Optimal Glucose Concentration Research Articles

Characterization of starch degradation during simple heating for bioethanol production from the avocado seed

We have successfully identified starch degradation with the presence of glucose from the avocado seed powder by simple heating method. This work was done by varying the composition of the avocado seed powder to obtain the effect of weight fraction increase in improving the concentration of glucose. From the Luff Schoorl test method, we found that the optimal glucose concentrations reached up to 14.86% that was produced from 80 g of the avocado seed powder. Furthermore, SEM showed the crystalline structure of glucose content and swelling of granules after heat treatment. FTIR spectra also indicated the presence of glucose at 1079.6 cm−1 (C-O-H bending) and 1412.38 cm−1 (CH2 bending modes).

Enhancement of Monascus pigment productivity via a simultaneous fermentation process and separation system using immobilized-cell fermentation

A mutant Monascus purpureus strain, M183, which produced monascus pigments (MPs) at 8460 U/g via solid-state batch-fermentation, was generated using the atmospheric and room temperature plasma (ARTP) mutation system. The optimal glucose concentration (80 g/L) in traditional fermentation media that yielded the highest MPs productivity was determined. Response surface methodology (RSM) was applied to maximize MPs production using liquid-state batch-fermentation. Under optimal conditions (0.58 g/L MgSO4·7H2O, 0.02 g/L ZnSO4·7H2O, 0.02 g/L FeSO4·7H2O and 4.85 g/L NH4NO3), 207.67 U/mL of MPs were produced with 98.12% validity based on the predicted value. Extracellular MPs production increased significantly to 35.52 U/mL, compared to 14.19 U/mL of the original strain, M. purpureus LQ-6. M. purpureus spores immobilized in sodium alginate were studied. A simultaneous fermentation and separation system was established for MPs using the novel absorption resin LX300C to enhance production efficiency of extracellular MPs.

Medium Optimization for Antimicrobial Production By Newly Screened Lactic Acid Bacteria

Lactic acid bacteria (LAB) are important for prevention of spoilage and pathogenic bacterial growth in foods due to their ability to generate antimicrobial substances. The objective of this study was to screen LAB for antimicrobial activity and to optimize culture medium for antimicrobial production using Response Surface Methodology (RSM) with Central Composite Design (CCD). Optimization of antimicrobial production of selected LAB was conducted with different combinations of glucose, NaCl, inoculum, and temperature. Our experimental results showed that from 129 LAB isolates, 55 showed significant inhibition against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, Aspergillus niger, and Candida albicans. No isolates inhibited the growth of Aspergillus flavus. Lactobacillus plantarum LIPI13-2-LAB011 was selected for further study on culture medium optimization to inhibit the growth of C. albicans. From statistical analysis, the production of antimicrobial substances was significantly influenced by temperature, NaCl, and concentration of glucose. Furthermore, the optimum concentrations of glucose, concentration of inoculum, temperature, and NaCl were 1.63 %, 3.03%, 33.74°C, and 3.4%, respectively, with a maximum predicted inhibition index of 1.916, which increased 3.56-fold compared to that obtained in medium before optimization processes. The result was confirmed as when the optimum concentration of nutritions used, the inhibition index increased 3.12-fold.

Comparative analysis of sperm freezability of sex-reversed female brook trout and sex-reversed female rainbow trout semen

The aim of our study was to compare quality of fresh and cryopreserved semen of sex-reversed female rainbow trout and sex-reversed female brook trout. The effect of different final sperm concentrations in straws with a constant extender concentration and final glucose concentration on the sperm motility parameters of cryopreserved semen was tested. Furthermore, we examined the effect of post-thaw storage time on sperm motility parameters at optimal sperm and glucose concentrations. The effects of semen cryopreservation from sex-reversed female rainbow trout and sex-reversed female brook trout on sperm fertilizing ability at the sperm-to-egg ratios 500,000:1 and 1,000,000:1 after 0 and 60 min of post-thaw storage of semen were investigated. We have demonstrated that final sperm concentrations in straws as well as final glucose concentrations in extended semen influenced post-thaw sperm motility parameters in both species. The high post-thaw sperm motility was recorded for sperm concentrations within the range of 1.0–4.0 × 109 spermatozoa ml−1 for both species. Furthermore, the glucose concentration appeared to be very important for cryopreservation success and its effect was species-specific. The final glucose concentrations of 0.15 M and 0.19 M, for sex-reversed female rainbow trout and sex-reversed female brook trout, respectively, produced the highest results for sperm motility after cryopreservation. The post-thaw sperm motility was unaffected by 60 and 360 min after thawing for sex-reversed female rainbow trout and sex-reversed female brook trout, respectively. The fertilization rates of cryopreserved semen of sex-reversed female rainbow trout were high and did not differ between the investigated sperm:egg ratios after 0 and 60 min of post-thaw storage. However, fertilization rates of cryopreserved semen of sex-reversed females brook trout were lower and decreased after 60 min of post-thaw storage of semen at sperm: egg ratio 1,000,000:1. In conclusion, our results demonstrated differences in freezability between the semen of sex-reversed female rainbow trout and sex-reversed female brook trout. The semen of both species can be cryopreserved at the final sperm concentration of 3.0 × 109 spermatozoa ml−1. However, the influence of final glucose concentration on cryopreservation success, as well as the duration of post-thaw storage time and fertilization rates, are species-specific. In our opinion, standardizing the procedure of semen cryopreservation presented in this study is a prerequisite for the development of repeatable procedures and the future implementation of cryopreserved semen from sex-reversed females into hatchery practice.

Response surface optimization of bioethanol production from third generation feedstock - Eucheuma cottonii

Abstract Response Surface Methodology (RSM) based on Central Composite Design (CCD) was employed to optimize the conditions of enzymatic hydrolysis and fermentation of the seaweed Eucheuma cottonii. The significant influence of cellulose loading, enzyme loading and incubation time in enzymatic hydrolysis that has been screened by Plackett-Burman Design (PBD) was optimized using CCD. The optimum glucose concentration of 24.24 g/L (81% glucose yield) was obtained at 3% (v/v) of cellulose loading, 4% (v/v) of enzyme loading and 54 h incubation time. Subsequently, PBD analysis showed the significant effects of inoculum concentration, pH, temperature and time on fermentation process. Further optimization study by CCD revealed that 12% (v/v) of inoculum concentration, pH 5.2, 32 °C and 72 h of fermentation time enhanced the bioethanol production up to 9.77 g/L with the yield of 0.40 g/g and 78% conversion efficiency. Thus, the RSM based optimization of bioethanol from Eucheuma cottonii showed satisfactory results in this research. In short, it can be concluded that this optimization approach will serve as a good foundation for the realization of a consistent bioethanol production in the future.

Medium Optimization for Antimicrobial Production By Newly Screened Lactic Acid Bacteria

Lactic acid bacteria (LAB) are important for prevention of spoilage and pathogenic bacterial growth in foods due to their ability to generate antimicrobial substances. The objective of this study was to screen LAB for antimicrobial activity and to optimize culture medium for antimicrobial production using Response Surface Methodology (RSM) with Central Composite Design (CCD). Optimization of antimicrobial production of selected LAB was conducted with different combinations of glucose, NaCl, inoculum, and temperature. Our experimental results showed that from 129 LAB isolates, 55 showed significant inhibition against Bacillus subtilis, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, Aspergillus niger, and Candida albicans. No isolates inhibited the growth of Aspergillus flavus. Lactobacillus plantarum LIPI13-2-LAB011 was selected for further study on culture medium optimization to inhibit the growth of C. albicans. From statistical analysis, the production of antimicrobial substances was significantly influenced by temperature, NaCl, and concentration of glucose. Furthermore, the optimum concentrations of glucose, concentration of inoculum, temperature, and NaCl were 1.63 %, 3.03%, 33.74°C, and 3.4%, respectively, with a maximum predicted inhibition index of 1.916, which increased 3.56-fold compared to that obtained in medium before optimization processes. The result was confirmed as when the optimum concentration of nutritions used, the inhibition index increased 3.12-fold.

EXTRACELLULAR POLYMERIC SUBSTANCE (EPS) FROM KOCURIA SP. BRI 36: A KEY COMPONENT IN HEAVY METAL RESISTANCE

Objective: Evaluation of Extracellular Polymeric Substance (EPS) induced heavy metal tolerance in Kocuria sp. BRI 36.Methods: Initially, the effect of different concentrations of glucose (1-10 %) on EPS production by BRI 36 was examined. At optimum glucose concentrations, EPS levels were measured by varying heavy metal concentrations (10-50 ppm) of Pb2+, Cd 2+and Cr3+. Maximum tolerable concentration (MTC) and survival percentage of BRI 36 were determined under conditions that support EPS synthesis. Comparative analysis of extracted crude EPS was performed by Fourier Transform Infrared Spectroscopy (FTIR) to establish functional groups involved in the metal interaction. Results: Kocuriasp. BRI 36 produced maximum EPS (1g/l) at 5% glucose. Increase in EPS production up to 89% (considering 1g/l as 100%) with an increase in concentrations of heavy metals up to 40 ppm. MTC levels of BRI 36 for heavy metals increased up to 700 ppm when it was cultivated in presence of 5% glucose indicating a major role of surface polymer in metal adsorption. The function of EPS as a protective cover was also evident from an increase in survival percentage of BRI 36 up to 39.4 at MTC. Comparative analysis of extracted crude EPS by FTIR revealed the involvement of O-H, C=O, and C-O-C groups in metal adsorptionConclusion: Antarctic oceanic isolate Kocuria sp. BRI 36 has an ability to produced EPS under stress conditions of heavy metals. Simultaneously, its MTC values increased due to increase in EPS levels. These observations suggest the possibility to develop gentle, environmentally safe and cost-effective method for heavy metal removal.

High level production of laccases and peroxidases from the newly isolated white-rot basidiomycete Marasmiellus palmivorus VE111 in a stirred-tank bioreactor in response to different carbon and nitrogen sources

Abstract The present work was carried out to determine the best sources and concentrations of carbon and nitrogen in the production of laccases, total peroxidases and manganese peroxidase by Marasmiellus palmivorus VE111. Among the carbon and nitrogen sources used, the combination of glucose and casein led to higher production of laccases (5134 U/mL), total peroxidases (187 U/mL) and manganese peroxidase (57 U/mL). Central composite rotatable design (CCRD) was used to determine the optimum concentrations of glucose and casein to produce enzymes. The experiments with better results were scaled up in a 5 L bioreactor. It was verified that lower concentrations of glucose (5 and 10 g/L) stimulated higher activity of total peroxidases (1285 U/mL) and laccases (3420 U/mL), respectively, while a higher concentration of glucose (30 g/L) favoured the production of manganese peroxidase (59 U/mL). These data indicate high performance of M. palmivorus VE111 in the production of ligninolytic enzymes.

Chicken feather peptone: A new alternative nitrogen source for pigment production by Monascus purpureus

Peptones are accepted as one of the most favourable nitrogen sources supporting pigment synthesis in Monascus purpureus. The present study was performed to test the feasibility of chicken feather peptone (CFP) as nitrogen source for pigment production from M. purpureus ATCC16365. CFP was compared with fish peptone (FP) and protease peptone (PP) in order to elucidate its effectiveness on pigment production. CFP was prepared from waste feathers using hydrolysis (KOH) and neutralization (H2SO4) methods. The protein content of CFP was determined as 67.2 g/100 g. Optimal concentrations of CFP and glucose for pigment production were determined as 3 and 20 g/L, respectively. A medium pH of 5.5 and an incubation period of 7-days were found to be more favourable for pigment production. In CFP, PP and FP media, yellow pigment absorbances were 2.819, 2.870 and 2.831, red pigment absorbances were 2.709, 2.304 and 2.748, and orange pigment absorbances were 2.643, 2.132 and 2.743, respectively. Sugar consumption and mycelia growth showed the similar trends in CFP, FP and PP media. This study indicates that the peptone from chicken feathers may be a good nutritional substrate for pigment production from M. purpureus.

Application of weighted response surface methodology for enhanced poly (3-hydroxybutyrate) production by endophytic bacillus cereus RCL 02

Application of statistical models in developing strategies for process optimization and enhanced product yield is well established. The present study is focused to enhance poly (3-hydroxybutyrate) [P(3HB)] production by Bacillus cereus RCL 02, a leaf endophyte of oleaginous plant Ricinus communis L. using weighted response surface methodology (WRSM). The most influencing process variables for growth and bio-polyester accumulation were initially selected through Plackett-Burman (PB) designed experiments. Further, WRSM was applied to navigate the experimental data obtained in accordance with the central composite design (CCD). Interaction of three independent variables viz. carbon source (glucose), nitrogen source (yeast extract) and initial pH of the medium exerted most significant impact on biomass formation as well as P(3HB) production. A second order polynomial equation obtained from multiple regression analysis and the interaction studies from surface plots helped to determine the optimum concentrations of glucose (25g/L), yeast extract (4g/L) and initial pH (7.6). Validation of this statistical model was executed using point prediction tool of WRSM where-from the optimum values of all three significant variables were employed and experiments were conducted. Under such optimized conditions the endophytic isolate produced 8.07g/L of P(3HB), which was very close to the predicted value (7.80g/L) and thereby validated the model. Finally, the identity of the intracellularly accumulated bio-polyester of B. cereus RCL 02 was confirmed by proton nuclear magnetic resonance (1H NMR) spectroscopic analysis.

Combining engineering strategies and fermentation technology to enhance docosahexaenoic acid (DHA) production from an indigenous Thraustochytrium sp. BM2 strain

The DHA productivity of Thraustochytrium sp. BM2 was improved by optimizing the bioreactor operation conditions. The effects of agitation rate and aeration rate on the microalgal growth and DHA production were first studied in 5-L stirred-tank fermenter. The results showed that 100 rpm agitation and 1.2 vvm aeration (i.e., kLa = 27 ± 1.1 h−1) achieved the highest biomass (4590 mg/L/d) and DHA (379 mg/L/d) productivities. Next, using an optimal glucose concentration (60 g/L) led to the highest biomass (5580 mg/L/d) and DHA (457 mg/L/d) productivities. The cellular DHA content decreased when increasing the agitation rate, probably due to the sensitivity of this strain to the shear stress. The effect of pneumatic and mechanical agitation under the same kLa was studied with two different types of fermenters (stirred-tank and air-lift) and cultivation in air-lift fermenter resulted in better biomass production (27.57 g/L), cellular DHA content (13.1%) and DHA productivity (610 mg/L/d).

Medium optimization for ε-poly-L-lysine production by Streptomyces diastatochromogenes using response surface methodology.

Medium optimization is a very practical and valuable tool for fermentation industry to improve product yield and minimize by-products as well as reduce overall manufacturing costs. The response surface methodology is not new, but it is still a very effective method in medium optimization research. This study used ε-polylysine fermentation as an example to demonstrate how the product yield can be significantly increased by medium optimization through surface response methodology. Similar approach can be used in other microbial fermentations such as in pharmaceutical, food, agricultural and energy industries. As an example, ε-polylysine is one of a few newly approved natural food-grade antimicrobials for food and beverages preservations. Yield improvement is economically beneficial to not only ε-polylysine manufacturers but also to their users and consumers due to lower costs and price.

Repeated-batch fermentation by immobilization of Clostridium beijerinckii NCIMB 8052 in a fibrous bed bioreactor for ABE (acetone-butanol-ethanol) production

In this study, a fibrous bed bioreactor (FBB) system was used to produce ABE (acetone-butanol-ethanol) by immobilized cells of Clostridium beijerinckii NCIMB 8052. To obtain the maximum ABE productivity and yield and maintain the stability of a repeated-batch fermentation process in the FBB system, the optimal dilution rate (0.17 min−1) and initial glucose concentration (18 g/l) in the bioreactor were determined. When the repeated-batch fermentation was maintained at 11 cycles under the optimal conditions, an average of 4.9 g/l butanol (maximum 5.3 g/l) was achieved with an average solvent productivity of 1.0 g/l/h and a yield of 0.41 g/g (maxima of 1.1 g/l/h and 0.43 g/g, respectively). However, the solvent productivity and yield in batch fermentation of free cells were just 0.29 g/l/h and 0.36 g/g, respectively. In addition, scanning electron micrographs demonstrated that C. beijerinckii cells can be adsorbed onto a cotton towel and they exhibited a significantly different morphology compared to immobilized Clostridium acetobutylicum.

Effects of glucose on the uptake and metabolism of glycine in pakchoi (Brassica chinensis L.) exposed to various nitrogen sources

BackgroundPlants can absorb amino acids as a nitrogen (N) source, and glucose is an important part of root rhizodeposition and the soil sugar pool, which participates in the regulation of plant growth and uptake. In pakchoi, the effect of glucose concentration on the glycine N uptake from a nutrient mixture composed of glycine, ammonium, and nitrate, or from a single N solution of glycine alone was studied using specific substrate 15N-labeling and 15N-gas chromatography mass spectrometry.ResultsThe optimal glucose concentration for plant growth was 4.5 μM or 25 μM when supplied with glycine alone or the N mixture, respectively, and resulted in a >25% increase in seedling biomass. The addition of glucose affected the relative contribution from organic or inorganic sources to overall N uptake. When glucose was added at optimal concentrations, glycine was preferentially used as an N source, while the relative contribution from nitrate was reduced. The limiting step for glycine N contribution was active uptake in the roots in high glucose and single-N-source conditions; however, root metabolism of glycine to serine was limiting in high-glucose and mixed-N-source conditions.ConclusionsThe addition of low concentrations of glucose increased the relative uptake of organic nitrogen and reduced the uptake of nitrate, suggesting a feasible way to decrease nitrate content and increase the edible quality of vegetables.

Production of bioethanol by Zymomonas mobilis in high-gravity extractive fermentations

Continuous removal of ethanol during production by the anaerobic bacterium Zymomonas mobilis mitigated ethanol inhibition. Ethanol inhibited its own production at a concentration of >20gL−1. Ethanol productivity was enhanced by continuous in situ extraction with water-immiscible organic solvents. Several solvents were evaluated for biocompatibility with Z. mobilis and the ability to extract ethanol from a batch fermentation. In situ batch extractive fermentations were carried out in a 2-L stirred bioreactor (1:1 volume ratio of solvent and fermentation broth) with an optimal glucose concentration of 150gL−1, 35°C, and an agitation speed of 150rpm. Oleyl alcohol, iso-octadecanol and 2-octyl-1-dodecanol were the three solvents that were most compatible with Z. mobilis. With these solvents, the cell viability relative to control (no solvent) was 1.48±0.40, 1.03±0.18 and 1.05±0.07, respectively, after two days of exposure. All solvents tested improved the final biomass concentration, the glucose consumption and ethanol production relative to control, but iso-octadecanol was clearly the most effective solvent. Using iso-octadecanol, the maximum ethanol concentration of 75±3gL−1 was attained. This was nearly 1.25-fold that of the control fermentation. For this solvent, the ethanol yield on glucose was 0.485±0.005gg−1 compared to a yield of 0.468±0.005gg−1 for the control culture.

Characteristics of hydrogen and bioflocculant production by a transposon-mutagenized strain of Pantoea agglomerans BH18

Based on the transposon-mutagenized library of Pantoea agglomerans BH18, the mutant strain 2-103 was obtained using mutant screens for high simultaneous production of hydrogen and bioflocculant. The mutant strain 2-103 was able to grow in medium with 50 μg/mL of kanamycin and could be amplified using Tn7-based transposon PCR amplification in cells from several passages, indicating that the mutant strain 2-103 transposon insertion was stable. The mutant strain 2-103 cell culture from batch experiments with varying initial pH values, glucose concentrations and NaCl concentrations was determined. The result indicated that the optimum initial pH for hydrogen production and bioflocculant activity was 7.0 and 8.0, respectively. The optimal glucose concentration for hydrogen and bioflocculant production was 20 g/L. In addition, the mutant strain 2-103 could produce hydrogen and bioflocculant under marine and fresh culture conditions. The mutant strain 2-103 had the highest production of hydrogen and bioflocculant with (1.55 ± 0.07) mol H2/mol glucose and (83.7 ± 5.89)% under marine culture conditions, which increased to (1.78 ± 0.08) mol H2/mol glucose and (93.5 ± 6.24)% under fresh culture conditions. This study found that the mutant strain 2-103 has the ability to produce hydrogen and bioflocculant within a range of initial pH values, glucose and NaCl concentrations, which is beneficial for the improvement of cost-effective bio-treatment processes.

Multi-Response Optimization of Granaticinic Acid Production by Endophytic Streptomyces thermoviolaceus NT1, Using Response Surface Methodology.

Streptomyces thermoviolaceus NT1, an endophytic isolate, was studied for optimization of granaticinic acid production. It is an antimicrobial metabolite active against even drug resistant bacteria. Different media, optimum glucose concentration, initial media pH, incubation temperature, incubation period, and inoculum size were among the selected parameters optimized in the one-variable-at-a-time (OVAT) approach, where glucose concentration, pH, and temperature were found to play a critical role in antibiotic production by this strain. Finally, the Box–Behnken experimental design (BBD) was employed with three key factors (selected after OVAT studies) for response surface methodological (RSM) analysis of this optimization study.RSM analysis revealed a multifactorial combination; glucose 0.38%, pH 7.02, and temperature 36.53 °C as the optimum conditions for maximum antimicrobial yield. Experimental verification of model analysis led to 3.30-fold (61.35 mg/L as compared to 18.64 mg/L produced in un-optimized condition) enhanced granaticinic acid production in ISP2 medium with 5% inoculum and a suitable incubation period of 10 days. So, the conjugated optimization study for maximum antibiotic production from Streptomyces thermoviolaceus NT1 was found to result in significantly higher yield, which might be exploited in industrial applications.

Biohydrogen production by microalgae isolated from the rice paddle field in Thailand

Hydrogen produced by cyanobacteria and green algae is a very interesting energy carrier because it is produced by a photosynthetic pathway using sunlight as an energy source. In this study, 59 cyanobacterial and green algal strains were isolated from soil and water sources of rice paddle field in Thailand. Out of them, 9 cyanobacterial isolates and 9 green algal isolates were purified. Among them, unicellular cyanobacterial isolate AngS1 showed the highest H 2 production rate. Its highest H 2 production rate of 389.630±72.084 nmolH 2 mg chl -1 h -1 was found in cells grown in BG11 for 1 week followed by incubating cells in BG11 0 for 24 hours and adaptation under dark anaerobic condition for 2 hours. The optimal concentrations of glucose, MgSO 4 .7H 2 O and Fe 3+ for H 2 production rate were 0.189 mmolC L -1 , 3 mM, and 20 μM, respectively. The highest H 2 accumulation of 4,174.364±278.324 nmolH 2 mg chl -1 was obtained when incubating cells in the optimal medium for 11 days.

Effects of carbon source and light intensity on the growth and total lipid production of three microalgae under different culture conditions.

We attempted to enhance the growth and total lipid production of three microalgal species, Isochrysis galbana LB987, Nannochloropsis oculata CCAP849/1, and Dunaliella salina, which are capable of accumulating high content of lipid in cells. Low nitrogen concentration under photoautotrophic conditions stimulated total lipid production, but a decreasing total lipid content and an increasing biomass were observed with increasing nitrogen concentration. Among the different carbon sources tested for heterotrophic cultivation, glucose improved the growth of all three strains. The optimal glucose concentration for growth of I. galbana LB987 and N. oculata CCAP849/1 was 0.02M, and that of D. salina was 0.05M. Enhanced growth occurred when they were cultivated under heterotrophic or mixotrophic conditions compared with photoautotrophic conditions. Meanwhile, high total lipid accumulation in cells occurred when they were cultivated under photoautotrophic or mixotrophic conditions. During mixotrophic cultivation, biomass production was not affected significantly by light intensity; however, both chlorophyll concentration and total lipid content increased dramatically with increasing light intensity up to 150µmol/m(2)/s. The amount and composition ratio of saturated and unsaturated fatty acids in cells were different from each other depending on both species and light intensity. The highest accumulation of total fatty acid (C16-C18) among the three strains was found from cells of N. oculata CCAP849/1, which indicates that this species can be used as a source for production of biodiesel.

효소연료전지의 Cathode 제조조건이 OCV에 미치는 영향

− Enzyme fuel cells were composed of enzyme cathode and PEMFC anode. Enzyme cathode was fabricated by compression of a mixture of graphite particle, laccase as a enzyme and ABTS as a redox mediator, and then coated with Nafion ionomer. Open circuit voltage (OCV) were measured with variation of cathode manufacture factors, to find optimum condition of enzyme cathode. Optimum pressure was 4.0 bar for enzyme cathode pressing process. Highest OCV was obtained at 95% graphite composition in enzyme cathodee. Optimum glucose concentration was 0.4 mol/l in cathode substrate solution.