Browsing by Author "Bankar, Sandip B."

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  • Adsorptive removal of unsaturated fatty acids using ion exchange resins
    (2021-01-14) Chavan, Prakash V.; Khedkar, Manisha A.; Satpute, Satchidanand R.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The main aim of the present investigation was to elucidate the efficacy of silver ion chromatography for selective separation of unsaturated (oleic, linoleic, and linolenic) fatty acids on a preparative scale. Accordingly, the present work was predominantly divided into two parts. In the first part, adsorption of oleic acid was carried out using commercially available ion exchange resins and silver-ion-loaded resins (R-Ag+) prepared in the laboratory from nonpolar and polar solvents in a batch mode. The maximum adsorption of oleic acid was found on R-Ag+ (454.55 g·kg−1) compared with other commercially available ion exchange resins from heptane at ambient temperature (303 K). The effect of temperature on the adsorption of oleic acid on R-Ag+ from heptane was investigated at 303, 313, and 323 K. The adsorption of oleic acid was favored at 303 K and decreased with a further increase in temperature. Experimental batch equilibrium data were modeled using the Langmuir and Freundlich isotherms. Further, thermodynamic parameters viz., ΔGads0, ΔHads0, and ΔSads0, were estimated. The negative values of ΔGads0 and ΔHads0 show that the adsorption of oleic acid on R-Ag+ was spontaneous and exothermic in nature. Based on the results obtained in the first part, the R-Ag+ resin was subjected to adsorption of fatty acids from industrial fatty acids mixture using heptane as a solvent at 303 K. A multicomponent Freundlich isotherm was used to model experimental batch equilibrium data. Linolenic acid and linoleic acid were preferentially adsorbed over oleic acid with selectivities of 1.40 and 1.16, respectively, from industrial fatty acids mixture.
  • Biobutanol production using pea pod waste as substrate Impact of drying on saccharification and fermentation: Impact of drying on saccharification and fermentation
    (2018-03-01) Nimbalkar, Pranhita R.; Khedkar, Manisha A.; Chavan, Prakash V.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Increasing worldwide energy consumption and limited availability of fossil fuels propelled the researchers to develop advanced fuels (biobutanol) for its commercial development. In the present work, pea pod waste from vegetable sector was investigated for biobutanol production using C. acetobutylicum B 527 through series of steps viz. compositional analysis, drying study, saccharification, detoxification, and fermentation. Proximate analysis suggested that pea pod waste is rich in holocellulose content with 32.08% of cellulose and 21.12% of hemicellulose on dry basis and hence has a huge potential to be used as carbon source during biobutanol production. In order to enhance storability and subsequent saccharification, drying kinetics of pea pod waste was carried out in varied temperature range (60–120 °C) and the experimental data was simulated by using moisture diffusion control model. Saccharification of pea pod waste samples resulted into total sugar release of 30–48 g/L. Subsequently, 95% phenolics and 30% acetic acid were removed using activated charcoal detoxification. The acetone-butanol-ethanol (ABE) fermentation of detoxified pea pod waste slurries resulted in 4.25–5.94 g/L total solvents with about 50% sugar utilization. Overall, the utilization of pea pod waste will serve as basis for valorization of vegetable waste biomass for ABE production.
  • Biobutanol: the outlook of an academic and industrialist
    (2013) Bankar, Sandip B.; Survase, Shrikant A.; Ojamo, Heikki; Granström, Tom
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    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.
  • Cauliflower waste utilization for sustainable biobutanol production: revelation of drying kinetics and bioprocess development
    (2017-07) Khedkar, Manisha A.; Nimbalkar, Pranhita R.; Chavan, Prakash V.; Chendake, Yogesh J.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Efficient yet economic production of biofuel(s) using varied second-generation feedstock needs to be explored in the current scenario to cope up with global fuel demand. Hence, the present study was performed to reveal the use of cauliflower waste for acetone–butanol–ethanol (ABE) production using Clostridium acetobutylicum NRRL B 527. The proximate analysis of cauliflower waste demonstrated to comprise 17.32% cellulose, 9.12% hemicellulose, and 5.94% lignin. Drying of cauliflower waste was carried out in the temperature range of 60–120 °C to investigate its effect on ABE production. The experimental drying data were simulated using moisture diffusion control model. The cauliflower waste dried at 80 °C showed maximum total sugar yield of 26.05 g L−1. Furthermore, the removal of phenolics, acetic acid, and total furans was found to be 90–97, 10–40, and 95–97%, respectively. Incidentally, maximum ABE titer obtained was 5.35 g L−1 with 50% sugar utilization.
  • Continuous two stage acetone-butanol-ethanol fermentation with integrated solvent removal using Clostridium acetobutylicum B 5313
    (2012) Bankar, Sandip B.; Survase, Shrikant A.; Singhal, Rekha S.; Granström, Tom
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    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.
  • Editorial: Design and application of biocatalysts for biofuel and bio-based material production
    (2022-09-26) Zabed, Hossain M.; Bankar, Sandip B.; Rehan, Mohammad; Nizami, Abdul Sattar; Alam, Md Asraful; Mofijur, M.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
  • Enhanced biobutanol production in folic acid-induced medium by using clostridium acetobutylicum NRRL B-527
    (2019-07-31) Nimbalkar, Pranhita R.; Khedkar, Manisha A.; Chavan, Prakash V.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The conventional acetone-butanol-ethanol fermentation process suffers from several key hurdles viz. low solvent titer, insufficient yield and productivity, and solvent intolerance which largely affect butanol commercialization. To counteract these issues, the effect of stimulator, namely, folic acid was investigated in the present study to improve butanol titer. Folic acid is involved in biosynthesis of a diverse range of cellular components, which subsequently alter the amino acid balance. Therefore, different concentrations of folic acid were screened, and 10 mg/L supplementation resulted in a maximum butanol production of 10.78 ± 0.09 g/L with total solvents of 18.91 ± 0.21 g/L. Folic acid addition at different time intervals was also optimized to get additional improvements in final butanol concentration. Overall, folic acid supplementation resulted in two-fold increase in butanol concentration and thus could be considered as a promising strategy to enhance solvent titers.
  • Enhanced isopropanol-butanol-ethanol (IBE) production in immobilized column reactor using modified Clostridium acetobutylicum DSM792
    (2014) Bankar, Sandip B.; Jurgens, German; Survase, Shrikant A.; Ojamo, Heikki; Granström, Tom
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
  • A green process for the production of butanol from butyraldehyde using alcohol dehydrogenase: process details
    (2014) Jadhav, Swati B.; Harde, Shirish; Bankar, Sandip B.; Granström, Tom; Ojamo, Heikki; Singhal, Rekha S.; Survase, Shrikant A.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
  • Improvements in the extraction of bioactive compounds by enzymes
    (2019-02-01) Marathe, Sandesh J.; Jadhav, Swati B.; Bankar, Sandip B.; Kumari Dubey, Kriti; Singhal, Rekha S.
     A2 Katsausartikkeli tieteellisessä aikakauslehdessä
    Bioactives from plants are always in high demand in nutraceutical, pharmaceutical, and functional food sectors due to their health benefits. This intensifies the need of extraction of bioactives by different methods that can improve the yield and purity of the compound. Enzymes help in the release of bioactives from the plant material under optimized conditions so as to make the extraction process efficient. Though enzymatic extraction of bioactives have been used since long, it needs improvement to further enhance the yield, reduce the process time, and make the process cost competitive. The combination of enzymatic extraction with other green techniques such as ultrasound extraction, supercritical fluid extraction, three-phase partitioning, ionic liquid extraction, and microwave extraction can boost the advantages of enzymatic extraction. This review focuses on the improvement in the enzymatic extraction techniques for the bioactives in detail.
  • Microbial Polyamino Acids: An Overview for Commercial Attention
    (2018-04-02) Bankar, Sandip B.; Nimbalkar, Pranhita R.; Chavan, Prakash V.; Singhal, Rekha S.
     A3 Kirjan tai muun kokoomateoksen osa
    Although, 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. Fermentation and 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.
  • New Insight into Sugarcane Industry Waste Utilization (Press Mud) for Cleaner Biobutanol Production by Using C. acetobutylicum NRRL B-527
    (2017-11) Nimbalkar, Pranhita R.; Khedkar, Manisha A.; Gaikwad, Shashank G.; Chavan, Prakash V.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In the present study, press mud, a sugar industry waste, was explored for biobutanol production to strengthen agricultural economy. The fermentative production of biobutanol was investigated via series of steps, viz. characterization, drying, acid hydrolysis, detoxification, and fermentation. Press mud contains an adequate amount of cellulose (22.3%) and hemicellulose (21.67%) on dry basis, and hence, it can be utilized for further acetone-butanol-ethanol (ABE) production. Drying experiments were conducted in the temperature range of 60–120 °C to circumvent microbial spoilage and enhance storability of press mud. Furthermore, acidic pretreatment variables, viz. sulfuric acid concentration, solid to liquid ratio, and time, were optimized using response surface methodology. The corresponding values were found to be 1.5% (v/v), 1:5 g/mL, and 15 min, respectively. In addition, detoxification studies were also conducted using activated charcoal, which removed almost 93–97% phenolics and around 98% furans, which are toxic to microorganisms during fermentation. Finally, the batch fermentation of detoxified press mud slurry (the sample dried at 100 °C and pretreated) using Clostridium acetobutylicum NRRL B-527 resulted in a higher butanol production of 4.43 g/L with a total ABE of 6.69 g/L.
  • Novel multistage solid-liquid circulating fluidized bed: Hydrodynamic characteristics
    (2018-06) Chavan, Prakash V.; Thombare, Manjusha A.; Bankar, Sandip B.; Kalaga, Dinesh V.; Patil-Shinde, Veena A.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The present work proposes a novel radially cross-flow multistage solid-liquid circulating fluidized bed (SLCFB). The SLCFB primarily consists of a single multistage column (having an inner diameter of 100. mm and length of 1.40. m), which is divided into two sections wherein both the steps of utilization or loading (e.g., adsorption and catalytic reaction) and regeneration of the solid phase can be carried out simultaneously in continuous mode. The hydrodynamic characteristics were studied using ion exchange resin as the solid phase and water as the fluidizing medium. The loading and flooding states were determined for three particle sizes; i.e., 0.30, 0.42, and 0.61. mm. The effects of the superficial liquid velocity and solid feed rate on the solid hold-up were investigated under loading and flooding conditions. The solid hold-up increases with an increase in the solid feed rate and decreases with an increase in the superficial liquid velocity. An artificial-intelligence formalism, namely the multilayer perceptron neural network (MLPNN), was employed for the prediction of the solid hold-up. The input space of MLPNN-based model consists of four parameters, representing operating and system parameters of the proposed SLCFB. The developed MLPNN-based model has excellent prediction accuracy and generalization capability.
  • Novel multistage solid–liquid circulating fluidized bed: liquid phase mixing characteristics
    (2020-02-17) Thombare, Manjusha A.; Kalaga, Dinesh V.; Bankar, Sandip B.; Kulkarni, Rahul K.; Satpute, Satchidanand R.; Chavan, Prakash V.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Liquid phase axial mixing studies have been carried out in the novel solid–liquid circulating fluidized bed (SLCFB). The SLCFB primarily consists of a single multistage column (having an inner diameter of 100 mm i.d. and length of 1.40 m) which is divided into two sections wherein both the steps of utilization, namely loading (e.g., adsorption and catalytic reaction) and regeneration of solid phase, can be carried out simultaneously in continuous mode. Weak base anion exchange resin was used as the solid phase, whereas water as the fluidizing medium. The effects of physical properties of solid phase, superficial liquid velocity, and solid circulation rate on liquid phase axial dispersion coefficient were investigated. The dispersion coefficient increases monotonically with an increase in the size of solid particle, superficial liquid velocity, and solid circulation rate. The axial dispersion model (ADM) was used to model experimental residence time distribution (RTD) data. A good agreement was found between ADM predictions and the experimental measurements. A unified correlation has also been proposed to determine dispersion coefficient as a function of physical properties of solid and liquid phases, superficial liquid velocity, and solid circulation rate based on all previous and present experimental data on multistage SLCFB.
  • Process intensification strategies for enhanced holocellulose solubilization: Beneficiation of pineapple peel waste for cleaner butanol production
    (2018-10-20) Khedkar, Manisha A.; Nimbalkar, Pranhita R.; Kamble, Sanjay P.; Gaikwad, Shashank G.; Chavan, Prakash V.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Biorefinery sector has become a serious dispute for cleaner and sustainable development in recent years. In the present study, pretreatment of pineapple peel waste was carried out in high pressure reactor using various pretreatment-enhancers. The type and concentration effect of each enhancer on hemicellulose solubilization was systematically investigated. The binary acid (phenol + sulfuric acid) at 180 °C was found to be superior amongst other studied enhancers, giving 81.17% (w/v) hemicellulose solubilization in liquid-fraction under optimized conditions. Solid residue thus obtained was subjected to enzymatic hydrolysis that resulted into 24.50% (w/v) cellulose breakdown. Treated solid residue was further characterized by scanning electron microscopy and fourier transform infrared spectroscopy to elucidate structural changes. The pooled fractions (acid treated and enzymatically hydrolyzed) were fermented using Clostridium acetobutylicum NRRL B 527 which resulted in butanol production of 5.18 g/L with yield of 0.13 g butanol/g sugar consumed. Therefore, pretreatment of pineapple peel waste evaluated in this study can be considered as milestone in utilization of low cost feedstock, for bioenergy production.
  • Solid-liquid circulating fluidized bed: A way forward
    (2019-01-01) Thombare, Manjusha A.; Chavan, Prakash V.; Bankar, Sandip B.; Kalaga, Dinesh V.
     A2 Katsausartikkeli tieteellisessä aikakauslehdessä
    Solid-liquid circulating fluidized beds (SLCFBs) offer several attractive features over conventional solid-liquid fluidized beds such as efficient liquid-solid contact, favorable mass and heat transfer, reduced back-mixing of phases, and integrated reactor and regenerator design. These unique features have stimulated theoretical and experimental investigations over the past two decades on transport phenomena in SLCFBs. However, there is a need to compile and analyze the published information with a coherent theme to design and develop SLCFB with sufficient degree of confidence for commercial application. Therefore, the present work reviews and analyzes the literature on hydrodynamic, mixing, heat transfer, and mass transfer characteristics of SLCFBs comprehensively. Suitable recommendations have also been made for future work in concise manner based on the knowledge gaps identified in the literature. Furthermore, a novel multistage SLCFB has been proposed to overcome the limitations of existing SLCFBs. The proposed model of SLCFB primarily consists of a single multistage column which is divided into two sections wherein both the steps of utilization viz. loading (adsorption, catalytic reaction, etc.) and regeneration of solid phase could be carried out simultaneously on a continuous mode.
  • Solvent extraction of butanol from synthetic solution and fermentation broth : Batch and continuous studies
    (2020-10-15) Khedkar, Manisha A.; Nimbalkar, Pranhita R.; Gaikwad, Shashank G.; Chavan, Prakash V.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Product recovery is one of the essential finishing steps to any commercial fermentation process. In acetone-butanol-ethanol (ABE) fermentation, butanol recovery is quite tedious mainly due to dilute product and multiple byproduct formation in complex media. Among different recovery methods, extraction has attracted considerable attention in biofuel recovery owing to its high selectivity, low energy consumption, and ease of operation. In present work, the butanol extraction performance from synthetic solvent mixture containing ABE was tested in batch and continuous operations using 20% (v/v) decanol in oleyl alcohol. The optimized extraction conditions were then validated using actual fermentation broth to confirm effectiveness of the extraction operation. The distribution coefficient (Kd) and batch extraction efficiency (E) were in the range of 5.60–9.80 and 87.70–86.90% for fermentation broth and synthetic solution, respectively for a given initial concentration of butanol in the aqueous phase. Further, E was relatively improved by supplementing different inorganic salts. Sodium hydroxide (5%, w/v) was highly effective to recover butanol from fermentation broth (E ~ 97.70%) with Kd of 33.10. Besides, the continuous counter current extraction of butanol in a packed column was performed. The volumetric mass transfer coefficient (kLa) was estimated to be 0.025 1/min at an optimized superficial velocity of the aqueous phase (0.28 cm/min) and sodium hydroxide concentration (5%, w/v). Height of the extraction column was estimated to be 28.32 cm using height of transfer unit (HTU) and number of transfer unit (NTU) concept for extraction efficiency of 97.20%. Overall, the present study has demonstrated an enhanced extraction efficiency of butanol from fermentation broth.
  • Stabilization of cutinase by covalent attachment on magnetic nanoparticles and improvement of its catalytic activity by ultrasonication
    (2019-07-01) Muley, Abhijeet B.; Chaudhari, Sandeep A.; Bankar, Sandip B.; Singhal, Rekha S.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    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.
  • Strategic intensification in butanol production by exogenous amino acid supplementation: Fermentation kinetics and thermodynamic studies
    (2019-05-21) Nimbalkar, Pranhita R.; Khedkar, Manisha A.; Kulkarni, Rahul K.; Chavan, Prakash V.; Bankar, Sandip B.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Amino acids are vital precursors in many biochemical production pathways in addition to efficient nitrogen source which could enhance microbial growth yields. Therefore, in present study, the effect of amino acids from aliphatic and aromatic family was comprehensively evaluated in batch and integrated fed batch fermentation system. Clostridium acetobutylicum NRRL B-527 was able to utilize 54.15 ± 1.0 g/L glucose to produce 12.43 ± 0.10 g/L butanol under batch cultivation. Interestingly, a significant step up in butanol titer (20.82 ± 0.33 g/L)was achieved by using fed-batch fermentation process integrated with liquid–liquid extraction module. Besides, mathematical modeling studies demonstrated the best fitting of experimental data with first order reaction kinetics. Overall, an enhancement in solvent titer by induction of essential cellular components coupled with advance bioprocess strategy was successfully utilized in this study for its further applications.
  • The two stage immobilized column reactor with an integrated solvent recovery module for enhanced ABE production
    (2013) Bankar, Sandip B.; Survase, Shrikant A.; Ojamo, Heikki; Granström, Tom
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    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.