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1.
E Parente M A Crudele A Ricciardi M Mancinià F Clementi 《Journal of industrial microbiology & biotechnology》2000,25(5):242-248
Growth and alginate production by Azotobacter vinelandii DSM576 as a function of initial ammonium sulphate concentration (0.45–1.05 g l−1) and agitation speed (300–700 rpm) were studied in batch fermentations at controlled pH. The time course of growth, alginate
production and substrate consumption and the effect of nitrogen concentration and agitation speed on kinetic parameters and
on maximum alginate molecular weight (MW) was modelled using empirical equations. The kinetics of growth, alginate production
and polymerization were deeply affected by agitation speed and, to a lesser extent, by inorganic nitrogen concentration. Average
and maximum specific growth rate and maximum alginate MW all increased with agitation speed, and were higher at intermediate
ammonium sulphate concentration. Maximum alginate MW (>250,000) was obtained at high agitation speed (600–700 rpm) and alginate
depolymerization was limited or did not occur at all when the agitation speed was higher than 500 rpm, while at 400 rpm depolymerization
significantly reduced the alginate. However, alginate yield was negatively affected by increasing agitation speed. A good
compromise between alginate yield (>2 g l−1) and quality (MW>250,000) was obtained with agitation speed of 500–600 rpm and 0.75–0.90 g l−1 of ammonium sulphate. Journal of Industrial Microbiology & Biotechnology (2000) 25, 242–248.
Received 23 February 2000/ Accepted in revised form 04 August 2000 相似文献
2.
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
3.
The degradation potential of trichloroethene by the aerobic methane- and ammonia-oxidizing microorganisms naturally associated
with wetland plant (Carex comosa) roots was examined in this study. In bench-scale microcosm experiments with washed (soil free) Carex comosa roots, the activity of root-associated methane- and ammonia-oxidizing microorganisms, which were naturally present on the
root surface and/or embedded within the roots, was investigated. Significant methane and ammonia oxidation were observed reproducibly
in batch reactors with washed roots incubated in growth media, where methane oxidation developed faster (2 weeks) compared
to ammonia oxidation (4 weeks) in live microcosms. After enrichment, the methane oxidizers demonstrated their ability to degrade
150 μg l−1 TCE effectively at 1.9 mg l−1 of aqueous CH4. In contrast, ammonia oxidizers showed a rapid and complete inhibition of ammonia oxidation with 150 μg l−1 TCE at 20 mg l−1 of NH4
+-N, which may be attributed to greater sensitivity of ammonia oxidizers to TCE or its degradation product. No such inhibitory
effect of TCE degradation was detected on methane oxidation at the above experimental conditions. The results presented here
suggest that microorganisms associated with wetland plant roots can assist in the natural attenuation of TCE in contaminated
aquatic environments. 相似文献
4.
The objective of this study was to improve the biological water–gas shift reaction for producing hydrogen (H2) by conversion of carbon monoxide (CO) using an anaerobic thermophilic pure strain, Carboxydothermus hydrogenoformans. Specific hydrogen production rates and yields were investigated at initial biomass densities varying from 5 to 20 mg volatile
suspended solid (VSS) L−1. Results showed that the gas–liquid mass transfer limits the CO conversion rate at high biomass concentrations. At 100-rpm
agitation and at CO partial pressure of 1 atm, the optimal substrate/biomass ratio must exceed 5 mol CO g−1 biomass VSS in order to avoid gas–liquid substrate transfer limitation. An average H2 yield of 94 ± 3% and a specific hydrogen production rate of ca. 3 mol g−1 VSS day−1 were obtained at initial biomass densities between 5 and 8 mg VSS−1. In addition, CO bioconversion kinetics was assessed at CO partial pressure from 0.16 to 2 atm, corresponding to a dissolved
CO concentration at 70°C from 0.09 to 1.1 mM. Specific bioactivity was maximal at 3.5 mol CO g−1 VSS day−1 for a dissolved CO concentration of 0.55 mM in the culture. This optimal concentration is higher than with most other hydrogenogenic
carboxydotrophic species. 相似文献
5.
Hui Li Hong Xu Hao Xu Sha Li Han-Jie Ying Ping-Kai Ouyang 《Bioprocess and biosystems engineering》2011,34(1):95-102
Batch fermentative production of welan gum by Alcaligenes sp. CGMCC2428 was investigated under various oxygen supply conditions using regulating agitation speed. Based on a three
kinetic parameters analysis that includes specific cell growth rate (μ), specific glucose consumption rate (q
s), and specific welan formation rate (q
p), a two-stage agitation speed control strategy was proposed to achieve high concentration, high yield, and high viscosity
of welan. During the first 22 h, the agitation speed in 7.5 L fermenter was controlled at 800 rpm to maintain high μ for cell growth. The agitation was then reduced step-wise to 600 rpm to maintain a changing profile with stable dissolved
oxygen levels and obtain high qp for high welan accumulation. Finally, the maximum concentration of welan was reached at 26.3 ± 0.89 g L−1 with a yield of 0.53 ± 0.003 g g−1 and the welan gum viscosity of 3.05 ± 0.10 Pa s, which increased by an average of 15.4, 15.2, and 20.1% over the best results
controlled by constant agitation speeds. 相似文献
6.
The effect of agitation rate and dissolved oxygen tension (DOT) on growth and gellan production by Sphingomonas paucimobilis was studied. Higher cell growth of 5.4 g l−1 was␣obtained at 700 rpm but maximum gellan (15 g l−1) was produced at 500 rpm. DOT levels above 20% had no effect on cell growth but gellan yield was increased to 23 g l−1 with increase in DOT level to 100%. Higher DOT levels improved the viscosity and molecular weight of the polymer with change in acetate and glycerate content of the polymer. 相似文献
7.
Kusampudi Shilpa Chinnasamy Selvakkumar Arun Kumar Senthil Baddireddi Subhadra Lakshmi 《Plant Cell, Tissue and Organ Culture》2010,101(1):105-109
Young leaf explants of Ocimum sanctum L. incubated on solidified Murashige and Skoog (MS) medium supplemented with 2 mg l−1 1-naphthaleneacetic acid (NAA) and 0.2 mg l−1 kinetin (Kn) developed rhizogenic callus. When these were subcultured onto MS medium supplemented with 1.5 mg l−1 2, 4-dichlorophenoxyacetic acid (2, 4-D) and 0.5 mg l−1 NAA, friable rhizogenic callus was observed. Upon transfer of this friable callus onto liquid MS medium containing 4 mg l−1 NAA and 1.3 mg l−1 6-benzyladnine (BA) under continuous agitation at 90 rpm and 16 h photoperiod, roots with an optimum dry weight of 1,460 mg l−1 were obtained. An ethyl acetate extract of these roots exhibited 1, 1–diphenyl-2-picrylhydrazyl (DPPH) radical scavenging
activity. 相似文献
8.
Decolorization of Acid red 151 by Aspergillus niger SA1 under different physicochemical conditions 总被引:1,自引:0,他引:1
Naeem Ali Ikramullah Ghosia Lutfullah Abdul Hameed Safia Ahmed 《World journal of microbiology & biotechnology》2008,24(7):1099-1105
The fungal strain A. niger SA1 isolated from textile wastewater pond proved to be an important source of remediation (decolorization/degradation) for
textile dye, AR 151 (Reactive diazo dye) under different physicochemical conditions. Decolorization assays of AR 151 were
carried out in Simulated textile effluent under shake flask condition for 8 days. Decolorization (at 20 mg l−1 of dye) and related biomass production overall decreased with increase in pH from 5 to 9, at 30°C. It was maximum (95.71%)
at pH 5 with highest amount of three residual products (36.91 (α-naphthol = 5.72) (sulfanilic acid = 24.81) (aniline = 6.38))
besides 2.05 mg ml−1 of biomass production at an optimum concentration 6 and 0.1 mg l−1 of glucose and urea respectively. The formation of the three products followed a quite different pattern at different pH
values, however, it was considerably low (Total = 2.81 mg l−1) compared to the amount of decolorization (67.26%) at pH 8. Decolorization (95–97%) was most favored under mesophilic temperature
(25–45°C). It increased i.e., 90–98% with subsequent increase in dye from 10 to 100 mg l−1, kept ≥50% below 400 mg l−1 and drastically declined to 17% at 500 mg l−1 of dye. Apparently, decolorization is found to be associated with fungal growth and hyphal uptake mechanism (Biosorption/Bioadsorption),
however, mineralization of AR 151 and related products under different operational conditions also suggested a metabolically
mediated decolorization/degradation. 相似文献
9.
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
10.
Alginate production by Azotobacter vinelandii growing in chemostat cultures was evaluated under different O2 transfer rates (OTR). As a result of modifying the culture’s agitation rate from 300 to 500 rpm, the OTR increased from 9
to 15.1 mmol l−1 h−1 and a slight variation in the alginate production (1.7–2.2 g l−1) was observed. At a constant growth rate (0.1 h−1), the mean molecular mass of the alginate was strongly influenced by changes in the OTR, varying from 860 to 1,690 kDa. These
results support a possible relationship between alginate polymerization-depolymerization process and the O2 uptake rate. 相似文献
11.
By adding a biomass carrier to an activated sludge system, the biomass concentration will increase, and subsequently the organic
removal efficiency will be enhanced. In this study, the possibility of using excess sludge from ceramic and tile manufacturing
plants as a biomass carrier was investigated. The aim of this study was to determine the effect of using fireclay as a biomass
carrier on biomass concentration, organic removal and nitrification efficiency in an activated sludge system. Experiments
were conducted by using a bench scale activated sludge system operating in batch and continuous modes. Artificial simulated
wastewater was made by using recirculated water in a ceramic manufactutring plant. In the continuous mode, hydraulic detention
time in the aeration reactor was 8 and 22 h. In the batch mode, aeration time was 8 and 16 h. Fireclay doses were 500, 1,400
and 2,250 mg l−1, and were added to the reactors in each experiment separately. The reactor with added fireclay was called a Hybrid Biological
Reactor (HBR). A reactor without added fireclay was used as a control. Efficiency parameters such as COD, MLVSS and nitrate
were measured in the control and HBR reactors according to standard methods. The average concentration of biomass in the HBR
reactor was greater than in the control reactor. The total biomass concentration in the HBR reactor (2.25 g l−1 fireclay) in the continuous mode was 3,000 mg l−1 and in the batch mode was 2,400 mg l−1. The attached biomass concentration in the HBR reactor (2.25 g l−1 fireclay) in the continuous mode was 1,500 mg l−1 and in the batch mode was 980 mg l−1. Efficiency for COD removal in the HBR and control reactor was 95 and 55%, respectively. In the HBR reactor, nitrification
was enhanced, and the concentration of nitrate was increased by 80%. By increasing the fireclay dose, total and attached biomass
was increased. By adding fireclay as a biomass carrier, the efficiency of an activated sludge system to treat wastewater from
ceramic manufacturing plants was increased. 相似文献
12.
Md. Zahangir Alam Mariatul F. Mansor K. C. A. Jalal 《Journal of industrial microbiology & biotechnology》2009,36(5):757-764
A laboratory-scale study was carried out to produce lignin peroxidase (ligninase) by white rot fungus (Phanerochaete chrysosporium) using sewage-treatment-plant (STP) sludge as the major substrate. The optimization was done using full-factorial design
(FFD) with agitation and aeration as the two parameters. Nine experiments indicated by the FFD were fermented in a stirred-tank
bioreactor for 3 days. A second-order quadratic model was developed using the regression analysis of the experimental results
with the linear, quadratic, and interaction effects of the parameters. Analysis of variance (ANOVA) showed a high coefficient
of determination (R
2) value of 0.972, thus indicating a satisfactory fit of the quadratic model with the experimental data. Using statistical
analysis, the optimum aeration and agitation rates were determined to be 2.0 vvm and 200 rpm, respectively, with a maximum
activity of 225 U l−1 in the first 3 days of fermentation. The validation experiment showed the maximum activity of lignin peroxidase was 744 U l−1 after 5 days of fermentation. The results for the tests of the stability of lignin peroxidase showed that the activity was
more than 80% of the maximum for the first 12 h of incubation at an optimum pH of 5 and temperature of 55°C. 相似文献
13.
C. Guerrero-Barajas E. I. García-Peña 《World journal of microbiology & biotechnology》2010,26(1):21-32
The evaluation of enrichments from pristine hydrothermal vents sediments on its capability of reducing trichloroethylene (TCE)
under sulfate reducing conditions with lactate and volatile fatty acids (VFAs) as substrates was performed. Effect of the
possible TCE biodegradation intermediates cis and trans 1,2 dichloroethenes on sulfate reduction (SR) was also evaluated. The influence of cyanocobalamin (CNB12) and riboflavin (RF) on the SR and biodegradation of TCE was also determined. Sediments from the vents were incubated at
37°C and supplemented with 4 g l−1 SO4
2−, lactate or VFAs and amended in the corresponding treatments with either CNB12 or RF in separated experiments. A percentage of TCE removal of 86 (150 μmol l−1 initial concentration) was attained coupled to 48% sulfate depletion with lactate as substrate. Up to 93% removal of TCE
(300 μmol l−1 initial concentration) and 40% of sulfate was reached for VFAs as electron donor. A combination of lactate and CNB12 yielded the best SR. The overall results suggest a syntrophic association in this microbial community in which sulfate reducers,
dehalogenating, and probably halorespiring bacteria may be interacting and taking advantage of the fermentation of substrates
differently, but without interruption of SR in spite of the fact that TCE was always present. It was also clear that sulfate
reduction must be established in the cultures before any degradation can occur. The microbial community present in these hydrothermal
vents sediments could be a new source of inoculum for bioreactors designed for dechlorination purposes. 相似文献
14.
Cell cultures of Commiphora wightii (Arnott.) Bhandari were grown in shake flasks and a bioreactor and an increase in guggulsterone accumulation up to 18 μg
l−1 was recorded in cells grown in the production medium containing a combination of sucrose:glucose (4% total), precursors (phenylalanine,
pyruvic acid, xylose, and sodium acetate), morphactin, and 2iP. A yield of 10 g l−1 biomass and ∼200 μg l−1 guggulsterone was recorded in a 3-l flask and in a 2-l stirred tank bioreactor compared with 6.6 g biomass and 67 μg l−1 guggulsterone in 250-ml flasks. Increased vessel size was correlated with increased biomass and guggulsterone accumulation.
2iP alone was not effective for biomass and guggulsterone accumulation in cell cultures of C. wightii. 相似文献
15.
Smita Srivastava Ashok Kumar Srivastava 《In vitro cellular & developmental biology. Plant》2012,48(1):73-84
Azadirachtin, a well-known biopesticide, is a secondary metabolite extracted from the seeds of Azadirachta indica. In the present study, azadirachtin was produced in hairy roots of A. indica, generated by Agrobacterium rhizogenes-mediated transformation of leaf explants. Liquid cultures of A. indica hairy roots were developed with a liquid-to-flask volume ratio of 0.15. The kinetics of growth and azadirachtin production
were established in a basal plant growth medium containing MS medium major and minor salts, Gamborg’s medium vitamins, and
30 g l−1 sucrose. The highest azadirachtin accumulation in the hairy roots (up to 3.3 mg g−1) and azadirachtin production (∼44 mg l−1) was obtained on Day 25 of the growth cycle, with a biomass production of 13.3 g l−1 dry weight. To enhance the production of azadirachtin, a Plackett–Burman experimental design protocol was used to identify
key medium nutrients and concentrations to support high root biomass production and azadirachtin accumulation in hairy roots.
The optimal nutrients and concentrations were as follows: 40 g l−1 sucrose, 0.19 g l−1 potassium dihydrogen phosphate, 3.1 g l−1 potassium nitrate, and 0.41 g l−1 magnesium sulfate. Concentrations were determined by a central composite design protocol and verified in shake-flask cultivation.
The optimized medium composition yielded a root biomass production of 14.2 g l−1 and azadirachtin accumulation of 5.2 mg g−1, which was equivalent to an overall azadirachtin production of 73.84 mg l−1, 68% more than that obtained under non-optimized conditions. 相似文献
16.
M. Sharari A. Jahan Latibari A. Guillet M. Aurousseau B. Mouhamadou Gh. Rafeiee A. Mirshokraei D. Parsapaghouh 《Biodegradation》2011,22(2):421-430
Biotreatment of bagasse effluent using Phanerochaete chrysosporium (white rot fungus) is investigated. This study confirmed that lignin is the major pollutant component in this effluent followed
by different carbohydrates. The treatment conditions must be very proper, especially in terms of biomass culture to achieve
a successful treatment. The best conditions of temperature, biomass concentration, pH and duration for biotreatment of this
effluent were 35°C, 552 mg l−1, 6 and 5 to 9 days, respectively. Under these conditions, a 9 days long treatment reduced by 98.7% the original biochemical
oxygen demand (of 2,780 mg l−1) and by 98.5% the dissolved chemical oxygen demand (initial 4,200 mg l−1). Moreover, fungal treatment reduced total dissolved solids from 3,950 to 575 mg l−1 and color from 560 mg l−1 PtCo to 111 mg l−1 PtCo. 相似文献
17.
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
18.
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
19.
Christopher J. Hewitt Ken Lee Alvin W. Nienow Robert J. Thomas Mark Smith Colin R. Thomas 《Biotechnology letters》2011,33(11):2325-2335
The effects on human mesenchymal stem cell growth of choosing either of two spinner flask impeller geometries, two microcarrier
concentrations and two cell concentrations (seeding densities) were investigated. Cytodex 3 microcarriers were not damaged
when held at the minimum speed, NJS, for their suspension, using either impeller, nor was there any observable damage to the cells. The maximum cell density
was achieved after 8–10 days of culture with up to a 20-fold expansion in terms of cells per microcarrier. An increase in
microcarrier concentration or seeding density generally had a deleterious or neutral effect, as previously observed for human
fibroblast cultures. The choice of impeller was significant, as was incorporation of a 1 day delay before agitation to allow
initial attachment of cells. The best conditions for cell expansion on the microcarriers in the flasks were 3,000 microcarriers
ml−1 (ca. 1 g dry weight l−1), a seeding density of 5 cells per microcarrier with a 1 day delay before agitation began at NJS (30 rpm), using a horizontally suspended flea impeller with an added vertical paddle. These findings were interpreted using
Kolmogorov’s theory of isotropic turbulence. 相似文献
20.
Luiz Fernando Ferreira Mario Aguiar Georgia Pompeu Tâmara Guido Messias Regina Rosim Monteiro 《World journal of microbiology & biotechnology》2010,26(9):1613-1621
Vinasse is a highly colored effluent with a high pollutant potential when disposed in the environment. Assays for decolorization
of vinasse were performed, selecting the fungus Pleurotus sajor-caju CCB 020. The discoloration was cocominant with the increase of the activities of laccase, manganese-peroxidase and peroxidases.
P. sajor-caju demonstrated a rise in biomass production (1.06 g 100 ml−1), and the enzyme activities such as laccase (varying from 400 to 450 IU l−1) reached between the 9th and 10th day of growth and for MnP at the 12th day of cultivation (varying from 60 to 100 IU l−1). It was concluded that the system P. sajor-caju/vinasse can be utilized as a bioprocess for color removal and degradation of complex vinasse compounds. It was observed an
improvement in the characteristics and detoxification allowing its utilization as reused water, laccase and manganese-peroxidase
enzymes production and for fungal biomass production with a high nutritional value. 相似文献