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1.
A purified culture of the fungal pathogenCurvularia lunata causing leaf blight of pearl millet was used for studies on the production of cell-wall-degrading enzymes. Czapek-Dox medium
was found to be the best medium of the five different nutrient media used for the production of cellulase and growth of the
fungus. Pectolytic enzymes could not be detected under different cultural conditions. Two-week incubation period, pH 6.0 and
temperature 25°C were found to be the most favorable conditions for good growth and maximum production of cellulase by the
fungus in present studies. The results are presented and discussed in the light of the earlier findings onC. lunata. 相似文献
2.
Joint aerobic biodegradation of wastewater from table olive manufacturing industries and urban wastewater 总被引:2,自引:0,他引:2
F. J. Rivas F. J. Beltrán P. Alvarez J. Frades O. Gimeno 《Bioprocess and biosystems engineering》2000,23(3):283-286
Wastewater generated in the elaboration of table olives has been treated using activated sludge from a municipal wastewater plant after adequate acclimation. To avoid bactericide properties of some chemical structures present in this type of effluents, synthetic urban wastewater has been used to dilute the original wastewater. The main parameters affecting efficiency of biological processes have been studied. Thus, initial biomass concentration, temperature up to 303 K (upper working temperature limit = 313 K) and initial substrate concentration exerted a positive influence on COD degradation rate. The optimum pH was found to be around 7, experiencing a slight inhibition on cell activity at pH 4. Under the experimental conditions investigated other parameters like polyphenol content, absorbance at 254 nm and total organic carbon were also reduced to some extent. Only nitrates amount was increased after the biological process took place. A kinetic model based on Monod equation was proposed and applied to experimental results. The maximum specific growth rate was calculated by means of the aforementioned kinetic model. The value of this parameter as a function of temperature was fitted to an Arrhenius expression, wmax = 9.43 2 1010 exp(72021/RT) hу (R in J molу Kу283 K < T < 303 K, pH , 7-10). 相似文献
3.
The effect of copper (II) ions on the growth of three brown-rot fungi, six white-rot fungi and one blue-stain fungus in solid
medium was evaluated. The fungi were grown in malt extract agar with different concentrations of copper added, and the radial
growth rate was determined. At the end of the incubation period, the mycelial biomass and the media pH were determined. The
white-rot and blue-stain fungus grew up to 3 mM and 6 mM copper, respectively and the brown-rot fungi were the only ones that
grew up to 10 mM, with higher growth rates than those shown by the other fungi. In general, the brown-rot fungi produced greater
acidification in the culture media than the white-rot fungi and blue-stain fungus, and the acidification increased when the
amount of copper was increased. The biomass production for the different species, in the absence or presence of copper, was
not related to the radial growth rate, and the fungal species that produced the greatest biomass amounts did not correspond
to those that presented the highest growth rates. The brown-rot fungi Wolfiporia cocos and Laetiporus sulfureus and blue-stain fungus Ophiostoma sp. demonstrated greater tolerance to high copper concentrations in solid medium than the white-rot fungi, determined as
radial growth rate. On the other hand, the highest biomass producers in solid medium with copper added were the white-rot
fungi Ganoderma australe and Trametes versicolor and the brown-rot fungus Gloeophyllum trabeum. 相似文献
4.
Glucose-limited chemostats were used to determine the growth yields of biomass of Bacillus clausii PP 473-8 producing an alkaline serine protease Savinase (Novozymes A/S, Bagsværd, Denmark) and a low yield of biomass on oxygen was observed. The energy metabolism was investigated further by setting up simple stoichiometric models for growth on glucose and citrate. In order to determine the parameters in the models, a macromolecular biomass composition was determined based on measured values of protein and RNA combined with literature data. From the macromolecular composition of the biomass the theoretical co-factor and building block requirements needed for biomass formation were calculated. Using the stoichiometric models and data for growth on glucose and citrate the amount of ATP needed for biomass synthesis was estimated to 42.0 mmol ATP/gDW, the P/O ratio to 0.68 and the ATP maintenance to 2.93 mmol ATP/gDW/h. From these values it is concluded that the high oxygen consumption compared with other Bacillus species is due to a low efficiency in respiration resulting in a low P/O ratio. Finally, the energetic parameters were estimated for different architectures of the respiratory chain. 相似文献
5.
The energy parameters of Endomyces magnusii cells and mitochondria were studied under the conditions of batch and continuous cultivation at different pH of the medium containing ethanol. The yeast was found to be capable of growth in the chemostat regime at D=0.2 h-1. Changes in the pH of the medium from 3.0 to 5.6 almost did not change the parameters characterizing oxidative phoshorylation of the mitochondria (the respiration chain contained three phosphorylation points). This correlated with the nearly identical biomass yield and economical coefficient. The content of RNA, DNA and protein remained unchanged at different pH values whereas the content of lipids increased at acid pH. 相似文献
6.
Optimal conditions for the expression of a single-chain antibody (scFv) gene in Pichia pastoris 总被引:6,自引:0,他引:6
Shi X Karkut T Chamankhah M Alting-Mees M Hemmingsen SM Hegedus D 《Protein expression and purification》2003,28(2):321-330
A Pichia pastoris system was used to express a single-chain antibody (scFv) targeted against Mamestra configurata (bertha armyworm) serpins. To improve scFv production we examined parameters such as proteinase activity, temperature, cell density, osmotic stress, medium composition, pH, and reiterative induction. P. pastoris was found to express several proteases; however, adjustment of medium pH to limit their activity did not correlate with increased scFv recovery. Induction medium pH values of 6.5-8.0 were most conducive to scFv production, despite significant differences in cell growth rates. Increasing inoculum density limited growth potential but gave rise to higher levels of scFv production. Three factors, medium composition, pre-induction osmotic stress, and temperature, had the greatest effects on protein production. Supplementation of the induction medium with arganine, casamino acids, or EDTA increased scFv production several fold, as did cultivation under osmotic stress conditions during pre-induction biomass accumulation. Incubation at 15 versus 30 degrees C extended the period whereby cells were capable of producing scFv from 1 to 7 days. Under optimal conditions, yeast cultures yielded 25 mg/L of functional scFv and could be subject to five reiterative inductions. 相似文献
7.
Rhizoctonia bataticola produced the highest amounts of amylase in medium containing starch than that lacking starch within the 10 days of culture. Doubling the concentration of starch in the growth medium resulted in a near doubling of the amylase activity. Amylase production by the fungus is related to the type of carbon source in the medium with maximum amylase produced in medium containing starch. The maximum activity of the enzyme was detected in extracellular filtrates obtained from 4 days cultures. After this period, amylase activity decreased at first, and then increased through the 10 days incubation period. The fungus produced maximum levels of amylase prior to attainment of maximum mycelial biomass. Peak activity of the extracellular amylase was recorded at a temperature and pH range of 20–25°C and 4–5 respectively. The role of the exoenzyme in the deterioration of stored food products and its possible use in industrial fermentation processes are discussed. 相似文献
8.
S. Sánchez V. Bravo E. Castro A. J. Moya F. Camacho 《Bioprocess and biosystems engineering》1999,21(6):525-532
We have performed a comparative analysis of the fermentation of the solutions of the mixtures of D-glucose and D-xylose with the yeasts Pachysolen tannophilus (ATCC 32691) and Candida shehatae (ATCC 34887), with the aim of producing bioethanol. All the experiments were performed in a batch bioreactor, with a constant aeration level, temperature of 30v°C, and a culture medium with an initial pH of 4.5. For both yeasts, the comparison was established on the basis of the following parameters: maximum specific growth rate, biomass productivity, specific rate of substrate consumption (qs) and of ethanol production (qE), and overall ethanol and xylitol yields. For the calculation of the specific rates of substrate consumption and ethanol production, differential and integral methods were applied to the kinetic data. From the experimental results, it is deduced that both Candida and Pachysolen sequentially consume the two substrates, first D-glucose and then D-xylose. In both yeasts, the specific substrate-consumption rate diminished over each culture. The values qs and qE proved higher in Candida, although the higher ethanol yield was of the same order for both yeasts, close to 0.4 kg kgу. 相似文献
9.
A locally isolated filamentous fungus belonging to the group phycomycetes namely Rhizopus oryzae was identified to secrete alkaline protease. The production of this enzyme through solid state fermentation process has been attempted. From fermented biomass extraction of the enzyme was found to depend on the different parameters like nature of solvent, time of soaking, temperature etc. While optimizing the extraction process, it was found that 10% ethanol with 3% glycerol was the best solvent for protease extraction, when the soaking time was 2 hours and temperature 30v°C. It was further observed that double wash of fermented biomass yielded almost total enzyme in the leachate. 相似文献
10.
Juarez Tomás MS Bru E Wiese B de Ruiz Holgado AA Nader-Macías ME 《Journal of applied microbiology》2002,93(4):714-724
AIMS: To study the influence of pH, temperature and culture medium on the growth and bacteriocin production by vaginal Lactobacillus salivarius subsp. salivarius CRL 1328. METHODS AND RESULTS: The study was performed using a complete factorial experimental design. Lactobacillus salivarius was cultivated in LAPTg and MRS broths, adjusted to specific initial pH, and at different temperatures of incubation. The growth, which was evaluated by the Gompertz model, was higher in MRS broth than in LAPTg broth. The initial pH of the culture medium and the temperature had a dramatic effect on the production of bacteriocin. The optimal conditions for bacteriocin production were different to those for optimal growth. The decrease in the pH of the culture medium was parallel to the growth; pH had similar final values in both the MRS and the LAPTg broths. CONCLUSIONS: The optimal growth conditions were recorded in MRS broth, with an initial pH of 6.5 and a temperature of 37 degrees C. The maximum bacteriocin activity was obtained in LAPTg after 6 h at 37 degrees C, and at an initial pH of 6.5 or 8.0. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of a complete factorial design, and the evaluation of the growth parameters through the Gompertz model, enabled a rapid and simultaneous exploration of the influence of pH, temperature and growth medium on both growth and bacteriocin production by vaginal Lact. salivarius CRL 1328. 相似文献
11.
Response surface methodology was applied for the simultaneous optimization of initial pH and temperature of fermentation for the production of tartaric acid by Gluconobacter suboxydans. A temperature of 32.8v°C and an initial pH of 6.05 was found to be most suitable. Kinetic analysis for the growth of Gluconobacter suboxydans and product formation was done and a logistic model was used to describe the growth of Gluconobacter suboxydans while the Leudeking-Piret model explained the product formation. Parameters of the model were evaluated and tartaric acid formation was found to be non-growth associated. 相似文献
12.
G. Annadurai S. Rajesh Babu V. R. Srinivasamoorthy 《Bioprocess and biosystems engineering》2000,23(6):607-612
Bacterial growth curve, which is asymptotic after a certain period, is described using three different mathematical models, namely, Logistic model, Gompertz model and Richards model. The equations for these three models are fitted by evaluating the mathematical parameters involved in these models. This is done by applying the method of partial sums to the data in Table 1 containing the optical density values for different cell mass at different time intervals. The sum of square of residuals between the expected optical density values and the experimental values is calculated for each of these models. In the cases tested, the Logistic model was found to be the best fit for the growth curve of Pseudomonas putida (NICM 2174) and was found to be easy to use. These results fit the data very well at 5% level for more than 70% of the readings. 相似文献
13.
Miss Usha Baijal 《Mycopathologia》1967,33(3-4):289-312
Summary The physiological conditions governing growth and sporulation ofSaksenaea vasiformis
Saksena, a fungus with outstanding morphological features quite peculiar for Mucorales, were determined. Earlier studies made byTiwari (1955) on a strain of the same species had shown that this fungus is incapable of sporulating on any synthetic medium normally employed for growing fungi.The fungus had been found to have a high tolerance for very low and high pH values. It showed maximum growth at two pH values, one near neutral point, at pH 6, and another at high alkaline pH value, i.e., pH 11. Reason for this behaviour of this fungus has already been discussed. The most suitable temperature for the growth of the fungus was found to be between 30–35° C.Nearly all the carbon, nitrogen and sulphur sources which generally favour growth of fungi were found to support vegetative growth of this fungus as well. However, sporulation in this fungus had peculiar nutritional needs. Only some of the carbon sources, viz., arabinose, rhamnose, sorbose, galactose, lactose and citric acid which supported poor growth, were found to support good or excellent sporulation. But it may be stated that not all carbon sources supporting poor growth could induce sporulation of the organism. Also none of the nitrogen or sulphur sources could induce the fungus to sporulate in presence of glucose as carbon source. 相似文献
14.
Luo H Yamamoto Y Jeon HS Liu YP Jung JS Koh YJ Hur JS 《Journal of microbiology (Seoul, Korea)》2011,49(1):66-70
The present study was conducted to evaluate the antibacterial activity of lichen-forming fungi (LFF) against Helicobacter pylori, and to optimize the culture conditions of LFF for maximum production of natural antibiotics against H. pylori. To accomplish this, a screening assay was first conducted among 19 species of LFF. The extract of Nephromopsis pallescens (KOLRI-040516) exhibited the strongest anti-ff. pylori activity. Bioautograghic TLC and HPLC analysis identified usnic acid as the main antibacterial substance produced by JV.
pallescens. The growth of JV. pallescens and production of antibacterial substances produced by the fungus were then investigated under several culture conditions
including the culture media, initial medium pHs, incubation temperatures, and the degree of aeration. The results indicated
that culture in MY medium with an initial pH of 6.0, a temperature of 15°C and a low degree of aeration supported the largest
usnic acid production of the fungus (16.4 ug usnic acid/g dry biomass). Especially, aeration was found to be an important
factor that affect both growth and usnic acid production of N. pallescens. 相似文献
15.
Design of experiments in the biodegradation of phenol using immobilized Pseudomonas pictorum (NICM-2077) on activated carbon 总被引:1,自引:0,他引:1
G. Annadurai S. Mathalai Balan T. Murugesan 《Bioprocess and biosystems engineering》2000,22(2):101-107
Pseudomonas pictorum (NICM-2077) immobilized on various matrices are used to protect the microbes from confronting shock loads of concentrated phenol. The cells were immobilized in activated carbon and were used in biodegradation of phenol. Biodegradation of phenol using immobilized Activated Carbon matrix played an important role in reducing the toxicity of phenol. The degradation was carried and using the Box-Behnken model and analysis of variance have been applied to the experimental degradation studies. Response surface method with three levels of phenol concentration (0.200, 0.400, 0.600 g/l), activated carbon (0.5, 1.0, 1.5 g/l) and pH (7, 8, 9) were used in the identification of significant effects and interactions in the biodegradation studies. Phenol removal rate increases especially when the degradation medium was supplemented with utilizable carbon sources. A first-order polynomial regression model, which was used at first for analysis of the experiment had a significant lack of fit. Therefore, linear and quadratic terms were incorporated into the regression model through variable selection procedures. Effect of incubation phenol concentration, activated carbon and pH were significant. The predicted values using Box-Behnken model was found to be in close agreement with the experimental values, as indicated by the correlation coefficient values of 0.9463. 相似文献
16.
A model for growth and overflow metabolism of Saccharomyces cerevisiae was applied to simulate continuous cultivations in a pH-auxostat. The concentrations of glucose, biomass and ethanol are controlled by the flow ratio r between fresh medium and titrant solution, both of which are pH-regulated. A critical value of r could be derived, below which the culture becomes substrate depleted, resulting in a stop-flow condition with retained biomass but without growth. At r-values slightly above the critical value the pH-auxostat is substrate limited and unstable. Further increase of the r value results in a stable continuous culture growing at wmax. Thus, the pH-auxostat complements the chemostat in the growth range at or close to wmax. Even at wmax conditions, the ethanol concentration can be controlled at a low level. 相似文献
17.
选择新疆阿魏植物内生真菌中一株药理活性较强的菌,研究其生长特性,分别考察不同培养基、温度、光照及起始pH值4个单因素对菌种生长的影响,通过响应面试验优化,确定菌种最佳生长条件。结果表明,在黑暗条件下,采用土豆培养基(PDA),pH值为7,温度25℃环境中,该菌种可正常生长和繁衍,菌株平均生长速率为10.25mm·d~(-1)。 相似文献
18.
Effect of various parameters such as size of inoculum, temperature, carbon source on decolorization of textile wastewater by Phanerochaete chrysosporium was investigated. Textile wastewater decolorization occurred during the primary phase of growth and secondary metabolism in carbon and nitrogen limited medium, respectively. It was found that glucose concentration up to 0.3 g/l has considerable effect on decolorisation rate. Further, it was also found that the concentration of the organic nitrogen of the effluent stream was sufficient to furnish the decolorisation process. It was observed that the inoculum size in this case within 10% increased the decolorisation rate rapidly. It was found that the temperature rise from 20 to 38 °C enhanced the rate of decolorization. The optimum temperature for decolorisation was found to be about 35 °C. Effect of pH from 2-4 on decolorization was also investigated. It is concluded that using Phanerochaete chrysosporium, decolorization of the azo dye containing effluent of the textile industry was achieved to about 96% within 28 h of operation. 相似文献
19.
The filamentous fungus Glarea lozoyensis produces a novel, pharmaceutically important pneumocandin (B0) that is used to synthesize a polypeptide, which demonstrates fungicidal activity against clinically relevant pathogens. The scale-up of the pneumocandin fermentation requires an understanding of the rheological properties of the broth and the factors that influence flow behavior. A systematic approach for characterizing the rheological properties using a standard methodology is presented here. An appropriate rheometer was chosen and the effects of shear rate ramping, broth handling, creep and yield testing were examined. The fed-batch fermentation used a soluble production medium that allowed the relationship between biomass and rheological properties to be studied up to the 19-m3 scale. The morphologically heterogeneous broth demonstrated time-dependent shear thinning behavior with thixotropy and a yield stress. The flow curves were described by the power law model, with flow behavior of 0.35-0.4 and consistency index up to 10 Pa.sn. The use of a cup and bob rheometer was preferable to alternative techniques, including turbine and spindle systems defined by Mitschka's technique. The consistency index and flow behavior were shown to have a non-linear relationship with biomass concentrations up to 140 g/L. The consistency index continually increased with biomass during the fermentation, while the flow behavior initially decreased rapidly and then remained at low values for the remainder of the batch cultivation. The consistency index and yield stress were influenced by temperature, osmotic pressure, and pH, while the flow behavior remained independent of these factors. 相似文献