Enhanced saccharification of lignocellulosic agricultural biomass and increased bioethanol titre using acclimated Clostridium thermocellum DSM1313

Abstract

Consolidated bioprocess assures an efficient lignocellulosic conversion to fermentable sugars and subsequently to bioethanol. Such a single-step hydrolysis and anaerobic fermentation was achieved with acclimated Clostridium thermocellum DSM 1313 on different mildly pre-treated agricultural lignocellulosic residues without any additional enzymes/and strains. Acclimation was achieved by serially sub-culturing in increasing concentration of individual substrates, such as rice husk, sugarcane bagasse, and banana pseudostem in the standard media, with cellobiose as an adjunct. The acclimated cellulolytic thermophile exhibited an early log phase entry with enhanced growth compared to the direct inoculation experiments with unacclimated culture. Around 672 mg/g of reducing sugar was produced from sugarcane bagasse media and 636 mg/g from rice husk media and 513 mg/g from banana pseudostem media with the acclimated organism. Bioethanol production also doubled in experiments with serially acclimated cultures, with a maximum of 1.21 and 1.0 g/L ethanol titre from sugarcane bagasse and rice husk, respectively. The serial acclimation experiments have increased the saccharification potentials of the organism towards the respective lignocellulosic substrates and also enhanced the bioethanol production.

Synthesis of Biopolymers from a Geobacillus sp. WSUCF1 Using Unprocessed Corn Stover

“…The cell growth was measured by optical density (OD) at 600 nm and transferred to dry cell weight by a calibration curve of cell concentration versus OD 600 . The insoluble corn stover particles were allowed to settle for 20 min before the OD test . Afterward, 100 μL fermentation broth without insoluble corn stover was added into a 96-well microtiter plate, and the absorbance was measured at 600 nm using a microplate reader (EPOCH 2, BioTek, Winooski, VT, U.S.A.).…”

“…The insoluble corn stover particles were allowed to settle for 20 min before the OD test. 16 Afterward, 100 μL fermentation broth without insoluble corn stover was added into a 96-well microtiter plate, and the absorbance was measured at 600 nm using a microplate reader (EPOCH 2, BioTek, Winooski, VT, U.S.A.). The bacterial cells were removed by centrifugation at 6000g for 15 min, and EPS in cell-free supernatant was precipitated by adding equal volume of chilled absolute ethanol.…”

Succinic Acid Production from Oil Palm Biomass: A Prospective Plastic Pollution Solution

“…Besides the pretreatment using acid and enzymatic hydrolysis, microbial hydrolysis of biomass for the valorisation of the fermentable sugars is one of the strategies worth exploring. Although the study on the microbial hydrolysis of oil palm biomass is still scarce, some research has been done to efficiently disintegrate the lignocellulosic substrate and release fermentable sugars from other types of biomasses, such as rice straw, sugarcane bagasse, rice husk, and banana pseudostem [86,87]. Fungal-derived cellulase can be used to hydrolyse cellulose in the biomass.…”

Biorefinery Gets Hot: Thermophilic Enzymes and Microorganisms for Second-Generation Bioethanol Production

“…Therefore, it is considered as a candidate organism for the establishment of a CBP for the conversion of lignocellulose to biofuels [135]. C. thermocellum is a Gram-positive, rod-shaped, obligate anaerobic bacterium, whose cellulolytic activity is due to the cell-wall-bound multi hydrolytic enzyme complexes (i.e., the cellulosome) that it secretes in addition to individual free enzymes [134,136]. Notably, its hydrolytic activity is often compared to that of commercial enzyme blends [137,138].…”