共查询到20条相似文献,搜索用时 15 毫秒
1.
Hefnawy MA 《Folia microbiologica》2001,46(5):407-412
The osmotolerant fungusAspergillus chevalieri tolerates up to 80% sucrose concentration in the growth medium. At 50% sucrose the growth rate is 1.5-fold higher than in
control (3% sucrose), at 80% sucrose it drops to 30% of the control level. Total proteins and lipids in the mitochondrial
fractions obtained from the mycelium rise with increasing sucrose concentration during growth (2.6 and 2.1 times at 80% sucrose).
The rate of respiration by whole cells and mitochondrial fractions increases with increased sucrose level in the growth medium.
The activity of respiratory enzymes, such as succinate dehydrogenase, cytochrome oxidase, NADH oxidase and succinate oxidase,
were also higher in cells growth in the presence of elevated sucrose concentrations. The largest increase was observed with
NADH dehydrogenase.A. chevalieri cells grown at high osmotic stress exhibited enlarged mitochondria. The mean mitochondrial diameter at 50 and 80% sucrose was approximately
2.9- and 2.6-fold larger than in the control, respectively. Agarose gel electrophoresis of nucleic acids revealed the presence
of high-density bands of RNA in mitochondrial fractions from cells grown at elevated sucrose levels. 相似文献
2.
Ki Moon Park Min Woo Song Jae Heung Lee 《Biotechnology and Bioprocess Engineering》2008,13(2):197-203
Batch culture kinetics of the red yeast, Xanthophyllomyces dendrorhous SKKU 0107, revealed reduction in biomass with glucose and lower intracellular carotenoid content with fructose. Figures were
different when compared to sucrose, which is a disaccharide of glucose and fructose. In contrast, specific growth rate constant
stayed between 0.094~0.098 h−1, irrespective of the carbon sources employed. Although the uptake rate of glucose was found to be 2.9-fold faster than that
of fructose, sucrose was found to be a more suitable carbon source for the production of carotenoids by the studied strain.
When sugar cane molasses was used, both the specific growth rate constant and the intracellular carotenoid content decreased
by 27 and 17%, respectively. Compared with the batch culture using 28 g/L sugar cane molasses, fed-batch culture with the
same strain resulted in a 1.45-fold higher cell yield together with a similar level of carotenoid content in X. dendrorhous SKKU 0107. 相似文献
3.
Diosgenin formation by freely suspended and entrapped plant cell cultures of Dioscorea deltoidea 总被引:1,自引:0,他引:1
Robertson GH Doyle LR Sheng P Pavlath AE Goodman N 《Biotechnology and bioengineering》1989,34(8):1114-1125
Altered phosphorus concentration, oxygen supply rate, and programmed addition of sucrose and phosphorus were applied to Dioscorea deltoidea plant cells in airlift suspension to increase the formation of the secondary metabolite diosgenin. A low oxygen supply rate (k(l)a' of 3.9 h(-1)) completely inhibited formation of diosgenin. A high oxygen supply rate (k(l)a' of 17.1 h(-1)) led to the greatest formation of diosgenin in 30 g/L sucrose when the sucrose-to-phosphorus mole ratio was 42.5:1. Programmed addition of nutrients over a 15-day period reduced growth of cell mass relative to diosgenin mass. Intentional aggregation by entrapment of virtually all cells in reticulated polyurethane foam led to reduced cell-mass yield, diosgenin yield and concentration relative to suspended cells at the same conditions. Entrapment of a small fraction of the cells led to a delayed development of a suspension culture and to formation of significantly higher concentrations of diosgenin. Nearly all of this increase was attributable to the suspended cells. This result suggested sequestering of nonproductive cells by the matrix or sequestering of important nutrients by the matrix-bound cells. Entrapped cells attained densities of 40 g/L in the matrix. 相似文献
4.
The effect of abscisic acid on growth, ultrastructure and nucleic acid biosynthesis was studied in tissue culture of spinach (Spinacia oleracea L.). Low concentration (0.01 mg l?1) of abscisic acid increased fresh and dry weight of calluses, whereas 1.0 mg l?1 was inhibitory. The stimulating effect was observed only in the presence of a relatively high concentration of kinetin (1 mg l?1). The inhibitory effect was partly overcome by the same kinetin concentration. The low concentration of abscisic acid probably accelerated the induction of callus growth after subculture and stimulated cell division in the exponential phase of growth. Electron microscopy showed the presence of numerous polysomes and rough endoplasmic reticulum in callus cells grown at the stimulating abscisic acid concentration. Control cells and cells at the inhibitory concentration had slightly hyaline cytoplasm and were more vacuolated. Incubation of callus tissue with 32P in the presence of stimulating concentration of abscisic acid showed a significant increase in the rate of biosynthesis of all nucleic acid classes after 8 h, whereas inhibitory concentration produced a decrease in 32P incorporation. However, when the tissue was grown in the presence of abscisic acid for 20 days, both concentrations decreased the rate of nucleic acid biosynthesis, as compared to the controls. 相似文献
5.
6.
During exponential growth ofStreptococcus faecalis, the distribution of cell arrangements remains constant, but depends on the growth rate. The predominant cell arrangements
are diplococci (about 60–80% of total cells) the amount of which varies only little with the growth rate. A clear correlation
exists for cells growing as chains; the amount decreases from about 20% at μ=2.0 to about 6% at μ=0.45. After cessation of
growth in the stationary phase, the number of diplococci and chains decreases and the number of monococci increases; after
10 h in the stationary phase, more than 50% of the cells have become monococci. The dry weight of 2.5×10−10 mg/cell remains constant at different growth rates, while cell size shows small differences on different growth media. Treatment
of exponentially growing cultures with crystal violet or nitrofurantoin results in faster sedimentation on sucrose gradients
of treated cultures compared to untreated cultures. While crystal violet effects an increased chain formation, treatment with
nitrofurantoin results in an increase of the size of the individual cell. 相似文献
7.
Plant cells utilize various sugars as carbon sources for growth, respiration and biosynthesis of cellular components. Suspension-cultured
cells of azuki bean (Vigna angularis) proliferated actively in liquid growth medium containing 1% (w/v) sucrose, glucose, fructose, arabinose or xylose, but did
not proliferate in medium containing galactose or mannose. These two latter sugars thus appeared distinct from other sugars
used as growth substrates. Galactose strongly inhibited cell growth even in the presence of sucrose but mannose did not, suggesting
a substantial difference in their effects on cell metabolism. Analysis of intracellular soluble-sugar fractions revealed that
galactose, but not mannose, caused a conspicuous decrease in the cellular level of sucrose with no apparent effects on the
levels of glucose or fructose. Such a galactose-specific decrease in sucrose levels also occurred in cells that had been cultured
together with glucose in place of sucrose, suggesting that galactose inhibits the biosynthesis, rather than uptake, of sucrose
in the cells. By contrast, mannose seemed to be metabolically inert in the presence of sucrose. From these results, we conclude
that sucrose metabolism is important for the heterotrophic growth of cells in plant suspension-cultures. 相似文献
8.
α-Tocopherol is the most biologically active component of vitamin E and is synthesized only by photosynthetic organisms. Two
heterotrophic cell lines of sunflower (Helianthus annuus L.) of differing α-tocopherol biosynthetic capability, three-fold higher in the high synthesizing cell line, HT, than in
the low synthesizing one, LT, were previously identified. To investigate the relationship between α-tocopherol biosynthesis
and photomixotrophic culture conditions, a new photomixotrophic sunflower cell line HS3 was established by selecting HT cells
able to grow in the presence of a ten-fold reduced sucrose concentration in the culture medium. The photosynthetic properties
of HS3 cells were characterized in comparison with HT and LT cells, revealing an increase in chlorophyll content, chloroplast
number, and level of the photosynthesis related enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Furthermore,
an enhanced expression of the gene encoding for the tocopherol biosynthetic enzyme geranyl-geranylpyrophosphate synthase (GGPPS)
was observed in HS3 cells. HS3 cells also revealed a 25% and a more than three-fold higher tocopherol level than HT and LT,
respectively, indicating a positive correlation between α-tocopherol biosynthesis of sunflower cell cultures and their photosynthetic
properties. These findings can be useful for improving the tocopherol yields of the sunflower in vitro production system. 相似文献
9.
10.
The effect of osmotic stress on cell growth and phenylethanoid glycosides (PeGs) biosynthesis was investigated in cell suspension
cultures of Cistanche deserticola Y. C. Ma, a desert medicinal plant grown in west region of China. Various initial sucrose concentrations significantly affected
cell growth and PeGs biosynthesis in the suspension cultures, and the highest dry weight and PeGs accumulation reached 15.9 g l−1-DW and 20.7 mg g−1-DW respectively at the initial osmotic stress of 300 mOsm kg−1 where the sucrose concentration was 175.3 mM. Stoichiometric analysis with different combinations of sucrose and non-metabolic
sugar (mannitol) or non-sugar osmotic agents (PEG and NaCl) revealed that osmotic stress itself was an important factor for
enhancing PeGs biosynthesis in cell suspension cultures of C. deserticola. The maximum PeGs contents of 26.9 and 23.8 mg g−1-DW were obtained after 21 days at the combinations of 87.6 mM sucrose with 164.7 mM mannitol (303 mOsm kg−1) or 20 mM PEG respectively, which was higher than that of C. deserticola cell cultures grown under an initial sucrose concentration of 175.3 mM after 30 days. The stimulated PeGs accumulation in
the cell suspension cultures was correlated to the increase of phenylalanine ammonium lyase (PAL) activity induced by osmotic
stress. 相似文献
11.
12.
Cells in the root meristem are organised in longitudinal files. Repeated transverse cell divisions in these files are the prime cause of root growth. Because of the orientation of the cell divisions, we expected to find mitoses with an spindle axis parallel to the file axis. However, we observed in the root cortex ofVicia faba large number of oblique chromosome orientations. From metaphase to telophase there was a dramatic increase of the rotation of the spindle axis. Measurements of both the size of the cortex cells and the chromosome configurations indicated that most cells were too small for an orientation of the spindle parallel to the file axis. Space limitation force the spindle into an oblique position. Despite this spindle axis rotation, most daughter cells remained within the original cell file. Only in extremely flat cells did the position of the daughter nuclei forced the cell to set a plane of division parallel to the file axis, which result in side-by-side orientation of the daughter cells. Telophase spindle axis rotations are also observed inCrepis capillaris andPetunia hybrida.. These species have respectively medium and small sized chromosomes compared toVicia. Since space limitation, which causes the rotation, depends both on cell and chromosome size, the frequency and extent of the phenomenon in former two species is comparatively low. 相似文献
13.
Summary Superoxide dismutase(SOD) was produced by carrot hairy roots. After increasing in the early exponential growth phase, SOD biosynthesis decreased as the growth rate of hairy roots declined. High sucrose concentration stimulated the SOD biosynthesis, while inhibiting the growth of hairy roots. Potential inducers were tested for the enhanced production of SOD. The addition of 0.3 mM CuSO4 to the broth showed about 6 fold increase in SOD biosynthesis compared to the results obtained with basic MS medium. Since CuSO4 in the broth inhibited the growth of hairy roots, the addition of CuSO4 to the broth at the late exponential growth phase led to a 12 times higher intracellular level of SOD compared to that in basic MS medium. 相似文献
14.
Motohiro Matsuura Yoshiki Tani Hideaki Yamada 《Bioscience, biotechnology, and biochemistry》2013,77(8):2127-2133
To establish an intact cell system to determine the rate of vitamin B6 (B6) biosynthesis, conditions suitable for the reaction were examined. Cells of Escherichia coli B WG2, a pdxH mutant, were used for the reaction. Pyridoxal-starved cells of a stationary phase culture showed a negligible change of cell mass and a constant increase of B6 in the reaction. The rate of B6 biosynthesis was reliably determined with a 2-hr reaction initiated with cells of 0.10 to 0.15mg per ml. The influence of endogenous metabolites was completely abolished by the use of such a low concentration of the starved cells.When glucose was used as a sole carbon substrate in the reaction system, the maximum rate of B6 biosynthesis was determined to be 0.5 to 0.6 nmol per mg cells per hr. The maximum rate increased to 0.8 to 0.9 nmol per mg cells per hr on supplementation of glycolaldehyde to the reaction mixture. The result led to the conclusion that the rate-limiting step in the reaction sequence of B6 biosynthesis lies the process of incorporation of the 5–5′ carbon fragment of the B6 molecule. This was also confirmed by a growth experiment with the wild type strain. 相似文献
15.
Bárbara Cuesta Jesús Vega Pedro Villar-Salvador José Mª Rey-Benayas 《Trees - Structure and Function》2010,24(5):899-908
Large and high nitrogen (N) concentration seedlings frequently have higher survival and growth in Mediterranean forest plantations
than seedlings with the opposite traits, which has been linked to the production of deeper and larger root systems in the
former type of seedlings. This study assessed the influence of seedling size and N concentration on root growth dynamics and
its relation to shoot elongation in Aleppo pine (Pinus halepensis Mill.) seedlings. We cultivated seedlings that differed in size and tissue N concentration that were subsequently transplanted
into transparent methacrylate tubes in the field. The number of roots, root depth, and the root and shoot elongation rate
(length increase per unit time) were periodically measured for 10 weeks. At the end of the study, we also measured the twig
water potential (ψ) and the mass of plant organs. New root mass at the end of the study increased with seedling size, which was linked to the
production of a greater number of new roots of lower specific length rather than to higher elongation rate of individual roots.
Neither plant size nor N concentration affected root depth. New root mass per leaf mass unit, shoot elongation rate, and pre-dawn
ψ were reduced with reduction in seedling size, while mid-day ψ and the root relative growth rate were not affected by seedling size. N concentration had an additive effect on plant size
on root growth but its overall effect was less important than seedling size. Shoot and roots had an antagonistic elongation
pattern through time in small seedlings, indicating that the growth of both organs depressed each other and that they competed
for the same resources. Antagonism between shoot and root elongation decreased with plant size, disappearing in large and
medium seedlings, and it was independent of seedling N concentration. We conclude that root and shoot growth but not rooting
depth increased with plant size and tissue N concentration in Aleppo pine seedlings. Since production of new roots is critical
for the establishment of planted seedlings, higher absolute root growth in large seedlings may increase their transplanting
performance relative to small seedlings. The lack of antagonism between root and shoot growth in large seedlings suggests
that these plants can provide resources to sustain simultaneous growth of both organs. 相似文献
16.
Bleaching herbicides of the phenylpyridazinone group (norflurazon, metflurazon, SAN 9774 and SAN 9785) and difunon and amitrole were added to cell suspension cultures of Dioscorea deltoidea at 1μM. Difunon inhibited growth and carotenoid biosynthesis and metflurazon inhibited growth. Norflurazon was the only herbicide tested that influenced diosgenin production. Norflurazon increased the rate of diosgenin biosynthesis so that 180mg/l were obtained after 14 days of incubation as compared to 30 days for the control to reach the same level. 相似文献
17.
Télef N Stammitti-Bert L Mortain-Bertrand A Maucourt M Carde JP Rolin D Gallusci P 《Plant molecular biology》2006,62(3):453-469
Tomato (Solanum lycopersicum) fruit ripening is characterized by a massive accumulation of carotenoids (mainly lycopene) as chloroplasts change to chromoplasts. To address the question of the role of sugars in controlling carotenoid accumulation, fruit pericarp discs (mature green fruits) were cultured in vitro in the presence of various sucrose concentrations. A significant difference in soluble sugar content was achieved depending on external sucrose availability. Sucrose limitation delayed and reduced lycopene and phytoene accumulation, with no significant effect on other carotenoids. Chlorophyll degradation and starch catabolism were not affected by variations of sucrose availability. The reduction of lycopene synthesis observed in sucrose-limited conditions was mediated through metabolic changes illustrated by reduced hexose accumulation levels. In addition, variations of sucrose availability modulated PSY1 gene expression. Taken together our results suggest that the modulation of carotenoid accumulation by sucrose availability occurs at the metabolic level and involves the differential regulation of genes involved in carotenoid biosynthesis. 相似文献
18.
Xiongfeng Dai Mya Warren Daniel Sévin Yi‐Ping Wang Terence Hwa 《Molecular systems biology》2015,11(10)
Understanding how the homeostasis of cellular size and composition is accomplished by different organisms is an outstanding challenge in biology. For exponentially growing Escherichia coli cells, it is long known that the size of cells exhibits a strong positive relation with their growth rates in different nutrient conditions. Here, we characterized cell sizes in a set of orthogonal growth limitations. We report that cell size and mass exhibit positive or negative dependences with growth rate depending on the growth limitation applied. In particular, synthesizing large amounts of “useless” proteins led to an inversion of the canonical, positive relation, with slow growing cells enlarged 7‐ to 8‐fold compared to cells growing at similar rates under nutrient limitation. Strikingly, this increase in cell size was accompanied by a 3‐ to 4‐fold increase in cellular DNA content at slow growth, reaching up to an amount equivalent to ~8 chromosomes per cell. Despite drastic changes in cell mass and macromolecular composition, cellular dry mass density remained constant. Our findings reveal an important role of protein synthesis in cell division control. 相似文献
19.
SHINSAKU TAKAYAMA MASANARU MISAWA KEIDO KO TOMOMASA MISATO 《Physiologia plantarum》1977,41(4):313-320
An extract of cultured Agroxieinma githago L. cells was found to show potent inhibitory activity against plans virus infection. The effects of cultural conditions on the growth of the cell suspension and on the production of the inhibitor were examined. Since the production of substance was dependent on growth. experiments were made to improve growth. The optimum temperature was 26 to 30°C and optimum pH of the medium before autoclaving was between 5 and 7. In a medium of higher osmotic pressure, the water content of the cultured cells was lowered markedly. The growth rate in a small volume of the medium was higher than that in a larger volume at an early stage of the cultivation, but it was not changed by different inoculum sizes. The cells required thiamine and 2,4-D for growth but no other vitamins or growth regulators. The optimum level of 2,4-D was 0.1 mg/l. Higher sucrose concentration in the medium gave higher production of cell mass and of the inhibitor. However, 3% of sucrose was selected as the most economical concentration. For normal cell growth, the presence of both NH4NO3 and KNO3 as nitrogen sources was required. The use of a single nitrogen source caused a long lag period or inhibition of the cell growth. KH2PO4 stimulated the growth when in was used in the level of 2.5 to 5 mM. The cell adhesion on the surface of the fermentor sometimes causes trouble in a large-scale cultivation. It was found that reducing the Ca2+ level in the medium prevented the cell adhesion and foaming remarkably. Based on the results obtained, a modified medium was established which was excellent for shortening the culture period and for efficient production of the anti-plant virus inhibitor. 相似文献
20.
Cell suspensions inoculated at low cell concentrations displayed a typical growth reduction, whereas root cultures displayed
an improvement in growth. Specific growth rate ofHyoscyamus muticus cell suspensions decreased from 0.25 to 0.12 d−1 as inoculum concentration was reduced from 4.0 to 0.02 g fresh weight per liter. In contrast, roots show an increase in growth
rate from 0.24 to 0.43 d−1. These contrasting growth patterns can be explained as the result of: a) the high specific surface area of cells as compared
to roots and, b) the differentiated structure of roots. The dispersed nature of cell suspensions makes them more prone to
leakage of key growth factors/cellular contents to medium. The results of this work indicate that cell cultures require substantially
higher inoculum concentrations. In contrast, roots can be inoculated at very low concentrations. These facts imply that whereas
seed vessels must be employed by cell suspensions, their use for root cultures is a compromise between an easier handling
of an entwined root mass and the reduction of the contamination risk of large medium volumes. 相似文献