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1.
Protocorm cultures of Dendrobium candidum were established in balloon type bubble bioreactors using Murashige and Skoog (MS) medium with 0.5 mg l−1 α-naphthaleneacetic acid (NAA), 2.5% (w/v) sucrose, 5:25 mM NH4:NO3 and 1% (v/v) banana homogenate for the production of biomass and bioactive compounds. In 3 l bioreactor containing 2 l medium, a maximum protocorm biomass (21.0 g l−1 dry biomass) and also optimum quantities of total polysaccharides (389.3 mg g−1 DW), coumarins (18.0 mg g−1 DW), polyphenolics (11.9 mg g−1 DW), and flavonoids (4.5 mg g−1 DW) were achieved after 7 weeks of culture. Based on these studies, 5 and 10 l bioreactor cultures were established to harvest 80 g and 160 g dry biomass. In 10 l bioreactors, the protocorms grown were accumulated with optimal levels of polysaccharides (424.1 mg g−1 DW), coumarins (15.8 mg g−1 DW), polyphenols (9.03 mg g−1 DW) and flavonoids (4.7 mg g−1 DW). The bioreactor technology developed here will be useful for the production of important bioactive compounds from D. candidum.  相似文献   

2.
A low-cost lipase preparation is required for enzymatic biodiesel synthesis. One possibility is to produce the lipase in solid-state fermentation (SSF) and then add the fermented solids (FS) directly to the reaction medium for biodiesel synthesis. In the current work, we scaled up the production of FS containing the lipases of Rhizopus microsporus. Initial experiments in flasks led to a low-cost medium containing wheat bran and sugarcane bagasse (50:50 w/w, dry basis), supplemented only with urea. We used this medium to scale-up production of FS, from 10 g in a laboratory column bioreactor to 15 kg in a pilot packed-bed bioreactor. This is the largest scale yet reported for lipase production in SSF. During scale-up, the hydrolytic activity of the FS decreased 57%: from 265 U g−1 at 18 h in the laboratory bioreactor to 113 U g−1 at 20 h in the pilot bioreactor. However, the esterification activity decreased by only 14%: from 12.1 U g−1 to 10.4 U g−1. When the FS produced in the laboratory and pilot bioreactors were dried and added directly to a solvent-free reaction medium to catalyze the esterification of oleic acid with ethanol, both gave the same ester content, 69% in 48 h.  相似文献   

3.
This work was aimed at optimizing biomass production by the edible basidiomycete Pleurotus ostreatus ATHUM 4438 in a submerged process with enhanced glucan and dietary fibres content. β-Glucan from Pleurotus sp. (pleuran) has been used as food supplements due to its immunosuppressive activity. Like other dietary fibre components, oyster mushroom polysaccharides can stimulate the growth of colon microorganisms (probiotics), i.e. act as prebiotics. We used the FF MicroPlate for substrate utilization and growth monitoring. The pattern of substrate catabolism forms a substrate assimilation fingerprint which is useful in selecting media components for media optimization of maximum biomass production. Different carbon sources (95) were used and then 8 of them were tested in shake flask cultures. The effect of various organic and complex nitrogen sources on biomass production was also examined and response surface methodology based on central composite design was applied to explore the optimal medium composition. When the optimized culture medium was tested in a 20-L stirred tank bioreactor, using 57 g L−1 xylose and 37 g L−1 corn steep liquor, high yields (39.2 g L−1) of dry biomass was obtained. The yield coefficients for total glucan and dietary fibres on mycelial biomass formed were 140 ± 4 and 625 ± 9 mg g−1 mycelium dry weight, respectively.  相似文献   

4.
The extensive prospects of violacein in the pharmaceutical industry have attracted increasing interest. However, the fermentation levels of violacein are currently inadequate to meet the demands of industrial production. This study was undertaken to develop an efficient process for the production of violacein by recombinant Citrobacter freundii. The effects of dissolved oxygen (DO) and pH on cell growth and violacein production in batch cultures were investigated first. When the DO and pH of the medium were controlled at around 25% and 7.0, respectively, the biomass and concentration of violacein were maximized. Based on the consumption of nutrients in the medium observed during batch culture, a fed-batch fermentation strategy with controlled DO and pH was implemented. By continuously feeding glycerol, NH4Cl, and l-tryptophan at a constant feeding rate of 16 mL h−1, the final concentration of violacein reached 4.13 g L−1, which was 4.09-fold higher than the corresponding batch culture, and the maximal dry cell weight (DCW) and average violacein productivity obtained for the fed-batch culture were 3.34 g DCW L−1 and 82.6 mg L−1 h−1, respectively. To date, this is the first report on the efficient production of violacein by genetically engineered strains in a fermentor.  相似文献   

5.
Continuous anaerobic fermentations were performed in a novel external-recycle, biofilm reactor using d-glucose and CO2 as carbon substrates. Succinic acid (SA) yields were found to be an increasing function of glucose consumption with the succinic acid to acetic acid ratio increasing from 2.4 g g−1 at a glucose consumption of 10 g L−1, to 5.7 g g−1 at a glucose consumption of 50 g L−1. The formic acid to acetic acid ratio decreased from an equimolar value (0.77 g g−1) at a glucose consumption of 10 g L−1 to a value close to zero at 50 g L−1. The highest SA yield on glucose and highest SA titre obtained were 0.91 g g−1 and 48.5 g L−1 respectively. Metabolic flux analysis based on the established C3 and C4 metabolic pathways of Actinobacillus succinogenes revealed that the increase in the succinate to acetate ratio could not be attributed to the decrease in formic acid and that an additional source of NADH was present. The fraction of unaccounted NADH increased with glucose consumption, suggesting that additional reducing power is present in the medium or is provided by the activation of an alternative metabolic pathway.  相似文献   

6.
The aim of this study was to develop a bioprocess for l- and d-lactic acid production from raw sweet potato through simultaneous saccharification and fermentation by Lactobacillus paracasei and Lactobacillus coryniformis, respectively. The effects of enzyme and nitrogen source concentrations as well as of the ratio of raw material to medium were investigated. At dried material concentrations of 136.36–219.51 g L−1, yields of 90.13–91.17% (w/w) and productivities of 3.41–3.83 g L−1 h−1 were obtained with lactic acid concentrations as high as 198.32 g L−1 for l-lactic acid production. In addition, d-lactic acid was produced with yields of 90.11–84.92% (w/w) and productivities of 2.55–3.11 g L−1 h−1 with a maximum concentration of 186.40 g L−1 at the same concentrations of dried material. The simple and efficient process described in this study will benefit the tuber and root-based lactic acid industries without requiring alterations in plant equipment.  相似文献   

7.
Conidiation and lytic enzyme production by Trichoderma viride at different solids concentration of pre-treated municipal wastewater sludge was examined in a 15-L fermenter. The maximum conidia concentration (5.94 × 107 CFU mL−1 at 96 h) was obtained at 30 g L−1 suspended solids. The maximum lytic enzyme activities were achieved around 12–30 h of fermentation. Bioassay against a fungal phytopathogen, Fusarium sp. showed maximum activity in the sample drawn around 96 h of fermentation at 30 g L−1 suspended solids concentration. Entomotoxicity against spruce budworm larvae showed maximum value ≈17290 SBU μL−1 at 30 g L−1 suspended solids concentration at the end of fermentation (96 h). Plant bioassay showed dual action of T. viride, i.e., disease prevention and growth promotion. The rheological analyses of fermentation sludges showed the pseudoplastic behaviour. In order to maintain required dissolved oxygen concentration ≥30%, the agitation and aeration requirements significantly increased at 35 g L−1 compared to 30 and 25 g L−1. The oxygen uptake rate and volumetric oxygen mass transfer coefficient, kLa at 35 g L−1 did not increase in comparison to 30 g L−1 due to rheological complexity of the broth during fermentation. Thus, the successful fermentation operation of the biocontrol fungus T. viride is a rational indication of its potential for mass-scale production for agriculture and forest sector as a biocontrol agent.  相似文献   

8.
《Process Biochemistry》2007,42(4):740-744
The conversion of glycerol to 1,3-propanediol (PDO) using Klebsiella pneumoniae M5al under anaerobic condition was scaled up from scale 5 to 5000 l in series. A simple strategy for scale-up was to transfer the optimized conditions of a lab scale bioreactor to pilot-scale fermentation. Multistage inocula were developed and their fermentation abilities were assessed in a small-scale fermenter. The experimental results showed that inoculum development in the early steps of a scale-up process could influence the outcomes of a large scale fermentation. Through three-stage liquid inoculum development and a pulse addition of (NH4)2SO4 and yeast extract at 30 h of fermentation, the best results in a 5000 l fermentation were achieved leading to 58.8 g l−1 1,3-propanediol with a yield of 0.53 mol mol−1 glycerol and productivity of 0.92 g l−1 h−1. This is the first report on pilot-scale 1,3-propanediol production using K. pneumoniae.  相似文献   

9.
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 (μm) and half-saturation concentration (KS) 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 gcell−1 day−1.  相似文献   

10.
《Process Biochemistry》2010,45(11):1779-1786
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 kLa, 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.  相似文献   

11.
《Process Biochemistry》2014,49(10):1595-1600
Ellagic acid is a high-value bioactive compound that is used in the food, cosmetic and pharmaceutical industries. The aim of this work was to develop a continuous system for ellagic acid production. Ellagitannase produced by solid-state fermentation and attached to polyurethane foam particles was used as a biocatalyst in a continuous bioreactor for the hydrolysis of ellagitannins from pomegranate by-product. A packed-bed reactor containing the biocatalyst (22.22 Units per gram of dry solid, U gds−1) was fed with a pomegranate ellagitannins solution (0.1%, w/v) at a flow rate of 0.27 mL min−1 at 60 °C. The bioreactor completed several biotransformations while maintaining the hydrolysis rate (60%) with a half-life of 10 continuous cycles of ellagic acid production. Volumetric productivity and ellagic acid yield were 1.09 g L−1 h−1 and 235.89 mg g−1 of pomegranate ellagitannins during the first 70 min of hydrolysis, respectively. The developed biocatalyst showed good operational and mechanical stability and may be successfully used for ellagitannin hydrolysis in a continuous system. This is the first report of high-yield continuous production of ellagic acid using an auto-immobilized enzyme.  相似文献   

12.
Simultaneous saccharification and fermentation (SSF) of renewable cellulose for the production of 3-phenyllactic acid (PhLA) by recombinant Escherichia coli was investigated. Kraft pulp recovered from biomass fractionation processes was used as a model cellulosic feedstock and was hydrolyzed using 10–50 filter paper unit (FPU) g−1 kraft pulp of a commercial cellulase mixture, which increased the glucose yield from 21% to 72% in an enzyme dose-dependent manner. PhLA fermentation of the hydrolyzed kraft pulp by a recombinant E. coli strain expressing phenylpyruvate reductase from Wickerhamia fluorescens TK1 produced 1.9 mM PhLA. The PhLA yield obtained using separate hydrolysis and fermentation was enhanced from 5.8% to 42% by process integration into SSF of kraft pulp (20 g L−1) in a complex medium (pH 7.0) at 37 °C. The PhLA yield was negatively correlated with the initial glucose concentration, with a five-fold higher PhLA yield observed in culture medium containing 10 g L−1 glucose compared to 100 g L−1. Taken together, these results suggest that the PhLA yield from cellulose in kraft pulp can be improved by SSF under glucose-limited conditions.  相似文献   

13.
The solubilization and acidification of waste activated sludge (WAS) were apparently enhanced by external rhamnolipid (RL) addition. The maximum solute carbohydrate concentrations increased linearly from 48 ± 5 mg COD L−1 in the un-pretreated WAS (blank) to 566 ± 19 mg COD L−1, and protein increased from 1050 ± 8 to 3493 ± 16 mg COD L−1 at RL dosage of 0.10 g g−1 TSS. The highest VFAs concentration peaked at 3840 mg COD L−1 at RL dosage of 0.04 g g−1 TSS, which was 4.24-fold higher than the blank test. RL was generated in situ during WAS fermentation when external RL was added. It was detected that RL concentration was increased from initial 880 ± 92 mg L−1 to 1312 ± 7 mg L−1 at the end of 96 h with RL dosage of 0.04 g g−1 TSS, which was increased to 1.49-fold. Meanwhile, methane production was notably reduced to a quite low level of 2.0 mL CH4 g−1 VSS, showing effective inhibition of methanogens by RL (58.8 mL CH4 g−1 VSS in the blank). In addition, the activity of hydrolytic enzymes (protease and α-glucosidase) was enhanced accordingly. VFAs accumulation and RL generation in situ demonstrated that the additional RL substantially performed enhanced biological effects for waste activated sludge fermentation.  相似文献   

14.
α-Glucuronidase (EC 3.2.1.139) of family GH 115 from Scheffersomyces stipitis is a valuable enzyme for the modification of water-soluble xylan into insoluble biopolymers, due to its unique ability to act on polymeric xylans. The influence of growth rate on the production of α-glucuronidase by recombinant Saccharomyces cerevisiae MH1000pbk10D-glu in glucose-limited fed-batch culture was studied at 14 and 100 L scale. At and below the critical specific growth rate (μcrit) of 0.12 h−1 at 14 L scale, the biomass yield coefficient (Yx/s) remained constant at 0.4 g g−1 with no ethanol production, whereas ethanol yields relative to biomass (keth/x) of up to 0.54 g g−1 and a steady decrease in Yx/s were observed at μ > 0.12 h−1. Production of α-glucuronidase was growth associated at a product yield (kα-glu/x) of 0.45 mg g−1, with the highest biomass (37.35 g/L) and α-glucuronidase (14.03 mg/L) concentrations, were recorded during fed-batch culture at or near to μcrit. Scale-up with constant kLa from 14 to 100 L resulted in ethanol concentrations of up to 2.5 g/L at μ = 0.12 h−1. At this scale, α-glucuronidase yield could be maximised at growth rates below μcrit, to prevent localised high glucose concentration pockets at the feed entry zone that would induce oxido-reductive metabolism. This is the first report where recombinant production of α-glucuronidase (EC 3.2.1.139) by S. cerevisiae was optimised for application at pilot scale.  相似文献   

15.
In wild-type Escherichia coli, 1 mol of CO2 was fixated in 1 mol of succinic acid generation anaerobically. The key reaction in this sequence, catalyzed by phosphoenolpyruvate carboxylase (PPC), is carboxylation of phosphoenolpyruvate to oxaloacetate. Although inactivation of pyruvate formate-lyase and lactate dehydrogenase is found to enhance the PPC pathway for succinic acid production, it results in excessive pyruvic acid accumulation and limits regeneration of NAD+ from NADH formed in glycolysis. In other organisms, oxaloacetate is synthesized by carboxylation of pyruvic acid by pyruvate carboxylase (PYC) during glucose metabolism, and in E. coli, nicotinic acid phosphoribosyltransferase (NAPRTase) is a rate-limiting enzyme of the NAD(H) synthesis system. To achieve the NADH/NAD+ ratio decrease as well as carbon flux redistribution, co-expression of NAPRTase and PYC in a pflB, ldhA, and ppc deletion strain resulted in a significant increase in cell mass and succinic acid production under anaerobic conditions. After 72 h, 14.5 g L−1 of glucose was consumed to generate 12.08 g L−1 of succinic acid. Furthermore, under optimized condition of CO2 supply, the succinic acid productivity and the CO2 fixation rate reached 223.88 mg L−1 h−1 and 83.48 mg L−1 h−1, respectively.  相似文献   

16.
Brazilian filamentous fungi Rhizopus sp. (SIS-31), Aspergillus sp. (SIS-18) and Penicillium sp. (SIS-21), sources of oxidases were isolated from Caatinga's soils and applied during the in situ cathodic oxygen reduction in fuel cells. All strains were cultivated in submerged cultures using an optimized saline medium enriched with 10 g L−1 of glucose, 3.0 g L−1 of peptone and 0.0005 g L−1 of CuSO4 as enzyme inducer. Parameters of oxidase activity, glucose consumption and microbial growth were evaluated. In-cell experiments evaluated by chronoamperometry were performed and two different electrode compositions were also compared. Maximum current densities of 125.7, 98.7 and 11.5 μA cm−2 were observed before 24 h and coulombic efficiencies of 56.5, 46.5 and 23.8% were obtained for SIS-31, SIS-21 and SIS-18, respectively. Conversely, maximum power outputs of 328.73, 288.80 and 197.77 mW m−3 were observed for SIS-18, SIS-21 and SIS-31, respectively. This work provides the primary experimental evidences that fungi isolated from the Caatinga region in Brazil can serve as efficient biocatalysts during the oxygen reduction in air-cathodes to improve electricity generation in MFCs.  相似文献   

17.
《Process Biochemistry》2007,42(6):1033-1038
Valienamine is an important medicinal intermediate with broad use in the synthesis of some stronger α-glucosidase inhibitors. In order to improve valienamine concentration in the fermentation broth and make the downstream treatment easy, a fed-batch process for the enhanced production of valienamine by Stenotrophomonas maltrophilia in a stirred tank bioreactor was developed. Results showed that supplementation of validamycin A in the process of cultivation could increase the valienamine concentration. One-pulse feeding was observed to be the best strategy. The maximum valienamine concentration of 2.35 g L−1 was obtained at 156 h when 86.4 g of validamycin A was added to a 15-L bioreactor containing 8 L fermentation medium with one-pulse feeding. The maximum valienamine concentration had a great improvement and was increased above 100% compared to batch fermentation in the stirred tank bioreactor. The pH-controlled experiments showed that controlling the pH in the process of one-pulse feeding fermentation had not obvious effect on the production of valienamine.  相似文献   

18.
Fermentations were performed in an external recycle bioreactor using CO2 and d-glucose at feed concentrations of 20 and 40 g L−1. Severe biofilm formation prevented kinetic analysis of suspended cell (‘chemostat’) fermentation, while perlite packing enhanced the volumetric productivity by increasing the amount of immobilised cells. The highest productivity of 6.35 g L−1 h−1 was achieved at a dilution rate of 0.56 h−1. A constant succinic acid yield of 0.69 ± 0.02 g/(g of glucose consumed) was obtained and found to be independent of the dilution rate, transient state and extent of biofilm build-up – approximately 56% of the carbon that formed phosphoenolpyruvate ended up as succinate. Byproduct analysis indicated that pyruvate oxidation proceeded solely via the formate-lyase pathway. Cell growth and corresponding biofilm formation were rapid at dilution rates higher than 0.35 h−1 when the product concentrations were low (succinic acid < 10 g L−1), while minimal growth was observed at succinic acid concentrations above this threshold.  相似文献   

19.
Low-molecular-weight hyaluronan (LMW-HA) has attracted much attention because of its many potential applications. Here, we efficiently produced specific LMW-HAs from sucrose in Bacillus subtilis. By coexpressing the identified committed genes (tuaD, gtaB, glmU, glmM, and glmS) and downregulating the glycolytic pathway, HA production was significantly increased from 1.01 g L−1 to 3.16 g L−1, with a molecular weight range of 1.40×106–1.83×106 Da. When leech hyaluronidase was actively expressed after N-terminal engineering (1.62×106 U mL−1), the production of HA was substantially increased from 5.96 g L−1 to 19.38 g L−1. The level of hyaluronidase was rationally regulated with a ribosome-binding site engineering strategy, allowing the production of LMW-HAs with a molecular weight range of 2.20×103–1.42×106 Da. Our results confirm that this strategy for the controllable expression of hyaluronidase, together with the optimization of the HA synthetic pathway, effectively produces specific LMW-HAs, and could also be used to produce other LMW polysaccharides.  相似文献   

20.
《Process Biochemistry》2014,49(10):1606-1611
The filamentous fungus Paecilomyces lilacinus was grown on n-hexadecane in submerged (SmC) and solid-state (SSC) cultures. The maximum CO2 production rate in SmC (Vmax = 11.7 mg CO2 Lg−1 day−1) was three times lower than in SSC (Vmax = 40.4 mg CO2 Lg−1 day−1). The P. lilacinus hydrophobin (PLHYD) yield from the SSC was 1.3 mg PLHYD g protein−1, but in SmC, this protein was not detected. The PLHYD showed a critical micelle concentration of 0.45 mg mL−1. In addition, the PLHYD modified the hydrophobicity of Teflon from 130.1 ± 2° to 47 ± 2°, forming porous structures with some filaments <1 μm and globular aggregates <0.25 μm diameter. The interfacial studies of this PLHYD could be the basis for the use of the protein to modify surfaces and to stabilize compounds in emulsions.  相似文献   

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