced 7.69% and 10.50% of lipids, respectively. Similar to vegetable oils and other yeasts, the lipids accumulated by Rhodotorula R1 contain mainly elaidic acid, palmitic acid, stearic acid, linoleic acid, and a lower percentage of other fatty acids, indicating a suitable composition for biodiesel production.