Bench‐scale fermentation for second generation ethanol and hydrogen production by Clostridium thermocellum DSMZ 1313 from sugarcane bagasse

Abstract

Exploration of eco‐friendly energy resources substituting conventional fossil fuels is the real challenge globally. Prospectively, current investigation accentuates the fermentative conversion of low‐cost lignocellulosic biomass waste, sugarcane bagasse (SCB) into bioethanol and biohydrogen exploiting thermophilic cellulolytic bacterium Clostridium thermocellum DSMZ 1313. Initially, the optimization of some key fermentation factors for bioethanol and biohydrogen productions was done in 150 ml serum bottles employing Taguchi orthogonal array L27 (3̂13) experimental design. Results elucidated that the most suitable factors for ethanologenesis were 70 g/L cellulose, 10 g/L corn‐steep liquor (CSL), 15 mg/L ferrous sulfate (FeSO4·6H2O), 1 g/L magnesium chloride (MgCl2·6H2O), pH 7, and 5 days incubation whereas for hydrogen fermentation were 60 g/L cellulose, 30 g/L CSL, 5 mg/L FeSO4·6H2O, 2 g/L MgCl2·6H2O, pH 7, and 3 days incubation. Quantitatively, 7.422 g/L ethanol and 56.891/50 ml hydrogen were produced from cellulose while 6.352 g/L ethanol and 51.685/50 ml hydrogen with H2SO4‐pretreated SCB (substituted with cellulose). Scaled‐up suspended‐cell fermentations in bench‐scale stirred‐tank bioreactor resulted in 11.77% increased ethanol yield (0.239 g ethanol/g of glucose) and twofold higher hydrogen volumes (106.88 ml hydrogen/g of glucose). The employment of SCB directly as substrate for biofuels production has appeared sustainable to meet the high global energy demands.

Adapted feeding strategies in fed-batch fermentation improve sugar delivery and ethanol productivity

“…As an example, Fujii et al [ 47 ] expanded the bioethanol production from a laboratory scale to a bench-scale and achieved higher sugar concentration from saccharification and higher ethanol concentration in fermentation with the bench-scale settings. Similar benefits from scaling up the bioprocess were found when ethanol yield was improved by 11.77% through scale-up from working with 150-mL serum bottles to 5-L bioreactors [ 48 ].…”

Cellulolytic and Ethanologenic Evaluation of Heterotermes indicola’s Gut-Associated Bacterial Isolates

“…The study was a stepping stone in establishing the large-scale process development of bioenergy production. As with every passing day, energy sources of the world are diminishing at alarmingly high speed, there is a great need to explore more efficient, sustainable, and renewable alternates. , Cellulose and hemicellulose present in the LCB, in the prospect, can contribute as the prime source substrates for bioenergy generation. The systematic conversion of cellulose (via the employment of cellulolytic bacteria) into fermentable sugar is considered as the most critical step in the biofuel production .…”

“…The cellulases obtained from microbes can be used in large scale for bioremediation of cellulosic wastes (Dixit et al), 133 for large-scale cellulosic substrate conversions into value-added products, e.g., biofuels (Ahmad et al), 129 biofertilizers (Yu et al), 134 animal feed (Azizi-Shotorkhoft et al), 135 pulp and paper (Karthika et al), 136 textile (Bussler et al). 137 As the study deals with the employment of native cellulolytic bacterial isolates, metabolic engineering can further enhance the cellulolytic and ethanologenic abilities of the microbes.…”