Sequential mild acid and alkali pretreatment of rice straw to improve enzymatic saccharification for bioethanol production

Sequential pretreatment using different NaOH concentrations (0.5%, 1.0%, 1.5%, w/w) and 1% H₂SO₄ (w/w) was evaluated as a strategy for effective hydrolysis of rice straw. The efficiency of sequential NaOH and H₂SO₄ (SNA) pretreatment against sequential H₂SO₄ and NaOH (SH) was assessed. SH pretreated biomass attained more sugar yield compared to SNA pretreated biomass. The sugar yields from pretreated biomass improved with increasing NaOH concentration in both SH and SNA treatments. The maximum sugar release of 40.6 mg/ml (83.2% efficiency) was obtained from SH pretreated biomass when the stage 2 alkali treatment was performed at 1.5% w/w NaOH. The non-detoxified hydrolysate from this biomass was fermented with 96.8% efficiency.

Evaluation of a wet processing strategy for mixed phumdi biomass conversion to bioethanol

Biorefineries typically use dry feedstock due to technical and logistic issues, but in unique cases where climatic conditions are unfavorable and where the biomass has to be processed without a holding time, wet processing might be advantageous. The present study evaluated the possibility of using the fresh (non-dried) mixed biomass harvested from Phumdis; which are floating vegetation unique to Loktak lake in Manipur, India, for bioethanol production. Pretreatment with dilute alkali (1.5% at 120 °C for 60 min) resulted in 36% lignin removal and an enhancement of cellulose content to 48% from 37%, and enzymatic hydrolysis released 25 g/L glucose. Fermentation of the hydrolysates was highly efficient at 95%, attained in 36 h and 80% in just 12 h. The new wet processing strategy could help in value addition of mixed phumdi biomass.

Optimization of Process Parameters for the Production of γ-Linolenic Acid by Cunninghamella elegans CFR C07 in Submerged Fermentation

The production of γ-linolenic acid (GLA) by the fungus Cunninghamella elegans CFR C07 in submerged fermentation was studied. Culture parameters such as carbon source and incubation time were optimized. Four different extraction methods using solvents with acid washed sand, glass beads, lyophilization and Soxhlet extraction were evaluated for improved extraction of lipids from the fungal biomass after fermentation. The GLA production was initially optimized in 250-mL flask and the process was demonstrated in a 3-litre fermentor. The maximum GLA production was 882 mg/L in shake flask culture and 733 mg/L in the fermentor. The study shows that Cunninghamella elegans CFR C07 is a potent organism for the production of GLA under submerged conditions.