Comparison of acid-, alkaline-, and ionic liquid–treated Napier grass as an immobilization carrier for butanol production by Clostridium beijerinckii JCM 8026

Modified Activated Carbon: A Supporting Material for Improving Clostridium beijerinckii TISTR1461 Immobilized Fermentation

“…The C. beijerinckii TISTR1461 culture was activated in a cooked meat medium (Difco™ laboratories, USA) supplemented with 20 g/L glucose (10 mL) in a 25 mL screw-capped bottle and then incubated at 37°C in an anaerobic jar for 48 h [ 13 , 20 , 32 ]. The resultant culture was transferred to P2 medium (60 g/L glucose, 1 g/L yeast extract, 0.5 g/L KH 2 PO 4 , 0.5 g/L K 2 HPO 4 , 2.2 g/L CH 3 COONH 4 , 1 mg/L para-amino-benzoic acid, 1 mg/L thiamin, 0.01 mg/L biotin, 0.2 g/L MgSO 4 •7H 2 O, 10 mg/L MnSO 4 •H 2 O, 10 mg/L FeSO 4 •7H 2 O, and 10 mg/L NaCl, pH 6.5) [ 33 , 34 ] (93 mL) in a 250 mL screw-capped bottle and incubated at 37°C in an anaerobic jar for 48 h [ 13 , 20 ].…”

“…The C. beijerinckii TISTR1461 inoculum was inoculated into a P2 medium (100 mL in 250 mL screw-capped bottle) to an initial optical density at 600 nm (OD 600 nm ) of 0.3 (1.03 g/L dried cell biomass) [ 13 ]. For the immobilized cultures, the untreated or treated AC was sterilized by autoclaving at 121°C for 15 min and then added at 2% (w/v) into the P2 medium inoculum.…”

“…For the immobilized cultures, the untreated or treated AC was sterilized by autoclaving at 121°C for 15 min and then added at 2% (w/v) into the P2 medium inoculum. The culture was then purged with 99.99% nitrogen gas (N 2 ) at a 10 mL/min flow rate for 5 min [ 13 ] and incubated at 37°C, 150 rpm orbital shaking for 120 h. The pH was not controlled in this study throughout the fermentation process. At 0, 12, 24, 48, 72, 96, and 120 h of incubation, the sample was collected, centrifuged (25°C for 20 min at 8000 rpm with RCF up to 14490 × g), filtered through a 0.22 µ m membrane, and kept at −20°C [ 13 ].…”

“…The immobilized culture has a high cell density and can be applied to batch, fed-batch, and continuous fermentations [ 6 , 7 , 11 ]. For instance, ABE fermentation using C. beijerinckii immobilized on alkaline-treated Napier grass produced a high butanol concentration (8.99 g/L), which was 25% higher than that in a free cell culture [ 13 ]. The potential supporting material for cell immobilization should be inexpensive, stable, reusable, and nontoxic [ 7 ].…”

“…The potential supporting material for cell immobilization should be inexpensive, stable, reusable, and nontoxic [ 7 ]. Many inorganic and organic materials have been used as supports, such as celite [ 14 ], sand [ 14 ], brick [ 14 ], glass beads [ 15 ], clay [ 16 ], ceramics [ 17 ], plastics [ 18 ], alginate [ 19 ], zeolite [ 20 ], lignocellulosic material [ 13 ], and activated carbon (AC) [ 21 , 22 ]. The porous nature of AC with its high surface area and high adsorption capacity makes it a promising material for bacterial immobilization [ 22 ].…”