Biobutanol: the outlook of an academic and industrialist.

Abstract The gradual shift of transportation fuels from oil based fuels to the alternative fuel resources and worldwide demand for energy has been the impetus for research to produce alcohol biofuels from renewable resources. Current bioethanol and biodiesel can, however, not cover an increasing demand for biofuels. Hence, there is an extensive need for advanced biofuels with superior fuel properties. The present review is focused on the developments of biobutanol, which is regarded to be superior to bioethanol in terms of energy density and hygroscopicity. Although acetone-butanolethanol (ABE) fermentation is one of the oldest large-scale fermentation processes, butanol yield by anaerobic fermentation remains sub-optimal. For sustainable industrial scale butanol production, a number of obstacles need to be addressed including choice of feedstock, low product yield, product toxicity to production strain, multiple end-products and downstream processing of alcohol mixtures. Metabolic engineering provides a means for fermentation improvements. Different strategies are employed in the metabolic engineering of Clostridia that aim to enhance the solvent production, improve selectivity for butanol production, and increase the tolerance of Clostridia to solvents. The introduction and expression of a non-clostridial butanol producing pathway in E. coli is most promising strategy for butanol biosynthesis. Several rigorous kinetic and physiological models for fermentation have been formulated, which form useful tool for optimization of the process. Due to the lower butanol titers in the fermentation broth, simultaneous fermentation and product removal techniques have been developed to improve production economics. With the use of new strains, inexpensive substrates, and superior reactor designs, economic ABE fermentation may further attract an attention of researchers all over the world. The present review is attempting to provide an overall outlook on discoveries and strategies that are being developed for commercial n-butanol production

Purification and characterization of poly-ε-lysine from <i>Streptomyces noursei </i>NRRL 5126

33-40The present article reports on the development of an effective downstream technique for the recovery of poly-ε-lysine (ε-PL), an unusual cationic homo-polyamide of L-lysine produced by fermentation using Streptomyces noursei NRRL 5126. Purification of ε-PL using cation exchange chromatography, ultrafiltration, solvent precipitation, and gel permeation chromatography was investigated. Loading of fermentation broth on Amberlite IRC 50 chromatographic column could purify the ε-PL with 95.84 % recovery. Subsequent fractionation with ultrafiltration (20kDa, and 5kDa) was found to be effective at minimal transmembrane pressure and optimal flux which resulted in 91.66 % product purity. Further, solvent precipitation and gel permeation chromatography which gave the highest possible purity (97.58%) and ε-PL yield (90.42%). Exclusion of ultrafiltration step negotiated the yield (88.62%) and purity (95.15) of ε-PL, if final application doesn’t demand highly pure sample. Characterization with respect to molecular weight, thin layer chromatography, IR and NMR confirmed the identity of ε-PL in purified sample

Biobutanol: the outlook of an academic and industrialist

The gradual shift of transportation fuels from oil based fuels to alternative fuel resources and worldwide demand for energy has been the impetus for research to produce alcohol biofuels from renewable resources. Currently bioethanol and biodiesel can, however, not cover an increasing demand for biofuels. Hence, there is an extensive need for advanced biofuels with superior fuel properties. The present review is focused on the development of biobutanol, which is regarded to be superior to bioethanol in terms of energy density and hygroscopicity. Although acetone–butanol–ethanol (ABE) fermentation is one of the oldest large-scale fermentation processes, butanol yield by anaerobic fermentation remains sub-optimal. For sustainable industrial scale butanol production, a number of obstacles need to be addressed including choice of feedstock, low product yield, product toxicity to production strain, multiple end-products and downstream processing of alcohol mixtures. Metabolic engineering provides a means for fermentation improvements. Different strategies are employed in the metabolic engineering of Clostridia that aim to enhance the solvent production, improve selectivity for butanol production, and increase the tolerance of Clostridia to solvents. The introduction and expression of a non-clostridial butanol producing pathway in E. coli is a most promising strategy for butanol biosynthesis. Several rigorous kinetic and physiological models for fermentation have been formulated, which form a useful tool for optimization of the process. Due to the lower butanol titers in the fermentation broth, simultaneous fermentation and product removal techniques have been developed to improve production economics. With the use of new strains, inexpensive substrates, and superior reactor designs, economic ABE fermentation may further attract the attention of researchers all over the world. The present review is attempting to provide an overall outlook on discoveries and strategies that are being developed for commercial n-butanol production.Peer reviewe

The two stage immobilized column reactor with an integrated solvent recovery module for enhanced ABE production

The production of acetone, butanol, and ethanol (ABE) by fermentation is a process that had been used by industries for decades. Two stage immobilized column reactor system integrated with liquid–liquid extraction was used with immobilized Clostridium acetobutylicum DSM 792, to enhance the ABE productivity and yield. The sugar mixture (glucose, mannose, galactose, arabinose, and xylose) representative to the lignocellulose hydrolysates was used as a substrate for continuous ABE production. Maximum total ABE solvent concentration of 20.30 g L−1 was achieved at a dilution rate (D) of 0.2 h−1, with the sugar mixture as a substrate. The maximum solvent productivity (10.85 g L−1 h−1) and the solvent yield (0.38 g g−1) were obtained at a dilution rate of 1.0 h−1. The maximum sugar mixture utilization rate was achieved with the present set up which is difficult to reach in a single stage chemostat. The system was operated for 48 days without any technical problems.Peer reviewe

Stabilization of cutinase by covalent attachment on magnetic nanoparticles and improvement of its catalytic activity by ultrasonication

This paper reports on stabilization of serine cutinase activity by immobilizing it through cross linking with glutaraldehyde on magnetic nanoparticles (Fe-NPs) and intensification of catalytic activity by ultrasonic treatment. The optimum parameters were cross linking with 10.52 mM glutaraldehyde for 90 min using 1:2 (w/w) ratio of enzyme:Fe-NPs. The characterization of cutinase-Fe-NPs was done by different instrumental analysis. Ultrasonic power showed a beneficial effect on the activity of free and immobilized cutinase at 5.76 and 7.63 W, respectively, after 12 min. Immobilization and ultrasonic treatment led to increments in kinetic parameters (K m and V max ) along with noticeable changes in the secondary structural fractions of cutinase. Cutinase-Fe-NPs showed augmented pH (4–8) and thermal stability (40–60 °C). Considerably higher thermal inactivation kinetic constants (k d , t 1/2 and D-value) and thermodynamic constants (E d , ΔH°, ΔG° and ΔS°) highlighted superior thermostability of cutinase-Fe-NPs. Cutinase-Fe-NPs and ultrasound treated cutinase-Fe-NPs retained 61.88% and 38.76% activity during 21-day storage, and 82.82 and 80.69% activity after fifth reusability cycle, respectively.Peer reviewe

Valorization of sugarcane straw to produce highly conductive bacterial cellulose / graphene nanocomposite films through in situ fermentation

Bacterial cellulose based nanocomposites have found a growing interest in recent decades due to their impressive inherent characteristics with potential applications in diverse sectors. However, there remain several challenges due to increased production cost, lower yield, and sustainability or biocompatibility issues after chemical-based modifications. This study demonstrates the fabrication of bacterial cellulose-reduced graphene oxide films via in-situ fermentation approach using abundantly available agricultural waste (sugarcane straw) as a feedstock. The presence of reduced graphene oxide at different concentrations in culture media, significantly altered the fermentation kinetics, as evident from kinetic parameter and yield coefficients. Higher yields of bacterial cellulose-reduced graphene oxide nanocomposites, with presence of strongly integrated network-like structures between bacterial cellulose nanofibers and reduced graphene oxide nanosheets were observed at 2 wt % reduced graphene oxide loadings.Formation of such percolated networks was confirmed from improved mechanical properties and enhanced electrical conductivity, through both experimental and modeling investigations. The proposed in-situ fermentation technique to produce highly conductive bacterial cellulose-reduced graphene oxide films provides an alternative approach to meet the growing demands of biomass-derived renewable and sustainable biomaterials with commercial significance.Peer reviewe

Continuous two stage acetone-butanol-ethanol fermentation with integrated solvent removal using Clostridium acetobutylicum B 5313

The objective of this study was to optimize continuous acetone–butanol–ethanol (ABE) fermentation using a two stage chemostat system integrated with liquid–liquid extraction of solvents produced in the first stage. This minimized end product inhibition by butanol and subsequently enhanced glucose utilization and solvent production in continuous cultures of Clostridium acetobutylicum B 5313. During continuous two-stage ABE fermentation, sugarcane bagasse was used as the cell holding material for the both stages and liquid–liquid extraction was performed using an oleyl alcohol and decanol mixture. An overall solvent production of 25.32 g/L (acetone 5.93 g/L, butanol 16.90 g/L and ethanol 2.48 g/L) was observed as compared to 15.98 g/L in the single stage chemostat with highest solvent productivity and solvent yield of 2.5 g/L h and of 0.35 g/g, respectively. Maximum glucose utilization (83.21%) at a dilution rate of 0.05 1/h was observed as compared to 54.38% in the single stage chemostat.Peer reviewe

Microbial Polyamino Acids

Elseltä on kysytty FAMin avaamisesta 2205./ MSoAlthough, polyamino acids are structurally similar to proteins, they are not proteins and do not have a specific sequence. Polyamino acids are polymerized from single amino acid that has molecular mass and polydispersity as similar as polysaccharides. Polyamino acid biosynthesis is considered to be an interesting example of biopolymer synthesis that is being produced by fermentation process. Furthermore, polyamino acids have a wide range of applications from food additives and biomedical agents to biodegradable and renewable resources. The materials produced from polyamino acids are environment friendly, biodegradable, and independent of oil-based resources. Three common natural polyamino acids studied extensively in the literature are, poly-ε-lysine, poly-ε-glutamic acid, and cyanophycin.This chapter covers a wide-range discussion on the importance of polyamino acids including structure, biosynthesis, and biodegradation of naturally occurring poly-ε-lysine, poly-ε-glutamic acid, and cyanophycin. Fermentationand biosynthetic pathway studies, along with downstream processing and characterization of these polyamino acids, are detailed extensively in the current chapter. Besides, large-scale production and challenges associated with it are also discussed. Multifarious applications of polyamino acids in the food as well as pharmaceutical industries have been summarized comprehensively. Finally, various challenges and opportunities in well-designed trials that are needed to improve the current knowledge on polyamino acids are conjectured.Peer reviewe