Evaluation of single cell oil from Aureobasidium pullulans var. melanogenum P10 isolated from mangrove ecosystems for biodiesel production

In this study, the yeast strain P10 which was identified to be a member of Aureobasidium pullulans var. melanogenum isolated from the mangrove ecosystems was found to be able to accumulate high content of oil in its cells. After optimization of the medium for lipid production and cell growth by the yeast strain P10, it was found that 8.0 g of glucose per 100 ml, 0.02 g of yeast extract per 100 ml, 0.02 g of ammonium sulfate per 100 ml, pH 6.0 in the medium were the most suitable for lipid production. During 10-l fermentation, a titer was 66.3 g oil per 100 g of cell dry weight, cell mass was 1.3 g per 100 ml, a yield was 0.11 g of oil per g of consumed sugar and a productivity was 0.0009 g of oil per g of consumed sugar per h within 120 h. At the same time, only 0.07 g of reducing sugar per 100 ml was left in the fermented medium. The compositions of the fatty acids produced were C_16:0 (26.7%), C_16:1(1.7%), C_18:0 (6.1%), C_18:1 (44.5%), and C_18:2 (21.0%). The biodiesel produced from the extracted lipid could be burnt well.     

Simultaneous production of single cell protein and killer toxin by Wickerhamomyces anomalus HN1-2 isolated from mangrove ecosystem

The yeast Wickerhamomyces anomalus (the previous name was Pichia anomala) HN1-2 isolated from the mangrove ecosystem was found to be able to produce high level of both killer toxin and single cell protein. When the killer yeast cells were grown by batch cultivation in 5-l fermentor, crude protein in the cells, cell mass, reducing sugar, and diameter of the inhibition zone reached 56.0 g per 100 g of cell dry weight, 7.3 g per liter, 9.5 g per liter, and 19.0 mm, respectively within 12 h and this yeast synthesized a large amount of the essential amino acids, such as lysine (7.8%), methionine (1.8%), and leucine (9.0%). The crude killer toxin produced by the killer yeast isolate HN1-2 could kill the cells of Lodderomyces elongisporus, Candida albicans, Metschnikowia bicuspidata, Pichia guilliermondii, Saccharomyces cerevisiae, Yarrowia lipolytica, and Kluyveromyces aestuarii, which were widely distributed in natural marine environments. The results also showed that the undesirable yeast could be avoided during cell growth of the killer yeast.     

Exploration of a natural reservoir of flocculating genes from various Saccharomyces cerevisiae strains and improved ethanol fermentation using stable genetically engineered flocculating yeast strains

Flocculating yeast strains with good fermentation ability are desirable for brewing industry as well as for fuel ethanol production, however, the genetic diversity of the flocculating genes from natural yeast strains is largely unexplored. In this study, FLO1, FLO5, FLO9, FLO10 and FLO11 PCR products were obtained from 16 yeast strains from various sources, and the PCR product amplified from FLO1 of the self-flocculating yeast strain SPSC01 was used for the construction of expression cassette flanked by homologous fragments of the endonuclease gene HO for chromosome integration. A genetically engineered flocculating yeast BHL01 with good fermentation performance was obtained by transforming an industrial strain Saccharomyces cerevisiae 4126 with the expression cassette. The fermentation performances of SPSC01 and BHL01 in flask fermentation were compared using 208 g/L glucose. BHL01 completed the fermentation 8 h earlier than SPSC01, while no significant difference between BHL01 and S. cerevisiae 4126 was observed. In very high gravity repeated batch ethanol fermentation using 255 g/L glucose, BHL01 maintained stable flocculation for at least over 24 batches, while SPSC01 displayed severe deflocculation under the same conditions. The natural reservoir of flocculating genes from yeast strains may represent an unexplored gene source for the construction of new flocculating yeast strains for improved ethanol production.     

A novel and efficient method for the isolation and purification of polysaccharides from lily bulbs by Saccharomyces cerevisiae fermentation

A water-soluble polysaccharide from lily bulbs was isolated and purified by Saccharomyces cerevisiae fermentation. Proteins present in lily bulb extract were removed by extracellular proteases secreted by S. cerevisiae during fermentation. This novel method differs from traditional protein removal methods. A suitable yeast strain was selected. Culture conditions were optimized. Response surface methodology (RSM) was utilized to evaluate the effects of variables on the lily polysaccharide (LP) yield and the protein removal ratio (PRR). The results of applying RSM revealed that the optimum fermentation conditions were 87.5 g L⁻¹ lily bulb powder, pH 5.6, and temperature 27.9 °C. When lily bulb extract was cultured with S. cerevisae under optimum conditions, the LP yield and the PRR were 6.56% and 91.46%, respectively. These values are in close agreement with the value predicted by the model. The resulting LP curding was further purified by DEAE Sepharose Fast Flow chromatography after isolation by alcohol precipitation post-fermentation. DEAE chromatography resulted in a fraction, LP-1 (yield: 4.46%) with a molecular weight of 65.0 kDa. LP-1 consisted of glucose and mannose in a molar ratio of 1:1.2.     

Granular activated carbon single-chamber microbial fuel cells (GAC-SCMFCs): A design suitable for large-scale wastewater treatment processes

As an emerging biotechnology capable of removing contaminants and producing electricity, microbial fuel cells (MFCs) hold a promising future in wastewater treatment. However, several main problems, including the high internal resistance (R_in), low power output, expensive material, and complicated configuration have severely hindered the large-scale application of MFCs. The study targeted these challenges by developing a novel MFC system, granular activated carbon single-chamber MFC, termed as GAC-SCMFC. The batch tests showed that GAC was a good substitute for carbon cloth and GAC-SCMFCs generated high and stable power outputs compared with the traditional two-chamber MFCs (2CMFCs). Critical operational parameters (i.e. wastewater substrate concentrations, GAC amount, electrode distance) affecting the performance of GAC-SCMFCs were examined at different levels. The results showed that the R_in gradually decreased from 60 Ω to 45 Ω and the power output increased from 0.2 W/m³ to 1.2 W/m³ when the substrate concentrations increased from 100 mg/L to 850 mg/L. However, at high concentrations of 1000–1500 mg/L, the power output leveled off. The R_in of MFCs decreased 50% when the electrode distance was reduced from 7.5 cm to 1 cm. The highest power was achieved at the electrode distance of 2 cm. The power generation increased with more GAC being added in MFCs due to the higher amount of biomass attached. Finally, the multi-anode GAC-SCMFCs were developed to effectively collect the electrons generated in the GAC bed. The results showed that the current was split among the multiple anodes, and the cathode was the limiting factor in the power production of GAC-SCMFCs.     

Synthesis of S-licarbazepine by asymmetric reduction of oxcarbazepine with Saccharomyces cerevisiae CGMCC No. 2266

S-licarbazepine was synthesized by asymmetric reduction of oxcarbazepine with CGMCC No. 2266. The optimum batch reduction conditions were found to consist of a reaction time of 36 h, temperature of 30 °C, and initial pH value of 7.0. The optimum concentration of the glucose co-substrate was found to be 0.3 mol L⁻¹. The addition of glucose contributed to in situ regeneration of NADPH in cells and improved conversion. Conversion increased with the addition of more biomass and with a decrease in the initial concentration of substrate. Within the membrane reactor, a continuous reduction process was used to improve production efficiency and reduce the inhibition of high-concentration substrate upon reduction. The optimum flux was found to be 20 ml h⁻¹. S-licarbazepine yield was 3.7678 mmol L⁻¹ d⁻¹ in continuous reduction over four days. The enantiometric excess of S-licarbazepine was 100% for both batch and continuous reduction processes.     

Estudios de la viabilidad y la vitalidad frente al congelado de la levadura probiótica Saccharomyces boulardii: efecto del preacondicionamiento fisiológico

The aim of this study was to evaluate the vitality and viability of the probiotic yeast Saccharomyces boulardii after freezing/thawing and the physiological preconditioning effect on these properties. The results indicate that the specific growth rate (0.3/h^?1) and biomass (2-3 × 10⁸ cells/ml) of S. boulardii obtained in flasks shaken at 28 °C and at 37 °C were similar. Batch cultures of the yeast in bioreactors using glucose or sugar-cane molasses as carbon sources, reached yields of 0.28 g biomass/g sugar consumed, after 10 h incubation at 28 °C; the same results were obtained in fed batch fermentations. On the other hand, in batch cultures, the vitality of cells recovered during the exponential growth phase was greater than the vitality of cells from the stationary phase of growth. Vitality of cells from fed-batch fermentations was similar to that of stationary growing cells from batch fermentations. Survival to freezing at –20 °C and subsequent thawing of cells from batch cultures was 0.31% for cells in exponential phase of growth and 11.5% for cells in stationary phase. Pre-treatment of this yeast in media with water activity (a_w) 0.98 increased the survival to freezing of S. boulardii cells stored at –20 °C for 2 months by 10 fold. Exposure of the yeast to media of reduced a_w and/or freezing/thawing process negatively affected cell vitality. It was concluded that stress conditions studied herein decrease vitality of S. boulardii. Besides, the yeast strain studied presented good tolerance to bile salts even at low pH values.     

Relation between pristinamycins production by Streptomyces pristinaespiralis,power dissipation and volumetric gas–liquid mass transfer coefficient,kLa

During bioreactor cultures, microorganisms are submitted to non-optimal conditions such as nutritional and hydrodynamic stresses which may lead to modifications of the physiological cell response; this is especially true for filamentous microorganisms like Streptomycetes also subjected to significant morphological changes. In the present work, growth and production of pristinamycins by Streptomyces pristinaespiralis in shaking flasks have been related to power dissipation. The filamentous bacteria were grown in different flask conditions with various total and working volumes and at two agitation rates, to test the influence of power dissipation and gas–liquid mass transfer coefficient on growth and antibiotics production. As a first step, computational fluid dynamics–volume of fluid (CFD–VOF) calculations were shown to be able to predict power dissipations for the various operating conditions in Newtonian flow conditions. Then, in non-Newtonian flow conditions (biomass concentration superior to 14 g L⁻¹), the rheological model of Sisko was implemented in CFD simulations for the calculation of the fluid viscosity and then of power dissipation. Whereas microbial growth was correlated to k_La, the antibiotics production onset was linked to the volume mean power dissipation. Once a minimal cell concentration of 15 g L⁻¹ was reached, the concentration of antibiotics was correlated to power dissipation with an optimal range of production, between 5.5 and 8.5 kW m⁻³. Higher power dissipation entailed a drop in production which could be explained by hydrodynamic cell damages.     

Evaluation of distant carbon sources in biosurfactant production by a gamma ray-induced Pseudomonas putida mutant

Pseudomonas putida 33 wild strain, subjected to gamma ray mutagenesis and designated as P. putida 300-B mutant was used as microbial rhamnolipid-producer by using distant carbon sources (viz. hydrocarbons, waste frying oils ‘WFOs’, vegetable oil refinery wastes and molasses) in the minimal media under shake flask conditions. The behavior of glucose as co-substrate and growth initiator was examined. The 300-B mutant strain showed its ability to grow on all the substrates tested and produced rhamnolipid surfactants to different extents however; soybean and corn WFOs were observed to be preferred carbon sources followed by kerosene and paraffin oils, respectively. The best cell biomass (3.5 g l⁻¹) and rhamnolipids yield (4.1 g l⁻¹) were obtained with soybean WFO as carbon source and glucose as growth initiator under fed-batch cultivation showing an optimum specific growth rate (μ) of 0.272 h⁻¹, specific product yield (q_p) of 0.318 g g⁻¹ h and volumetric productivity (P_V) of 0.024 g l⁻¹ h. The critical micelle concentration of its culture supernatant was observed to be 91 mg rhamnolipids l⁻¹ and surface tension as 31.2 mN m⁻¹.     

Escherichia coli HGT: Engineered for high glucose throughput even under slowly growing or resting conditions

Aerobic production-scale processes are constrained by the technical limitations of maximum oxygen transfer and heat removal. Consequently, microbial activity is often controlled via limited nutrient feeding to maintain it within technical operability. Here, we present an alternative approach based on a newly engineered Escherichia coli strain. This E. coli HGT (high glucose throughput) strain was engineered by modulating the stringent response regulation program and decreasing the activity of pyruvate dehydrogenase. The strain offers about three-fold higher rates of cell-specific glucose uptake under nitrogen-limitation (0.6 g_Glc g_CDW⁻¹ h⁻¹) compared to that of wild type, with a maximum glucose uptake rate of about 1.8 g_Glc g_CDW⁻¹ h⁻¹ already at a 0.3 h⁻¹ specific growth rate. The surplus of imported glucose is almost completely available via pyruvate and is used to fuel pyruvate and lactate formation. Thus, E. coli HGT represents a novel chassis as a host for pyruvate-derived products.     

Correlations between reduction–oxidation potential profiles and growth patterns of Saccharomyces cerevisiae during very-high-gravity fermentation

When Saccharomyces cerevisiae was grown under three glucose concentrations (ca. 200, 250, and 300 g/l), controlled at three reduction–oxidation (redox) potentials (no control, −150 and −100 mV) by manipulating two aerations (0.82 and 1.3 vvm), we observed that the recorded redox potential profiles resembled bathtub curves, and the profiles correlated well to the growth patterns measured under the same conditions. According to the shape of bathtub curve, we subdivided the curve into four regions. Region I features an abrupt decline in redox potential (corresponding to the growth phase from lag and logarithmic to the onset of stationary phase) that correlates to rapid yeast propagation, resulting from fast glucose uptake. Region II (corresponding to the stationary phase in yeast growth, characterizes a constant level of redox potential) is maintained by proper sparging and constant agitation. The continual buildup of ethanol causes growth arrest of yeast, resulting in the reduction of net NADH production. As a result, an uprising of redox potential is the feature of Region III, which signifies the end of stationary phase followed by the commencement of death phase. The severity of growth environment due to ethanol toxicity results in a rapid decrease in yeast population. Region IV (corresponding to the death phase during yeast growth) characterizes a drastic reduction in yeast viability and a gradual leveling of redox potential. A low glucose feed correlates to a fast decline of redox potential, a small basin in the bathtub curve, short fermentation duration, and complete glucose utilization. Imposing the current redox potential settings to low glucose feeds exerts no appreciable effect on ethanol production. In contrast, a high glucose feed connects to a sluggish bathtub curve for all four regions and incomplete glucose utilization. Proximate analysis on carbon balance indicates that controlling redox potential at −150 mV and under ca. 250 and 300 g glucose/l conditions, gave the highest fermentation efficiency as compared to other conditions; but there were no beneficiary effect to control redox potential under ca. 200 g glucose/l conditions.     

Alkaliphilus serpentinus sp. nov. and Alkaliphilus pronyensis sp. nov., two novel anaerobic alkaliphilic species isolated from the serpentinite-hosted Prony Bay Hydrothermal Field (New Caledonia)

Two novel anaerobic alkaliphilic strains, designated as LacT^T and LacV^T, were isolated from the Prony Bay Hydrothermal Field (PBHF, New Caledonia). Cells were motile, Gram-positive, terminal endospore-forming rods, displaying a straight to curved morphology during the exponential phase. Strains LacT^T and LacV^T were mesophilic (optimum 30 °C), moderately alkaliphilic (optimum pH 8.2 and 8.7, respectively) and halotolerant (optimum 2% and 2.5% NaCl, respectively). Both strains were able to ferment yeast extract, peptone and casamino acids, but only strain LacT^T could use sugars (glucose, maltose and sucrose). Both strains disproportionated crotonate into acetate and butyrate. Phylogenetic analysis revealed that strains LacT^T and LacV^T shared 96.4% 16S rRNA gene sequence identity and were most closely related to A. peptidifermentans Z-7036, A. namsaraevii X-07-2 and A. hydrothermalis FatMR1 (95.7%–96.3%). Their genome size was of 3.29 Mb for strain LacT^T and 3.06 Mb for strain LacV^T with a G + C content of 36.0 and 33.9 mol%, respectively. The ANI value between both strains was 73.2 %. Finally, strains LacT^T (=DSM 100337 = JCM 30643) and LacV^T (=DSM 100017 = JCM 30644) are proposed as two novel species of the genus Alkaliphilus, order Clostridiales, phylum Firmicutes, Alkaliphilus serpentinus sp. nov. and Alkaliphilus pronyensis sp. nov., respectively. The genomes of the three Alkaliphilus species isolated from PBHF were consistently detected in the PBHF chimney metagenomes, although at very low abundance, but not significantly in the metagenomes of other serpentinizing systems (marine or terrestrial) worldwide, suggesting they represent indigenous members of the PBHF microbial ecosystem.     

Characterization of inducible cold-active β-glucosidases from the psychrotolerant bacterium Shewanella sp. G5 isolated from a sub-Antarctic ecosystem

The psychrotolerant bacterium Shewanella sp. G5 was used to study differential protein expression on glucose and cellobiose as carbon sources in cold-adapted conditions. This strain was able to growth at 4 °C, but reached the maximal specific growth rate at 37 °C, exhibiting similar growing rates values with glucose (μ: 0.4 h⁻¹) and cellobiose (μ: 0.48 h⁻¹). However, it grew at 15 °C approximately in 30 h, with specific growing rates of 0.25 and 0.19 h⁻¹ for cellobiose and glucose, respectively. Thus, this temperature was used to provide conditions related to the environment where the organism was originally isolated, the intestinal content of Munida subrrugosa in the Beagle Channel, Fire Land, Argentina. Cellobiose was reported as a carbon source more frequently available in marine environments close to shore, and its degradation requires the enzyme β-glucosidase. Therefore, this enzymatic activity was used as a marker of cellobiose catabolism. Zymogram analysis showed the presence of cold-adapted β-glucosidase activity bands in the cell wall as well as in the cytoplasm cell fractions. Two-dimensional gel electrophoresis of the whole protein pattern of Shewanella sp. G5 revealed 59 and 55 different spots induced by cellobiose and glucose, respectively. Identification of the quantitatively more relevant proteins suggested that different master regulation schemes are involved in response to glucose and cellobiose carbon sources. Both, physiological and proteomic analyses could show that Shewanella sp. G5 re-organizes its metabolism in response to low temperature (15 °C) with significant differences in the presence of these two carbon sources.     

Metabolic engineering of Saccharomyces cerevisiae for the biotechnological production of succinic acid

The production of bio-based succinic acid is receiving great attention, and several predominantly prokaryotic organisms have been evaluated for this purpose. In this study we report on the suitability of the highly acid- and osmotolerant yeast Saccharomyces cerevisiae as a succinic acid production host. We implemented a metabolic engineering strategy for the oxidative production of succinic acid in yeast by deletion of the genes SDH1, SDH2, IDH1 and IDP1. The engineered strains harbor a TCA cycle that is completely interrupted after the intermediates isocitrate and succinate. The strains show no serious growth constraints on glucose. In glucose-grown shake flask cultures, the quadruple deletion strain Δsdh1Δsdh2Δidh1Δidp1 produces succinic acid at a titer of 3.62 g L^?1 (factor 4.8 compared to wild-type) at a yield of 0.11 mol (mol glucose)^?1. Succinic acid is not accumulated intracellularly. This makes the yeast S. cerevisiae a suitable and promising candidate for the biotechnological production of succinic acid on an industrial scale.     

Alkaline lipase from a novel strain Burkholderia multivorans: Statistical medium optimization and production in a bioreactor

An alkaline lipase from Burkholderia multivorans was produced within 15 h of growth in a 14 L bioreactor. An overall 12-fold enhanced production (58 U mL⁻¹ and 36 U mg⁻¹ protein) was achieved after medium optimization following the “one-variable-at-a-time” and the statistical approaches. The optimal composition of the lipase production medium was determined to be (% w/v or v/v): KH₂PO₄ 0.1; K₂HPO₄ 0.3; NH₄Cl 0.5; MgSO₄·7H₂O 0.01; yeast extract 0.36; glucose 0.1; olive oil 3.0; CaCl₂ 0.4 mM; pH 7.0; inoculum density 3% (v/v) and incubation time 36 h in shake flasks. Lipase production was maximally influenced by olive oil/oleic acid as the inducer and yeast extract as the additive nitrogen. Plackett–Burman screening suggested catabolite repression by glucose. Amongst the divalent cations, Ca²⁺ was a positive signal while Mg²⁺ was a negative signal for lipase production. RSM predicted that incubation time, inoculum density and oil were required at their higher levels (36 h, 3% (v/v) and 3% (v/v), respectively) while glucose and yeast extract were required at their minimal levels for maximum lipase production in shake flasks. The production conditions were validated in a 14 L bioreactor where the incubation time was reduced to 15 h.     

Biological hydrogen production from CO: Bioreactor performance

This paper presents an alternative solution to the current problem faced by the world; diminishing of fossil fuel. Bioconversion of synthesis gas to hydrogen as clean fuel was catalyzed by a photosynthetic bacterium, Rhodospirillum rubrum. The clean fuel production was biologically mediated by the water–gas shift reaction in a 2 l bioreactor. The work performed was on agitation effects on hydrogen production, K_La and power consumption. The results show that 500 rpm was the suitable agitation rate to be employed. The hydrogen production was optimized at 0.44 ± 0.023 atm giving a K_La of 86.4 ± 3.5 h⁻¹. The production rate was 9.6 mmol H₂/h. The maximum light conversion efficiency at agitation speed of 800 rpm, light intensity of 500 lux (732 kW/m²) and 4 g/l inlet acetate concentration was about 10.84 ± 1.73%. At this condition, the maximum CO conversion efficiency was found to be 81 ± 5.6%. The ratio of power per volume was calculated to be 322.30 ± 12.14 kW/m³ and foaming problem was successfully avoided. The corresponding power consumption was estimated to be about 0.64 ± 0.03 kW, while the output hydrogen energy was determined to be 643.2 ± 26 kW. A prolonged operation of continuous hydrogen production employing a microsparger showed stable behaviour for a duration of 27 days.     

Synthesis of polypyrrole within the cell wall of yeast by redox-cycling of [Fe(CN)6]3−/[Fe(CN)6]4−

Yeast cells are often used as a model system in various experiments. Moreover, due to their high metabolic activity, yeast cells have a potential to be applied as elements in the design of biofuel cells and biosensors. However a wider application of yeast cells in electrochemical systems is limited due to high electric resistance of their cell wall. In order to reduce this problem we have polymerized conducting polymer polypyrrole (Ppy) directly in the cell wall and/or within periplasmic membrane. In this research the formation of Ppy was induced by [Fe(CN)₆]³⁻ions, which were generated from K₄[Fe(CN)₆], which was initially added to polymerization solution. The redox process was catalyzed by oxido-reductases, which are present in the plasma membrane of yeast cells. The formation of Ppy was confirmed by spectrophotometry and atomic force microscopy. It was confirmed that the conducting polymer polypyrrole was formed within periplasmic space and/or within the cell wall of yeast cells, which were incubated in solution containing pyrrole, glucose and [Fe(CN)₆]⁴⁻. After 24 h drying at room temperature we have observed that Ppy-modified yeast cell walls retained their initial spherical form. In contrast to Ppy-modified cells, the walls of unmodified yeast have wrinkled after 24 h drying. The viability of yeast cells in the presence of different pyrrole concentrations has been evaluated.     

β-carotene production from soap stock by loofa-immobilized Rhodotorula rubra in an airlift photobioreactor

In this study, the soap stock as a sole carbon source was used for growing a carotenoid producing yeast (Rhodotorula rubra). The application of soap stock resulted in increase of carotenoids yield up to 5.36 folds when compared with the grown cultures on glucose. On the best Monod equation fitted on the specific growth rate (μ) data, the maximum specific growth rate (μ_m) and half-saturation concentration (K_S) were respectively determined at 0.064 h⁻¹ and 3.26 g L⁻¹ for total fatty acids presented in soap stock. Further tests on the carotenogenesis process were carried out in a cell-immobilized airlift photobioreactor where the natural loofa sponge was used for immobilization of the cells. The performance of the bioreactor was statistically studied by the response surface methodology (RSM) where aeration rate of 0.11 vvm and light irradiation intensity of 2517 Lx provided an optimum condition for producing β-carotene with a specific production rate of 22.65 mg g_cell⁻¹ day⁻¹.     

2,3-Butanediol production using Klebsiella oxytoca ATCC 8724: Evaluation of biomass derived sugars and fed-batch fermentation process

For this study, 2,3-butanediol (BD) fermentation from pure and biomass-derived sugar were optimized in shake-flask and 5-L bioreactor levels using Klebsiella oxytoca ATCC 8724. The results showed that 70 g/L of single sugar (glucose or xylose) and 90 g/L of mixed-sugar (glucose:xylose = 2:1) were optimum concentrations for efficient 2,3-BD fermentation. At optimum sugar concentrations, 2,3-BD productivities were 1.03, 0.64 and 0.50 gL⁻¹ h⁻¹, and yields were 0.43, 0.36 and 0.35 g/g in glucose, xylose and mixed-sugar medium, respectively. The lack of simultaneous utilization of glucose and xylose led to the lowest productivity in the mixed-sugar medium. Detoxification of biomass hydrolyzates was necessary for efficient 2,3-BD fermentation when sugar concentrations in the medium was 90 g/L or higher, but not with sugar concentrations of 30 g/L or less. A fed-batch fermentation using glucose medium led to an increase 2,3-BD titer to 79.4 g/L and yields 0.47 g/g, while productivity decreased to 0.79 gL⁻¹ h⁻¹. However, the fed-batch process was inefficient using mixed-sugar and biomass hydrolyzates because of poor xylose utilization. These results indicated that appropriate biomass processing technologies must be developed to generate separate glucose and xylose streams to produce high 2,3-BD titer from biomass-derived sugar using a fed-batch process.