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1.
In the course of selecting a useful mutant strain for a fermentative production of L-valine, it was found that an arginine-pyrimidine auxotroph of Paracolobactrum coliforme accumulated Nδ-acetyl-L-ornithine (δ-AO) in the culture medium. The accumulation of it reached a level of 16 mg/ml with medium containing 12.5 % glucose, 2.2% (NH4)2SO4, 0.5% peptone and 300 μg/ml of uracil. The wild strain 775 also accumulated 1.4 mg/ml of δ-AO in the medium supplemented with a high level (300μg/ml) of uracil when L-ornithine (10 mg/ml) was added in the middle phase of fermentation. The mutant cells elongated under the condition with limited supply of uracil.The mechanism of the accumulation of δ-AO was discussed from the information of relevant biosynthetic regulation in other organisms. 相似文献
2.
Summary Equations are described which relate nutrient feed rate to specific microbial growth rate in fed batch culture. Fed batch cultures are classified into three types: 1) those allowing constant specific microbial growth rate, 2) those in which the rate of change of flow rate is constant and 3) those in which the nutrient flow rate is constant. The basic properties of these three types are described.Symbols
F
medium flow rate, L3 T–1
-
F
o
medium flow rate at zero time, L3 T–1
-
g
rate of change of flow rate with time, L3 T–2
-
K
v
volume constant, being the total cell weight at zero time divided by the product of the yield coefficient and growth-limiting substrate concentration in the feed, L3
-
s
r
growth limiting substrate concentration in the feed, ML–3
-
V
volume of liquid in the growth vessel, L3
-
V
f
volume of medium fed to the growth vessel, L3
-
V
o
volume of liquid in the growth vessel at zero time, L3
-
X
total weight of cells, M
-
x
concentration of cells, ML–3
-
X
g
total weight of cells grown, M
-
X
o
total weight of cells at zero time, M
-
Y
yield coefficient, weight of cells grown per unit weight of growth-limiting substrate
-
specific microbial growth rate, T–1 相似文献
3.
Walter Borzani 《Biotechnology letters》1995,17(12):1295-1298
Summary The following equations represent the influence of the ethanol concentration (E) on the specific growth rate of the yeast cells () and on the specific production rate of ethanol () during the reactor filling phase in fed-batch fermentation of sugar-cane blackstrap molasses: =
0 - k · E and v = v
0
· K/(K +E)
Nomenclature E
ethanol concentration in the aqueous phase of the fermenting medium (g.L–1)
- Em
value of E when = 0 or = 0 (g.L–1)
- F
medium feeding rate (L.h–1)
- k
empirical constant (L.g–1.h–1)
- K
empirical constant (g.L–1)
- Mas
mass of TRS added to the, reactor (g)
- Mcs
mass of consumed TRS (g)
- Me
mass of ethanol in the aqueous phase of the fermenting medium (g)
- Ms
mass of TRS in the aqueous phase of the fermenting medium (g)
- Mx
mass of yeast cells (dry matter) in the fermenting medium (g)
- r
correlation coefficient
- S
TRS concentration in the aqueous phase of the fermenting medium (g.L–1)
- Sm
TRS concentration of the feeding medium (g.L–1)
- t
time (h)
- T
temperature (° C)
- TRS
total reducing sugars calculated as glucose
- V
volume of the fermenting medium (L)
- V0
volume of the inoculum (L)
- X
yeast cells concentration (dry matter) in the fermenting medium (g.L–1)
-
filling-up time (h)
-
specific growth rate of the yeast cells (h–1)
- 0
value of when E=0
-
specific production rate of ethanol (h–1)
- 0
value of when E=0
-
density of the yeast cells (g.L–1)
-
dry matter content of the yeast cells 相似文献
4.
An isoleucine leaky auxotroph of Arthrobacter paraffineus, which was isolated by Takayama et al.3) as a mutant producing L-threonine and L-valine from n-paraffin, was subjected to further mutagenesis in an attempt to obtain better L-threonine producers. Some of the double auxotrophs derived from the isoleucine auxotroph and some of their revertants with respect to isoleucine requirement produced more L-threonine than the original isoleucine auxotroph. In contrast to the original isoleucine auxotroph, a revertant derived from a methionine plus isoleucine double auxotroph, KY7135, produced an increased amount of L-threonine and a decreased amount of L-valine. The optimum level of L-methionine for L-threonine production in KY7135 was much higher (1000 ~ 2000 μg/ml) with n-paraffin medium than with sorbitol or mannitol medium (10 ~ 50 μg/ml). L-Threonine production reached a maximum level (11.5 mg/ml) in 7 days incubation with the medium containing 10% n-paraffin (C12 ~ C14 rich). Several mutants which produce L-threonine more than 12 mg/ml were obtained from KY 7135 by monocolony isolation procedure. 相似文献
5.
The presence of hexavalent chromium salt in culture medium negatively affected the growth dynamics and physiological parameters
of the benthic microalga Attheya ussurensis. After 1 day of exposure to toxicant at concentrations of 2, 4, 7, and 10 mg/l, the cell counts were 10, 7.9, 5.6, and 4.3
× 103 cells/ml, respectively (versus 13 × 103 cells/ml in the control). A tendency towards a decrease in cell number remained until the end of the experiments; after 7
days of exposure the cell counts were 133, 102, 11, and 7.5 × 103 cells/ml (versus 204 × 103 cells/ml in the control). With increase in potassium bichromate concentration in the culture medium, there was an increase
in the ratio of cell height to width and a change in the form of the cell to horseshoe shaped. The contents of chlorophyll
a in microalgal cells after 1 day of exposure to 2, 4, 7, and 10 mg/l were 40, 37, 34, and 30 μg/l, respectively (45 μg/l in
the control). After 7 days, at chromium salt concentrations of 2 and 4 mg/l, the chlorophyll a content was higher (670 and 647 μg/l) than in the control (605 μg/l); at 7 and 10 mg/l, it significantly decreased to 87
and 65 μg/l, respectively. The contents of carotinoids in microalgal cells after 7 days of exposure to 2 and 4 mg/l were comparable
to the control values, while at 7 and 10 mg/l they decreased sharply. The amount of phaeophytin (as a percentage of total
chlorophyll a content) increased with increasing potassium bichromate concentration. 相似文献
6.
R. Haapala E. Parkkinen P. Suominen S. Linko 《Applied microbiology and biotechnology》1995,43(5):815-821
Polyurethane foam and nylon-web carriers were compared for simultaneous production of endo-1, 4-β-glucanase and xylanase by
immobilizedTrichoderma reesei on a medium based on lactose (27 g/l), cellulose (3 g/l) and sorbose (0.3 g/l). Nylon sheet with 1.2 cm2 carrier surface/ml medium was superior to the others, and it was selected for further studies. The carbon source had a marked
effect on enzyme production by the immobilized fungus. With pure cellulose (10 g/l) as substrate, the maximum endoglucanase
activity was 690 nkat/ml and xylanase activity 4800 nkat/ml. Supplementation with 0.5 g/l of sorbose resulted in an increase
in both endoglucanase and xylanase activities in all media studied. A more detailed study on the effect of sorbose on a lactose(7
g/l)-and cellulose(3 g/l)-based medium revealed a clear optimum sorbose concentration of 1.5 g/l, with a maximum endoglucanase
activity of 660 nkat/ml, xylanase activity of 3670 nkat/ml, and filter-paper activity (overall cellulolytic activity) of 2.0
filter-paper units/ml. However, the addition of 1.5 g/l sorbose to the pure-cellulose(10 g/l)-based medium resulted in a slight
decrease in the enzyme production. 相似文献
7.
B. Bugarski G. A. King G. Jovanovic A. J. Daugulis M. F. A. Goosen 《Applied microbiology and biotechnology》1989,30(3):264-269
Summary The performance of an external loop air-lift bioreactor was investigated by assessing the inter-relationships between various hydrodynamic properties and mass transfer. The feasibility of using this bioreactor for the production of monoclonal antibodies by mouse hybridoma cells immobilized in calcium alginate gel beads and alginate/poly-l-lysine microcapsules was also examined. When the superficial gas velocity, V
g
, in the 300 ml reactor was varied from 2 to 36 cm/min, the average liquid velocity increased from 3 to 14 cm/sec, the gas hold-up rose from 0.2 to 3.0%, and the oxygen mass transfer coefficient, k
L
a, increased from 2.5 to 18.1 h-1. A minimum liquid velocity of 4 cm/s was required to maintain alginate gel beads (1000 m diameter, occupying 3% of reactor volume) in suspension. Batch culture of hybridoma cells immobilized in alginate beads followed logarithmic growth, reaching a concentration of 4×107 cells/ml beads after 11 days. Significant antibody production did not occur until day 9 into the culture, reaching a value of 100 g/ml of medium at day 11. On the other hand, bioreactor studies with encapsulated hybridoma cells gave monoclonal antibody concentrations of up to 800 g/ml capsules (the antibody being retained within the semipermeable capsule) and maximum cell densities of 2×108 cells/ml capsule at day 11. The volumetric productivities of the alginate gel immobilized cell system and the encapsulated cell system were 9 and 3 g antibody per ml of reactor volume per day, respectively. The main advantage of the bioreactor system is its simple design, since no mechanical input is required to vary the hydrodynamic properties. 相似文献
8.
Large scale transient 5-HT3 receptor production with the Semliki Forest Virus Expression System 总被引:1,自引:0,他引:1
H. D. Blasey B. Brethon R. Hovius H. Vogel H A. P. Tairi K. Lundström L. Rey A. R. Bernard 《Cytotechnology》2000,32(3):199-208
The expression of recombinant proteins with the Semliki Forest Virus (SFV) system has been scaled up to bioreactor scale. As a model protein for this study the human 5-HT3 receptor was chosen. The gene for the receptor was subcloned into the SFV expression plasmid pSFV1. Virus production by in vivo packaging and production of the recombinant protein was scaled up, the latter to a reactor volume of 11.5 l. A VibromixTM agitation system was chosen to overcome aggregation problems of BHK cells in suspension. In the process, cells were first grown to a density of 106 cells/ml, the medium was then exchanged with fresh medium and the culture was infected with the recombinant virus at an estimated multiplicity of infection of 30. 24 h post infection we measured an expression level of 3 million functional 5-HT3 receptors per cell. For harvesting, the cells were pelleted by centrifugation. The receptor protein was purified in a single step (Hovius et al., 1998) by exploiting the hexa-His tag at minimal protein loss (51% yield). Experiments to optimise expression resulted in yields up to 8 million receptors per cell, when the pH of a suspension culture was controlled at pH 7.3. Rapid virus generation and protein production, high protein yields as well as successful large scale application have made the SFV expression system attractive to produce large quantities of recombinant protein in a very short time. After optimisation of the expression conditions (in particular by setting the pH at 7.3), yields were increased twofold. 相似文献
9.
In this study, an Agrobacteriurn tumefaciens-mediated transformation (ATMT) protocol was successfully developed for the genetic transformation of a taxol-producing fungus,
Cladosporium cladosporioides MD2, and the co-cultivation conditions affecting the transformation efficiency were optimized. The optimal transformation
conditions were that 1 ml of C. cladosporioides MD2 spore suspension (108 spores/ml) was mixed with an equal volume of A. tumefaciens cultures, which contained 400 μl of A. tumefaciens LBA4404 (OD660 ≈ 0.6) and 600 μl LB medium that were used to make up difference in volume, and the mix cultures were supplemented with 300 μM
acetosyringone (AS) and co-cultivated at 26°C and 50 rpm for 48 h. Stable transformants were obtained through analysis of
the mitotic stability of inserted T-DNA and the presence of hygromycin resistance gene (hpt II). This study laid a fine groundwork for development of transgenic C. cladosporioides MD2 strains. 相似文献
10.
M. W. Breedveld L. P. T. M. Zevenhuizen H. C. J. Canter Cremers A. J. B. Zehnder 《Antonie van Leeuwenhoek》1993,64(1):1-8
The influence of growth rate and medium composition on exopolymer production byRhizobium leguminosarum was studied. When grown in medium containing 10g/l mannitol and 1g/l glutamic acid,Rhizobium leguminosarum biovartrifolii TA-1 synthesized up to 2.0g/l of extracellular polysaccharide (EPS), and up to 1.6g/l of capsular polysaccharide (CPS). Under non-growing cell conditions in medium without glutamic acid, CPS synthesis by strain TA-1 could proceed to 2.1g/l, while EPS-production remained relatively low (0.8g/l). Maximal CPS-yield was 2.9g CPS/l medium in a medium containing 20g/l mannitol and 2g/l glutamic acid. TheEPS-deficient strain R. leguminosarum RBL5515,exo4::Tn5 was able to produce CPS to similar levels as strain TA-1, but CPS-recovery was easier because of the low viscosity of the medium and growth of the cells in pellets. With strain TA-1 in nitrogen-limited continuous cultures with a constant biomass of 500mg cell protein/l, EPS was the most abundant polysaccharide present at every dilution rate D (between 0.12 and 0.02 h–1). The production rates were 50–100mg/g protein/h for EPS and 15–20mg/g protein/h for CPS. Only low amounts of cyclic -(1,2)-glucans were excreted (10–30 mg/l) over the entire range of growth rates.Abbreviations bv
biovar
- CPS
capsular polysaccharide
- EPS
extracellular polysaccharide
- HMr
high molecular mass
- LMr
low molecular mass
- YEMCR
Yeast Extract-Mannitol-Congo Red agar 相似文献
11.
Habib Ur Rehman Attiq Ur Rehman Kakar Mohammed Yaqoob Muhammad Asghar Syed Saeed Ahmed Khair Un Nisa 《Luminescence》2023,38(2):99-108
A novel flow injection-chemiluminescence (FI–CL) approach is proposed for the assay of pioglitazone hydrochloride (PG-HCl) based on its enhancing influence on the tris(2,2′-bipyridyl)ruthenium(II)–silver(III) complex (Ru(bipy)32+-DPA) CL system in sulfuric acid medium. The possible CL reaction mechanism is discussed with CL and ultraviolet (UV) spectra. The optimum experimental conditions were found as: Ru(bipy)32+, 5.0 × 10−5 M; sulfuric acid, 1.0 × 10−3 M; diperiodatoargentate(III) (DPA), 1.0 × 10−4 M; potassium hydroxide, 1.0 × 10−3 M; flow rate 4.0 ml min−1 for each flow stream and sample loop volume, 180 μl. The CL intensity of PG-HCl was linear in the range of 1.0 × 10−3 to 5.0 mg L−1 (R2 = 0.9998, n = 10) with limit of detection [LOD, signal-to-noise ratio (S/N) = 3] of 2.2 × 10−4 mg L−1, limit of quantification (LOQ, S/N = 10) of 6.7 × 10−4 mg L−1, relative standard deviation (RSD) of 1.0 to 3.3% and sampling rate of 106 h−1. The methodology was satisfactorily used to quantify PG-HCl in pharmaceutical tablets with recoveries ranging from 93.17 to 102.77 and RSD from 1.9 to 2.8%. 相似文献
12.
Wei Shen Jun Chen Madeleine Gantz Gilbert Velasquez Mark Punyanitya Steven B. Heymsfield 《Obesity (Silver Spring, Md.)》2012,20(12):2458-2463
Earlier cross‐sectional studies found that a single magnetic resonance imaging (MRI) slice predicts total visceral and subcutaneous adipose tissue (VAT and SAT) volumes well. We sought to investigate the accuracy of trunk single slice imaging in estimating changes of total VAT and SAT volume in 123 overweight and obese subjects who were enrolled in a 24‐week CB‐1R inverse agonist clinical trial (weight change, ?7.7 ± 5.3 kg; SAT change, ?5.4 ± 4.9 l, VAT change, ?0.8 ± 1.0 l). VAT and SAT volumes at baseline and 24 weeks were derived from whole‐body MRI images. The VAT area 5–10 cm above L4—L5 (A+5–10) (R2 = 0.59–0.70, P < 0.001) best predicted changes in VAT volume but the strength of these correlations was significantly lower than those at baseline (R2 = 0.85–0.90, P < 0.001). Furthermore, the L4—L5 slice poorly predicted VAT volume changes (R2 = 0.24–0.29, P < 0.001). Studies will require 44–69% more subjects if (A+5–10) is used and 243–320% more subjects if the L4—L5 slice is used for equivalent power of multislice total volume measurements of VAT changes. Similarly, single slice imaging predicts SAT loss less well than cross‐sectional SAT (R2 = 0.31–0.49 vs. R2 = 0.52–0.68, P < 0.05). Results were the same when examined in men and women separately. A single MRI slice 5–10 cm above L4—L5 is more powerful than the traditionally used L4—L5 slice in detecting VAT changes, but in general single slice imaging poorly predicts VAT and SAT changes during weight loss. For certain study designs, multislice imaging may be more cost‐effective than single slice imaging in detecting changes for VAT and SAT. 相似文献
13.
Cell Culture Derived AgMNPV Bioinsecticide: Biological Constraints and Bioprocess Issues 总被引:1,自引:0,他引:1
Valeria M. Rodas Fabiano H. Marques Marcelo T. Honda Daniela M. Soares Soraia A. C. Jorge Marta M. Antoniazzi Claudia Medugno Maria E. B. Castro Bergmann M. Ribeiro Marlinda L. Souza Aldo Tonso Carlos A. Pereira 《Cytotechnology》2005,48(1-3):27-39
We have studied parameters for optimizing the Spodoptera frugiperda (Sf9) cell culture and viral infection for the production of Anticarsia gemmatalis multiple nucleopolyhedrosis virus (AgMNPV) polyhedra inclusion bodies (PIBs) in shaker-Schott or spinner bottles and bioreactors.
We have assayed the kLa of the systems, initial cell seeding, cell culture volume, dissolved oxygen (DO), multiplicity of infection (MOI), nutrients
consumption, and metabolites production. The medium surface oxygen transfer was shown to be higher in shaker bottles than
in spinner ones, which was in direct correlation to the higher cell density obtained. Best quantitative performances of PIBs
production were obtained with a SF900II medium volume/shaker-bottle volume ratio of 15% and MOI of 0.5 to 1 performed at a
cell concentration at infection (CCI) of 1 to 2.5×106 cells/ml in a medium containing enough glucose and glutamine. Upon infection, a decrease in the cell multiplication was observed
to be dependent on the MOI used, and the μX at the exponential growth phase in infected and non-infected cultures were, respectively,
of 0.2832 and 0.3914 (day−1). The glucose consumption and lactate production were higher in the infected cultures (μGlucose and μLactate of, respectively,
0.0248 and 0.0089×10−8 g/cell×day in infected cultures and 0.0151 and 0.0046×10−8 g/cell×day in non infected ones). The glutamine consumption did not differ in both cultures (μGlutamine of 0.0034 and 0.0037×10−8 g/cell×day in, respectively, infected and non infected cultures). When a virus MOI of 0.1 to 1 was used for infection, a
higher concentration of PIBs/ml was obtained. This was in direct correlation to a higher cell concentration present in these
cultures, where a decrease in cell multiplication due to virus infection is minimized. When a MOI of 1 was used, a more effective
decrease in cell multiplication was observed and a lower concentration of PIBs/ml was obtained, but with the best performance
of PIBs/cell. Correlations between MOI and CCI indicate that a MOI 0.1 to 1.4 and a CCI of 106 to 2×106 cells/ml led to the best PIBs production performances. The virulence of PIBs produced in cultures infected at low or high
MOI showed comparable DL50. Culture and infection in scaling-up conditions, performed in a bioreactor, were shown to provide the cells with a better
environment and be capable of potentially improving the shaker-Schott findings. For an accurate qualitative control of PIB
virulence, hemolymph from AgMNPV infected Anticarsia gemmatalis was used as starting material for passages in Sf9 cells. These led to a loss of virulence among the PIBs with an increase
in the DL50. The loss of virulence was accompanied by a loss in budded virus titer, a decreased number of PIBs produced and an altered
DNA restriction pattern, suggesting the generation of defective interference particles (DIPs). Transmission electron microscopy
(TEM) studies revealed that after cell passages, PIBs lacking virions were progressively synthesized. The study described
here point out the biological constraints and bioprocess issues for the preparation of AgMNPV PIBs for biological control. 相似文献
14.
Prasanna D. Belur Floyd L. Inman III Leonard D. Holmes 《Biocontrol Science and Technology》2013,23(12):1458-1468
Photorhabdus luminescens, a bacterial symbiont of entomoparasitic nematodes, was cultured in a 10 L bioreactor. Cellular density and bioluminescence were recorded and volumetric oxygen transfer coefficient (kLa) and specific oxygen transfer rates were determined during the batch process. Exponential phase of the bacterium lasted for 20 h, showing a maximum specific growth rate of 0.339 h?1 in a defined medium. Bioluminescence peaked within 21h, and was maintained until the end of the batch process (48 h). The specific oxygen uptake rate (SOUR) was high during both lag and early exponential phase, and eventually reached a stable value of 0.33 mmol g?1 h?1 during stationary phase. Maintenance of 200 rpm agitation and 1.4 volume of air per volume of medium per minute (vvm) aeration, gave rise to a kLa value of 39.5 h?1. This kLa value was sufficient to meet the oxygen demand of 14.4 g L?1 (DCW) biomass. This research is particularly relevant since there are no reports available on SOURs of symbiotic bacteria or their nematode partners. The insight gained through this study will be useful during the development of a submerged monoxenic culture of Heterorhabditis bacteriophora and its symbiotic bacterium P. luminescens in bioreactors. 相似文献
15.
Qi Ye Ximu Li Ming Yan Hou Cao Lin Xu Yueyuan Zhang Yong Chen Jian Xiong Pingkai Ouyang Hanjie Ying 《Applied microbiology and biotechnology》2010,87(2):517-525
To develop an economical industrial medium, untreated cane molasses (UCM) was tested as a carbon source for fermentation culturing
of Escherichia coli. To test the industrial application of this medium, we chose a strain co-expressing a carbonyl reductase (PsCR) and a glucose
dehydrogenase (BmGDH). Although corn steep liquor (CSL) could be used as an inexpensive nitrogen source to replace peptone,
yeast extract could not be replaced in E. coli media. In a volume of 40 ml per 1-l flask, a cell concentration of optical density (OD600) 15.1 and enzyme activities of 6.51 U/ml PsCR and 3.32 U/ml BmGDH were obtained in an optimized medium containing 25.66 g/l
yeast extract, 3.88 g/l UCM, and 7.1% (v/v) CSL. When 3.88 g/l UCM was added to the medium at 6 h in a fed-batch process, the E. coli concentration increased to OD600 of 24, and expression of both PsCR and BmGDH were twofold higher than that of a batch process. Recombinant cells from batch
or fed-batch cultures were assayed for recombinant enzyme activity by testing the reduction of ethyl 4-chloro-3-oxobutanoate
to ethyl (S)-4-chloro-3-hydroxybutanoate (CHBE). Compared to cells from batch cultures, fed-batch cultured cells showed higher recombinant
enzyme expression, producing 560 mM CHBE in the organic phase with a molar yield of 92% and an optical purity of the (S)-isomer of >99% enantiomeric excess. 相似文献
16.
The study of the rhizobial root nodules of the monocotyledonous tree Roystonea regia revealed that the Rhizobium sp. isolated from the root nodules produced high amounts (45.6 μg/ml) of indole acetic acid (IAA) from L‐tryptophan supplemented basal medium. The IAA production reached its optimum using 3 mg/ml of L‐tryptophan. The preferred carbon and nitrogen sources were glucose and KNO3 and the optimum concentrations 1% and 0.02%, respectively. FeSO4 × 7 H2O was found to be the only metal ion that increased IAA production. An optimum IAA production was also achieved when the basal medium was supplemented with glucose (1%), FeSO4 × 7 H2O (10 μg/ml), KNO3 (0.02%) as well as EDTA (5 μg/ml) and L‐tryptophan (3 mg/ml). The possible role of IAA production in the monocotyledonous tree‐Rhizobium symbiosis is discussed. Hormone production is shown to be the beneficial aspect of this symbiosis as shown earlier in dicotyledonous plants. 相似文献
17.
A system was developed for protoplast isolation and culture from suspension cultured cells of winged bean,Psophocarpus tetragonolobus. Cells from a three-day-old suspension were incubated in an enzyme mixture containing 6% cullulysin, 1% Macerase, 1% desalted
Rhozyme, 0.4M sorbitol, and 0.1M CaCl2 at pH 5.5. Average yields of protoplasts were 6.5 × 106 per gram fresh weight of cells. Protoplasts were cultured in modified B5 medium containing 68.4 g/l glucose, 250 mg/l xylose,
0.1 mg/l 2,4-D, 0.5 mg/l BAP, 250 mg/l N-Z amine type AS, and 20 ml/l coconut water.
After 24 h of culture, the protoplasts had synthesized a new wall, and in three days had begun division. The optimum plating
density was 1–2 × 103 protoplasts/ml. The division frequency ranged between 40%–60% for most experiments with a high of 72% in one experiment.
After three weeks, cell colonies could be transferred to solid MS medium containing N-Z amine and coconut water where callus
developed. This protoplast system is technically comparable to soybean for experiments concerned with genetic manipulation
involving legumes. 相似文献
18.
Nilegaonkar S.S. Kanekar P.P. Sarnaik S.S. Kelkar A.S. 《World journal of microbiology & biotechnology》2002,18(8):785-789
An extracellular protease was produced by Arthrobacter ramosus isolated from the alkaline lake of Lonar, Buldhana District of Maharashtra, India when grown on a synthetic medium of pH 10 containing casein. The optimum conditions for production were 3.0% initial casein concentration, 2% inoculum of 1 × 108 cells/ml, pH 9.0, temperature 30 °C and shaken culture conditions. The protease was purified by ammonium sulphate precipitation followed by Sephadex G-100 chromatography. Two proteases viz. Arthro I and Arthro II, having molecular weights 21 and 11.4 kDa respectively were isolated. The Arthro II fraction had K
m 395 g/ml and V
max 10.55 g/min for azocasein. The maximum activity of enzyme was at 55 °C and pH 8. It was thermostable (up to 80 °C), alkali stable (pH 12) and stable in commercial detergent. The enzyme may contain a thiol group at the active site. 相似文献
19.
Abstract Potato (cv. Crystal) protoplast-derived callus tissue was evaluated for survival and growth when exposed to Erwinia carotovora subsp. carotovora (strain Ecc71). Calli were either directly exposed to the pathogen by inoculation or to metabolites produced by the pathogen via a bilayer medium. Individual calli were inoculated with 0.5 μl of bacterial suspensions at 104, 105, 106, 107, 108 and 109 cfu/ml. The bilayer consistedof 10 ml of callus proliferation medium supplemented with pectin (2 g/l) and contained bacteria at 102, 103, 104, 105 and 106 cfu/ml. This medium was overlaid with 10 ml of bacteria free callus induction medium. Mean callus diameter of the inoculated treatments increased for 24 h, then declined. Over 90% of the inoculated calli were killed within 5 days but some survived as long as 14 days. Calli grown on the bilayer medium containing 106, 105 and 104 cfu/ml also decreased in size. Most were killed within 9 days but some survived 20 days. Calli exposed to 103 and 102 cfu/ml experienced limited growth with 20% and 7%, respectively, surviving after 27 days. Reactions to the pathogen varied considerably within the callus populations and individual calli with extended survival were identified in both experiments. 相似文献
20.
Suction volume and filtering efficiency of silver carp (Hypophthalmichthys molitrix Val.) and bighead carp (Aristichthys nobilis Rich.) 总被引:1,自引:0,他引:1
Shuanglin Dong Deshang Li Xuwen Bing Qingfeng Shi Fang Wang 《Journal of fish biology》1992,41(5):833-840
Experiments were conducted to measure the suction volume of silver carp and bighead carp of age 1 + with respiratory chamber, and to calculate the suction volume and the filtering efficiency with respect to changes in concentrations of food particles. Suction volume (B. ml/mouth) and filtering efficiency (E. %) were calculated using the following formula: C 1=C0(1-BE/v)n where C0 and C1 were the concentrations of specific food particles at the beginning and at the end of experiment, respectively, V was the volume (ml) of experimental water, and n was the total number of observation of suction made during the experimental period. The relationships between suction volume (ml/mouth) of age I+ silver carp (Bh) and bighead carp (Ba) and their standard lengths (L, cm) were: B h=0.561L-8.94, Ba= 0.627L-7.48 while those of the fingerlings were: B h= O.l70L-0.837, Ba= 0.157L-0.418. The suction volume of the fingerlings was mainly affected by fish size, the function of temperature between 15 and 25° C being negligible. However, temperature affected filtering rate (filtered volume per unit time) through its effect on filtering frequency. The filtering efficiency of the fishes for rotifers (Brachionus caliciflorus) was 100 per cent. The relationships between filtering efficiency and sizes of food particles smaller than or equal to that of a rotifer were: E h=25.1 ln e.s.d. -13.6, Ea=22.2 In e.s.d. -33.1 where Eh and Ea were filtering efficiency of silver carp and bighead carp, respectively, and e.s.d. was the equivalent spherical diameter (μm) of food particles. 相似文献