CAROTENOIDS PRODUCTION IN DIFFERENT CULTURE CONDITIONS BY Sporidiobolus pararoseus

Carotenoids produced by Sporidiobolus pararoseus were studied. It was found that biomass was connected with carbon source, temperature, and pH, but carotenoids proportion was seriously influenced by dissolved oxygen and nitrogen source. Different carotenoids could be obtained by using selected optimum conditions. In the end we established the strategies to produce β-carotene or torulene. Fed-batch fermentation in fermentor was used to prove the authenticity of our conclusions. The cell biomass, β-carotene content, and β-carotene proportion could reach 56.32 g/L, 18.92 mg/L and 60.43%, respectively, by using corn steep liquor at 0–5% of dissolved oxygen saturation. β-Carotene content was 271% higher than before this addition. The cell biomass, torulene content, and torulene proportion could reach 62.47 g/L, 31.74 mg/L, and 70.41%, respectively, by using yeast extract at 30–35% of dissolved oxygen saturation. Torulene content was 152% higher than before this addition. The strategy for enhancing specific carotenoid production by selected fermentation conditions may provide an alternative approach to enhance carotenoid production with other strains.     

Carotenoids production in different culture conditions by Sporidiobolus pararoseus

Carotenoids produced by Sporidiobolus pararoseus were studied. It was found that biomass was connected with carbon source, temperature, and pH, but carotenoids proportion was seriously influenced by dissolved oxygen and nitrogen source. Different carotenoids could be obtained by using selected optimum conditions. In the end we established the strategies to produce β-carotene or torulene. Fed-batch fermentation in fermentor was used to prove the authenticity of our conclusions. The cell biomass, β-carotene content, and β-carotene proportion could reach 56.32?g/L, 18.92?mg/L and 60.43%, respectively, by using corn steep liquor at 0-5% of dissolved oxygen saturation. β-Carotene content was 271% higher than before this addition. The cell biomass, torulene content, and torulene proportion could reach 62.47?g/L, 31.74?mg/L, and 70.41%, respectively, by using yeast extract at 30-35% of dissolved oxygen saturation. Torulene content was 152% higher than before this addition. The strategy for enhancing specific carotenoid production by selected fermentation conditions may provide an alternative approach to enhance carotenoid production with other strains.     

Continuous conversion of D-xylose to ethanol by immobilized pachysolen tannophilus

The yeast Pachysolen tannophilus was entrapped in calcium alginate beads to ferment D-xylose on a continous basis in the presence of high cell densities. Experimental operating variables included the feed D-xylose concentration, the dilution rate, and the fermentor biomass concentration. Under favorable operating conditions, cultures retained at least 50% of their initial productivity after 26 days of operation. The specific ehanol production rate was dependent on the substrate level in the fermentor, passing through an optimum when the D-xylose concentration was between 28 and 35 g/L. Consequently, reactor productivity increased with dilution rate and feed D-xylose concentration until a maximum was reached. The ethanol content of the effluent always decreased with increasing dilution rate, but excessive dilution rates diminished the ethanol content without increasing productivity. Unlike production rate, ethanol yield declined monotonically from 0.35 g/g as the fermentor substrate concentration increased. The yield was 69% of that theoretically possible when the D-xylose concentration was near zero, as opposed to 42% when it was in the range supporting the optimum specific rate of ethanol production. As long as D-xylose was supplied to cells faster than they could consume it, productivity increased with the mass of cells immobilized. The effectiveness factor associated with the calcium alginte beads used in this system was 0.4, indicating that only 40% of the entrapped biomass was effective in converting D-xylose to ethanol because of diffusion limitations.     

Studies on the production of Scytalidium acidophilum biomass

Summary The conversion of nutrient-supplemented and non-supplemented acid-extracts from peat to biomass of the acid-resistant fungus Scytalidium acidophilum is described. Yeast extract and several inorganic salts were tested as nutrient supplement to the peat extract in shake-flask experiments and in an agitated and aerated fermentor. The best results were obtained in the fermentor, with 0.3% yeast extract, which produced 6.2 g dry biomass/1 with a yield of 41% and an efficiency of 30%, at 200 rpm and 1.75 vvm in 8 days. Although higher agitation speeds appeared detrimental to the mycelial physiology, it was detected that the dissolved oxygen concentration at 200 rpm could limit the growth of S. acidophilum if higher biomass concentrations are obtained. The potential for utilizing the residual fermentation medium as a plant liquid fertilizer is reported.     

Lipase production of Aspergillus oryzae

Aspergillus oryzae produced a small amount of lipase (0.05–0.8 U/wet-g of solid medium) in solid cultures, in contrast to the larger amount (0.46 U/ml) in a shake-flask culture in a modified GYP medium containing 2% glucose, 1% yeast extract and 2% Polypepton. Optimum conditions of lipase production in the submerged culture of A. oryzae were determined in terms of pH, composition of medium, and temperature. In a shake-flask culture at 28°C, the maximum amount of lipase increased to 0.78 U/ml upon the addition of 3% soybean oil to the modified GYP medium. In a jar fermentor culture, 30 U/ml lipase activity was obtained after 72 h at 28°C under appropriate conditions. Lipase production was greatly influenced by the culture temperature, and the optimum temperature for lipase production was about 24°C with a narrow temperature range, which was 10 degrees lower than that for the growth. In the submerged cultures, two kinds of lipase at least exhibiting different substrate specificities were also suggested.     

Production of sorbitol and ethanol from Jerusalem artichokes by Saccharomyces cerevisiae ATCC 36859

Summary This study shows the possibile use of Jerusalem artichokes for the production of sorbitol and ethanol by Saccharomyces cerevisiae ATCC 36859. Ethanol was produced from the beginning of the process, while sorbitol production started after glucose had been entirely consumed from Jerusalem artichoke (J.a.) juice. The importance of yeast extract and inoculum concentrations on the production of sorbitol from the above raw material was demonstrated. With a low initial biomass concentration sorbitol was not produced in pure J.a. juice. When the juice was supplemented with 3% yeast extract, the concentration of sorbitol was 4.6%. The sorbitol, ethanol and biomass yields (gram of product produced per gram of sugars consumed) were 0.259, 0.160 and 0.071 at the end of the process respectively. Adding glucose to increase its concentration to about 9% in the J.a. juice with 3% yeast extract had a positive effect on the production of ethanol, while commencement of the production of sorbitol was delayed and its final concentration was less than 50% of its concentration in the medium without added glucose. The effect of glucose was much stronger when it was added during the process than when added at the beginning of the process. Offprint requests to: Z. Duvnjak     

Optimization of culture conditions for production of yeast biomass using bamboo wastewater by response surface methodology

Response surface methodology (RSM) was applied to optimize culture conditions for the growth of Candida utilis with bamboo wastewater. A significant influence of initial pH, fermentation time and yeast extract on biomass of C. utilis was evaluated by Plackett–Burman design (PBD). These factors were further optimized using a central composite design (CCD) and RSM. A combination of initial pH 6.1, fermentation time 69 h and yeast extract 1.17 g/L was optimum for maximum biomass of C. utilis. A 1.7-fold enhancement of biomass of C. utilis was gained after optimization in shake-flask cultivation. The biomass of C. utilis reached 19.17 g/L in 3 L fermentor.     

Alkaline lipase activity from the marine protists,thraustochytrids

Two thraustochytrid protists of the genus Thraustochytrium isolated from coastal and mangrove habitats of Goa, India were studied for extracellular alkaline lipase production. Maximum lipase production was supported by a combination of peptone and yeast extract in the growth medium while strong inhibition of enzyme production was observed in presence of glucose. The inducible nature of the enzyme production was evidenced by the requirement of olive oil in the medium. Lipase production was salt-dependent and optimum production required 3.4% (w/v) crude sea salt. Ideal conditions for maximum production of lipases were therefore adopted as incubation at 30 ± 2°C for 168 h at an initial pH of 6.0 in a medium consisting of 0.5% peptone, 0.01% yeast extract, 0.5% olive oil and 3.4% crude salt. Extracellular lipase production by the two thraustochytrid isolates [designated TZ (ATCC #PRA-295) and AH-2 (ATCC #PRA-296)] was increased threefold under these optimized culture conditions. This appears to be the first report on optimization of cultivation conditions for the production of alkaline lipases by thraustochytrids.     

Influence of pH,nitrogen and phosphorus sources on the production of hepatitis B virus pre-S2 antigen by Hansenula polymorpha

Experimental design techniques were used to study the influence of the composition of the culture medium on the production of hepatitis B virus pre-S2 antigen by the methylotrophic yeast Hansenula polymorpha. pH, phosphoric acid, ammonium chloride and yeast extract concentrations were selected as experimental factors and their influence was investigated using Central Composite design techniques. The results indicated that antigen yield was maximized at high pH and in a culture medium containing both ammonium chloride and yeast extract. Phosphoric acid was found to have a detrimental effect on antigen production. This study allowed a 50% increase in antigen production in a medium in which the yeast extract cocentration was decreased to 32 g/1. These optimal conditions have been confirmed with an octagonal design experiment. Moreover, it was shown that the antigen produced was very stable up to at least 8 days after induction and that the yeast extract concentration could be lowered to 22 g/1 without apprciable effect on antigen yield. The increase in antigen production was not due to an increase in cell biomass, since no correlation could be found between these two parameters. The newly defined culture medium should allow a greatly increased antigen production at the fermentor level, at a lower cost and with minimal operational problems.Correspondence to: D. Groleau     

Effect of lard oil,olive oil and castor oil on oxygen transfer in an agitated fermentor

Adding lard oil, olive oil or castor oil into a baffled and agitated fermentor decreased the volumetric oxygen transfer coefficient (K_La) in the low concentration range. However, K_La was increased when concentration reached 0.25% (v/v) at 400 rpm. Experimental results indicated that 1% (v/v) olive oil was as good as 0.1% (v/v) polypropylene glycol when added to a yeast fermentation.     

Physiological, biochemical, and mathematical studies of micro-aerobic continuous ethanol fermentation by Saccharomyces cerevisiae. I: hysteresis, oscillations, and maximum specific ethanol productivities in chemostat culture

The growth and metabolism of Saccharomyces cerevisiae was studied in steady-state chemostat cultures under conditions of scarce oxygen and excess glucose. The specific ethanol productivity and specific glucose uptake rate were stimulated by 50% within a narrow range of air/nitrogen mixtures to the fermentor. Fermentation was inhibited at slightly higher and lower air/nitrogen ratios, confirming similar results by previous investigators. This stimulation could not be caused by obvious mechanisms, such as the Pasteur or Crabtree effects. Since this maximum in the fermentation rate occurred in a steady-state chemostat and at a constant dilution rate, the ATP yield of the culture necessarily attained a minimum. Thus, changes in the energetic efficiency of growth or the degree of wasting of ATP were surmised. The steady-state biomass concentration at various oxygenation rates exhibited hysteresis phenomena. Ignition and extinction of the biomass concentration occurred as critical oxygen feed rates were passed. The hysteresis was prevented by adding yeast extract to or reducing the antifoam concentration in the medium. These medium alterations had the simultaneous effect of stimulating the fermentation rate, suggesting that ATP has a critical role in dictating the biomass concentration in micro-aerobic culture. Silicone polymer antifoam was found to stimulate glycerol production at the expense of ethanol production, having consequences for the energy generation and the biomass concentration of the culture.     

Experimental simulation of oxygen profiles and their influence on baker's yeast production: II. Two-fermentor system

A reactor configuration consisting of two reactors with an exchange flow was used for the experimental simulation of large-scale conditions. The influence of fluctuations in oxygen concentration on the growth and metabolite production of baker's yeast was investigated by sparging one fermentor with air and one with nitrogen gas. It was found that the biomass yield decreased and the metabolite formation increased with rising circulation time (longer oxygen-unlimited and oxygen-limited periods). Not only was the performance of the oxygen-limited fermentor characterised by (partly) reductive metabolism, but that of the oxygen-unlimited fermentor as well. The results of the experiments in this reactor system were compared with those from the experiments carried out in a one-fermentor system with periodically changing oxygen concentrations. The formation of acetic acid, which is characteristic for transient states, showed a distinct difference between the two reactor systems.     

Variations of alcohol dehydrogenase activity and fermentative pyruvate,ethanol production of F. equiseti and F. acuminatum depend on the yeast extract and urea concentrations

In this study, pyruvate production of Fusarium equiseti was significantly increased when the yeast extract concentration was raised from 5 to 25 g/L while it was increased to only up to 10 g/L yeast extract in F. acuminatum. Upon supplementation with urea as an alternative nitrogen source, production of pyruvate for both of the Fusarium species were decreased with respect to increase in urea concentration in medium. On the other hand, ethanol production and alcohol dehydrogenase activity of F. equiseti were decreased approximately 1.9- and 1.6-fold with an increase in yeast concentration from 5 to 25 whereas the levels of F. acuminatum were increased 2.3- and 1.8-fold, respectively. In addition, ethanol productions and ADH activities in F. equiseti and F. acuminatum significantly increased on the 12th day up to 15 and 25 g/L urea concentrations, respectively. However, they were significantly decreased under these conditions at higher nitrogen sources. In addition, ethanol production and alcohol dehydrogenase activity in urea supplemented medium were higher than yeast extract supplemented. The results may suggest that the pyruvate, ethanol production and ADH enzyme activity variations and balance between aerobic and anaerobic respiration in F. equiseti and F. acuminatum were effected from yeast extract and urea concentrations in the nutrient medium.     

Citric acid production by Yarrowia lipolytica: Effect of nitrogen and biomass concentration on yield and productivity

Summary Citric acid yields of Yarrowia lipolytica (NRRL Y-1095) grown on glucose ranged from 0.38–0.77 g/g and were dependent on both biomass and nitrogen concentration (as NH₄Cl and yeast extract). Increasing the biomass concentration by 3% (w/v) increased fermentor productivities from 0.6 to 1.22 g citric acid/L h.     

Cultivation of the yeast Candida lipolytica on hydrocarbons. II. One-stage continuous cultivation on gas oil

Continuous cultivation of the yeast Candida lipolytica on gas oil was studied from the viewpoint of biomass production and oil deparaffination. Optimum conditions wore found at the dilution rate D = 0.16–0.19 when biomass productivity 1.7 g/l/hr and yield coefficient. y = 0.92 were achieved. At deparaffination to the same freezing point, more than double the production of biomass and deparaffined oil during a given time unit was achieved in a continuous process than in batch cultivation. Consumption of substrate was followed in both cultivation processes and it was confirmed that individual n-alkanes of gas oil were degraded at various rates and yields. Results proved optimum cultivation conditions to depend on concentration and composition of the paraffinic fraction of gas oil used. To achieve these conditions the continuous process may be controlled by choice; of suitable dilution rate and concentration of gas oil.     

Ultrasonic pretreatment and acid hydrolysis of sugarcane bagasse for succinic acid production using Actinobacillus succinogenes

Immense interest has been devoted to the production of bulk chemicals from lignocellulose biomass. Diluted sulfuric acid treatment is currently one of the main pretreatment methods. However, the low total sugar concentration obtained via such pretreatment limits industrial fermentation systems that use lignocellulosic hydrolysate. Sugarcane bagasse hemicellulose hydrolysate is used as the carbon and nitrogen sources to achieve a green and economical production of succinic acid in this study. Sugarcane bagasse was ultrasonically pretreated for 40 min, with 43.9 g/L total sugar obtained after dilute acid hydrolysis. The total sugar concentration increased by 29.5 %. In a 3-L fermentor, using 30 g/L non-detoxified total sugar as the carbon source, succinic acid production increased to 23.7 g/L with a succinic acid yield of 79.0 % and a productivity of 0.99 g/L/h, and 60 % yeast extract in the medium could be reduced. Compared with the detoxified sugar preparation method, succinic acid production and yield were improved by 20.9 and 20.2 %, respectively.     

Optimizing conditions for poly(β-hydroxybutyrate) production by <Emphasis Type="Italic">Halomonas boliviensis</Emphasis> LC1 in batch culture with sucrose as carbon source

Halomonas boliviensis LC1 is able to accumulate poly(β-hydroxybutyrate) (PHB) under conditions of excess carbon source and depletion of essential nutrients. This study was aimed at an efficient production of PHB by growing H. boliviensis to high cell concentrations in batch cultures. The effect of ammonium, phosphate, and yeast extract concentrations on cell concentration [cell dry weight (CDW)] and PHB content of H. boliviensis cultured in shake flasks was assayed using a factorial design. High concentrations of these nutrients led to increments in cell growth but reduced the PHB content to some extent. Cultivations of H. boliviensis under controlled conditions in a fermentor using 1.5% (w/v) yeast extract as N source, and intermittent addition of sucrose to provide excess C source, resulted in a polymer accumulation of 44 wt.% and 12 g l⁻¹ CDW after 24 h of cultivation. Batch cultures in a fermentor with initial concentrations of 2.5% (w/v) sucrose and 1.5% (w/v) yeast extract, and with induced oxygen limitation, resulted in an optimum PHB accumulation, PHB concentration and CDW of 54 wt.%, 7.7 g l⁻¹ and 14 g l⁻¹, respectively, after 19 h of cultivation. The addition of casaminoacids in the medium increased the CDW to 14.4 g l⁻¹ in 17 h but reduced the PHB content in the cells to 52 wt.%.     

The production of recombinant beta-galactosidase inEscherichia coli in yeast extract enriched medium

Summary The productivity ofEscherichia coli biomass and recombinant beta-galactosidase was increased in Luria broth (LB) enriched with yeast extract. In flask culture under conditions of LB limitation, yeast extract suplementation gave the highest biomass (strain HB101/pRW756) stimulation per unit of component added compared with supplementation by various amounts of amino acids, vitamins, minerals, purines/pyrimidines, tryptone, casamino acids, casein peptone or gelatin peptone. The biomass production ofE. coli HB101/pRW756, XL-1 blue/puc118, XL-1 Blue FF/puc118 and TB-1/p1034 cells was stimulated in fermentor-scale experiments with additional yeast extract in LB. Total beta-galactosidase production from plasmid genes in fermentor-scale experiments was increased 105.4% in XL-1 blue/puc118 cells, 365.5% in XL-1 blue FF/puc118 cells and 421.4% in TB-1/p1034 cells by 0.5%, 1% and 1% weight per volume of additional yeast extract in LB, respectively. Depending on different strains, the increase of the enzyme production was obtained either by increased biomass, or the combination of enhanced gene expression and increased biomass. Neither the biomass nor beta-galactosidase production was stimulated in N4830/p1034 cells by the increase in yeast extract concentration in the medium.     

Development of a new commercial-scale airlift fermentor for rapid growth of yeast

To grow yeast rapidly, it is necessary to supply sufficient oxygen to the yeast and to effectively remove the heat of the fermentation. We succeeded in developing a commercial-scale fermentor for growing a food yeast (Candida utilis) to produce RNA rapidly. This fermentor is an internal-loop airlift type with vertical heat transfer tubes between inner and the outer columns. The volume of the fermentor is 145 m³ (working volume 75 m³). The oxygen transfer rate (OTR) was 9.9 kg-O₂/m³/h using a superficial gas velocity of 30 cm/s based on the outer column. Much of the heat of fermentation and the energy resulting from aeration could be removed effectively by the heat transfer tubes. This unique airlift fermentor was driven at a dilution rate of 0.43 h⁻¹ for about 70 d, with the yeast concentration being maintained at 22.8 kg-dry cell/m³. The yeast production rate was 9.79 kg-dry cell/m³/h. Compared with a traditional stirred-type fermentor, two Vogelbush-type fermentors and another airlift fermentor, our fermentor was far superior with respect to OTR and yeast productivity.     

Pyranose 2-oxidase (P2O): Production from Trametes versicolor in Stirred Tank Reactor andits Partial Characterization

Abstract

Optimization of pyranose-2-oxidase (P2O) production conditions from Trametes versicolor was carried out in shaking cultures containing glucose, malt, and yeast extracts; the optimum concentration values were found to be 1.5% glucose, 1.0% yeast extract, and 1.0% malt extract, pH 5.0, temperature, 26°C, and agitation rate 150 rpm. For the first time, P2O production was also carried out in a stirred tank reactor (STR) with 2.2 L working volume in the optimized medium composition, and biomass, P2O activity, protein, nitrogen and glucose concentrations were also monitored besides pH and dissolved oxygen (DO). In the STR, P2O activity peaked on day 9. Partial enzyme characterization occurred and optimum pH and temperature were detected as 7.0 and 37°C, respectively. K _m value was found to be 1.009 mM.