High Rate Production in Static Culture of Bacterial Cellulose from Sucrose by a Newly Isolated Acetobacter Strain

For the industrial production of bacterial cellulose from sucrose in static cultures, the possibility of a high rate of cellulose production was investigated. An Acetobacter strain, S-35, which had been isolated from a grape, was selected from 1500 isolates. This strain was found to produce a large amount of cellulose from either glucose or fructose. Using this strain, high cellulose production rates of 3.3g/liter/d or 40g/m²/d from sucrose were seen in static culture.     

Effect of sugar concentration on camptothecin production in cell suspension cultures ofCamptotheca acuminata

Studies for the effects of sugar concentration on camptothecin production in suspension cultures ofCamptotheca acuminata were made with different concentrations of sucrose, glucose, and fructose. Sucrose among tested carbon sources increased the camptothecin production. The highest camptothecin, 29×10⁴ mg/L, was obtained at 6% of sucrose that was 11 times higher than that at 2% of sucrose. Kinetics of camptothecin production with 6% of sucrose showed the camptothecin production was increased up to 3 days and then decreased after 6 days from inoculation. The highest camptothecin was obtained on the third day from inoculation.     

不同碳源对小球藻Chlorella zofingiensis异养产虾青素的影响

研究了葡萄糖、蔗糖和果糖对小球藻(Chlorella zofingiensis)异养生长及产虾青素的影响,结果表明,在糖浓度为20g/L时,细胞生长较快,但干重较小,虾青素含量较低;在糖浓度为50g/L时,细胞生长较慢,但干重较大,虾青素含量较高。3种碳源中蔗糖和葡萄糖效果较好,在蔗糖浓度为50g/L时,虾青素含量和产量分别达到0.94 mg/g和9.61 mg/L。     

Influence of growth factor supplements on butyric acid production from sucrose byClostridium butyricum

During batch fermentation of sucrose to butyric acid byClostridium butyricum the effect of growth factor supplementation was determined: addition of yeast extract (5 g/L) stimulated most. Using biotin as the sole growth factor, average productivity was definitely lower. Beet molasses as a combined source of carbon and growth factor were effective only at a high concentration (150 g/L). The optimal butyric acid production (45 g/L, yield 45%) was achieved with sucrose concentration of 100 g/L in a medium supplemented with yeast extract (5 g/L). It represents an average productivity of 0.90 gL⁻¹ h⁻¹ and relative butyric acid concentration of 91%.     

Effects of inoculum concentration,temperature, and carbon sources on tannase production during solid state fermentation of cashew apple bagasse

In this study, the optimization of tannase production by solid state fermentation was investigated using cashew apple bagasse (CAB), an inexpensive residue produced by the cashew apple agroindustry, as a substrate. To accomplish this, CAB was enriched with 2.5% (w/w) tannic acid and 2.5% (w/w) ammonium sulphate and then moistened with water (60 mL/100 g of dry CAB). The influence of inoculum concentration (10⁴ to 10⁷ spores/g), temperature (20, 25, 30, and 35°C) and several additional carbon sources (glucose, starch, sucrose, maltose, analytical grade glycerol, and glycerol produced during biodiesel production) on enzyme production by Aspergillus oryzae was then evaluated. Supplementation with maltose and glycerol inhibited tannase synthesis, which resulted in lower enzyme activity. Starch and sucrose supplementation increased enzyme production, but decreased the enzyme productivity. The maximum tannase activity (4.63 units/g of dry substrate) was obtained at 30°C, using 10⁷ spores/g and 1.0% (w/v) sucrose as an additional carbon source.     

Effect of various carbon and nitrogen sources on cellulose synthesis by Acetobacter xylinum

The effect of various carbon and nitrogen sources on cellulose membrane production by Acetobacter xylinum was evaluated. Among the carbon sources, sucrose, glucose and mannitol were found to be suitable for optimum levels of cellulose production. The strain was able to utilize a wide range of protein and nitrogen sources such as peptone, soybean meal, glycine, casein hydrolysate, and glutamic acid for cellulose synthesis. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of pellicle proteins (PP) revealed electrophoretic bands of molecular masses in the range of 116–20 kDa. Furthermore, the strain can be useful for the removal of various nitrogenous and carbon substrates present in waste waters.     

Growth ofCandida albicans in a minimal synthetic medium without biotin

Summary Growth ofCandida albicans strain B 311-10 was observed in a minimal synthetic biotin-free medium, using different glucose concentrations, during the first 30 hours of its development at 28 °C. The yeast's growth was observed spectrophotometrically at 675 nm reading its optical density every hour. The minimal medium of Shepherdet al. [12], with glucose (15 g/L) and biotin was modified: this vitamin was eliminated and the concentration of glucose was gradually lowered to 0.5 g/L. At 5 g/L of glucose and without biotin very good growth was obtained. Based on our results during the first 30 hours of growth, biotin has no influence on the yeast's growth. This medium would be useful for the study of the physiology ofC. albicans during the first period of its development.     

Characterization of exopolysaccharide (EPS) produced by Weissella hellenica SKkimchi3 isolated from kimchi

Weissella hellenica SKkimchi3 produces the higher exopolysaccharide (EPS) on sucrose than lactose, glucose, and fructose at pH 5 and 20°C. Sucrose was exclusively used to cultivate SKkimchi3 in all experiments base on the EPS production tests. The molecular mass of EPS, as determined by gel permeation chroma-tography, was 203,000. ¹H and ¹³C NMR analysis indicated that the identity of EPS may be a glucan. When EPS, starch, and cellulose was treated with a-amylase, glucoamylase, glucosidase, and cellulase, glucose was produced from starch and cellulose but was not produced from EPS. Based on HPLC analysis, elemental analysis, ¹H and ¹³C NMR analysis, and enzymatic hydrolysis tests, EPS was estimated to be a glucan. EPS suspension was not precipitated even by centrifugation at 10,000×g for 60 min, and EPS made the fermented milk and bacterial culture viscous.     

Optimization of medium for the production of a novel aquaculture probiotic,<Emphasis Type="Italic">Micrococcus</Emphasis> MCCB 104 using central composite design

A marine isolate ofMicrococcus MCCB 104 has been identified as an aquaculture probiotic antagonistic toVibrio. In the present study different carbon and nitrogen sources and growth factors in a mineral base medium were optimized for enhanced biomass production and antagonistic activity against the target pathogen,Vibrio harveyi, following response surface methodology (RSM). Accordingly the minimum and maximum limits of the selected variables were determined and a set of fifty experiments programmed employing central composite design (CCD) of RSM for the final optimization. The response surface plots of biomass showed similar pattern with that of antagonistic activity, which indicated a strong correlation between the biomass and antagonism. The optimum concentration of the carbon sources, nitrogen sources, and growth factors for both biomass and antagonistic activity were glucose (17.4 g/L), lactose (17 g/L), sodium chloride (16.9 g/L). ammonium chloride (3.3 g/L), and mineral salts solution (18.3 mL/L).     

Production of carotenoids by β-ionone-resistant mutant of <Emphasis Type="Italic">Xanthophyllomyces dendrorhous</Emphasis> using various carbon sources

Batch culture kinetics of the red yeast, Xanthophyllomyces dendrorhous SKKU 0107, revealed reduction in biomass with glucose and lower intracellular carotenoid content with fructose. Figures were different when compared to sucrose, which is a disaccharide of glucose and fructose. In contrast, specific growth rate constant stayed between 0.094~0.098 h⁻¹, irrespective of the carbon sources employed. Although the uptake rate of glucose was found to be 2.9-fold faster than that of fructose, sucrose was found to be a more suitable carbon source for the production of carotenoids by the studied strain. When sugar cane molasses was used, both the specific growth rate constant and the intracellular carotenoid content decreased by 27 and 17%, respectively. Compared with the batch culture using 28 g/L sugar cane molasses, fed-batch culture with the same strain resulted in a 1.45-fold higher cell yield together with a similar level of carotenoid content in X. dendrorhous SKKU 0107.     

Three‐Enzyme Phosphorylase Cascade for Integrated Production of Short‐Chain Cellodextrins

Cellodextrins are linear β‐1,4‐gluco‐oligosaccharides that are soluble in water up to a degree of polymerization (DP) of ≈6. Soluble cellodextrins have promising applications as nutritional ingredients. A DP‐controlled, bottom‐up synthesis from expedient substrates is desired for their bulk production. Here, a three‐enzyme glycoside phosphorylase cascade is developed for the conversion of sucrose and glucose into short‐chain (soluble) cellodextrins (DP range 3–6). The cascade reaction involves iterative β‐1,4‐glucosylation of glucose from α‐glucose 1‐phosphate (αGlc1‐P) donor that is formed in situ from sucrose and phosphate. With final concentration and yield of the soluble cellodextrins set as targets for biocatalytic synthesis, three major factors of reaction efficiency are identified and partly optimized: the ratio of enzyme activity, the ratio of sucrose and glucose, and the phosphate concentration used. The efficient use of the phosphate/αGlc1‐P shuttle for cellodextrin production is demonstrated and the soluble product at 40 g L^?1 is obtained under near‐complete utilization of the donor substrate offered (88 mol% from 200 mm sucrose). The productivity is 16 g (L h)^?1. Through a simple two‐step route, the soluble cellodextrins are recovered from the reaction mixture in ≥95% purity and ≈92% yield. Overall, this study provides the basis for their integrated production.     

Effect of triton X-100 on compactin production from<Emphasis Type="Italic">Penicillium citrinum</Emphasis>

Glucose alone was found to be the most effective carbon source for producing compactin. An initial glucose concentration of 40 g/L gave the highest compactin concentration of 250 mg/L. Among the various nitrogen sources, when 5 g/L of pharmamedia and soybean meal as the sole nitrogen source were used, respectively, the compactin concentration was higher than 250 mg/L. Especially, in the case of the mixture of 6 g/L of pharmamedia and 8 g/L of soybean meal, the compactin concentration was 400 mg/L. To select the best surfactant for effective compactin production, various surfactants were investigated. When Triton X-100 was used, the maximum compactin concentration was 445 mg/L. With the initial concentration ranging from 1.5 to 2.0 g/L, the compactin concentration was the highest at 465–450 g/L. The cell concentration was similar to that of the control without the addition of Triton X-100. On the other hand, when the above 4.0 g/L of Triton X-100 were used, the cell concentration decreased. Using the based results the continuous fed-batch cultures by adding the Triton X-100 were carried out for 10 days in an air-lift bioreactor. When 1.5 g/L of Triton X-100 was added to the culture broth at 0, 4, and 8 days of culture, respectively, the compactin production was increased with the increase of culture time. The maximum compactin concentration after 10 days of culture was 1,200 mg/L, which was about 2.0-fold higher than that of the control without the addition of Triton X-100.     

β‐poly(l‐malic acid) production by fed‐batch culture of Aureobasidium pullulans ipe‐1 with mixed sugars

β‐poly(l ‐malic acid) (PMLA) is a biopolyester, which has attracted growing attention due to its potential applications in medicine and other industries. In this study, the biosynthetic pathway of PMLA and the fermentation strategies with mixed sugars were both investigated to enhance PMLA production by Aureobasidium pullulans ipe‐1. Metabolic intermediates and inhibitors were used to study the biosynthetic pathway of PMLA. It showed that exogenous addition of l ‐malic acid, succinic acid, TFA, and avidin had negligible effect on PMLA production, while pyruvic acid and biotin were the inhibitors, indicating that PMLA biosynthesis was probably related to phosphoenolpyruvate via oxaloacetate catalyzed by phosphoenolpyruvate carboxylase. Sucrose was suitable for achieving the highest PMLA concentration, while fructose generated a higher yield of PMLA (PMLA produced per biomass). Furthermore, the fed‐batch culture using fed solution with different sugar mixture for PMLA production was implemented. During the fed‐batch culture with mixed solution, fructose could increase PMLA production. Compared with the batch culture, the feeding with mixed sugar (sucrose and glucose) increased PMLA concentration by 23.9%, up to 63.2 g/L, and the final volume of the broth was increased by 25%. These results provide a good reference for process development and optimization of PMLA production.     

Optimization of a fermentation process for bioinsecticide production by <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>

In an attempt to develop a cost-effective process for bioinsecticide production by B. thuringiensis, the feeding regime during aerobic cultivation of the bacterium was investigated and optimized. The process was designed as a two-stage process; a first stage of active growth, where glucose and other nutrients were adequately supplied to the growing cells over 12 h, followed by a second stage of 2 h for spore formation and toxin release. In order to maximize spore and toxin yield and productivity, different quantities of glucose and nutrients were fed separately to the growing cells in four different fermentation runs. In all runs, glucose was converted to bacterial biomass during the first stage and subsequently to spores and crystal protein during the second phase. The best results were obtained with a fermentation run supplied with 190 g glucose in 1500 ml. Up to 20.1 g of bacterial insecticides/l were recovered from fermentation broth with a glucose to toxin conversion yield of 0.159 g/g. Also, a markedly high spore concentration of 2.31 × 10¹² c.f.u./ml was obtained. The spore–crystal protein mixture obtained was tested for its insecticidal activity against three of the most agronomically important pests. Among the bioinsecticide-treated insect pests, Egyptian cotton leafworm, Spodoptera littoralis was the most susceptible pest with the lowest LC₅₀ of the bioinsecticides against its larval instar and the highest virulence against adults emerged later on from the surviving larvae.     

Optimization of Nutritional Factors for Exopolysaccharide Production by Submerged Cultivation of the Medicinal Mushroom Oudemansiella radicata

Summary Effects of nutritional factors on exopolysaccharide production by submerged cultivation of the medicinal mushroom Oudemansiella radicata were investigated in shake flasks. Sucrose and peptone were optimal carbon and nitrogen sources for cell growth and exopolysaccharide production. The exopolysaccharide production was increased with an increase in initial sucrose concentration within the range of 10–40 g l⁻¹ and initial peptone concentration within the range of 1–3 g l⁻¹. To enhance further exopolysaccharide production, the effect of carbon/nitrogen ratios was studied using central composite design (CCD) and response surface analysis. The maximum exopolysaccharide production of 2.67 ± 0.15 g l⁻¹ was achieved in medium with optimized carbon and nitrogen sources, i.e. 39.3 g sucrose l⁻¹ and 3.16 g peptone l⁻¹ in the same cultivation conditions. The information obtained is helpful for the hyperproduction of exopolysaccharide by submerged cultivation of O. radicata on a large scale.     

Enhancing yield of <Emphasis Type="Italic">S</Emphasis>-adenosylmethionine in <Emphasis Type="Italic">Pichia pastoris</Emphasis> by controlling NH<Subscript>4</Subscript><Superscript>+</Superscript> concentration

Yield of S-adenosylmethionine was improved significantly in recombinant Pichia pastoris by controlling NH₄ ⁺ concentration. The highest production rate was 0.248 g/L h when NH₄ ⁺ concentration was 450 mmol/L and no repression of cell growth was observed. Within very short induction time (47 h), 11.63 g/L SAM was obtained in a 3.7 L bioreactor.     

Production of succinate by a <Emphasis Type="Italic">pfl</Emphasis>B <Emphasis Type="Italic">ldh</Emphasis>A double mutant of <Emphasis Type="Italic">Escherichia coli</Emphasis> overexpressing malate dehydrogenase

The gene encoding malate dehydrogenase (MDH) was overexpressed in a pflB ldhA double mutant of Escherichia coli, NZN111, for succinic acid production. With MDH overexpression, NZN111/pTrc99A-mdh restored the ability to metabolize glucose anaerobically and 0.55 g/L of succinic acid was produced from 3 g/L of glucose in shake flask culture. When supplied with 10 g/L of sodium bicarbonate (NaHCO₃), the succinic acid yield of NZN111/pTrc99A-mdh reached 1.14 mol/mol glucose. Supply of NaHCO₃ also improved succinic acid production by the control strain, NZN111/pTrc99A. Measurement of key enzymes activities revealed that phosphoenolpyruvate (PEP) carboxykinase and PEP carboxylase in addition to MDH played important roles. Two-stage culture of NZN111/pTrc99A-mdh was carried out in a 5-L bioreactor and 12.2 g/L of succinic acid were produced from 15.6 g/L of glucose. Fed-batch culture was also performed, and the succinic acid concentration reached 31.9 g/L with a yield of 1.19 mol/mol glucose.     

Cellulose degradation and glucose accumulation byClostridium thermocellum ATCC 27405 under different cultural conditions

Effect of various cultural parameters on cellulose degradation, glucose accumulation and ethanol production byClostridium thermocellum ATCC 27405 were investigated. Optimum pH values for glucose accumulation and ethanol production were determined as 7 and 10, respectively. Highest amount of ethanol (0.92 g/l) was obtained from the culture which contains 10 g urea/l with 34.5% decrease in glucose accumulation. Addition of 100 mM phosphate to the medium increased ethanol production while cellulose degradation and sugar accumulation decreased by 34 and 99%, respectively. Among minerals tested, Mg⁺² was found to be the most important element which affects cellulose degradation. When the medium contained no Mg⁺², residual cellulose concentration was 4.3 g cellulose/l. When the cultural parameters were optimised, glucose accumulation started at early days of fermentation and glucose concentration was 60% higher than that of the control at the 10^th day of fermentation.     

Production of polyhydroxyalkanoates by <Emphasis Type="Italic">Azotobacter vinelandii</Emphasis> UWD using swine wastewater: Effect of supplementing glucose,yeast extract,and inorganic salts

This study examined the effect of adding glucose, yeast extract, and inorganic salts to swine wastewater (SWW) in a batch culture on the production of a biodegradable plastic, polyhydroxyalkanoate (PHA). A bacterial strain, Azotobacter vinelandii UWD, was used to produce PHA without limiting the non-carbon nutrients. The addition of glucose (30 g/L) to the SWW medium increased the level of cell growth (4.4∼7.0 times) and PHA production (3.8∼8.5 times) depending upon the dilution of SWW. A 50% dilution of SWW was found to be optimal considering the dry cell weight (9.40 g/L), PHA content (58 wt%), and hydroxyvalerate (HV) mol fraction in the PHA (4.3 mol%). A 75% SWW medium was more advantageous for producing PHA with a higher HV fraction (7.1 mol%) at the expense of losing 22% of PHA production. The undiluted SWW medium produced less than one third of the PHA compared with the 50% SWW medium, but the HV fraction was the highest (10.8 mol%). Regarding the effect of the glucose concentration, at 20 g/L glucose, the dry cell weight and level of PHA production increased to 9.34 g/L (0.63 g PHA/g dry cell weight) and 5.90 g/L, respectively. At 50 g/L glucose, there was no significant increase in PHA production. For the glucose-supplemented (30 g/L) 50% SWW medium, the addition of a nitrogen source (1 g/L of yeast extract) did not increase the level of cell growth or PHA production because the C:N ratio (23:1) was already close to the optimal value (22:1). Better aeration increased the productivity of PHA. External nitrogen supplements (1 g/L of yeast extract) and other essential mineral salts was not necessary for bacterial growth because they were contained in the SWW. These results suggest that SWW is an excellent feedstock for producing larger amounts of the value-added material, PHA, if it is combined with carbohydrate-rich organic waste.     

An inexpensive medium for production of arachidonic acid by <Emphasis Type="Italic">Mortierella alpina</Emphasis>

The production of arachidonic acid was studied in the fungus Mortierella alpina using an inexpensive medium. Glucose derived from maize starch hydrolysate was the sole carbon source and defatted soybean meal and sodium nitrate were the nitrogen sources. Optimal arachidonic acid yield (1.47 g l^-1) was observed at a glucose concentration of 100 g l^-1. Various treatments of defatted soybean meal to extract soluble nitrogen nutrients were evaluated. Alkali extract was the most effective for arachidonic acid production. A mixture of soybean alkali-extract protein and sodium nitrate was an excellent nitrogen source for fungal growth, lipid accumulation, and arachidonic acid production. A maximum yield of 1.87 g arachidonic acid l^-1 was obtained with a soybean protein concentration of 4.6 g l^-1 and a sodium nitrate concentration of 2.3 g l^-1. Electronic Publication