共查询到20条相似文献,搜索用时 31 毫秒
1.
Michelin M Polizeli Mde L Silva DP Ruzene DS Vicente AA Jorge JA Terenzi HF Teixeira JA 《Journal of industrial microbiology & biotechnology》2011,38(12):1979-1984
Fungi producing high xylanase levels have attracted considerable attention because of their potential industrial applications.
Batch cultivations of Aspergillus terricola fungus were evaluated in stirred tank and airlift bioreactors, by using wheat bran particles suspended in the cultivation
medium as substrate for xylanase and β-xylosidase production. In the stirred tank bioreactor, in physical conditions of 30°C,
300 rpm, and aeration of 1 vvm (1 l min−1), with direct inoculation of fungal spores, 7,475 U l−1 xylanase was obtained after 36 h of operation, remaining constant after 24 h. In the absence of air injection in the stirred
tank reactor, limited xylanase production was observed (final concentration 740 U l−1). When the fermentation process was realized in the airlift bioreactor, xylanase production was higher than that observed
in the stirred tank bioreactor, being 9,265 U l−1 at 0.07 vvm (0.4 l min−1) and 12,845 U l−1 at 0.17 vvm (1 l min−1) aeration rate. 相似文献
2.
Claucia Fernanda Volken de Souza Rafael Costa Rodrigues Marco Antônio Záchia Ayub 《Biotechnology and Bioprocess Engineering》2009,14(5):571-576
The effects of oxygenation in cultures of Bacillus circulans BL32 on transglutaminase (TGase) production and cell sporulation were studied by varying the agitation speed and the volume
of aeration. Kinetics of cultivations has been studied in batch systems using a 2 L bioreactor, and the efficiency of agitation
and aeration was evaluated through the oxygen volumetric mass transfer coefficient (kLa). It was adopted a two-stage aeration rate control strategy: first stage to induce biomass formation, followed by a second
stage, in which cell sporulation was stimulated. A correlation of TGase production, spores formation, and oxygen concentration
was established. Under the best conditions (500 rpm; 2 vvm air flow, followed by no air supply during stationary phase; kLa of 33.7 h−1), TGase production reached a volumetric production of 589 U/L after 50 h of cultivation and the enzyme yield was 906 U/g
cells. These values are 61% higher than that obtained in shaker cultures and TGase productivity increased 82%, when kLa varied from 4.4 to 33.7 h−1. The maximal cell concentration increased four times in relation to shaker cultures and the cultivation time for the highest
TGase activity was reduced from 192 h to just 50 h. These results show the importance of bioprocess design for the production
of microbial TGase, especially concerning the oxygen supply of cultures and the induction of cell sporulation. 相似文献
3.
Jesús Adolfo Jiménez Nieves Alonso-Blázquez Dolores López-Vela Cristina Celestino Mariano Toribio Jesus Alegre 《In vitro cellular & developmental biology. Plant》2011,47(5):578-588
Somatic embryogenesis can be induced in the leaves of cork oak (Quercus suber L.) trees. The use of this propagation system in multivarietal forestry requires the mass production of cloned plants at
low cost. Investigations were made into the influence of three types of Erlenmeyer flask and three orbiting speeds (60, 110,
and 160 rpm) on oxygen transfer rate (KL
a), the shear force index (SFI), biomass production, and the proliferation of embryogenic clumps (EMCs) in cultures during
the proliferation phase. KL
a varied between 0.11 and 1.47 h−1 without biomass production being limited by oxygen availability. The EMCs grew even in hypoxic conditions, although the suppression
of gaseous exchange strongly reduced biomass production. Cultures with different levels of hydrodynamic stress and SFI values
(1.4·10−3–8.8·10−3 cm min−1) were obtained. Proliferation rates of EMCs increased with agitation rate and the SFI. The largest number of EMCs was obtained
in baffled flasks agitated at 160 rpm (KL
a of 1.47 h−1, and SFI of 8.8·10−3 cm min−1) with mild hydrodynamic stress enhancing growth. Biomass production increased with agitation and hydrodynamic stress, but
only when the SFI value was below 5·10−3 cm min−1. The greatest biomass production was obtained in smooth 100 ml flasks agitated at 160 rpm. The differentiation of embryos
was favoured by the lowest KL
a (0.11 h−1) and SFI (1.40·103 cm min−1) values, achieved using these flasks when agitated at 60 rpm. 相似文献
4.
Teodoro JC Baptista-Neto A Cruz-Hernández IL Hokka CO Badino AC 《Applied microbiology and biotechnology》2006,72(3):450-455
First, the effect of different levels of nitrogen source on clavulanic acid (CA) production was evaluated in batch cultivations utilizing complex culture medium containing glycerol and three different levels of soy protein isolate (SPI). Cellular growth, evaluated in terms of the rheological parameter K, was highest with a SPI concentration of 30 g.L−1 (4.42 g.L−1 N total). However, the highest production of CA (380 mg.L−1) was obtained when an intermediate concentration of 20 g.L−1 of SPI (2.95 g.L−1 total N) was used. To address this, the influences of volumetric flow rate (F) and glycerol concentration in the complex feed medium (CsF) in fed-batch cultivations were investigated. The best experimental condition for CA production was F=0.01 L.h−1 and CsF=120 g.L−1, and under these conditions maximum CA production was practically twice that obtained in the batch cultivation. A single empirical equation was proposed to relate maximum CA production with F and CsF in fed-batch experiments. 相似文献
5.
The effect of agitation and aeration on the growth and antibiotic production by Xenorhabdus nematophila YL001 grown in batch cultures were investigated. Efficiency of aeration and agitation was evaluated through the oxygen mass
transfer coefficient (K
L
a). With increase in K
L
a, the biomass and antibiotic activity increased. Activity units of antibiotic and dry cell weight were increased to 232 U ml−1 and 19.58 g l−1, respectively, productivity in cell and antibiotic was up more than 30% when K
L
a increased from 115.9 h−1 to 185.7 h−1. During the exponential growth phase, DO concentration was zero, the oxygen supply was not sufficient. So, based on process
analysis, a three-stage oxygen supply control strategy was used to improved the DO concentration above 30% by controlling
the agitation speed and aeration rate. The dry cell weight and activity units of antibiotic were further increased to 24.22 g l−1 and 249 U ml−1, and were improved by 24.0% and 7.0%, compared with fermentation at a constant agitation speed and a constant aeration rate
(300 rev min−1, 2.5 l min−1). 相似文献
6.
Chia-Hung Su Liang-Jung Chien James Gomes Yu-Sheng Lin Yuan-Kun Yu Jhang-Song Liou Rong-Jhih Syu 《Journal of applied phycology》2011,23(5):903-908
Reserve lipids of microalgae are promising for biodiesel production. However, optimization of cultivation conditions for both
biomass yield and lipid production of microalgae is a contradictory problem because required conditions for both targets are
different. In this study, a two-stage cultivation strategy is proposed to enhance lipid production of the microalga Nannochloropsis oculata. Biomass growth and lipid production were carried out in two separate and non-interacting stages. In first-stage cultivation,
microalgae were cultivated in optimal conditions for cell growth. Then, microalgae were harvested and transferred into a growth-limited
environment, thus enhancing lipid production of microalgae. Here, optimization of the lipid production stage (second stage)
with respect to different levels of inoculum concentration, salinity of culture broth, and intensity of irradiance was performed.
The results show that irradiance exhibits a significant influence on lipid production. The highest lipid productivity of 0.324 g L−1 day−1 was obtained with an inoculum concentration of 2.3 g L−1, a salinity of 35 g L−1, and an irradiance of 500 μmol photons m−2 s−1. The final yield of lipid obtained from the two-stage process was 2.82-times higher than that from traditional single-stage
batch cultivation systems. 相似文献
7.
Sathyanarayana N. Gummadi Swati Sucharita Dash Santhosh Devarai 《Journal of industrial microbiology & biotechnology》2009,36(5):713-720
The effect of pH, aeration rate, and agitation rate on specific productivity of caffeine demethylase from Pseudomonas sp. was studied in a bioreactor. Maximum specific productivity of caffeine demethylase of 2,214 U g cell dry weight−1 h−1 was obtained at 0.27 vvm, 700 rpm, and pH 7.0. Under these conditions, volumetric oxygen transfer coefficient was 74.2 h−1, indicating that caffeine demethylase production by Pseudomonas sp. was highly oxygen-dependent. Different metabolite formation at different agitation and aeration rates can be used as
a strategy for recovery of pharmaceutically important metabolites from caffeine by manipulation of conditions in a bacterial
culture. This is the first report on production of high levels of caffeine demethylase in bioreactors. 相似文献
8.
Methee Khamduang Kanoktip Packdibamrung Jarun Chutmanop Yusuf Chisti Penjit Srinophakun 《Journal of industrial microbiology & biotechnology》2009,36(10):1267-1274
The production of l-phenylalanine is conventionally carried out by fermentations that use glucose or sucrose as the carbon source. This work
reports on the use of glycerol as an inexpensive and abundant sole carbon source for producing l-phenylalanine using the genetically modified bacterium Escherichia coli BL21(DE3). Fermentations were carried out at 37°C, pH 7.4, using a defined medium in a stirred tank bioreactor at various
intensities of impeller agitation speeds (300–500 rpm corresponding to 0.97–1.62 m s−1 impeller tip speed) and aeration rates (2–8 L min−1, or 1–4 vvm). This highly aerobic fermentation required a good supply of oxygen, but intense agitation (impeller tip speed
~1.62 m s−1) reduced the biomass and l-phenylalanine productivity, possibly because of shear sensitivity of the recombinant bacterium. Production of l-phenylalanine was apparently strongly associated with growth. Under the best operating conditions (1.30 m s−1 impeller tip speed, 4 vvm aeration rate), the yield of l-phenylalanine on glycerol was 0.58 g g−1, or more than twice the best yield attainable on sucrose (0.25 g g−1). In the best case, the peak concentration of l-phenylalanine was 5.6 g L−1, or comparable to values attained in batch fermentations that use glucose or sucrose. The use of glycerol for the commercial
production of l-phenylalanine with E. coli BL21(DE3) has the potential to substantially reduce the cost of production compared to sucrose- and glucose-based fermentations. 相似文献
9.
Chris J. Hulatt Aino-Maija Lakaniemi Jaakko A. Puhakka David N. Thomas 《Bioenergy Research》2012,5(3):669-684
Mass culture of microalgae is a potential alternative to cultivation of terrestrial crops for bioenergy production. However, microalgae require nitrogen fertiliser in quantities much higher than plants, and this has important consequences for the energy balance of these systems. The effect of nitrogen fertiliser supplied to microalgal bubble-column photobioreactor cultures was investigated using different nitrogen sources (nitrate, urea, ammonium) and culture conditions (air, 12% CO2). In 20 L cultivations, maximum biomass productivity for Chlorella vulgaris cultivated using nitrate and urea was 0.046 and 0.053 g L−1 day−1, respectively. Maximum biomass productivity for Dunaliella tertiolecta cultivated using nitrate, urea and ammonium was 0.033, 0.038 and 0.038 g L−1 day−1, respectively. In intensive bubble-column photobioreactors using 12% CO2, maximum productivity reached 0.60 and 0.83 g L−1 day−1 for C. vulgaris and D. tertiolecta, respectively. Recycling of nitrogen within the photobioreactor system via algal exudation of nitrogenous compounds and bacterial activity was identified as a potentially important process. The energetic penalty incurred by supply of artificial nitrogen fertilisers, phosphorus, power and CO2 to microalgal photobioreactors was investigated, although analysis of all energy burdens from biomass production to usable energy carriers was not conducted. After subtraction of the power, nitrogen and phosphorus energy burdens, maximum net energy ratios for C. vulgaris and D. tertiolecta cultivated in bubble columns were 1.82 and 2.10. Assuming CO2 was also required from a manufactured source, the net energy ratio decreased to 0.09 and 0.11 for C. vulgaris and D. tertiolecta, so that biomass production in this scenario was unsustainable. Although supply of nitrogen is unlikely to be the most energetically costly factor in sparged photobioreactor designs, it is still a very significant penalty. There is a need to optimise both cultivation strategies and recycling of nitrogen in order to improve performance. Data are supported by measurements including biochemical properties (lipid, protein, heating value) and bacterial number by epifluorescence microscopy. 相似文献
10.
Anjali Madhavan Sriappareddy Tamalampudi Aradhana Srivastava Hideki Fukuda Virendra S. Bisaria Akihiko Kondo 《Applied microbiology and biotechnology》2009,82(6):1037-1047
Previously, a Saccharomyces cerevisiae strain was engineered for xylose assimilation by the constitutive overexpression of the Orpinomyces xylose isomerase, the S. cerevisiae xylulokinase, and the Pichia stipitis SUT1 sugar transporter genes. The recombinant strain exhibited growth on xylose, under aerobic conditions, with a specific growth
rate of 0.025 h−1, while ethanol production from xylose was achieved anaerobically. In the present study, the developed recombinant yeast was
adapted for enhanced growth on xylose by serial transfer in xylose-containing minimal medium under aerobic conditions. After
repeated batch cultivations, a strain was isolated which grew with a specific growth rate of 0.133 h−1. The adapted strain could ferment 20 g l−1 of xylose to ethanol with a yield of 0.37 g g−1 and production rate of 0.026 g l−1 h−1. Raising the fermentation temperature from 30°C to 35°C resulted in a substantial increase in the ethanol yield (0.43 g g−1) and production rate (0.07 g l−1 h−1) as well as a significant reduction in the xylitol yield. By the addition of a sugar complexing agent, such as sodium tetraborate,
significant improvement in ethanol production and reduction in xylitol accumulation was achieved. Furthermore, ethanol production
from xylose and a mixture of glucose and xylose was also demonstrated in complex medium containing yeast extract, peptone,
and borate with a considerably high yield of 0.48 g g−1. 相似文献
11.
Juan Wang Wen-Yuan Gao Jian Zhang Bei-Mei Zuo Li-Ming Zhang Lu-Qi Huang 《In vitro cellular & developmental biology. Plant》2012,48(1):107-112
Based on the results of carbon source consumption in cell suspension culture of Panax quinquefolium L., 30 g L−1 sucrose was fed into a 5-L stirred tank bioreactor on day 16 of culture to enhance cell density and metabolite production.
Using a fed-batch cultivation strategy, polysaccharide production was enhanced to 1.608 g L−1, which was 1.96-fold greater than with batch cultivation. The maximum saponin yield (7.828 mg L−1) was obtained on day 24 and was about 36% higher than the yields obtained using batch cultivation. In a two-stage culture
process, a combined treatment with sucrose, lactoalbumin hydrolysate, and methyl jasmonate caused a significant increase in
total saponin yield (31.52 mg L−1) in cell cultures after 27 d. This value represents an increase of 4.03-fold compared with the total saponin yield in fed-batch
cultivation. The two-stage culture mode provided the best method for the in vitro production of secondary metabolites from P. quinquefolium. 相似文献
12.
Zhijian Peng Jun Fang Jianghua Li Long Liu Guocheng Du Jian Chen Xiaoyuan Wang Jianfei Ning Liming Cai 《Bioprocess and biosystems engineering》2010,33(3):339-345
The effect of both dissolved oxygen (DO) and pH on l-isoleucine production by batch culture of Brevibacterium lactofermentum was investigated. A two-stage agitation speed control strategy was developed, and the isoleucine production reached 23.3 g L−1 in a relative short time (52 h), increased by 11.6% compared to the results obtained in the single agitation speed control
process. In order to make sure whether the combination of DO and pH control can boost the production by a mutual effect, different
control modes were conducted, based on the data obtained from the two-stage agitation speed control strategy and the analysis
of kinetics parameters at different pH values. The results showed that the mode of combining two-stage DO with two-stage pH
control strategy was the optimal for isoleucine production. The isoleucine production can reach 26.6 g L−1 at 56 h, increased by 14.3% comparing to that obtained by the single two-stage DO control strategy. 相似文献
13.
John Chi-Wei Lan Tau Chuan Ling Grant Hamilton Andrew Lyddiatt 《Biotechnology and Bioprocess Engineering》2006,11(5):425-431
The development of fermentation conditions for the production of C595 diabody fragment (dbFv) inE. coli HB2151 clone has been explored. Investigations were carried out to study the effect of carbon supplements over the expression
period, the comparison of C595 dbfv production in synthetic and complex media, the influence of acetic acid upon antibody
production, and comparison of one-stage and two-stage processes operated at batch or fed-batch modes in bioreactor. Yeast
extract supplied during expression yielded more antibody fragment than any other carbon supply. The synthetic medium presented
higher specific productivity (0.066 mg dbFv g−1 dry cell weight) when compared to the complex medium (0.044 mg dbFv g−1 DCW). The comparison of fermentation strategies demonstrated that (1) one-stage fed-batch fermentation performed higher C595
dbFv production than that operated in batch mode which was significantly affected by acetate concentration; (2) a two-stage
batch operation could enhance C595 dbFv production. It was found that a concentration of 12.3 mg L−1 broth of C595 dbFv and a cell concentration of 10.8 g L−1 broth were achieved at the end of two-stage operation in 5-L fermentation. 相似文献
14.
Ducros E Ferrari M Pellegrino M Raspanti C Bogni C 《Bioprocess and biosystems engineering》2009,32(1):143-148
The modified rotating simplex method has been successfully used to determine the best combination of agitation rate and aeration
rate for maximum production of extracellular proteases by Staphylococcus aureus mutant RC128, in a stirred tank bioreactor operated in a discontinuous way. This mutant has shown altered exoprotein production,
specially enhanced protease production. Maximum production of proteases (15.28 UP/ml), measured using azocasein as a substrate,
was obtained at exponential growth phase when the bioreactor was operated at 300 rpm and at 2 vvm with a volumetric oxygen
transfer coefficient (K
L
a) of 175.75 h−1. These conditions were found to be more suitable for protease production. 相似文献
15.
The impact of flask geometry on Streptomyces lividans growth and morphology, production and O-mannosylation of a recombinant O-glycoprotein (APA from Mycobacterium tuberculosis) was described and associated to the evolution of the volumetric power input (P/V) in three shake flask geometries. During the exponential growth, the highest P/V was found in baffled flasks (BF) with 0.51 kW/m3, followed by coiled flasks (CF) with 0.44 kW/m3 and normal Erlenmeyer flasks (NF) with 0.20 kW/m3 (flasks volume of 250 mL, filling with 50 mL and agitated at 150 rpm). During the stationary phase, P/V decreased 20% in BF and CF, but increased two times in NF, surely due to changes in mycelial morphology and its effects on rheology. Also, NF cultures were carried out at a filling volume and agitation of 15 mL, 150 rpm (15 mL-NF), and 25 mL, 168 rpm (25 mL-NF), in order to raise P/V closely to the values obtained in CF. However, different growth, morphology and recombinant protein productivity were obtained. These data indicate that P/V is not a definitive parameter that can determine bacteria growth and morphology, not even glycoprotein production. But it can be proposed that the oxygen transfer in the center of the pellets and hydromechanical stress might be the more relevant parameters than P/V. 相似文献
16.
Lang YJ Bai L Ren YN Zhang LH Nagata S 《Extremophiles : life under extreme conditions》2011,15(2):303-310
Using ectoine-excreting strain Halomonas salina DSM 5928T, we developed a new process for high-efficiency production of ectoine, which involved a combined process of batch fermentation
by growing cells and production by resting cells. In the first stage, batch fermentation was carried out using growing cells
under optimal fermentation conditions. The second stage was the production phase, in which ectoine was synthesized and excreted
by phosphate-limited resting cells. Optimal conditions for synthesis and excretion of ectoine during batch fermentation in
a 10 l fermentor were 0.5 mol l−1 NaCl and an initial monosodium glutamate concentration of 80 g l−1 respectively. The pH was adjusted to 7.0 and the temperature was maintained at 33°C. In phosphate-limited resting cells medium,
monosodium glutamate and NaCl concentration was 200 g l−1 and 0.5 mol l−1, respectively, as well as pH was 7.0. The total concentration of ectoine produced was 14.86 g l−1, the productivity and yield of ectoine was 7.75 g l−1 day−1 and 0.14 g g−1, respectively, and the percentage of ectoine excreted was 79%. These levels of ectoine production and excretion are the highest
reported to date. 相似文献
17.
Héctor Guzmán Doan Van-Thuoc Javier Martín Rajni Hatti-Kaul Jorge Quillaguamán 《Applied microbiology and biotechnology》2009,84(6):1069-1077
The paper reports a study involving the use of Halomonas boliviensis, a moderate halophile, for co-production of compatible solute ectoine and biopolyester poly(3-hydroxybutyrate) (PHB) in a
process comprising two fed-batch cultures. Initial investigations on the growth of the organism in a medium with varying NaCl
concentrations showed the highest level of intracellular accumulation of ectoine (0.74 g L−1) at 10–15% (w/v) NaCl, while at 15% (w/v) NaCl, the presence of hydroxyectoine (50 mg L−1) was also noted. On the other hand, the maximum cell dry weight and PHB concentration of 10 and 5.8 g L−1, respectively, were obtained at 5–7.5% (w/v) NaCl. A process comprising two fed-batch cultivations was developed—the first culture aimed at obtaining high cell mass
and the second for achieving high yields of ectoine and PHB. In the first fed-batch culture, H. boliviensis was grown in a medium with 4.5% (w/v) NaCl and sufficient levels of monosodium glutamate, NH4+, and PO43−. In the second fed-batch culture, the NaCl concentration was increased to 7.5% (w/v) to trigger ectoine synthesis, while nitrogen and phosphorus sources were fed only during the first 3 h and then stopped
to favor PHB accumulation. The process resulted in PHB yield of 68.5 wt.% of cell dry weight and volumetric productivity of
about 1 g L−1 h−1 and ectoine concentration, content, and volumetric productivity of 4.3 g L−1, 7.2 wt.%, and 2.8 g L−1 day−1, respectively. At salt concentration of 12.5% (w/v) during the second cultivation, the ectoine content was increased to 17 wt.% and productivity to 3.4 g L−1 day−1. 相似文献
18.
Aims: To evaluate the effect of different physicochemical parameters such as agitation, aeration and pH on the growth and nitrile hydratase production by Rhodococcus erythropolis MTCC 1526 in a stirred tank reactor. Methods and Results: Rhodococcus erythropolis MTCC 1526 was grown in 7‐l reactor at different agitation, aeration and controlled pH. The optimum conditions for batch cultivation in the reactor were an agitation rate of 200 rev min?1, aeration 0·5 v/v/m at controlled pH 8. In this condition, the increase in nitrile hydratase activity was almost threefold compared to that in the shake flask. Conclusion: Agitation and aeration rate affected the dissolved‐oxygen concentration in the reactor which in turn affected the growth and enzyme production. Significance and Impact of the Study: Cultivation of R. erythropolis MTCC 1526 in the reactor was found to have significant effect on the growth and nitrile hydratase production when compared to the shake flask. 相似文献
19.
《Enzyme and microbial technology》2008,42(6-7):683-688
The impact of encapsulation on the anaerobic growth pattern of S. cerevisiae CBS 8066 in a defined synthetic medium over 20 consecutive batch cultivations was investigated. In this period, the ethanol yield increased from 0.43 to 0.46 g/g, while the biomass and glycerol yields decreased by 58 and 23%, respectively. The growth rate of the encapsulated cells in the first batch was 0.13 h−1, but decreased gradually to 0.01 h−1 within the 20 sequential batch cultivations. Total RNA content of these yeast cells decreased by 39% from 90.3 to 55 mg/g, while the total protein content decreased by 24% from 460 to 350 mg/g. On the other hand, the stored carbohydrates, that is, glycogen and trehalose content, increased by factors of 4.5 and 4 within 20 batch cultivations, respectively. Higher biomass concentrations inside capsules led to a lower glucose diffusion rate through the membrane, and volumetric mass transfer coefficient for glucose was drastically decreased from 6.28 to 1.24 (cm3/min) by continuing the experiments. Most of the encapsulated yeast existed in the form of single and non-budding cells after long-term application. 相似文献
20.
In this research, the combined effects of polydimethylsiloxane (PDMS) and different conditions of oxygen volumetric mass transfer
coefficient (kLa) on lipase production by Staphylococcus warneri EX17 were studied and optimized in bioreactor cultures. Raw glycerol from biodiesel synthesis was used as the sole carbon
source. Full-factorial central composite design and the response surface methodology were employed for the experimental design
and analysis of the results. The optimal polydimethylsiloxane concentration and mass coefficient transfer (kLa) were found to be 13.5% (v/v) and 181 h−1, respectively. Under these conditions, the maximal cell production obtained was 10.0 g/l, and the volumetric lipase activities
of approximately 490 U/l, after 6 h of cultivation. These results are in close agreement with the model predictions. Results
obtained in this work reveal the positive effects of PDMS on oxygen volumetric mass transfer coefficient (kLa) in the Staphylococcus warneri EX17 cultivation and lipase production. 相似文献