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1.
Production of sophorolipids from whey 总被引:5,自引:0,他引:5
Otto RT Daniel HJ Pekin G Müller-Decker K Fürstenberger G Reuss M Syldatk C 《Applied microbiology and biotechnology》1999,52(4):495-501
Sophorolipids, obtained by a two-stage process starting from deproteinized whey concentrate using Cryptococcus curvatus ATCC 20509 and Candida bombicola ATCC 22214, were compared to products from one-stage processes, using different lipidic compounds as substrates. Results
showed that above all carbon source and not cultivation conditions had a distinct influence on the composition of the crude
product mixture and therefore on the physicochemical and biological properties of the sophorolipids, such as, for example,
surface activity, cytotoxicity and stability against hydrolases. The results were completed by corresponding data for purified
mono- and diacetylated (17-hydroxyoctadecenoic)-1′,4′′-lactonized sophorolipids. Crude sophorolipid mixtures showed moderate
to good surface active properties (SFTmin 39 mN m−1, CMC 130 mg l−1), water solubilities (2–3 g l−1) and low cytotoxicities (LC50 300–700 mg l−1). In contrast, purified sophorolipids were more surface active (SFTmin 36 mN m−1, CMC 10 mg l−1), less water soluble (max. 70 mg l−1) and showed stronger cytotoxic effects (LC50 15 mg l−1). Incubation of crude sophorolipid mixtures with different hydrolases demonstrated that treatment with commercially available
lipases such as from Candida rugosa and Mucor miehei distinctly reduced the surface active properties of the sophorolipids, while treatment with porcine liver esterase and glycosidases
had no effect.
Received: 23 February 1999 / Received revision: 27 May 1999 / Accepted: 28 May 1999 相似文献
2.
Nitrite accumulates during biological denitrification processes when carbon sources are insufficient. Acetate, methanol, and
ethanol were investigated as supplementary carbon sources in the nitrite denitrification process using biogranules. Without
supplementary external electron donors (control), the biogranules degraded 200 mg l−1 nitrite at a rate of 0.27 mg NO2–N g−1 VSS h−1. Notably, 1,500 mg l−1 acetate and 700 mg l−1 methanol or ethanol enhanced denitrification rates for 200 mg l−1 nitrite at 2.07, 1.20, and 1.60 mg NO2–N g−1 VSS h−1, respectively; these rates were significantly higher than that of the control. The sodium dodecyl sulfate polyacrylamide
gel electrophoresis of the nitrite reductase (NiR) enzyme identified three prominent bands with molecular weights of 37–41 kDa.
A linear correlation existed between incremental denitrification rates and incremental activity of the NiR enzyme. The NiR
enzyme activity was enhanced by the supplementary carbon sources, thereby increasing the nitrite denitrification rate. The
capacity of supplementary carbon source on enhancing NiR enzyme activity follows: methanol > acetate > ethanol on molar basis
or acetate > ethanol > methanol on an added weight basis. 相似文献
3.
4-Chlorophenol degradation by a bacterial consortium: development of a granular activated carbon biofilm reactor 总被引:5,自引:0,他引:5
Caldeira M Heald SC Carvalho MF Vasconcelos I Bull AT Castro PM 《Applied microbiology and biotechnology》1999,52(5):722-729
A bacterial consortium that can degrade chloro- and nitrophenols has been isolated from the rhizosphere of Phragmitis communis. Degradation of 4-chlorophenol (4-CP) by a consortium attached to granular activated carbon (GAC) in a biofilm reactor was
evaluated during both open and closed modes of operation. During the operation of the biofilm reactor, 4-CP was not detected
in the column effluent, being either adsorbed to the GAC or biodegraded by the consortium. When 4-CP at 100 mg l−1 was fed to the column in open mode operation (20 mg g−1 GAC total supply), up to 27% was immediately available for biodegradation, the rest being adsorbed to the GAC. Biodegradation
continued after the system was returned to closed mode operation, indicating that GAC bound 4-CP became available to the consortium.
Biofilm batch cultures supplied with 10–216 mg 4-CP g−1 GAC suggested that a residual fraction of GAC-bound 4-CP was biologically unavailable. The consortium was able to metabolise
4-CP after perturbations by the addition of chromium (Cr VI) at 1–5 mg l−1 and nitrate at concentrations up to 400 mg l−1. The development of the biofilm structure was analysed by scanning electron microscopy and confocal laser scanning microscopy
(CLSM) techniques. CLSM revealed a heterogeneous structure with a network of channels throughout the biofilm, partially occupied
by microbial exopolymer structures.
Received: 17 March 1999 / Received revision: 27 May 1999 / Accepted: 28 May 1999 相似文献
4.
Concentrations of plankton, suspended particles 0.74–87 μm equivalent spherical diameter and dissolved organic carbon (DOC)
were measured from May to February at an Antarctic coastal site. Bacteria-sized particles 0.74–1 μm diameter, and bacterial
cells and heterotrophic protists all exhibited a seasonal minimum during winter and maxima in summer. Bacteria composed <10%
of the bacteria-sized particles. Release of autotrophic protists from the ice caused water column biomass of autotrophs to
reach maximum concentrations in October and November, but maximum cell concentration in the water column was reached in January.
Microheterotroph biomass weakly reflected the release of the ice algal community but reached maximum concentration during
the water column bloom in January. Total DOC concentrations varied from 0.36 mg C l−1 in July to 3.10 mg C l−1 in October, with a yearly average of 1.51 mg C l−1. Ultrafiltration of DOC revealed that the molecular weight composition of the DOC differed greatly through the year. DOC
<5 kDa molecular weight reached a maximum of 1.25 mg C l−1 in October and accounted for up to 60% of total DOC in July. Concentrations of high molecular weight DOC (>100 kDa) were
highest in July and November, with the DOC (100 kDa–0.5 μm) fraction reaching a maximum of 1.22 mg C l−1 in November and composing 82% of the total DOC in January. Wet chemical oxidation and high-temperature catalytic oxidation
organic carbon analyses were compared. Good correlation was observed between methods during summer but no significant correlation
existed in winter, indicating that winter DOC may be refractory.
Accepted: 21 March 2000 相似文献
5.
Wang Xi-Ling Zhou Jin-Xing Yu Mao-De Li Zhen-Gang Jin Xiao-Yun Li Qi-You 《In vitro cellular & developmental biology. Plant》2011,47(3):434-440
Efficient plant regeneration is essential for successful transformation and in vitro polyploidy induction in mulberry. A high frequency (80%) of plant regeneration from hypocotyls occurred under in vitro conditions in mulberry (Morus multicaulis Poir.). We identified three key factors for enhancing successful regeneration based on earlier work: (1) hypocotyl position,
(2) the combination and concentration of growth regulators, and (3) the addition of AgNO3. The highest frequency of shoot regeneration was achieved using hypocotyl segments, which are proximal to apical meristems,
and the optimal culture conditions were Murashige and Skoog’s (MS) (Murashige and Skoog, 1962) basal medium supplemented with 3.0 mg l−1 6-benzylamino purine, 0.3 mg l−1 indole-3-acetic acid, 0.1% polyvinypyrrolidone, and 1.0 mg/l silver nitrate (AgNO3) under subdued light at 25 ± 2°C. Treating the shoots with 0.2% colchicine (dipping for 72 h) resulted in a 14% tetraploid
frequency, whereas a 20% tetraploid frequency resulted from using a 0.25% colchicine (dripping for 5 d) treatment, as determined
by chromosome number counts. The diploid plant chromosome number was 28 (2n = 2x = 28) and that of tetraploid plants was 56 (2n = 4x = 56). Regenerated shoots rooted easily in 8–10 d using half-strength basal MS medium with 0.5 mg l−1 indole-3-butyric acid and were successfully established in the soil. 相似文献
6.
The influence of ammonia on the anaerobic degradation of peptone by mesophilic and thermophilic populations of biowaste was
investigated. For peptone concentrations from 5 g l−1 to 20 g l−1 the mesophilic population revealed a higher rate of deamination than the thermophilic population, e.g. 552 mg l−1 day−1 compared to 320 mg l−1 day−1 at 10 g l−1 peptone. The final degree of deamination of the thermophilic population was, however, higher: 102 compared to 87 mg NH3/g peptone in the mesophilic cultures. If 0.5–6.5 g l−1 ammonia was added to the mesophilic biowaste cultures, deamination of peptone, degradation of its chemical oxygen demand
(COD) and formation of biogas were increasingly inhibited, but no hydrogen was formed. The thermophilic biowaste cultures
were most active if around 1 g ammonia l−1 was present. Deamination, COD degradation and biogas production decreased at lower and higher ammonia concentrations and
hydrogen was formed in addition to methane. Studies of the inhibition by ammonia of peptone deamination, COD degradation and
methane formation revealed a K
i (50%) for NH3 of 92, 95 and 88 mg l−1 at 37 °C and 251, 274 and 297 mg l−1 at 55 °C respectively. This indicated that the thermophilic flora tolerated significantly more NH3 than the mesophilic flora. In the mesophilic reactor effluent 4.6 × 108 peptone-degrading colony-forming units (cfu)/ml were culturable, whereas in the thermophilic reactor effluent growth of only
5.6 × 107 cfu/ml was observed.
Received: 24 April 1998 / Received revision: 26 June 1998 / Accepted: 27 June 1998 相似文献
7.
Saba Ambreen Memon Xilin Hou Bo Zhu Joseph N. Wolukau 《Acta Physiologiae Plantarum》2009,31(6):1191-1196
The objective of the present work was selection of cultivar and suitable medium for regenerating shoots from leaf segments
of non-heading Chinese cabbage. We evaluated six types of supplemented media with 2.0, 5.0 and 10.0 mg l−1 6-BA; 1.0 and 2.0 mg l−1 TDZ; 0.1, 0.3, 0.5, 0.8 and 1.0 mg l−1NAA; 3.0, 5.0 and 7.5 mg l−1AgNO3; 0.01 mg l−1 2–4, D and 4.0 mg l−1 KT for shoot regeneration and six cultivars “Sanchidaye”, “Liuchuandasuomian”, “Qingyou 4”, “Liangbaiye”, “AiKang 5” and
“Hanxiao F3”, furthermore for root formation three types of supplemented media with 0.2, 0.3, 0.5 mg l−1 NAA, and for survival rate two types of base media: turf + vermiculite + manure (1:2:0.2) and soil + vermiculite (1:2). Culturing
leaf segments on MS medium supplemented with 2 mg l−1 TDZ; 0.5 mg l−1 NAA and 7.5 mg l−1 AgNO3 gave the highest number of shoots per leaf segment (66) while roots were best formed on the medium supplemented with 0.2 mg l−1 NAA. Survival rate was highest (61.6%) in the turf: vermiculite: manure (1:2:0.2) medium. The highest percentage of responding
leaf segments, number of shoots per leaf segment, rooting percentage and survival rate were observed in “Liuchuandasuomian”.
The plantlets were transferred to the soil and grown into mature plants in pots. These results could be used for preliminary
selections of cultivars to transfer disease resistance (Bt) gene through agrobacterium in non-heading Chinese cabbage. 相似文献
8.
An efficient Agrobacterium-mediated protocol for the stable genetic transformation of Eschscholzia californica Cham. (California poppy) via somatic embryogenesis is reported. Excised cotyledons were co-cultivated with A. tumefaciens strain GV3101 carrying the pBI121 binary vector. Except for the co-cultivation medium, all formulations included 50 mg l−1 paromomycin as the selective agent and 200 mg l−1 timentin to eliminate the Agrobacterium. Four to five weeks after infection, paromomycin-resistant calli grew on 80% of explants in the presence of 2.0 mg l−1 1-naphthaleneacetic acid (NAA) and 0.1 mg l−1 6-benzylaminopurine (BAP). Calli were cultured on somatic embryogenesis induction medium containing 1.0 mg l−1 NAA and 0.5 mg l−1 BAP, and somatic embryos were visible on 30% of the paromomycin-resistant calli within 3–4 weeks. Three to four weeks after
the somatic embryos were transferred to phytohormone-free plant regeneration medium, 32% converted to paromomycin-resistant
plants. Detection of the neomycin phosphotransferase gene and high levels of β-glucuronidase (GUS) mRNA and enzyme activity, and the cytohistochemical localization of GUS activity in all plant tissues
confirmed the integrative transformation of the regenerated plants. The normal alkaloid profile of California poppy was unaffected
by the transformation process; thus, the reported protocol could serve as a valuable tool to investigate the molecular and
metabolic regulation of the benzophenanthridine alkaloid pathway.
Received: 27 October 1999 / Revision received: 6 December 1999 / Accepted: 11 January 2000 相似文献
9.
The use of silica gel prepared by sol-gel method and polyurethane foam as microbial carriers in the continuous degradation of phenol 总被引:5,自引:0,他引:5
A mixed microbial culture was immobilized by entrapment into silica gel (SG) and entrapment/ adsorption on polyurethane foam
(PU) and ceramic foam. The phenol degradation performance of the SG biocatalyst was studied in a packed-bed reactor (PBR),
packed-bed reactor with ceramic foam (PBRC) and fluidized-bed reactor (FBR). In continuous experiments the maximum degradation
rate of phenol (q
s
max) decreased in the order: PBRC (598 mg l−1 h−1) > PBR (PU, 471 mg l−1 h−1) > PBR (SG, 394 mg l−1 h−1) > FBR (PU, 161 mg l−1 h−1) > FBR (SG, 91 mg l−1 h−1). The long-term use of the SG biocatalyst in continuous phenol degradation resulted in the formation of a 100–200 μm thick
layer with a high cell density on the surface of the gel particles. The abrasion of the surface layer in the FBR contributed
to the poor degradation performance of this reactor configuration. Coating the ceramic foam with a layer of cells immobilized
in colloidal SiO2 enhanced the phenol degradation efficiency during the first 3 days of the PBRC operation, in comparison with untreated ceramic
packing.
Received: 2 December 1999 / Revision received: 2 February 2000 / Accepted: 4 February 2000 相似文献
10.
Bioenergetics and RNA/DNA ratios in the common carp (Cyprinus carpio ) under hypoxia 总被引:2,自引:0,他引:2
Zhou BS Wu RS Randall DJ Lam PK 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2001,171(1):49-57
Hypoxia caused by eutrophication occurs over large areas in aquatic systems worldwide. Common carp (Cyprinus carpio) exposed to hypoxia (1 mg · O2 · l−1 and 2 mg · O2 · l−1) for 1 week showed a significant reduction in feeding rate, respiration rate, faecal production and nitrogenous excretion
compared to those maintained at normoxia (7 mg · O2 · l−1). Fish exposed to hypoxia showed negative scope for growth (SfG), but no significant difference in the specific growth rate
was revealed after 1 week in both hypoxic groups. A significant reduction in RNA/DNA ratio was, however, clearly evident in
the white muscle of the 1 mg · O2 · l−1 treatment group, but not in the 2 mg · O2 · l−1 treatment group. Both specific growth rate and RNA/DNA ratio were significantly reduced when fish were exposed to severe
hypoxia (0.5 mg · O2 · l−1) for 4 weeks. At all levels of hypoxia, growth reduction was accompanied by a significant decrease in RNA/DNA ratio in white
muscle. Covariance analysis showed no significant difference between the slope of RNA/DNA ratio and growth rate under normoxic
conditions and 0.5 mg · O2 · l−1 for 4 weeks (F=1.036, P > 0.326), as well as 1.0 mg · O2 · l−1 and 2.0 mg · O2 · l−1 for 1 week (F = 0.457, P > 0.5), indicating that the RNA/DNA ratio serves as a biomarker of growth under all oxygen levels, at least under controlled
experimental conditions. SfG also appears to be more sensitive than the RNA/DNA ratio in responding to hypoxia in fish.
Accepted: 15 September 2000 相似文献
11.
In order to provide a better understanding of the dynamics of phytoplankton in the coastal regions of high latitudes, a study
was carried out to estimate the dynamics of carbon biomass of autotrophic and heterotrophic algal groups over the austral
spring-summer 1997/1998 period. At a fixed station located in the central basin (Paso Ancho) of the Straits of Magellan (53°S),
surface water samples were collected at least once a week from September 1997 (early spring) to March 1998 (late summer).
Quantitative analysis of biomass of phytoplankton was estimated from geometric volumes, using non-linear equations, and converted
to biomass. The pattern of chlorophyll a showed a strong temporal variability, with maximum values (mean 2.8 mg m−3) at the austral spring phytoplankton increase or bloom (October/November) and minimum values during early spring (September:
<0.5 mg m−3) and summer (January/March: 0.5–1.0 mg m−3). During the spring bloom, diatoms made up to 90% of the total phytoplankton carbon (0.01–189 μg l−1), followed by a maximum of thecate dinoflagellates (0.08–34 μg l−1), and sporadic high biomass of phytoflagellates during summer. Heterotrophic algal groups such as Gymnodinium and Gyrodinium spp. dominated (70%, in the 5- to 25-μm size range) shortly before the main diatom bloom, and small peaks were observed within
spring and early summer periods (0–0.4 μg l−1). Phytoflagellates dominated earlier (spring) with higher carbon biomass (8 μg l−1) and post-bloom periods (summer) when carbon biomass ranged between 1 and 4 μg l−1.
Accepted: 6 September 2000 相似文献
12.
Inhibition of methane production from whey by heavy metals – protective effect of sulfide 总被引:1,自引:0,他引:1
A whey solution was used as a substrate for methane production in an anaerobic fixed-bed reactor. At a hydraulic retention
time of 10 days, equivalent to a space loading of 3.3 kg (m3 day)−1, 90% of the chemical oxygen demand was converted to biogas. Only a little propionate remained in the effluent. Toxicity tests
with either copper chloride, zinc chloride or nickel chloride were performed on effluent from the reactor. Fifty per cent
inhibition of methanogenesis was observed in the presence of ≥10 mg CuCl2 l−1≥40 mg ZnCl2 l−1 and ≥60 mg NiCl2 l−1, respectively. After exposure to Cu2+, Zn2+ or Ni2+ ions for 12 days, complete recovery of methanogenesis by equimolar sulfide addition was possible upon prolonged incubation.
Recovery failed, however, for copper chloride concentrations ≥40 mg l−1. If the sulfide was added simultaneously with the three heavy metal salts, methanogenesis was only slightly retarded and
the same amount of methane as in non-inhibited controls was reached either 1 day (40 mg ZnCl2 l−1) or 2 days later (10 mg CuCl2 l−1). Up to 60 mg NiCl2 l−1 had no effect if sulfide was present. Sulfide presumably precipitated the heavy metals as metal sulfides and by this means
prevented heavy metal toxicity.
Received: 8 October 1999 / Received revision: 3 January 2000 / Accepted: 4 January 2000 相似文献
13.
Behzad Ahmadi Khoshnood Alizadeh Jaime A. Teixeira da Silva 《Plant Cell, Tissue and Organ Culture》2012,109(3):525-533
The effects of three periods of incubation (10, 20 and 30 min) at different levels of bleomycin (0, 0.1, 0.2, 0.3, 0.4 and
0.5 μg ml−1), as well as three periods of exposure (12, 24 and 48 h) to different levels of the anti-auxin p-chlorophenoxyisobutyric acid (PCIB), including 1, 2, 3, 4 and 5 mg l−1, on microspore embryogenesis of rapeseed cv. ‘Amica’ were investigated. Microspore embryogenesis was significantly enhanced
following 20 min treatment with 0.2 μg ml−1 bleomycin compared with untreated cultures. Highest embryo yield (163 embryos Petri dish−1) was observed with 24 h treatment of 4 mg l−1 PCIB. The highest percentage of secondary embryogenesis was observed on B5 medium containing 0.15 mg l−1 of gibberellic acid (GA3) and 0.2 mg l−1 6-benzyladenine (BA) in 4–6 mm microspore-derived embryos (MDEs). Most callus formed on B5 medium containing 0.15 mg l−1 GA3, 0.1 mg l−1 BA and 0.1 mg l−1 indole-3-acetic acid (IAA) when 4–6 mm embryos were used. Regeneration was highest on B5 medium containing 0.05 mg l−1 GA3 or 0.1 mg l−1 BA and 0.2 mg l−1 IAA with 2–4 mm embryos. Microspore embryogenesis and plant regeneration could be improved by both bleomycin and PCIB when
the appropriate MDE length and phytohormone level were selected. 相似文献
14.
Water and surficial sediment samples of Lake Chascomús and its tributaries were analyzed in order to relate changes in diatom
community structure to chemical variables. Over the course of 13 months of sampling, the lake exhibited major changes in water
level (1.15–1.98 m average depth), total dissolved solids (821–1972 mg l−1), silica (0.098–8.22 mg l−1), and total algal biomass (21.4–145.9 μg Chl a l−1). However, despite these large fluctuations, the diatom species composition was relatively stable. The dominant species in
the water column was always Synedra berolinensis (68.9%–90.1% total frustules), with Fragilaria construens and F. brevistriata as subdominants. In the sediments the latter two species dominated the frustule counts. These results indicate an unusual
floristic stability of this eutrophic ecosystem, with persistent dominance by broadly tolerant, generalist species.
Received: April 24, 2001 / Accepted: January 23, 2002 相似文献
15.
Federico A. Gutiérrez-Miceli Lourdes Arias Nicolás Juarez-Rodríguez Miguel Abud-Archila Aldo Amaro-Reyes Luc Dendooven 《In vitro cellular & developmental biology. Plant》2010,46(1):57-63
This paper reports on the optimum concentrations of naphthalene acetic acid (NAA) and 6-benzyladenine (BA) to stimulate callus
growth and NAA; kinetin and silver nitrate (AgNO3) for callus redifferentiation in Dianthus caryophyllus L. Meristems were excised and placed in MS medium with 30 g l−1 sucrose and 9.0 μM 2,4-d. Callus clusters were transferred to MS medium containing NAA (0, 1.7, 3.3, and 5.0 μM) and BA (0, 1.7, 3.3, and 5.0 μM)
for proliferation and to MS medium with 30 g l−1 sucrose, 2.5 g l−1 phytagel, kinetin (0, 33, and 66 μM); NAA (0, 7.95, and 15.9 μM) and AgNO3 (0, 23.54 and 47.08 μM) for shoot and root induction. Treatments were applied according to a Box–Behnken design. After callus
growth and redifferentiation, plants were incubated in the greenhouse at 18 ± 2°C for 4 wk and at 20–26°C for 4 wk. Finally,
plants were changed to near-commercial greenhouse conditions with different day (30–35°C) and night (16–24°C) temperatures.
Results showed better callus growth at higher NAA concentrations. A maximum callus weight was found with 5.0 μM NAA but without
BA. A maximum of 78% calluses with shoots was obtained with 15.9 μM NAA, 47.08 μM AgNO3, and 0.74 μM kinetin and 58% with roots with 15.7 μM NAA and 47.08 μM AgNO3, but without kinetin. The shoots obtained showed little hyperhydricity. Vigorous plants were obtained after gradual acclimatization
with an 80% survival rate under nursery conditions. 相似文献
16.
A. M. Vieitez E. Corredoira A. Ballester F. Muñoz J. Durán M. Ibarra 《Plant Cell, Tissue and Organ Culture》2009,98(2):135-145
North American oak species, with their characteristic strong episodic seasonal shoot growth, are highly problematic for clonal
micropropagation, resulting in the inability to achieve a stabilized shoot multiplication stage. The potential for initiating
and proliferating shoot cultures derived from Quercus alba, Q. bicolor and Q. rubra explants was investigated, and a micropropagation method for these species was developed. Branch segments from 6 to 7-year-old
trees were forced-flushed and the forced shoots were used as source of explants for culture initiation. A consistent shoot
multiplication stage was achieved, in 13 of the 15 genotypes established in vitro, although marked differences occurred in
explants from different genotypes/species. The control of efficient shoot multiplication involved the culture of decapitated
shoots in a stressful horizontal position on cytokinin-containing medium with a sequence of transfers within a 6-week subculture
cycle, which was beneficial to overcoming the episodic character of shoot growth. During each subculture cycle, the horizontally
placed explants were cultured on media containing 0.2 mg l−1 benzyladenine (BA) for 2 weeks with two successive transfers (2 weeks each) to fresh medium with 0.1 mg l−1 BA, giving a 6-week subculture cycle. The general appearance and vigor of Q. alba and Q. bicolor shoot cultures were improved by the inclusion of both 0.1 mg l−1 BA and 0.5 mg l−1 zeatin in the medium used for the second transfer within the 6-week subculture cycle. Addition of AgNO3 (3 mg l−1) to the shoot proliferation medium of Q. rubra had a significant positive effect on shoot development pattern by reducing deleterious symptoms, including shoot tip necrosis
and early senescence of leaves. The three species showed acceptable in vitro rooting rates by culturing microcuttings in medium
containing 25 mg l−1 indolebutyric acid for 48 h with subsequent transfer to auxin-free medium supplemented with 0.4% activated charcoal. Although
an initial 5-day dark period generally improved the rooting response, it was detrimental to the quality of regenerated plantlets.
However, activated charcoal stimulated not only the rooting frequencies, but it also enhanced plant quality, as evidenced
by root, shoot and leaf growth. 相似文献
17.
Jonny E. Scherwinski-Pereira Rodrigo S. da Guedes Paulo César P. FerminoJr Tatiane L. Silva Frederico Henrique S. Costa 《In vitro cellular & developmental biology. Plant》2010,46(4):378-385
An efficient procedure has been developed for inducing somatic embryogenesis and regeneration of plants from tissue cultures
of oil palm (Elaeis guineensis Jacq.). Thin transverse sections (thin cell layer explants) of different position in the shoot apex and leaf sheath of oil
palm were cultivated in Murashige and Skoog (MS) (Physiol Plant 15:473–497, 1962) medium supplemented with 0–450 μM picloram and 2,4-D with 3.0% sucrose, 500 mg L−1 glutamine, and 0.3 g L−1 activated charcoal and gelled with 2.5 g L−1 Phytagel. Embryogenic calluses were evaluated 12 wk after inoculation. Picloram (450 μM) was effective in inducing embryogenic
calluses in 41.5% of the basal explants. Embryogenic calluses were maintained on a maturation medium composed of basal media,
plus 0.6 μM NAA and 12.30 μM 2iP, 0.3 g L−1 activated charcoal, and 500 mg L−1 glutamine, with subcultures at 4-wk intervals. Somatic embryos were converted to plants on MS medium with macro- and micronutrients
at half-strength, 2% sucrose, and 1.0 g L−1 activated charcoal and gelled with 2.5 g L−1 Phytagel. 相似文献
18.
D. A. Steinmacher G. C. Cangahuala-Inocente C. R. Clement M. P. Guerra 《In vitro cellular & developmental biology. Plant》2007,43(2):124-132
The factors affecting the induction and development of somatic embryos and plantlet acclimatization of peach palm (Bactris gasipaes Kunth) were evaluated to establish an efficient regenerative protocol based on somatic embryogenesis. Mature zygotic embryos
were cultured in Murashige and Skoog (MS) medium supplemented with 0–40 μM of picloram (4-amino-3,5,6-trichloropicolinic acid)
and 0 or 5 μM of 2-isopentyladenine (6-dimethylaminopurine) (2-iP). After 5 mo. in culture embryogenic callus arose from primary
calli. Picloram (10 μM) was effective in inducing embryogenic calli in 9.8% of the explants. The use of 1 μM of AgNO3 enhanced embryogenic competence. Embryogenic calli showed an organized structure, a globular aspect, and were white to yellowish
in color. Histological analyses showed that cell proliferation arose from subepidermal cells adjacent to vascular bundles,
resulting in primary callus formed by a meristematic zone from which somatic embryos arose. Protein profile analyses revealed
two high molecular mass bands in these embryogenic calli, but not in other tissues. Embryogenic calli were transferred to
a culture medium containing 40 μM of 2,4-dichlorophenoxyacetic acid, 10 μM of 2-iP, plus 1 g l−1 of glutamine, hydrolyzed 0.5 g l−1 casein, and activated 1.5 g l−1 of charcoal. Morphogenetic responses achieved in this medium were the development of somatic embryos, rooting, and loss of
embryogenic capacity. Somatic embryos were converted to plantlets on MS medium plus 24.6 μM of 2-iP and 0.44 μM of naphthalene
acetic acid. Plantlets were maintained in MS medium with activated charcoal (1.5 g l−1) until they were 6 cm tall, and then acclimatized. After 16 wk, 84.2 ± 6.4% survival was observed.
M. P. Guerra and C. R. Clement are Fellows of the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brasília,
DF. 相似文献
19.
Effect of dissolved oxygen and carbon–nitrogen loads on denitrification by an aerobic consortium 总被引:10,自引:0,他引:10
Patureau D Bernet N Delgenès JP Moletta R 《Applied microbiology and biotechnology》2000,54(4):535-542
Four samples of natural ecosystems and one sample from an activated sludge treatment plant were mixed together and progressively
adapted to alternating aerobic/anoxic phases in the presence of nitrate in order to enrich the microflora in aerobic denitrifiers.
Aerobic denitrifying performances of this mixed ecosystem at various dissolved oxygen concentrations and various carbon–nitrogen
loads were evaluated and compared to those obtained with the aerobic denitrifier Microvirgula aerodenitrificans. The consortium and the pure strain exhibited an aerobic denitrifying activity at air saturation conditions (7 mg dissolved
oxygen l–1), i.e. there was co-respiration of the two electron acceptors with significant specific nitrate reduction rates. Dissolved
oxygen concentrations had no influence on denitrifying performances above a defined threshold: 0.35 mg l–1 for the consortium and 4.5 mg l–1 for M. aerodenitrificans respectively. Under these thresholds, decreasing the dissolved oxygen concentrations enhanced the denitrifying activity of
each culture. The higher the carbon and nitrogen loads, the higher the performance of the aerobic denitrifying ecosystem.
However, for M. aerodenitrificans, the nitrate reduction percentage was affected more by variations in nitrogen load than in carbon load.
Received: 6 December 1999 / Received revision: 8 March 2000 / Accepted: 10 March 2000 相似文献
20.
A. Othmani C. Bayoudh N. Drira M. Marrakchi M. Trifi 《Plant Cell, Tissue and Organ Culture》2009,97(1):71-79
Plant regeneration through somatic embryogenesis from young leaf explants (5–10 mm long) adjacent to the apex of 5–6 year
old offshoots of Tunisian date palm (Phœnix dactylifera L.), cultivar Boufeggous was successfully achieved. Factors affecting embryogenic callus initiation, including plant growth
regulators and explant size, were investigated. The highest induction frequencies of embryogenic calli occurred after 6–7 months
on MS medium supplemented with 10 mg l−1 2,4-D and 0.3 mg l−1 activated charcoal. The subculture of these calli onto maintenance medium resulted in the formation of proembryos. Fine chopping
and partial desiccation (6 and 12 h) of embryogenic calli with proembryos prior to transfer to MS medium supplemented with
1 mg l−1 ABA stimulated the rapid maturation of somatic embryos. Maturated somatic embryo yield per 0.5 g FW of embryogenic callus
was 51 embryos with an average maturation time of 55 days. This was increased to 422 with finely chopped callus, and 124 and
306 embryos following 6 and 12 h desiccation treatments, respectively. The average time to maturation for these 3 treatments
was 35, 43 and 38 days, respectively. Subsequent substitution of ABA in MS medium with 1 mg l−1 NAA resulted in the germination and conversion of 81% of the somatic embryos into plantlets with normal roots and shoots.
The growth of regenerated somatic plants was also monitored in the field. 相似文献