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1.
《Bioscience, biotechnology, and biochemistry》2013,77(7):1642-1654
The present investigation showed that active processes were involved in the uptake of 2,4-dichlorophenoxyacetate (2,4-D) by Delftia acidovorans MC1. With 2,4-D-grown cells, uptake at pH 6.8 was highly affine and showed a complex pattern-forming intermediary plateau at 20–100 μM 2,4-D. The kinetics became increasingly sigmoidal with raising of the pH to 7.5 and 8.5, and complexity disappeared. The apparent maximum was obtained at around 400 μM 2,4-D at either pH, and amounted to 15–20 nmol/min*mg protein. Higher substrate concentrations resulted in significant inhibition. With cells grown on (RS)-2-(2,4-dichlorophenoxy)propionate, 2,4-D uptake increased significantly and reached 45 nmol/min*mg, hinting at induction of a specific carrier(s). The kinetic characteristics made it apparent that several proteins contribute to 2,4-D uptake in MC1. An open reading frame was detected which has similarity to genes encoding major facilitator superfamily (MFS) transporters. Mutant strains that lacked this gene showed altered kinetics with decreased affinity to 2,4-D at pH 6.8. A mutant with complete deficiency in phenoxyalkanoate utilization showed an almost linear uptake pattern hinting at sole diffusion. Cloning of tfdK encoding a specific transporter for 2,4-D resulted in an increased uptake rate and, above all, higher affinity at slightly alkaline conditions due to hyperbolic kinetics. The presence of carbonylcyanide m-chlorophenylhydrazone led to the subsequent strong inhibition of 2,4-D uptake, suggesting proton symport as the likely active mechanism. 相似文献
2.
The ratios of hapten and bovine serum albumin (BSA) in an antigen conjugate were determined by matrix-assisted laser desorption/ionization
time-of-flight (MALDI-TOF) mass spectrometry. Hybridomas secreting monoclonal antibodies against 2,4-dichlorophenoxyacetic
acid (2,4-D) were produced by fusing 2,4-D-BSA conjugate-immunized splenocytes with a HAT-sensitive mouse myeloma cell line,
P3-X63-Ag8-653. A substantial cross-reaction was observed for 2,4-dichlorophenol (2,4-DP) when compared with that observed
for 2,4-D. The full measurement range for this assay is 0.2–3 μg ml−1 for 2,4-DP. On the other hand, the range for 2,4-D is between 1 and 20 μg ml−1.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
The growth performance of malolactic fermenting bacteria Oenococcus oeni NCIMB 11648 and Lactobacillus brevis X2 was assessed in continuous culture. O. oeni grew at a dilution rate range of 0.007 to 0.052 h−1 in a mixture of 5:6 (g l−1) of glucose/fructose at an optimal pH of 4.5, and L. brevis X2 grew at 0.010 to 0.089 h−1 in 10 g l−1 glucose at an optimal pH of 5.5 in a simple and safe medium. The cell dry weight, substrate uptake and product formation
were monitored, as well as growth kinetics, yield parameters and fermentation balances were also evaluated under pH control
conditions. A comparison of growth characteristics of two strains was made, and this showed significantly different performance.
O. oeni has lower maximum specific growth rate (μmax=0.073 h−1), lower maximum cell productivity (Q
x
max=17.6 mg cell l−1 h−1), lower maximum biomass yield (Y
x/s
max=7.93 g cell mol−1 sugar) and higher maintenance coefficient (m
s=0.45 mmol−1 sugar g−1 cell h−1) as compared with L. brevis X2 (μmax=0.110 h−1; Q
x
max=93.2 g−1 cell mol−1 glucose; Y
x/s
max=22.3 g cell mol−1 glucose; m
s=0.21 mmol−1 glucose g−1 cell h−1). These data suggest a possible more productive strategy for their combined use in maturation of cider and wine. 相似文献
4.
Three post-emergence herbicides (2,4-D, picloram and glyphosate) were applied to samples of an Alberta agricultural soil at
concentrations of 0, 2, 20, and 200 μg g−1. The effects of these chemicals on certain microbial variables was monitored over 27 days. All herbicides caused enhancement
of basal respiration but only for 9 days following application, and only for concentrations of 200 μg g−1. Substrate-induced respiration was temporarily depressed by 200 μg g−1 picloram and 2,4-D, and briefly enhanced by 200 μg g−1 glyphosate. It is concluded that because changes in microbial variables only occurred at herbicide concentrations of much
higher than that which occurs following field application, the side-effects of these chemicals is probably of little ecological
significance. 相似文献
5.
Kiviharju K Moilanen U Leisola M Eerikäinen T 《Applied microbiology and biotechnology》2007,73(6):1267-1274
The behavior of Streptomyces peucetius var. caesius N47 was studied in a glucose limited chemostat with a complex cultivation medium. The steady-state study yielded the characteristic
constants μ
max over 0.10 h−1, Y
XS 0.536 g g−1, and mS 0.54 mg g−1 h−1. The product of secondary metabolism, ɛ-rhodomycinone, was produced with characteristics Y
PX 12.99 mg g−1 and m
P 1.20 mg g−1 h−1. Significant correlations were found for phosphate and glucose consumption with biomass and ɛ-rhodomycinone production. Metabolic
flux analysis was conducted to estimate intracellular fluxes at different dilution rates. TCA, PPP, and shikimate pathway
fluxes exhibited bigger values with production than with growth. Environmental perturbation experiments with temperature,
airflow, and pH changes on a steady-state chemostat implied that an elevation of pH could be the most effective way to shift
the cells from growing to producing, as the pH change induced the biggest transient increase to the calculated ɛ-rhodomycinone
flux. 相似文献
6.
Calli were induced from mature caryopses of timothy grass (Phleum pratense L.) on MS medium (Murashige and Skoog 1962) supplemented with 500 mg·dm−3 casein hydrolysate and 5 mg·dm−3 2,4-D (2,4-dicholorophenoxyacetic acid) or 2 mg·dm−3 dicamba (3,6-dichloro-o-anisic acid). Twelve-week-old calli were passaged on media with reduced levels of auxins (2 mg·dm−3 2,4-D or 1 mg·dm−3 dicamba). Tissues induced on medium with 2,4-D were transferred on medium with 2,4-D and on medium with dicamba; parallely
calli initiated on medium with dicamba were passaged on medium with 2,4-D or dicamba. Calli from various media sequences were
used to establish cell suspension cultures in media containing 2 mg·dm−3 2,4-D or 1 mg·dm−3 dicamba. An assessment of regeneration ability of calli was made on MS medium containing 0.2 mg·dm−3 kinetin. Callus tissue induced and/or subcultured on any of the media with 2,4-D did not regenerate plants while dicamba
added to the media was the effective stimulator of regenerability. In the presence of 2,4-D calli and suspensions produced
a jelly-like extracellular matrix. In cell suspension this phenomenon was observed 4–5 days after each passage. The measurements
of electric potential of calli, growing on MS medium with kinetin were performed. Non-regenerating callus areas had an electric
potential close to 0 mV while parts of tissue with meristematic centres were characterized by lower values of electric potential. 相似文献
7.
Mohammad BT Wright PC Bustard MT 《Journal of industrial microbiology & biotechnology》2006,33(12):975-983
The bioconversion of high concentration isopropanol (2-propanol, IPA) was investigated by a solvent tolerant strain of bacteria, which was identified as Sphingobacterium mizutae ST2 by partial 16S rDNA gene sequencing. This strain of bacteria exhibited the ability to utilise high concentration isopropanol as the sole carbon source, with mineralization occurring via an acetone intermediate into central metabolism. The biodegradative performance of this strain for IPA was examined over a 2–38 g l−1 concentration range, using specific growth rate (μ) and conversion rate analysis. Maximum specific growth rates (μmax) of 0.0045 h−1 were routinely obtainable on IPA. In addition, the highest specific IPA degradation rate was obtained at a concentration of 7.5 g l−1 with a corresponding value of 0.045 g IPA g cells−1 h−1. While the highest acetone yield reached its maximum value of 0.940 g acetone g IPA−1 at 7.5 g IPA l−1. This is the first report on bioconversion of isopropanol at such high concentration by this solvent tolerant strain of S. mizutae and may allow its application in novel biocatalytic processes for effective biological conversion in two-phase solvent systems. 相似文献
8.
Piccolo A Conte P Cozzolino A Paci M 《Journal of industrial microbiology & biotechnology》2001,26(1-2):70-76
Phenoxyalkanoic acids are a widely used class of herbicides. This work employed high-resolution 13C NMR to study the structural changes induced by humic substances and horseradish perodixase on 2,4-dichorophenoxyacetic acid
(2,4-D) 13C-labelled in the side chain. NMR spectra showed that humic substances chemically catalyze abiotic splitting of [13C]2,4-D into 2,4-dichlorophenol and [13C]acetic acid at pH 7 but not at pH 4.7. Peroxidase did not catalyze the oxidative degradation of [13C]2,4-D at any pH tested and inhibited the effect of humic substances. Catalytic degradation by humic substances was attributed
to free-radical reactions enhanced by the stereochemical contribution of large conformational structures formed by heterogeneous
humic molecules at neutral pHs. Inhibition of 2,4-D degradation when humic substances were combined with peroxidase was explained
by modification of both chemical and conformational humic structure due to peroxidase-promoted oxidative cross-coupling among
humic molecules. Our findings show for the first time that the abiotic degradation of 2,4-D is catalyzed by dissolved humic
substances at neutral pH. Journal of Industrial Microbiology & Biotechnology (2001) 26, 70–76.
Received 09 February 2000/ Accepted in revised form 22 May 2000 相似文献
9.
Bustard MT McEvoy EM Goodwin JA Burgess JG Wright PC 《Applied microbiology and biotechnology》2000,54(3):424-431
The aerobic biodegradation of high concentrations of 1-propanol and 2-propanol (IPA) by a mixed microbial consortium was
investigated. Solvent concentrations were one order of magnitude greater than any previously reported in the literature. The
consortium utilized these solvents as their sole carbon source to a maximum cell density of 2.4 × 109 cells ml−1. Enrichment experiments with propanol or IPA as carbon sources were carried out in batch culture and maximum specific growth
rates (μmax) calculated. At 20 °C, μ
max values were calculated to be 0.0305 h−1 and 0.1093 h−1 on 1% (v/v) IPA and 1-propanol, respectively. Growth on propanol and IPA was carried out between temperatures of 10 °C and
45 °C. Temperature shock responses by the microbial consortium at temperatures above 45 °C were demonstrated by considerable
cell flocculation. An increase in propanol substrate concentration from 1% (v/v) to 2% (v/v) decreased the μ
max from 0.1093 h−1 to 0.0715 h−1. Maximum achievable biodegradation rates of propanol and IPA were 6.11 × 10−3% (v/v) h−1 and 2.72 × 10−3% (v/v) h−1, respectively. Generation of acetone during IPA biodegradation commenced at 264 h and reached a maximum concentration of
0.4% (v/v). The results demonstrate the potential of mixed microbial consortia in the bioremediation of solvent-containing
waste streams.
Received: 14 December 1999 / Received revision: 3 April 2000 / Accepted: 7 April 2000 相似文献
10.
The formation of effective root nodules on a non-nodulating line (T201) of soybean (Glycine max (L.) Merr.,) was induced by a treatment with 2,4-dichlorophenoxyacetate (2,4-D). The induced nodules, inoculated with mixed Bradyrhizobium japonicum strains A1017 and IRj2101, had a normal internal structure, red in colour and the cells being filled with bacteroids. Externally, the induced nodules were of unusual shape, being paired or gourd-like in form and were attached to thickened roots. The nodules were capable of acetylene reduction (3.1–3.5 moles g-1 fresh weight nodules h-1), allowing the growth of plants with dark green leaves. 相似文献
11.
Plant regeneration through somatic embryogenesis of Areca catechu L. was established using leaf, root and stem segments as explants. Embryogenic callus was induced and maintained on medium
supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) or 3,6-dichloro-2-methoxybenzoic acid (dicamba) at concentrations
2, 4, 6 and 8 mg dm−3 in darkness. Somatic embryos were found on primary callus in the presence of 2 and 4 mg dm−3 dicamba and during subculture on 2 – 8 mg dm−3 2,4-D or 2 – 4 mg dm−3 dicamba-containing media. Plantlet conversion from embryos was successfully achieved on growth regulator-free medium. The
plants grew well when transplanted to containers in shaded greenhouse. 相似文献
12.
Yesenia Herrera Anthony I. Okoh Laura Alvarez Norma Robledo María R. Trejo-Hernández 《World journal of microbiology & biotechnology》2008,24(1):55-60
As part of our effort at establishing microbial consortia of relevance for the bioremediation of xenobiotics polluted environments
in Mexico, we assessed the aerobic biodegradation of 2,4-dichlorophenol (2,4-DCP) by a consortium of four Bacillus species
that were isolated from a polluted soil by enrichment using a mixture of chlorophenols. The bacterial consortium effectively
biodegraded 2-chlorophenol, 3-chlorophenol and 2,4-dichlorophenol at degradation rates of between 1.7 and 6.7 μmoles l−1 h−1. In the presence of NH4Cl or KNO2 as nitrogen sources, 2,4-DCP was variously degraded. Under both conditions, cell biomass attained highest values of 350 and 450 mg l−1 respectively, while the amounts of 2,4-DCP metabolized in 21 days reached peak values of 2.1 and 2.5 mM representing between
70 and 85% degradation respectively. Chloride releases during the same period were highest at 4.7 mM and 5.3 mM in the presence
of the two nitrogen sources. The presence of free-chloride in the culture medium had a significant impact on the catabolism
of 2,4-dichlorophenol. 相似文献
13.
M.N. Ogburia 《Biologia Plantarum》2003,47(3):429-432
Explants of four F1 hybrids (OMR 36-41/1, OMR 36-41/2, OMR 36-41/4 and OMR 36-41/5) and two cultivars (Rayong 1 and Rayong 60) of cassava (Manihot esculenta Crantz) were subjected to different combinations of 2,4-dichlorophenoxyacetic acid (2,4-D), 1-naphthaleneacetic acid (NAA),
kinetin (KIN) and N6-benzylaminopurine (BAP) to induce somatic embryogenesis, organogenesis and micropropagation. Shoot apices of the F1 hybrids exhibited higher frequency (62 – 74 %) of proliferation of somatic embryos than the cultivars (21 – 43 %) in Murashige
and Skoog basal medium supplemented with 8 mg dm−3 2,4-D and 0.5 mg dm−3 NAA. Nodal explants of regenerated plantlets were rapidly micropropagated with 90 % efficiency on a medium containing 0.1
mg dm−3 NAA and 0.05 mg dm−3 BAP irrespective of explant source.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Yoshifumi Kawana Raiki Yamamoto Yukira Mochida Kunio Suzuki Shigeyuki Baba Hamako Sasamoto 《Plant biotechnology reports》2007,1(4):219-226
Liquid cultures were successfully generated from cotyledons of two Sonneratia species, S. alba and S. caseolaris in Murashige and Skoog (MS) medium containing 0.1 μmol L−1 2,4-dichlorophenoxyacetic acid (2,4-D). Adventitious roots differentiated from cotyledons of S. alba. Proliferated cells were subcultured and a large volume of suspension cells was subsequently established in 100-mL flasks.
All the cytokinins tested inhibited cell proliferation. After three years of culture, the potential to differentiate was tested
as indicated by greening of the cells. Greening occurred when suspension cells were transferred to solid MS medium with and
without 0.1 μmol L−1 2,4-D. Greening was stimulated by low concentrations of the weak auxins indolebutyric acid (IBA) and naphthaleneacetic acid
(NAA) while 2,4-D stimulated late-stage greening. Abscisic acid (ABA) inhibited greening. Gibberellic acid (GA3) at 1.0 μmol L−1 stimulated callus greening and was not inhibitory even when tested at high concentrations. Cytokinins were inhibitory in
combination with 0.1 μmol L−1 of either IBA or NAA. The cause of different effects of plant hormones on growth and differentiation was discussed. Small-scale
liquid media and 24-well culture plates of solid media methods developed in this paper are suitable for the optimization of
hormonal conditions for cell proliferation and differentiation. 相似文献
15.
T. Chakbavarty J. G. Norcini J. H. Aldrich R. S. Kalmbacher 《In vitro cellular & developmental biology. Plant》2001,37(5):550-554
Summary Creeping bluestem (Schizachyrium scoparium (Michx.) Nash var. stoloniferum (Nash) J. Wipff) embryogenic callus growing on solid medium was used to establish a cell suspension culture in Murashige
and Skoog (MS) basal medium supplemented with 1.5 mg l−1 (6.8 μM) 2,4-dichlorophenoxyacetic acid (2,4-D), 0.2 mg l−1 (0.88 μM) 6-benzylaminopurine (BA), 0.5 mg l−1 (1.4 μM) zeatin, 0.2 mg l−1 (0.58 μM) gibberellic acid (GA3), and 10% (v/v) of coconut water (CW). Pro-embryos from suspension culture matured on semi-solid MS medium in about 18 wk,
and were then cultured on semi-solid MS medium without growth regulators for 2–3 wk. Shoots were regenerated on MS basal medium
supplemented with 3.0 mg L−1 (13.6 μM) 2,4-D, 1.0 mg l−1 (4.4 μM) BA, 1.0 mg l−1 (2.9 μM) GA3, 0.5 mg l−1 (2.7 μM) 1-naphthaleneacetic acid (NAA), 500 mg l−1 easein hydrolysate, and 10% (v/v) CW. Rooted plantlets were successfully accelimatized to greenhouse and outdoor conditions.
Using this protocol, it would be possible to produce at least 1300 fully acclimatized plantlets annually. 相似文献
16.
Candida cylindracea NRRL Y-17506 was grown to produce extracellular lipase from oleic acid as a carbon source. Through flask cultures, it was found that the optimum initial oleic acid concentration for cell growth was 20 g l−1. However, high initial concentrations of oleic acid up to 50 g l−1 were not inhibitory. The highest extracellular lipase activity obtained in flask culture was 3.0 U ml−1 after 48 h with 5 g l−1 of initial oleic acid concentration. Fed-batch cultures (intermittent and stepwise feeding) were carried out to improve cell concentration and lipase activity. For the intermittent feeding fed-batch culture, the final cell concentration was 52 g l−1 and the extracellular lipase activity was 6.3 U ml−1 at 138.5 h. Stepwise feeding fed-batch cultures were carried out to simulate an exponential feeding and to investigate the effects of specific growth rate (0.02, 0.04 and 0.08 h−1) on cell growth and lipase production. The highest final cell concentration obtained was 90 g l−1 when the set point of specific growth rate (μset) was 0.02 h−1. High specific growth rate (0.04 and 0.08 h−1) decreased extracellular lipase production in the later part of fed-batch cultures due to build-up of the oleic acid oversupplied. The highest extracellular lipase activity was 23.7 U ml−1 when μset was 0.02 h−1, while the highest lipase productivity was 0.31 U ml−1 h−1 at μset of 0.08 h−1. 相似文献
17.
Klebsiella planticola strain DSZ1 has the ability to degrade different aromatic compounds such as benzoate and organochlorinated as propachlor
and alachlor. DSZ1 strain cells mineralised 4-hydroxybenzoate (4HBA) through a meta-cleavage pathway, yielding protocatechuate
as dihydroxylated intermediate, with a specific rate of CO2 formation 0.12 × 10−6 (cpm/OD) h−1, and a rate of 4-HBA utilisation of 0.75 mmol h−1. Aerobically the 4HBA transport system is driven by gradient of protons (ΔpH), but is not ATP-driven. Under anaerobic conditions,
the system can use the nitrate reduction as a final electron acceptor in respiration. A kinetic analysis of the 4HBA transport
system revealed a Kt value of 16 μM with a Vmax value of 25 nmol/min.mg at pH 7.
Received: 28 March 2001/Accepted: 14 May 2001 相似文献
18.
Bruce R. Lyon Danny J. Llewellyn John L. Huppatz Elizabeth S. Dennis W. James Peacock 《Plant molecular biology》1989,13(5):533-540
Plants resistant to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) were produced through the genetic engineering of a novel detoxification pathway into the cells of a species normally sensitive to 2,4-D. We cloned the gene for 2,4-D monooxygenase, the first enzyme in the plasmid-encoded 2,4-D degradative pathway of the bacterium Alcaligenes eutrophus, into a cauliflower mosaic virus 35S promoter expression vector and introduced it into tobacco plants by Agrobacterium-mediated transformation. Transgenic tobacco plants expressing the highest levels of the monooxygenase enzyme exhibited increased tolerance to 2,4-D in leaf disc and seed germination assays, and young plants survived spraying with levels of herbicide up to eight times the usual field application rate. The introduction of the gene for 2,4-D monooxygenase into broad-leaved crop plants, such as cotton, should eventually allow 2,4-D to be used as an inexpensive post-emergence herbicide on economically important dicot crops. 相似文献
19.
Tissue culture and plant regeneration of blue grama grass, Bouteloua gracilis (H.B.K.) Lag. Ex Steud
Gerardo Armando Aguado-Santacruz José Luis Cabrera-Ponce Víctor Olalde-Portugal M. A. Rosario Sánchez-González Judith Márouez-Guzmán Luis Herrera-Estrella 《In vitro cellular & developmental biology. Plant》2001,37(2):182-189
Summary As a first step towards applying biotechnology to blue grama, Bouteloua gracilis (H. B. K.) Lag. ex Steud., we have developed a regenerable tissue culture system for this grass. Shoot apices were isolated
from 3-d-old seedlings and cultured in 15 different growth regulator formulations combining 2,4-dichlorophenoxyacetic acid
(2,4-D), Picloram (4-amino-3, 5,6-trichloropicolinic acid), N6-benzyladenine (BA) or adenine (6-aminopurine). The highest induction of organogenic callus was obtained with formulations
containing 1 mg l−1 (4.52 μM) 2,4-D plus 0.5 mg l−1 (2.22 μM) BA. and 2 mg l−1 (8.88 μM) BA plus 1 mg l−1 (4.14 μM) Picloram with or without 40 mg l−1 (296.08 μM) adenine. Lower frequencies of induction were obtained for embryogenic as compared to organogenic callus. The most efficient
treatments for induction of embryogenic callus contained 2 mg l−1 (9.05 μM) 2,4-D combined with 0.25 (1.11 μM) or 0.50 mg l−1 (2.22 μM) BA, or 1 mg l−1 (4.52 μM) 2,4-D with 0.50 mg l−1 (2.22 μM) BA. Regeneration was achieved in hormonefree Murashige anmd Skoog (MS) medium, half-strength MS medium or MS medium plus
1 mg l−1 (1.44 μM) gibberellic acid. The number of plantlets regenerated per 500 mg callus fresh weight on MS medium ranged from 9 for 2 mg
l−1 (9.05 μM) 2,4-D to 62.2 for induction medium containing 2 mg l−1 (8,28 μM) Picloram, 1 mg l−1 (4.44 μM) BA and 40 mg l−1 (296.08 μM) adenine. Regnerated plants grown in soil under greenhouse conditions reached maturity and produced seeds. 相似文献
20.
Bao-Hong Zhang Hong-Mei Wang Fang Liu Yun-Hai Li Zheng-De Liu 《In vitro cellular & developmental biology. Plant》2001,37(2):300-304
Summary 2,4-Dichlorophenoxyacetic acid (2,4-D) resistant plants of transgenic cotton (Gossypium hirsutum L.) were produced using Agrobacterium tumefaciens containing a plasmid carrying the neomycin phosphotransferase II (npt II) and 2,4-D monooxygenase (tfd A) genes. An in vitro assay was performed to determine the sensitivity of seed germination, and the growth of seedlings of transgenic and non-transgenic
cotton to various concentrations of kanamycin and 2,4-D. The results indicated that kanamycin caused the cotyledons of non-transgenic
plants to turn white, but transgenic plants grew normally. Seed germination and seedling growth of non-transgenic plants were
strongly inhibited by 2,4-D, but only slightly for transgenic plants. Transgenic plants and non-transgenic plants can be clearly
distinguished by the use of 2 mg l−1 2,4-D in seed germination medium. There was a high correlation between the response of seed germination and the growth of
seedlings to kanamycin or 2,4-D, based on the germination ration, albino ratio, dry weight or fresh weight. On this basis,
we development a rapid method for identifying transgenic plants that has been verified in the field. These findings will allow
identification of cotton transformants at an early stage of plant development, saving time and improving cultivars containing
the 2,4-D resistance trait. 相似文献