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1.
Dissociated cells separated from a natural colony of Nostoc flagelliforme were cultivated heterotrophically in the darkness on glucose under fed-batch culture conditions. The effects of carbon sources (glucose, fructose, xylose, and sucrose) and concentrations on cell growth and extracellular polysaccharide (EPS) production were investigated. At harvest, the culture contained 1.325 g L?1 of biomass and 117.2 mg L?1 of EPS, respectively. The gravimetric EPS production rate was 16.7 mg g?1 cell dry weight day?1, which was 2.1 times higher than previously reported. Using sigmoid model, batch fermentation of N. flagelliforme was kinetically simulated to obtain equations including substrate consumption, biomass growth, and EPS accumulation. Results from a simulation correlated well with the experimental ones, indicating that this method could be useful in studying EPS production from batch and fed-batch cultures.  相似文献   

2.
AIMS: The objective of the present study was to determine the optimal culture conditions for mycelial biomass and exo-polysaccharide (EPS) by Cordyceps militaris C738 in submerged culture. METHODS AND RESULTS: The optimal temperatures for mycelial biomass and EPS production were 20 degrees C and 25 degrees C, respectively, and corresponding optimal initial pHs were found to be 9 and 6, respectively. The suggested medium composition for EPS production was as follows: 6% (w/v) sucrose, 1% (w/v) polypeptone, and 0.05% (w/v) K2HPO4. The influence of pH on the fermentation broth rheology, morphology and EPS production of C. militaris C738 was carried out in a 5-l stirred-tank fermenter. The morphological properties were comparatively characterized by pellet roughness and compactness by use of image analyser between the culture conditions with and without pH control. The roughness and compactness of the pellets indicated higher values at pH-stat culture (pH 6.0), suggesting that larger and more compact pellets were desirable for polysaccharide production (0.91 g g(-1) cell d(-1). CONCLUSIONS: Under the optimized culture conditions (with pH control at 6), the maximum concentration of biomass and EPS were 12.7 g l(-1) and 7.3 g l(-1), respectively, in a 5-l stirred-tank fermenter. SIGNIFICANCE AND IMPACT OF THE STUDY: The critical effect of pH on fungal morphology and rheology presented in this study can be widely applied to other mushroom fermentation processes.  相似文献   

3.
A new kind of extracellular polysaccharide (EPS) from Pseudomonas fluorescens PGM37 was obtained and culture media was optimized using the statistical methods single factor experiments and response surface methodology (RSM) design. As a result, the optimum cultivation conditions initial pH value, medium volume, inoculum size, temperature, and rotation speed were 7.5, 100 mL/250 mL, 5 %, 28 °C, and 180 rpm, respectively. The optimized media: sucrose 36.23 g?L?1, yeast extract 3.32 g?L?1, sodium chloride 1.13 g?L?1, and calcium chloride 0.20 g?L?1. The maximum predicted yield of EPS was 10.1163 g?L?1 under these conditions. The validation data was 10.012 g?L?1, which could strongly confirm the correlation between the experimental and theoretical values. Gas Chromatography analysis revealed that the polymer was made up of mannose and glucose in the ratio of 1:1. Infrared spectroscopy showed that the polysaccharide had β-D-pyranoid configuration and contained no other substituent. Graded by different multiples of alcohol after specific degradation by enzyme and then detected by LC-ESI-MS, the EPS structure was β-D-Glcp-(1, 4)-β-D-Manp-(1, 4)-β-D-Glcp-(1, 4)-β-D-Manp. The moisture retention ability of the EPS was found to be superior to glycerol and only a little inferior to hyaluronic acid (HA), which presented potential application value in cosmetics and clinical medicine fields.  相似文献   

4.
To probe the effects of renewal regime on the production of polysaccharides, Porphyridium cruentum was cultured semi-continuously in flat plate photobioreactor. Uniform design was used to optimize renewal conditions. Quadratic mathematic models related to productivity, total recovery yield of biomass and polysaccharides were set up to clarify the influence of individual factors and their interactions. According to the mathematic models, the optimal semi-continuous condition for total yield of polysaccharide was NaNO3 3.5 g/L, renewal rate 27%, renewal period 2.91 days. The optimal condition for polysaccharide output rate was NaNO3 0.5 g/L, renewal rate 5%, renewal period 7 days. With the optimal renewal regime, the maximal total recovery yields of polysaccharide achieved at 29.4 g, which was 1.57 times higher than that of batch cultivation. The maximum output rate of polysaccharide was 68.64 mg/L per day, which was 2.02 times higher than previous reported data.  相似文献   

5.
In this study, we examined the long-term effects of copper oxide nanoparticles (CuO NPs) on the production and properties of EPS and the resulting variations in surface physicochemical characteristics of biofilms in a sequencing batch biofilm reactor. After exposure to 50 mg/L CuO NPs for 45 days, the protein (PRO) and polysaccharide (PS) contents in loosely bound EPS (LB-EPS) decreased as the production of LB-EPS decreased from 34.4 to 30 mg TOC/g EPS. However, the production of tightly bound EPS (TB-EPS) increased by 16.47 % as the PRO and PS contents increased. The content of humic-like substances (HS) increased significantly, becoming the predominant constituent in EPS with the presence of 50 mg/L CuO NPs. Furthermore, the results of three-dimensional excitation-emission fluorescence spectra confirmed the various changes in terms of the LB-EPS and TB-EPS contents after exposure to CuO NPs. Fourier transform infrared spectroscopy showed that the –OH and –NH2 groups of proteins in EPS were involved in the reaction with CuO NPs. Moreover, the chronic exposure to CuO NPs induced a negative impact on the flocculating efficiency of EPS and on the hydrophobicity and aggregation ability of microbial cells. The PRO/PS ratios of different EPS fractions were consistent with their hydrophobicities (R 2 >0.98) and bioflocculating efficiencies (R 2 >0.95); however, there was no correlation with aggregation ability. Additionally, the presence of bovine serum albumin (BSA) prevented the physical contact between CuO NPs and EPS as a result of NP aggregation and electrostatic repulsion.  相似文献   

6.
In this study, various additives including organic acids, alcohols, vegetable oils, surfactants and polymers were added in the cultural medium to investigate their stimulatory effects on Grifola umbellate mycelia growth and exopolysaccharide (EPS) production. It was found that the commonly used stimulatory additives, effective in other mushrooms’ cultures, exhibited negative results in Grifola umbellata submerged culture. In contrast, the polymer additive, polyethylene glycol (PEG), displayed an effective stimulatory effect on both biomass and EPS productions. With the addition of PEG8 (molecular weight: 8,000 Da), the mycelial biomass production at day 12 was increased from 4.69 to 6.30 g/L, accounting for a 34% increase. Meanwhile, the EPS production was enhanced from 0.478 to 0.767 g/L, accounting for 60% increase.  相似文献   

7.
The aim of the present study was to evaluate the effect of the initial caffeine concentration (1–8 g/L) on growth and caffeine consumption by Aspergillus tamarii as well as pellet morphology, in submerged fermentation. Caffeine was used as sole nitrogen source. At 1 g/L of initial caffeine concentration, caffeine degradation was not affected, resulting in a production of 8.7 g/L of biomass. The highest biomass production (12.4–14.8 g/L) was observed within a range of 2 to 4 g/L of initial caffeine concentration. At these initial caffeine concentrations, after 96 h of fermentation, 41–51 % of the initial caffeine was degraded. Using an initial caffeine concentration of 2–3 g/L, the highest specific growth rate was observed (μ?=?0.069 1/h). Biomass production decreased at 8 g/L of initial caffeine concentration. A. tamarii formed mainly pellets at all concentrations tested. The size of the pellet decreased at a caffeine concentration of 8 g/L.  相似文献   

8.
Netrium digitus is a representative of the species-rich class Zygnematophyceae (Streptophyta). Its intensive extracellular polysaccharide (EPS) production makes this alga interesting for biotechnological applications with a focus on cosmetics and food additives. Quantitative data on growth and EPS production in suspension and, for the first time, in immobilized culture using lab-scale porous substrate bioreactors, so-called Twin-Layer (TL) systems, is presented. It is shown that the cell as well as the EPS dry weight content is increased at least sixfold in immobilized compared to suspension culture. Due to the high amount of EPS, the biofilms reach a thickness of more than 8 mm after 27 days at 70 μmol photons m?2 s?1 and with 1.5% CO2 supply. Frequent exchange of the growth medium results in a linear cell biomass increase of 2.02?±?0.09 g m?2 growth area day?1 compared to 2.99?±?0.09 g m?2 day?1, when the medium is not exchanged. Under this mode of cultivation, the EPS production is lower and a final concentration of 12.18?±?1.25 g m?2 compared to 20.76?±?0.85 g m?2, when medium was exchanged, is reached. It is clearly demonstrated that the relatively slow growing, but excessively EPS producing, microalgal species N. digitus can be grown in porous substrate bioreactors and that this culturing technique is a promising alternative to suspension culture for the Zygnematophyceae.  相似文献   

9.
The effect of NaCl on cell growth and polysaccharide biosynthesis in the medicinal mushroom Phellinus linteus was studied. With the increase of NaCl concentration between 1 g/l and 7 g/l in the culture medium, the cell growth and intracellular polysaccharide (IPS) accumulation were decreased; extracellular polysaccharide (EPS) concentration was enhanced, with an increase of NaCl concentration from 1 g/l to 3 g/l. Under the optimum NaCl concentration of 3 g/l, the maximum EPS and IPS production reached 2.2±0.15 g/l and 53.6±2.45 mg/g DW on day 12, which improved 32.27% and decreased 16.89% compared to the control, respectively. Both EPS and IPS showed new polysaccharide components by fractionation with DEAE-cellulose ion exchange chromatography compared to the control. The results presented in this study are considered helpful for further investigation on the diversity of polysaccharide biosynthesis of this medicinal fungus under NaCl environments.  相似文献   

10.
Exopolysaccharide produced by a unique avirulent Bacillus anthracis strain PFAB2 of hot spring origin has been characterized and its functional properties are investigated which is a first report. Maximum yield of EPS is 7.66 g/l with 2% glucose and 1% peptone as optimum carbon and nitrogen source respectively. The EPS is found to be a homopolymer consisting of only glucose as principle monosaccharide component. Through 1H NMR study, different dextran-like proton peaks are observed. Molecular weight of the EPS resembles low molecular weight bacterial origin polysaccharides. Melting transition of the EPS has started after 276 °C which indicates good thermal stability. The EPS also shows potent antioxidant activity in terms of DPPH and ABTS mediated free radical scavenging property compared to standard ascorbic acid. Emulsifying property of the EPS is also observed and has shown good emulsification of vegetable oils. The polysaccharide forms a thermo resistant gel during the heating phase, with G′ higher than G″ indicating excellent shear-thinning behaviour and viscoelastic nature of the EPS.  相似文献   

11.
Production of biomass and extracellular polysaccharide (EPS) from psychrophilic Sporobolomyces salmonicolor AL1 in a stirred bioreactor was studied. The aspects of production technical-scale parameters, namely, bioreactor flow field, biomass and EPS production rates, oxygen mass transfer per input power, as well as important product properties, such as rheology and stability of EPS mixtures, were considered. The bioprocess was found to proceed in non-Newtonian flow with consistency coefficient rising typically to 0.03 Pa.sn and flow index declining to 0.7. Flow modeling was carried out and showed good homogenization for substrate delivery at agitation rates exceeding 400 rpm. Agitation rates lower than 400 rpm were considered counterproductive due to flow field non-uniformity. The cell density reached 5 g/l and EPS production yield reached 5.5 g/l at production rate 0.057 g EPS/l per hour (0.01 g EPS/g biomass per hour). Oxygen uptake rate and oxygen transfer rate were in the range of 0.5–1.7 mmolO2/l per hour and 2–4.7 mmolO2/l per hour, respectively. The mass transfer coefficient at reaction conditions was found to be in the range $ {K_L}a\tilde{\mkern6mu} 0.004-0.01{{\mathrm{s}}^{-1 }} $ . The bioprocess biological performance was higher at moderate agitation speed and revealed biomass diminution and cell inactivation by increasing impeller revolutions and shear rate. The product EPS was found to introduce shear-thinning behavior in water solutions with apparent viscosity of up to 30 mPa.s and to stabilize 1–2 % oil-in-water emulsions improving their lipophilic properties. The emulsion dispersion index was found to be comparable with the one of Arlacel 165, the emulsifier used in cosmetic. The long-term performance of the complex cream mixtures of the glucomannan prepared in commercial format was found promising for further application.  相似文献   

12.
The production of extracellular polysaccharide, EPS WN9, fromPaenibacillus sp. and its suitability as a viscosity modifying admixture for cement mortar mixing were investigated. After 48 h culture in an optimized medium, cell growth and EPS production were 1,2 g/L and 4.0 g/L, respectively. By adding EPS WN9 to mortar, it was possible to prepare a homogeneous mortar without material segregation and excess air entrapment. The optimal amount of EPS addition to mortar was found to be 0.02 to 0.05%(w/w) of the cement used. Increasing the dosage of EPS WN9 from 0 to 0.05%(w/w) resulted in a setting retardation of 0.14 h to 0.8 h and an increase in the compressive strength of mortar of 10 to 20%.  相似文献   

13.
Due to the amount of nutrients available in the agroindustrial wastes, these can be converted into high added-value products by the action of microorganisms in solid-state bioprocesses. The aim of this work was to evaluate the growth physiology and lipase production of the fungus Lichtheimia ramosa using the following Brazilian savannah fruit wastes as substrates: bocaiuva (Acrocomia aculeata), pequi (Caryocar brasiliense), guavira (Campomanesia pubescens), araticum (Annona crassiflora) and seriguela (Spondias purpurea). These residues were triturated, homogenized, adjusted to pH 5.0 and 60 % moisture, sterilized and packaged in plastic tray-type bioreactors before inoculation with 10 % (w/v) of L. ramosa pre-culture medium. The cultivations were conducted in a bacteriological incubator at 30 °C for 40 days. Samples were taken every 5 days and fungi and bacteria contents, proximate composition and lipase activity were evaluated. The maximum fungal counting was observed between 25 and 35 days. L. ramosa reached the stationary phase next to 40 days in all substrates. Mesophilic and psicrophilic aerobic bacteria were not detected. Protein enrichment was obtained for all media, being superior in seriguela residues (391.66 %), followed by pequi (160.04 %), araticum (143.31 %), guavira (102.42 %), and bocaiuva (67.88 %). Lipase production was observed in all cultivated media, except in pequi residues that showed decreasing lipase activity. The higher production was observed in guavira (1.12 U/g) followed by araticum (0.58 U/g), seriguela (0.41 U/g) and bocaiuva (0.21 U/g) waste substrates. It was concluded that the studied fruit wastes have been successfully utilized as substrates for protein enrichment and lipase production with L. ramosa.  相似文献   

14.
We investigated the enhancement of bioethanol production in Enterobacter aerogenes ATCC 29007 by co-fermentation of carbon sources such as glycerol, glucose, galactose, sucrose, fructose, xylose, starch, mannitol and citric acid. Biofuel production increases with increasing growth rate of microorganisms; that is why we investigated the optimal growth rate of E. aerogenes ATCC 29007, using mixtures of different carbon sources with glycerol. E. aerogenes ATCC 29007 was incubated in media containing each carbon source and glycerol; growth rate and bioethanol production improved in all cases compared to those in medium containing glycerol alone. The growth rate and bioethanol production were highest with mannitol. Fermentation was carried out at 37 °C for 18 h, pH 7, using 50 mL defined production medium in 100 mL serum bottles at 200 rpm. Bioethanol production under optimized conditions in medium containing 16 g/L mannitol and 20 g/L glycerol increased sixfold (32.10 g/L) than that containing glycerol alone (5.23 g/L) as the carbon source in anaerobic conditions. Similarly, bioethanol production using free cells in continuous co-fermentation also improved (27.28 g/L) when 90.37 % of 16 g/L mannitol and 67.15 % of 20 g/L glycerol were used. Although naturally existing or engineered microorganisms can ferment mixed sugars sequentially, the preferential utilization of glucose to non-glucose sugars often results in lower overall yield and productivity of ethanol. Here, we present new findings in E. aerogenes ATCC 29007 that can be used to improve bioethanol production by simultaneous co-fermentation of glycerol and mannitol.  相似文献   

15.
Cuphea aequipetala Cav. (Lythraceae), a species highly valued for its medicinal properties, is threatened in the wild. To provide an alternative source of material for production of bioactive compounds, we established adventitious root cultures of C. aequipetala and determined their phenolic compounds contents and antioxidant activity. Cultures were initiated from root tips of in vitro C. aequipetala plantlets and were grown in B5 or SH culture medium containing either indole butyric acid (IBA) or α-naphthalene acetic acid at 0, 5 or 10 µM. The maximum root biomass (1.6 g/L dry mass (DM) per L medium) was recorded after 14 days of growth in B5 + 5 µM IBA. Roots in B5 medium remained green, whereas they tended to oxidize in SH medium. The highest contents of total phenolic compounds (9.1 ± 0.1 µg gallic acid equivalents/g DM) and flavonoids (37.5 ± 0.7 µg quercetin equivalents/g DM) were in roots grown in B5 + 5 µM IBA after 14 days of growth. Root cultures accumulated mainly flavan-3-ols, whereas roots or leaves from whole plants accumulated mainly flavonols. We analyzed the antioxidant properties of root extracts using in vitro assays. Roots grown in B5 medium showed stronger free-radical scavenging activity than that of roots grown in SH medium. Our results show that adventitious root cultures of C. aequipetala are a promising system for research on antioxidant compounds biosynthesis and for scaled-up production of useful biological materials.  相似文献   

16.
Gordonia polyisoprenivorans CCT 7137 was isolated from groundwater contaminated with leachate in an old controlled landfill (São Paulo, Brazil), and cultured in GYM medium at different concentrations of sugarcane molasses (2%, 6%, and 10%). The strain growth was analyzed by monitoring the viable cell counts (c.f.u. mL?1) and optical density and EPS production was evaluated at the end of the exponential phase and 24 h after it. The analysis of the viable cell counts showed that the medium that most favored bacterial growth was not the one that favored EPS production. The control medium (GYM) was the one that most favored the strain growth, at the maximum specific growth rate of 0.232 h?1. Differences in bacterial growth when cultured at three different concentrations of molasses were not observed. Production of EPS, in all culture media used, began during the exponential phase and continued during the growth stationary phase. The highest total EPS production, after 24 h of stationary phase, was observed in 6% molasses medium (172.86 g L?1) and 10% (139.47 g L?1) and the specific total EPS production was higher in 10% molasses medium (39.03 × 10?11 g c.f.u.?1). After the exponential phase, in 2%, 6%, and 10% molasses media, a higher percentage of free exopolysaccharides (EPS) was observed, representing 88.4%, 62.4%, and 64.2% of the total, respectively. A different result was observed in pattern medium, which presented EPS made up of higher percentage of capsular EPS (66.4% of the total). This work is the first study on EPS production by G. polyisoprenivorans strain in GYM medium and in medium utilizing sugarcane molasses as the sole nutrient source and suggests its potential use for EPS production by G. polyisoprenivorans CCT 7137 aiming at application in biotechnological processes.  相似文献   

17.
Paecilomyces variotii is a filamentous fungus that occurs worldwide in soil and decaying vegetation. Optimization of the fermentation process for exopolysaccharide (EPS) production from the fungus P. variotii, structure determination and immuno-stimulating activity of EPS were performed. Response surface methodology (RSM) coupled with central composite design (CCD) was used to optimize the physical and chemical factors required to produce EPS in submerged fermentation. Preliminary investigations to choose the three factors for the present work were made using a factorial experimental design. Glucose, ammonium nitrate (NH4NO3) and pH were used as variables for which, with constant temperature of 28 °C and agitation of 90 rpm, the optimal process parameters were determined as glucose values of 0.96%, NH4NO3 0.26% and pH 8.0. The three parameters presented significant effects. In this condition of culture, the main composition of the isolated EPS was a linear β-(1 → 6)-linked-D-glucan, as determined by Nuclear Magnetic Resonance (NMR) and methylation analysis. This polysaccharide is a very unusual as an EPS from fungi, especially a filamentous fungus such as P. variotii. Murine peritoneal macrophages cultivated with β-glucan for 6 and 48 h showed an increase in TNF-α, IL-6 and nitric oxide release with increased polysaccharide concentrations. Therefore, we conclude that the β-(1 → 6)-linked-D-glucan produced in optimised conditions of P. variotii cultivation has an immune-stimulatory activity on murine macrophages.  相似文献   

18.
The present study investigated the feasibility of cultivating microalgae in dairy farm wastewater. The growth of microalgae and the removal rate of the nutrient from the wastewater were examined. The wastewater was diluted 20, 10 and 5 times before applied to cultivate microalgae. A 5 dilution yielded 0.86 g/L dry weight in 6 days with a relative growth rate of 0.28 d?1, the 10× dilution gave 0.74 g/L and a relative growth rate of 0.26 d?1 while the 20× dilution 0.59 g/L and a relative growth rate 0.23 d?1. The nutrients in the wastewater could be removed effectively in different diluted dairy wastewater. The greatest dilution (20×) showed the removal rates: ammonia, 99.26%; P, 89.92%; COD, 84.18%. A 10× dilution removal% was: ammonia 93; P 91 and COD 88. The 5× dilution removal% was: ammonia 83; P 92; COD 90.  相似文献   

19.
The fermentation of Grifola frondosa was investigated in the shake flasks and a 5-L jar fermenter in batch and fed-batch modes. In the shake-flask experiments, the preferable mycelial growth and exopolysaccharide (EPS) production was observed at relatively low pH; maltose and glucose were preferred carbon sources for high mycelial production. The EPS was doubled after 13 d of cultivation when glucose was increased from 2% to 4%. Yeast extract (YE) (0.4%) in combination with corn steep powder (CSP) (0.6%) and YE (0.8%) in combination with CSP (1.2%) were preferred nitrogen sources for high mycelial production and EPS production, respectively. All plant oils tested significantly stimulate cell growth of G. frondosa but they failed to enhance EPS production. The EPS products usually consisted of two fractions of different molecular sizes varied by the plant oils used. The fed-batch fermentation by glucose feeding was performed when the glucose concentration in the medium was lower than 0.5% (5g/L), which greatly enhanced the accumulation of mycelial biomass and EPS; the mycelial biomass and EPS were 3.97g/L and 1.04g/L before glucose feeding, which reached 8.23g/L and 3.88g/L at 13 d of cultivation. In contrast, the mycelial biomass and EPS in the batch fermentation were 6.7g/L and 3.3g/L at 13 d of cultivation.  相似文献   

20.
A haloalkaliphilic, thermophilic Bacillus strain (T14), isolated from a shallow hydrothermal vent of Panarea Island (Italy), produced a new exopolysaccharide (EPS). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain T14 was highly related (99 % similarity) to Bacillus licheniformis DSM 13T and Bacillus sonorensis DSM 13779T. Further DNA–DNA hybridization analysis revealed 79.40 % similarity with B. licheniformis DSM 13T and 39.12 % with B. sonorensis DSM 13779T. Sucrose (5 %) was the most efficient carbon source for growth and EPS production. The highest EPS production (366 mg l?1) was yielded in fermenter culture at 300 rpm after 48 h of incubation. The purified fraction EPS1 contained fructose/fucose/glucose/galactosamine/mannose in a relative proportion of 1.0:0.75:0.28:tr:tr and possessed a molecular weight of 1,000 kDa displaying a trisaccharide unit constituted by sugars with a β-manno-pyranosidic configuration. Screening for biological activity showed anti-cytotoxic effect of EPS1 against Avarol in brine shrimp test, indicating a potential use in the development of novel drugs.  相似文献   

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