Favouring butyrate production for a new generation biofuel by acidogenic glucose fermentation using cells immobilised on γ-alumina (original) (raw)
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Biotechnology for Biofuels, 2015
Background: This investigation comprises a contribution on the production of a new generation biofuel using the industrial liquid waste of bioethanol distilleries, known as vinasse. This study focuses on the exploitation of vinasse as an acidogenesis substrate for volatile fatty acids and simultaneous ethanol production. These products can be used for ester production, which is the new generation biofuel. Therefore, the aims of the present study are (i) to examine any promotional effect of γ-alumina on acidogenesis of a sucrose-raffinose mixture simulating vinasse, (ii) to study the operational stability of the continuous acidogenesis of sucrose and raffinose and subsequently of vinasse, and (iii) to determine the volatile fatty acid chemical composition and ethanol formation.
Tailored production of butyric acid from mixed culture fermentation of food waste
Food and Bioproducts Processing, 2024
Volatile fatty acids (VFA) are high-value-added products obtained from the fermentation of waste feedstock. These are generally produced as a VFA mixture of C2 - C6 acids through mixed culture fermentation. The prospect of tailoring the process conditions in mixed culture fermentation is attractive since it can produce a predominance of a target VFA without the need for a sterile, pure culture-based process. Among VFAs, butyric acid has a wide range of industrial applications which are currently met by chemical synthesis. This study showed a targeted production of butyric acid in a mixed culture VFA fermentation under psychrophilic temperature. Compared to mesophilic conditions, the butyric acid produced at 17°C accumulated to up to 7 days at 0.5 g/L compared to in 37°C where it was not detected after day 1. The microbial community study showed the increased abundance of Sporosarcina and Solibacillus genus which degrades proteins, aiding the Clostridium_sensu_stricto spp. in producing butyric acid potentially through protein degradation. Within the detected bacterial diversity showing a lower Shannon index of 0.84 at 17ºC, these genera also showed a higher abundance. For further enhancing the hydrolysis, thermal-alkaline pretreatment of food waste was performed. However, it reduced the subsequent production of butyric acid as compared to untreated food waste. Under 17ºC, butyric acid’s concentration was 0.06 g/L, while at 37ºC, it was 0.12 g/L. This showed that intrinsic microflora of food waste was essential for its production. This selective accumulation of butyric acid over other VFAs offers a means of targeted VFA production using mixed culture fermentation under psychrophilic temperature.
Designer synthetic media for studying microbial-catalyzed biofuel production
Biotechnology for Biofuels, 2015
Background: The fermentation inhibition of yeast or bacteria by lignocellulose-derived degradation products, during hexose/pentose co-fermentation, is a major bottleneck for cost-effective lignocellulosic biorefineries. To engineer microbial strains for improved performance, it is critical to understand the mechanisms of inhibition that affect fermentative organisms in the presence of major components of a lignocellulosic hydrolysate. The development of a synthetic lignocellulosic hydrolysate (SH) media with a composition similar to the actual biomass hydrolysate will be an important advancement to facilitate these studies. In this work, we characterized the nutrients and plant-derived decomposition products present in AFEX™ pretreated corn stover hydrolysate (ACH). The SH was formulated based on the ACH composition and was further used to evaluate the inhibitory effects of various families of decomposition products during Saccharomyces cerevisiae 424A (LNH-ST) fermentation. Results: The ACH contained high levels of nitrogenous compounds, notably amides, pyrazines, and imidazoles. In contrast, a relatively low content of furans and aromatic and aliphatic acids were found in the ACH. Though most of the families of decomposition products were inhibitory to xylose fermentation, due to their abundance, the nitrogenous compounds showed the most inhibition. From these compounds, amides (products of the ammonolysis reaction) contributed the most to the reduction of the fermentation performance. However, this result is associated to a concentration effect, as the corresponding carboxylic acids (products of hydrolysis) promoted greater inhibition when present at the same molar concentration as the amides. Due to its complexity, the formulated SH did not perfectly match the fermentation profile of the actual hydrolysate, especially the growth curve. However, the SH formulation was effective for studying the inhibitory effect of various compounds on yeast fermentation.
2010
Bio-butanol Acetone-Butanol-Ethanol ABE) ABEfermentation Butyric acid Clostridium C. acetobutylicum ATCC 824 C. beijerinckii ATCC 55025 C. beijerinckii BA 101 C. beijerinckii NCIMB 8052 Fibrous-bed Bioreactor (FBB) Batch Suspended cell culture Immobilized cell system. DEDICATION I would like to dedicate this M.Sc. Thesis to my beloved Family for all their love and encouragement and for always been supportive of my choices. "I am among those who think that science has great beauty. A scientist in his laboratory is not only a technician: he is also a child placed before natural phenomena, which impress him like a fairy tale." − Marie Curie
Bioresource Technology, 2010
The feasibility of bioplastics production as poly(β-OH)butyrate (PHB) was studied with individual volatile fatty acids (VFA) and acid-rich effluents from a biohydrogen producing reactor (HBR) as primary substrates employing aerobic consortia as biocatalyst under anoxic microenvironment. Butyrate as substrate showed higher PHB productivity (33%) followed by acetate (32%), acids mixture (16%) and propionate (11%) among synthetic VFA studied. Acid-rich effluents from HBR yielded higher PHB productivity (25%) especially at lower substrate loading conditions. Decrement observed in PHB production (from 25% to 6%) with increase in substrate load might be due to the presence of high concentration of residual carbon along with acid metabolites. Neutral redox operation showed effective PHB production compared to acidic and basic conditions due to associated higher metabolic activity of the biocatalyst. The integrated approach helped to treat additional COD from acid-rich HBR effluents apart from by-product recovery.
Bioresource …, 2010
The feasibility of bioplastics production as poly(b-OH)butyrate (PHB) was studied with individual volatile fatty acids (VFA) and acid-rich effluents from a biohydrogen producing reactor (HBR) as primary substrates employing aerobic consortia as biocatalyst under anoxic microenvironment. Butyrate as substrate showed higher PHB productivity (33%) followed by acetate (32%), acids mixture (16%) and propionate (11%) among synthetic VFA studied. Acid-rich effluents from HBR yielded higher PHB productivity (25%) especially at lower substrate loading conditions. Decrement observed in PHB production (from 25% to 6%) with increase in substrate load might be due to the presence of high concentration of residual carbon along with acid metabolites. Neutral redox operation showed effective PHB production compared to acidic and basic conditions due to associated higher metabolic activity of the biocatalyst. The integrated approach helped to treat additional COD from acid-rich HBR effluents apart from by-product recovery.
Development of heterogeneous catalysts for butyl butyrate production
2016
Butyl butyrate is an environmentally friendly biofuel component that can be produced through the esterification of butyric acid with n-butanol, both of which are obtainable from waste products with a two-step fermentation process. To catalyse the production of butyl butyrate, heterogeneous solid acid catalysts were developed by sulfonation of char obtained from the carbonisation of Miscanthus x giganteus and solid residues derived from the fermentation of brown bin waste (digestate). In the case of Miscanthus derived material, prior to sulfonation, part of the char underwent chemical activation with the purpose of increasing the surface area of the char (from 6.4 to 571 m2·g after chemical activation at 500°C). The catalysts possessing the highest surface area and acid density were shown to have the highest catalytic activity and thus performed better giving competitive results to Amberlyst 15 and H2SO4 (96 % yield), after 24 hours reaction. Activated Miscanthus based catalysts and ...
The Effect of Initial Butyric Acid Addition on ABE Fermentation by C. acetobutylicum NCIMB 619
Journal of Applied Sciences, 2010
The addition of organic acids to the growth medium has been shown to stimulate solvent production and protect against the degeneration of ABE-producing clostridia. The objective of this study is to demonstrate the effect of introduction of butyric acid in the fermentation media on the solvent production by C. acetobutylicum NCIMB 619. In this study, batch cultures were carried out in Reinforced Clostridial Media (RCM) containing 0.0015, 2.0 and 5.0 g/l of butyric acid, simultaneously with a control media (without addition of butyric acid) at 37°C for 72 hours. Samples were periodically withdrawn for analysis purposes. It was found that the presence of butyric acid during the early stage of the fermentation process favor the solvent yield to glucose utilization and productivity up to 139%. By adding butyric acid, the concentration of acetone, butanol and ethanol generated was improved significantly. In the case of 5.0 g/l butyric acid addition, acetone, butanol and ethanol production was increased approximately 92, 8 and 2 folds, respectively compared to control culture. The result obtained in this study showed that the addition of butyric acid has successfully enhanced the cell growth and subsequently promoted solvent production by C. acetobutylicum NCIMB 619.
Applied Biochemistry and Microbiology, 2018
⎯Pyrolysate obtained from the pyrolysis of waste cotton is a source of fermentable sugars that could be fermented into bioethanol fuel and other chemicals via microbial fermentation. However, pyrolysate is a complex mixture of fermentable and non-fermentable substrates causing inhibition of the microbial growth. The aim of this study was to detoxify the hydrolysate and then ferment it into bio-ethanol fuel in shake flasks and fermenter applying yeast strain Saccharomyces cerevisiae 2.399. Pyrolysate was hydrolyzed to glucose with 0.2 M sulfuric acid, neutralized with Ba(OH) 2 followed by treatment with ethyl acetate and activated carbon to remove fermentation inhibitors. The effect of various fermentation parameters such as inoculum concentration, pH and hydrolysate glucose was evaluated in shake flasks for optimum ethanol fermentation. With respect to inoculum concentration, 20% v/v inoculum i.e. 8.0 × 10 8-1.2 × 10 9 cells/mL was the optimum level for producing 8.62 ± 0.33 g/L ethanol at 9 h of fermentation with a maximum yield of 0.46 g ethanol/g glucose. The optimum pH for hydrolysate glucose fermentation was found to be 6.0 that produced 8.57 ± 0.66 g/L ethanol. Maximum ethanol concentration, 14.78 g/L was obtained for 4% hydrolysate glucose concentration after 16 h of fermentation. Scale-up studies in stirred fermenter produced much higher productivity (1.32 g/L/h-1) compared to shake flask fermentation (0.92 g/L/h-1). The yield of ethanol reached a maximum of 91% and 89% of the theoretical yield of ethanol in shake flasks and fermenter, respectively. The complex of integrated models of development was applied, that has been successfully tested previously for the mathematical analysis of the fermentation processes.