Production of bacterial cellulose by Gluconacetobacter sp. RKY5 isolated from persimmon vinegar

The optimum fermentation medium for the production of bacterial cellulose (BC) by a newly isolated Gluconacetobacter sp. RKY5 was investigated. The optimized medium composition for cellulose production was determined to be 15 g/L glycerol, 8 g/L yeast extract, 3 g/L K₂HPO₄, and 3 g/L acetic acid. Under these optimized culture medium, Gluconacetobacter sp. RKY5 produced 5.63 g/L of BC after 144 h of shaken culture, although 4.59 g/L of BC was produced after 144 h of static culture. The amount of BC produced by Gluconacetobacter sp. RKY5 was more than 2 times in the optimized medium found in this study than in a standard Hestrin and Shramm medium, which was generally used for the cultivation of BC-producing organisms.     

Optimization of medium by orthogonal matrix method for submerged mycelial culture and exopolysaccharide production in Collybia maculata

Optimization of submerged culture conditions for the production of mycelial growth and exopolysaccharides (EPSs) by Collybia maculata was investigated. The optimum temperature and the initial pH for EPS production in a shake-flask culture of C. maculata were found to be 20°C and 5.5, respectively. Among the various medium’s constituents examined, glucose, Martone A-1, K₂HPO₄, and CaCl₂ were the most suitable carbon, nitrogen, and mineral sources for EPS production, respectively. The optimum concentration of the medium’s ingredients determined using the orthogonal matrix method was as follows: 30 g/L of glucose, 20 g/L of Martone A-1, 1g/L of K₂HPO₄, and 1g/L of CaCl₂. Under the optimized culture conditions, the maximum concentration of EPSs in a 5-L stirred-tank reactor was 2.4 g/L, which was approximately five times higher than that in the basal medium. A comparative fermentation result showed that the EPS productivity in an airlift reactor was higher than that in the stirred-tank reactor despite the lower mycelial growth rate. The specific productivities and the yield coefficients in the airlift reactor were higher than those in the stirred-tank reactor even though the volumetric productivities were higher in the stirred-tank reactor than in the airlift reactor.     

Production of succinic acid by anaerobiospirillum succiniciproducens

The effect of an external supply of carbon dioxide and pH on the production of succinic acid byAnaerobiospirillum succiniciproducens was studied. In a rich medium containing yeast extract and peptone, when the external carbon dioxide supply was provided by a 1.5M Na₂CO₃ solution that also was used to maintain the pH at 6.0, no additional carbon dioxide supply was needed. In fact, sparging CO₂ gas into the fermenter at 0.025 L/L-min or higher rates resulted in significant decreases in both production rate and yield of succinate. Under the same conditions, the production of the main by-product acetate was not affected by sparging CO₂ gas into the fermenter. The optimum pH (pH 6.0) for the production of succinic acid was found to be in agreement with results previously reported in the literature. Succinic acid production also was studied in an industrial-type inexpensive medium in which light steep water was the only source of organic nutrients. At pH 6.0 and with a CO₂ gas sparge rate of 0.08 L/L-min, succinate concentration reached a maximum of 32 g/L in 27 h with a yield of 0.99 g succinate/g glucose consumed.     

Medium optimization for polysaccharide production of Cordyceps sinensis

As a potential anticarcinogenic agent, polysaccharides from Cordyceps sinensis have been demonstrated to possess strong antioxidation activity. The aim of the present research was to study the optimal medium to produce polysaccharides of C. sinensis by using response surface methodology (RSM). The composition of optimized medium for polysaccharide production calculated from the regression model of RSM was 6.17% sucrose, 0.53% corn steep powder, 0.5% (NH₄)₂HPO₄, and 0.15% KH₂PO₄ at pH 4.44, with a predicted maximum polysaccharide production of 3.17 g/L. When applying this optimal medium, the maximum polysaccharide production was 3.05 and 3.21 g/L in a shake flask and a 5-L jar fermentor, respectively. When the pH was controlled at a higher level such as pH 5.0, both cell growth and polysaccharide production were inhibited. A low pH of 2.85 was required for maximum production of polysaccharides.     

Effects of Carbon and Nitrogen Sources and Oxygenation on the Production of Inulinase by <Emphasis Type="Italic">Kluyveromyces marxianus</Emphasis>

Cultivations of Kluyveromyces marxianus var. bulgaricus ATCC 16045 were performed on both minimal and complex media using different carbon and nitrogen sources either in the presence or absence of aeration. The results collected were worked out and compared so as to provide a useful contribution to the optimization of inulinase production. Kinetics of extracellular inulinase release were similar on glucose, fructose, and sucrose. Inulinase was detected at basal level since the beginning of batch runs on these three carbon sources and overproduced after their depletion. The highest inulinase activity in minimal medium containing 10 g/l sucrose (6.4 IU/ml) was obtained at an initial (NH₄)₂SO₄ concentration of 5 g/l, whereas it was reduced to about one fourth of this value and detected only at the beginning under nitrogen-limited conditions. The best sucrose concentrations for the enzyme production were 30 and 20 g/l in minimal and complex media, yielding 15.4 and 208 IU/ml, respectively. In general, the enzyme activity was much higher in complex than in minimal medium under all conditions. O₂-enriched air neither improved inulinase production nor prevented ethanol formation.     

Optimization of culture medium and conditions for penicillin acylase production by streptomyces lavendulae ATCC 13664

The culture medium for Streptomyces lavendulae ATCC 13664 was optimized on a shake-flask scale by using a statistical factorial design for enhanced production of penicillin acylalse. This extracellularenzyme recently has been reported to bea penicillin Kacylase, presenting also high hydrolytic activity against penicillin V and other natural aliphatic penicillins such as penicillin K, penicillin F, and penicillin dihydroF,. The factorial design indicated that the main factors that positively affect penicillin acylase production by S. lavendulae were the concentration of yeast extract and the presence of oligoelements in the fermentation medium, whereas the presence of olive oil in the medium had no effect on enzyme production. An initial concentration of 2.5% (w/v) yeast extract and 3 μg/mL of CuSO₄·5H₂O was found to be best for acylase production. In such optimized culture medium, fermentation, of the microorganism yielded 289 IU/L of enzyme in 72 h when employing a volume medium/volume flask ratio of 0.4 and a 300-rpm shaking speed. The presence of copper, alone and in combination with other metals, stimulated biomass as well as penicillin acylase production. The time course of penicillin acylase production was also studied in the optimized medium and conditions. Enzyme production showed catabolite repression by different carbon sources such as glucose, lactose, citrate, glycerol, and glycine.     

Optimization of cyclodextrin glucanotransferase production from Bacillus clausii E16 in submerged fermentation using response surface methodology

Cyclodextrin glucanotransferase production from Bacillus clausii E16, a new bacteria isolated from Brazilian soil samples was optimized in shake-flask cultures. A 2(4) full-factorial central composite design was performed to optimize the culture conditions, using a response surface methodology. The combined effect among the soluble starch concentration, the peptone concentration, the yeast extract concentration, and the initial pH value of the culture medium was investigated. The optimum concentrations of the components, determined by a 2(4) full-factorial central composite design, were 13.4 g/L soluble starch, 4.9 g/L peptone, 5.9 g/L yeast extract, and initial pH 10.1. Under these optimized conditions, the maximum cyclodextrin glucanotransferase activity was 5.9 U/mL after a 48-h fermentation. This yield was 68% higher than that obtained when the microorganism was cultivated in basal culture medium.     

An Indigenous Hyperproductive Species of Aureobasidium pullulans RYLF-10: Influence of Fermentation Conditions on Exopolysaccharide (EPS) Production

In recent years, a significant interest has been generated in discovering and developing exopolysaccharides (EPS) produced by microorganisms, especially fungi due to their multifaceted industrial and pharmacological applications. A number of filamentous and cellular fungi have been explored for this; however, according to the existing literature, the work on exopolysaccharide production by indigenous culture on this aspect is still very less and requires a serious attention. The present work is an attempt in this regard and aims to optimize the submerged culture conditions to produce the exopolysaccharides from an indigenous yeast Aureobasidium pullulans RYLF-10 with respect to several operating parameters in shake flask fermentation. The yeast A. pullulans RYLF-10 was identified by 18s RNA sequencing and detailed study on its nutritional requirements, and environmental conditions for submerged culture have been optimized. The optimal temperature and pH for both the vegetative growth and EPS production were found to be 28?±?1 °C and 5.0, respectively, while the agitation speed and inoculum size were reported to be 150 rpm and 1 % (v/v), respectively. Sucrose (50 g/l) and yeast extract (1 g/l) were found to be the most suitable carbon and nitrogen sources which worked best in the ratio of 60:1 and resulted in the maximum EPS yield. Similarly, the other variables like growth regulator (riboflavin) and minerals (NaCl?+?K₂HPO₄?+?MgSO₄) altogether resulted in a noteworthy EPS yield of 45.24 g/l which is the maximum yield from this indigenous isolate of A. pullulans RYLF-10.     

Effect of Nutrients on Fermentation of Pretreated Wheat Straw at very High Dry Matter Content by Saccharomyces cerevisiae

Wheat straw hydrolysate produced by enzymatic hydrolysis of hydrothermal pretreated wheat straw at a very high solids concentration of 30% dry matter (w/w) was used for testing the effect of nutrients on their ability to improve fermentation performance of Saccharomyces cerevisiae. The nutrients tested were MgSO₄ and nitrogen sources; (NH₄)₂SO₄, urea, yeast extract, peptone and corn steep liquor. The fermentation was tested in a separate hydrolysis and fermentation process using a low amount of inoculum (0.33 g kg^?1) and a non-adapted baker’s yeast strain. A factorial screening design revealed that yeast extract, peptone, corn steep liquor and MgSO₄ were the most significant factors in obtaining a high fermentation rate, high ethanol yield and low glycerol formation. The highest volumetric ethanol productivity was 1.16 g kg^?1 h^?1 and with an ethanol yield close to maximum theoretical. The use of urea or (NH₄)₂SO₄ separately, together or in combination with MgSO₄ or vitamins did not improve fermentation rate and resulted in increased glycerol formation compared to the use of yeast extract. Yeast extract was the single best component in improving fermentation performance and a concentration of 3.5 g kg^?1 resulted in high ethanol yield and a volumetric productivity of 0.6 g kg^?1 h^?1.     

Purification and Characterization of Extracellular Inulinase from a Marine Yeast <Emphasis Type="Italic">Cryptococcus aureus</Emphasis> G7a and Inulin Hydrolysis by the Purified Inulinase

The extracellular inulinase in the supernatant of the cell culture of the marine yeast Cryptococcus aureus G7a was purified to homogeneity with a 7.2-fold increase in specific inulinase activity compared to that in the supernatant by ultrafiltration, concentration, gel filtration chromatography (Sephadex™ G-75), and anion exchange chromatography (DEAE sepharose fast flow anion exchange). The molecular mass of the purified enzyme was estimated to be 60.0 kDa. The optimal pH and temperature of the purified enzyme were 5.0 and 50 °C, respectively. The enzyme was activated by Ca²⁺, K⁺, Na⁺, Fe²⁺, and Zn²⁺. However, Mg²⁺, Hg²⁺, and Ag⁺ acted as inhibitors in decreasing the activity of the purified inulinase. The enzyme was strongly inhibited by phenylmethanesulphonyl fluoride (PMSF), iodoacetic acid, EDTA, and 1,10-phenanthroline. The K _m and V _max values of the purified enzyme for inulin were 20.06 mg/ml and 0.0085 mg/min, respectively. A large amount of monosaccharides were detected after the hydrolysis of inulin with the purified inulinase, indicating the purified inulinase had a high exoinulinase activity.     

Effect of nutrient supplements addition on ethanol production from cheese whey usingCandida pseudotropicalis under batch condition

Candida pseudotropicalis ATCC 8619 was selected among nine strains of lactose fermenting yeast for the production of ethanol from cheese whey. The effects of three nutrients (ammonium sulfate (NH₄)₂SO₄, dipotassium hydrogen phosphate K₂HPO₄, yeast extract, and a combination of them) on the ethanol yield from cheese whey were investigated. The results indicated that no addition of nutrient supplement is necessary to achieve complete lactose utilization during the cheese whey ethanol fermentation. However, addition of a small concentration (0.005% w/v) of these supplements reduced the lag period and the total fermentation time and increased the specific growth rate of the yeast. Higher concentrations (0.01 and 0.015% w/v) of ammonium sulfate and dipotassium hydrogen phosphate inhibited the cell growth and reduced lactose consumption. The highest ethanol (21.17 g/L) was achieved using yeast extract at a concentration of 0.01% w/v, given a conversion efficiency of 98.3%. No indication of alcohol inhibition was observed in this study.     

Optimization of critical medium components for the maximal production of gentamicin by Micromonospora echinospora ATCC 15838 using response surface methodology

Optimization of the fermentation medium components for maximum gentamicin production by Micromonospora echinospora ATCC 15838 was carried out. Response surface methodology was applied to optimize the medium constituents. A 2⁴full-factorial central composite design was chosen to explain the combined effects of the four medium constituents, viz. starch, soyabean meal, K₂HPO₄, and CoCl₂ and to design a minimum number of experiments. A second order model was developed and fitted using least square method. The R ² value of the model was 0.9723, which shows that model is best fit for the present studies. The results of analysis of variance and regression of a second order model showed that the linear effects of starch (p<0.001697) and CoCl₂(p<7.99E-13), and cross product effects of starch and soyabean meal (p<0.029876) and soyabean meal and CoCl₂ (p<0.008909) were more significant, suggesting that these were critical variables having the greatest effect on the production of gentamicin in the production medium. The optimized medium consisting of 9 g/L starch, 3 g/L soyabean meal, 0.9 g/L K₂HPO₄, and 0.01 g/L CoCL₂ predicted 850 mg/L of gentamicin which was almost 110% higher than that of the unoptimized medium. The amounts of starch, soyabean meal, and K₂HPO₄ required were also reduced with RSM.     

Nitrogen Source Optimization for Cellulase Production by Penicillium funiculosum, using a Sequential Experimental Design Methodology and the Desirability Function

The present study aimed at maximizing cellulase production by Penicillium funiculosum using sequential experimental design methodology for optimizing the concentrations of nitrogen sources. Three sequential experimental designs were performed. The first and the second series of experiments consisted of a 2⁴ and a 2³ factorial designs, respectively, and in the third one, a central composite rotational design was used for better visualizing the optimum conditions. The following nitrogen sources were evaluated: urea, ammonium sulfate, peptone, and yeast extract. Peptone and ammonium sulfate were removed from the medium optimization since they did not present significant statistical effect on cellulase production. The optimal concentrations of urea and yeast extract predicted by the model were 0.97 and 0.36 g/L, respectively, which were validated experimentally. By the use of the desirability function, it was possible to maximize the three main enzyme activities simultaneously, which resulted in values for FPase of 227 U/L, for CMCase of 6,917 U/L, and for β-glucosidase of 1,375 U/L. These values corresponded to increases of 3.3-, 3.2-, and 6.7-folds, respectively, when compared to those obtained in the first experimental design. The results showed that the use of sequential experimental designs associated to the use of the desirability function can be used satisfactorily to maximize cellulase production by P. funiculosum.     

Processing Parameters Matching Effects upon Rhizobium tropici Biopolymers’ Rheological Properties

The combined effects of the processing parameters upon rheological properties of biopolymers produced by Rhizobium tropici were studied as a function of the Ca(+2) ions' concentration variation, yeast extract concentration added to the medium, aeration, and agitation, maintaining the mannitol concentration in 10 g/L. The experiments were carried out using a fermenter with 20-L capacity as a reactor. All processing parameters were monitored online. The temperature [(30 +/- 1) degrees C] and pH values (7.0) were kept constant throughout the experimental time. As a statistical tool, a complete 2(3) factorial design with central point and response surface was used to investigate the interactions between relevant variables of the fermentation process: calcium carbonate concentration, yeast extract concentration, aeration, and agitation. The processing parameter setup for reaching the maximum response for rheological propriety production was obtained when applying mannitol concentration of 10.0 g/L, calcium carbonate concentration 1.0 g/L, yeast extract concentration 1.0 g/L, aeration 1.30 vvm, and agitation 800 rpm. The viscosimetric investigation of polysaccharide solutions exposed their shear-thinning behavior and polyelectrolytic feature.     

Improvement of culture conditions forl-proline production by a recombinant strain ofSerratia marcescens

Serratia marcescens SP511 was previously reported to be anl-proline-producing strain that harbors a recombinant plasmid carrying the mutant type of the proline operon. This strain produced 65 g/L ofl-proline in a medium containing 22% sucrose and urea after 5 d of incubation under the conventional culture conditions. We searched for more suitable culture conditions for more abundantl-proline production by SP511. To improve the supply of a nitrogen source to cells, ammonium was used instead of urea and fed to a culture under control of the pH of the medium. The concentrations of MgSO₄ and K₂HPO₄ were increased, and in addition, sucrose was continuously added to the culture at a final concentration of 32%. Under these conditions, the cell amount was increased twofold over that under the previous conditions andl-proline production reached a maximum of more than 100 g/L after 4 d of incubation.     

Optimization of keratinase production and enzyme activity using response surface methodology with streptomyces sp7

A two-step response surface methodology (RSM) study was conducted for the optimization of keratinase production and enzyme activity from poultry feather byStreptomyces sp7. Initially different combinations of salts were screened for maximal production of keratinase at a constant pH of 6.5 and feather meal concentration of 5 g/L. A combination of K₂HPO₄, KH₂PO₄, and NaCl gave a maximum yield of keratinase (70.9 U/mL) production. In the first step of the RSM study, the selected five variables (feather meal, K₂HPO₄, KH₂PO₄, NaCl, and pH) were optimized by a 2⁵ full-factorial rotatable central composite design (CCD) that resulted in 95 U/mL of keratinase production. The results of analysis of variance and regression of a second-order model showed that the linear effects of feather meal concentration (p<0.005) and NaCl (p<0.029) and the interactive effects of all variables were more significant and that values of the quadratic effects of feather meal (p<1.72e-5), K₂HPO₄ (p<4.731e-6), KH₂PO₄ (p<1.01e-10), and pH (p 7.63e-7) were more significant than the linear and interactive effects of the process variables. In the second step, a 2³ rotatable full-factorial CCD and response surface analysis were used for the selection of optimal process parameters (pH, temperature, and rpm) for keratinase enzyme activity. These optima were pH 11.0, 45°C, and 300 rpm.     

Xylose reductase activity of Candida guilliermondii during xylitol production by fed-batch fermentation

Xylose reductase activity of Candida guilliermondii FTI 20037 was evaluated during xylitol production by fed-batch fermentation of sugarcane bagasse hydrolysate. A 2^4-1 fractional factorial design was used to select process variables. The xylose concentrations in the feeding solution (S _F ) and in the fermentor (S ₀), the pH, and the aeration rate were selected for optimization of this process, which will be undertaken in the near future. The best experimental result was achieved at S _F =45 g/L, S ₀=40 g/L, pH controlled at 6.0, and aeration rate of 1.2 vvm. Under these conditions, the xylose reductase activity was 0.81 U/mg of protein and xylitol production was 26.3 g/L, corresponding to a volumetric productivity of 0.55 g/(L·h) and a xylose xylitol yield factor of 0.68 g/g.     

Alcoholic Fermentation with Flocculant Saccharomyces cerevisiae in Fed-Batch Process

Studies have been conducted on selecting yeast strains for use in fermentation for ethanol production to improve the performance of industrial plants and decrease production costs. In this paper, we study alcoholic fermentation in a fed-batch process using a Saccharomyces cerevisiae yeast strain with flocculant characteristics. Central composite design (CCD) was used to determine the optimal combination of the variables involved, with the sucrose concentration of 170 g/L, a cellular concentration in the inoculum of 40 % (v/v), and a filling time of 6 h, which resulted in a 92.20 % yield relative to the theoretical maximum yield, a productivity of 6.01 g/L h and a residual sucrose concentration of 44.33 g/L. With some changes in the process such as recirculation of medium during the fermentation process and increase in cellular concentration in the inoculum after use of the CCD was possible to reduce the residual sucrose concentration to 2.8 g/L in 9 h of fermentation and increase yield and productivity for 92.75 % and 9.26 g/L h, respectively. A model was developed to describe the inhibition of alcoholic fermentation kinetics by the substrate and the product. The maximum specific growth rate was 0.103 h^?1, with K _I and K _s values of 109.86 and 30.24 g/L, respectively. The experimental results from the fed-batch reactor show a good fit with the proposed model, resulting in a maximum growth rate of 0.080 h^?1.     

Application of Response Surface Methodology for Maximizing Dextransucrase Production from Leuconostoc mesenteroides NRRL B-640 in a Bioreactor

The production of dextransucrase from Leuconostoc mesenteroides NRRL B-640 was investigated using statistical approaches. Plackett-Burman design with six variables, viz. sucrose, yeast extract, K(2)HPO(4), peptone, beef extract, and Tween 80, was used to screen the nutrients that significantly affected the dextransucrase production. 2(4)-Central composite design with four selected variables (sucrose, K(2)HPO(4), yeast extract, and beef extract) was used for response surface methodology (RSM) for optimizing the enzyme production. The culture was grown under flask culture with 100 ml optimized medium containing 30 g/l sucrose, 18.5 g/l yeast extract, 15.3 g/l K(2)HPO(4), and 5 g/l beef extract at 25 degrees C and shaking at 200 rpm gave dextransucrase with specific activity of 0.68 U/mg. Whereas the same optimized medium in a 3.0-l bioreactor (1.4 l working volume) gave an experimentally determined value of specific activity of 0.70 U/mg, which was in perfect agreement with the predicted value of 0.65 U/mg by the statistical model.     

Use of Propionibacterium freudenreichii T82 Strain for Effective Biosynthesis of Propionic Acid and Trehalose in a Medium with Apple Pomace Extract and Potato Wastewater

Propionic acid bacteria are the source of many metabolites, e.g., propionic acid and trehalose. Compared to microbiological synthesis, the production of these metabolites by petrochemical means or enzymatic conversion is more profitable. The components of microbiological media account for a large part of the costs associated with propionic fermentation, due to the high nutritional requirements of Propionibacterium. This problem can be overcome by formulating a medium based on the by-products of technological processes, which can act as nutritional sources and at the same time replace expensive laboratory preparations (e.g., peptone and yeast extract). The metabolic activity of P. freudenreichii was investigated in two different breeding environments: in a medium containing peptone, yeast extract, and biotin, and in a waste-based medium consisting of only apple pomace and potato wastewater. The highest production of propionic acid amounting to 14.54 g/L was obtained in the medium containing apple pomace and pure laboratory supplements with a yield of 0.44 g/g. Importantly, the acid production parameters in the waste medium reached almost the same level (12.71 g/L, 0.42 g/g) as the medium containing pure supplements. Acetic acid synthesis was more efficient in the waste medium; it was also characterized by a higher level of accumulated trehalose (59.8 mg/g d.s.). Thus, the obtained results show that P. freudenreichii bacteria exhibited relatively high metabolic activity in an environment with apple pomace used as a carbon source and potato wastewater used as a nitrogen source. This method of propioniate production could be cheaper and more sustainable than the chemical manner.