Production of butanol from starch-based waste packing peanuts and agricultural waste

We examined the fermentation of starch-based packing peanuts and agricultural wastes as a source of fermentable carbohydrates using Clostridium beijerinckii BA101. Using semidefined P2 medium containing packing peanuts and agricultural wastes, instead of glucose as a carbohydrate source, we measured characteristics of the fermentation including solvent production, productivity, and yield. With starch as substrate (control), the culture produced 24.7 g l⁻¹ acetone–butanol–ethanol (ABE), while with packing peanuts it produced 21.7 g l⁻¹ total ABE with a productivity of 0.20 g l⁻¹ h⁻¹ and a solvent (ABE) yield of 0.37. Cell growth in starch, packing peanuts, and agricultural wastes medium was different, possibly due to the different nature of these substrates. Using model agricultural waste, 20.3g l⁻¹ ABE was produced; when using actual waste, 14.8 g l⁻¹ ABE was produced. The use of inexpensive substrates will increase the economic viability of the conversion of biomass to butanol, and can provide new markets for these waste streams. Journal of Industrial Microbiology & Biotechnology (2002) 29, 117–123 doi: 10.1038/sj.jim.7000285 Received 14 November 2001/ Accepted in revised form 07 June 2002     

Butanol production from agricultural residues: Impact of degradation products on Clostridium beijerinckii growth and butanol fermentation

During pretreatment and hydrolysis of fiber-rich agricultural biomass, compounds such as salts, furfural, hydroxymethyl furfural (HMF), acetic, ferulic, glucuronic, rho-coumaric acids, and phenolic compounds are produced. Clostridium beijerinckii BA101 can utilize the individual sugars present in lignocellulosic [e.g., corn fiber, distillers dry grain solubles (DDGS), etc] hydrolysates such as cellobiose, glucose, mannose, arabinose, and xylose. In these studies we investigated the effect of some of the lignocellulosic hydrolysate inhibitors associated with C. beijerinckii BA101 growth and acetone-butanol-ethanol (ABE) production. When 0.3 g/L rho-coumaric and ferulic acids were introduced into the fermentation medium, growth and ABE production by C. beijerinckii BA101 decreased significantly. Furfural and HMF are not inhibitory to C. beijerinckii BA101; rather they have stimulatory effect on the growth of the microorganism and ABE production.     

Butanol production by Clostridium beijerinckii. Part I: use of acid and enzyme hydrolyzed corn fiber

Fermentation of sulfuric acid treated corn fiber hydrolysate (SACFH) inhibited cell growth and butanol production (1.7 ± 0.2 g/L acetone butanol ethanol or ABE) by Clostridium beijerinckii BA101. Treatment of SACFH with XAD-4 resin removed some of the inhibitors resulting in the production of 9.3 ± 0.5 g/L ABE and a yield of 0.39 ± 0.015. Fermentation of enzyme treated corn fiber hydrolysate (ETCFH) did not reveal any cell inhibition and resulted in the production of 8.6 ± 1.0 g/L ABE and used 24.6 g/L total sugars. ABE production from fermentation of 25 g/L glucose and 25 g/L xylose was 9.9 ± 0.4 and 9.6 ± 0.4 g/L, respectively, suggesting that the culture was able to utilize xylose as efficiently as glucose. Production of only 9.3 ± 0.5 g/L ABE (compared with 17.7 g/L ABE from fermentation of 55 g/L glucose-control) from the XAD-4 treated SACFH suggested that some fermentation inhibitors may still be present following treatment. It is suggested that inhibitory components be completely removed from the SACFH prior to fermentation with C. beijerinckii BA101. In our fermentations, an ABE yield ranging from 0.35 to 0.39 was obtained, which is higher than reported by the other investigators.     

Recent advances in ABE fermentation: hyper-butanol producing Clostridium beijerinckii BA101

This is an overview of the mutant strain Clostridium beijerinckii BA101 which produces solvents (acetone–butanol–ethanol, ABE) at elevated levels. This organism expresses high levels of amylases when grown on starch. C. beijerinckii BA101 hydrolyzes starch effectively and produces solvent in the concentration range of 27–29 g l⁻¹. C. beijerinckii BA101 has been characterized for both substrate and butanol inhibition. Supplementing the fermentation medium (MP2) with sodium acetate enhances solvent production to 33 g l⁻¹. The results of studies utilizing commercial fermentation medium and pilot plant-scale reactors are consistent with the results using small-scale reactors. Pervaporation, a technique to recover solvents, has been applied to fed-batch reactors containing C. beijerinckii BA101, and solvent production as high as 165 g l⁻¹ has been achieved. Immobilization of C. beijerinckii BA101 by adsorption and use in a continuous reactor resulted in reactor productivity of 15.8 g l⁻¹ h⁻¹. Recent economic studies employing C. beijerinckii BA101 suggested that butanol can be produced at US$0.20–0.25 lb⁻¹ by employing batch fermentation and distillative recovery. Application of new technologies such as pervaporation, fed-batch culture, and immobilized cell reactors is expected to further reduce these prices. Journal of Industrial Microbiology & Biotechnology (2001) 27, 287–291. Received 12 September 2000/ Accepted in revised form 27 January 2001     

Continuous solvent production by Clostridium beijerinckii BA101 immobilized by adsorption onto brick

The performance of a continuous bioreactor containing Clostridium beijerinckii BA101 adsorbed onto clay brick was examined for the fermentation of acetone, butanol, and ethanol (ABE). Dilution rates from 0.3 to 2.5 h^–1 were investigated with the highest solvent productivity of 15.8 g l^–1 h^–1 being obtained at 2.0 h^–1. The solvent yield at this dilution rate was found to be 0.38 g g^–1 and total solvent concentration was 7.9 g l^–1. The solvent yield was maximum at 0.45 at a dilution rate of 0.3 h^–1. The maximum solvent productivity obtained was found to be 2.5 times greater than most other immobilized continuous and cell recycle systems previously reported for ABE fermentation. A higher dilution rate (above 2.0 h^–1) resulted in acid production rather than solvent production. This reactor was found to be stable for over 550 h. Scanning electron micrographs (SEM) demonstrated that a large amount of C. beijerinckii cells were adsorbed onto the brick support.     

Production of acetone butanol (AB) from liquefied corn starch,a commercial substrate,using <Emphasis Type="Italic">Clostridium beijerinckii</Emphasis> coupled with product recovery by gas stripping

A potential industrial substrate (liquefied corn starch; LCS) has been employed for successful acetone butanol ethanol (ABE) production. Fermentation of LCS (60 g l⁻¹) in a batch process resulted in the production of 18.4 g l⁻¹ ABE, comparable to glucose: yeast extract based medium (control experiment, 18.6 g l⁻¹ ABE). A batch fermentation of LCS integrated with product recovery resulted in 92% utilization of sugars present in the feed. When ABE was recovered by gas stripping (to relieve inhibition) from the fed-batch reactor fed with saccharified liquefied cornstarch (SLCS), 81.3 g l⁻¹ ABE was produced compared to 18.6 g l⁻¹ (control). In this integrated system, 225.8 g l⁻¹ SLCS sugar (487 % of control) was consumed. In the absence of product removal, it is not possible for C. beijerinckii BA101 to utilize more than 46 g l⁻¹ glucose. A combination of fermentation of this novel substrate (LCS) to butanol together with product recovery by gas stripping may economically benefit this fermentation. Mention of trade names of commercial products in this article/publication is solely for the purpose of providing scientific information and does not imply recommendation or endorsement by the United States Department of Agriculture.     

Production of acetone,butanol and ethanol by Clostridium beijerinckii BA101 and in situ recovery by gas stripping

We examined the effect of gas-stripping on the in situ removal of acetone, butanol, and ethanol (ABE) from batch reactor fermentation broth. The mutant strain (Clostridium beijerinckii BA101) was not affected adversely by gas stripping. The presence of cells in the fermentation broth affected the selectivities of ABE. A considerable improvement in the productivity and yield was recorded in this work in comparison with the non-integrated process. In an integrated process of ABE fermentation-recovery using C. beijerinckii BA101, ABE productivities and yield were improved up to 200 and 118%, respectively, as compared to control batch fermentation data. In a batch reactor C. beijerinckii BA101 utilized 45.4 g glucose l^–1 and produced 17.7 g total ABE l^–1, while in the integrated process it utilized 161.7 g glucose l^–1 and produced total ABE of 75.9 g l^–1. In the integrated process, acids were completely converted to solvents when compared to the non-integrated process (batch fermentation) which contained residual acids at the end of fermentation. In situ removal of ABE by gas stripping has been reported to be one of the most important techniques of solvent removal. During these studies we were able to maintain the ABE concentration in the fermentation broth below toxic levels.     

High titer ethanol production from simultaneous enzymatic saccharification and fermentation of aspen at high solids: a comparison between SPORL and dilute acid pretreatments

Native aspen (Populus tremuloides) was pretreated using sulfuric acid and sodium bisulfite (SPORL) and dilute sulfuric acid alone (DA). Simultaneous enzymatic saccharification and fermentation (SSF) was conducted at 18% solids using commercial enzymes with cellulase loadings ranging from 6 to 15 FPU/g glucan and Saccharomyces cerevisiae Y5. Compared with DA pretreatment, the SPORL pretreatment reduced the energy required for wood chip size-reduction, and reduced mixing energy of the resultant substrate for solid liquefaction. Approximately 60% more ethanol was produced from the solid SPORL substrate (211 L/ton wood at 59 g/L with SSF efficiency of 76%) than from the solid DA substrate (133 L/ton wood at 35 g/L with SSF efficiency 47%) at a cellulase loading of 10 FPU/g glucan after 120 h. When the cellulase loading was increased to 15 FPU/g glucan on the DA substrate, the ethanol yield still remained lower than the SPORL substrate at 10 FPU/g glucan.