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1.
Okeke BC 《Journal of industrial microbiology & biotechnology》2008,35(12):1571-1579
Pollution of terrestrial surfaces and aquatic systems by hexavalent chromium, Cr(VI), is a worldwide public health problem.
A chromium resistant bacterial isolate identified as Exiguobacterium sp. GS1 by 16S rRNA gene sequencing displayed high rate of removal of Cr(VI) from water. Exiguobacterium sp. GS1 is 99% identical to Exiguobacterium acetylicum. The isolate significantly removed Cr(VI) at both high and low concentrations (1–200 μg mL−1) within 12 h. The Michaelis–Menten K
m
and V
max for Cr(VI) bioremoval were calculated to be 141.92 μg mL−1 and 13.22 μg mL−1 h−1, respectively. Growth of Exiguobacterium sp. GS1 was indifferent at 1–75 μg mL−1 Cr(VI) in 12 h. At initial concentration of 8,000 μg L−1, Exiguobacterium sp. GS1 displayed rapid bioremoval of Cr(VI) with over 50% bioremoval in 3 h and 91% bioremoval in 8 h. Kinetic analysis
of Cr(VI) bioremoval rate revealed zero-order in 8 h. Exiguobacterium sp. GS1 grew and significantly reduced Cr(VI) in cultures containing 1–9% salt indicating high salt tolerance. Similarly
the isolate substantially reduced Cr(VI) over a wide range of temperature (18–45 °C) and initial pH (6.0–9.0). The T
opt and initial pHopt were 35–40 °C and 7–8, respectively. Exiguobacterium sp. GS1 displayed a great potential for bioremediation of Cr(VI) in diverse complex environments. 相似文献
2.
Yasmin Khambhaty Kalpana Mody Shaik Basha Bhavanath Jha 《World journal of microbiology & biotechnology》2009,25(8):1413-1421
The removal of hexavalent chromium from aqueous solution was studied in batch experiments using dead biomass of three different
species of marine Aspergillus after alkali treatment. All the cultures exhibited potential to remove Cr(VI), out of which, Aspergillus niger was found to be the most promising one. This culture was further studied employing variation in pH, temperature, metal ion
concentration and biomass concentration with a view to understand the effect of these parameters on biosorption of Cr(VI).
Higher biosorption percentage was evidenced at lower initial concentration of Cr(VI) ion, while the sorption capacity of the
biomass increased with rising concentration of ions. Biomass as low as 0.8 g l−1 could biosorb 95% Cr(VI) ions within 2,880 min from an aqueous solution of 400 mg l−1 Cr(VI) concentration. Optimum pH and temperature for Cr(VI) biosorption were 2.0 and 50°C, respectively. Kinetic studies
based on pseudo second order models like Sobkowsk and Czerwinski, Ritchie, Blanchard and Ho and Mckay rate expressions have
also been carried out. The nature of the possible cell–metal ion interactions was evaluated by FTIR, SEM and EDAX analysis. 相似文献
3.
Chromium(VI) resistance and removal by <Emphasis Type="Italic">Acinetobacter haemolyticus</Emphasis>
Quek Hsiao Pei Shafinaz Shahir A. S. Santhana Raj Zainul Akmar Zakaria Wan Azlina Ahmad 《World journal of microbiology & biotechnology》2009,25(6):1085-1093
The present work highlighted the studies on Cr(VI) reduction by cells of Acinetobacter haemolyticus (A. haemolyticus). The strain tolerated 90 mg Cr(VI) l−1 in LB broth compared to only 30 mg Cr(VI) l−1 in LB agar. From the FTIR analysis, the Cr(III) species formed was also most likely to form complexes with carboxyl, hydroxyl,
and amide groups from the bacteria. A TEM study showed the absence of precipitates on the cell wall region of the bacteria.
Instead, microprecipitates were observed in the cytoplasmic region of the cells, suggesting the transportation of Cr(VI) into
the cells. Intracellular reduction of Cr(VI) was supported by a reductase test using soluble crude cell-free extracts. The
specific reductase activity obtained was 0.52 μg Cr(VI) reduced per mg of protein an hour at pH 7.2 and 37°C. Our results
indicated that A. haemolyticus can be used as a promising microorganism for Cr(VI) reduction from industrial wastewaters. 相似文献
4.
By adding a biomass carrier to an activated sludge system, the biomass concentration will increase, and subsequently the organic
removal efficiency will be enhanced. In this study, the possibility of using excess sludge from ceramic and tile manufacturing
plants as a biomass carrier was investigated. The aim of this study was to determine the effect of using fireclay as a biomass
carrier on biomass concentration, organic removal and nitrification efficiency in an activated sludge system. Experiments
were conducted by using a bench scale activated sludge system operating in batch and continuous modes. Artificial simulated
wastewater was made by using recirculated water in a ceramic manufactutring plant. In the continuous mode, hydraulic detention
time in the aeration reactor was 8 and 22 h. In the batch mode, aeration time was 8 and 16 h. Fireclay doses were 500, 1,400
and 2,250 mg l−1, and were added to the reactors in each experiment separately. The reactor with added fireclay was called a Hybrid Biological
Reactor (HBR). A reactor without added fireclay was used as a control. Efficiency parameters such as COD, MLVSS and nitrate
were measured in the control and HBR reactors according to standard methods. The average concentration of biomass in the HBR
reactor was greater than in the control reactor. The total biomass concentration in the HBR reactor (2.25 g l−1 fireclay) in the continuous mode was 3,000 mg l−1 and in the batch mode was 2,400 mg l−1. The attached biomass concentration in the HBR reactor (2.25 g l−1 fireclay) in the continuous mode was 1,500 mg l−1 and in the batch mode was 980 mg l−1. Efficiency for COD removal in the HBR and control reactor was 95 and 55%, respectively. In the HBR reactor, nitrification
was enhanced, and the concentration of nitrate was increased by 80%. By increasing the fireclay dose, total and attached biomass
was increased. By adding fireclay as a biomass carrier, the efficiency of an activated sludge system to treat wastewater from
ceramic manufacturing plants was increased. 相似文献
5.
Results of this study describe the feasibility of anaerobic treatment of highly concentrated phenol synthetic wastewater using
an anaerobic fluidized bed reactor (AFBR) in both continuous and batch modes. Wastewater with a maximum load of 2,100 mg C·l−1 was prepared using phenol (maximum concentration of 1,600 mg C·l−1) as substrate and a mixture of acetic, propionic and butyric acids (500 mg C·l−1) as co-substrate. AFBR reached total organic carbon (TOC) and phenol removal efficiency over 95% treating the highest organic
loading rate (OLR) containing phenol studied for this kind of reactor (5.03 g C·l−1·d−1). The phenol loading rate rise caused volumetric biogas rate increase up to 4.4 l·l−1·d−1 (average yield of 0.28 l CH4·g−1 CODremoved) as well as variation in the biogas composition; the CO2 percentage increased while the CH4 percentage decreased. Morphological examination of the bioparticles at 4.10 g C·l−1·d−1, revealed significant differences in the biofilm structure, microbial colonization and bacterial morphological type development.
The five batch assays showed that phenol degradation may be favoured by the presence of volatile fatty acids (VFAs) (co-metabolism),
whereas VFAs degradation may be inhibited by phenol. AFBR reached initial phenol degradation velocity of 0.25 mg C·l−1·min−1. 相似文献
6.
Effects of post-harvest application of two plant growth regulators viz., gibberellic acid (GA3) and benzyl adenine (BA) with sucrose in the vase solution on cell membrane stability and vase life of gladiolus were investigated.
The vase solution treatment combinations of GA3 and BA with sucrose significantly increased the membrane stability index and enhanced the vase life as compared to the sucrose
alone treatments or the controls. Vase solution treatment of GA3 (50 mg l−1), followed by BA (50 mg l−1) with sucrose (50 g l−1) significantly increased solution uptake, fresh weight and dry weight of cut spikes. The same treatments also enhanced the
concentration of reducing and non-reducing sugars in gladioli petals 4 days after treatment (DAT). Cut spikes in vase solution
enriched with 50 mg l−1 GA3 + 50 g l−1 sucrose showed higher antioxidative enzyme activities of superoxide dismutase (SOD) and glutathione reductase (GR), lower
lipoxygenase (LOX) activity and lipid peroxidation (measured as TBARS). Petal membrane stability index was also highest in
cut spikes 6 DAT with 50 mg l−1 GA3 + 50 g l−1 sucrose vase solution. Treatment of gladiolus cut spikes with 50 mg l−1 GA3 + 50 g l−1 sucrose vase solution showed two fold increase in vase life and improved flower quality with a higher number of open flower
per spike at any one time. These results suggest that post-harvest application of GA3 (50 mg l−1) with sucrose (50 g l−1) maintains higher spike fresh and dry weight, improves anti-oxidative defence, stabilizes membrane integrity leading to a
delay in petal cell death. 相似文献
7.
Smita Srivastava Ashok Kumar Srivastava 《In vitro cellular & developmental biology. Plant》2012,48(1):73-84
Azadirachtin, a well-known biopesticide, is a secondary metabolite extracted from the seeds of Azadirachta indica. In the present study, azadirachtin was produced in hairy roots of A. indica, generated by Agrobacterium rhizogenes-mediated transformation of leaf explants. Liquid cultures of A. indica hairy roots were developed with a liquid-to-flask volume ratio of 0.15. The kinetics of growth and azadirachtin production
were established in a basal plant growth medium containing MS medium major and minor salts, Gamborg’s medium vitamins, and
30 g l−1 sucrose. The highest azadirachtin accumulation in the hairy roots (up to 3.3 mg g−1) and azadirachtin production (∼44 mg l−1) was obtained on Day 25 of the growth cycle, with a biomass production of 13.3 g l−1 dry weight. To enhance the production of azadirachtin, a Plackett–Burman experimental design protocol was used to identify
key medium nutrients and concentrations to support high root biomass production and azadirachtin accumulation in hairy roots.
The optimal nutrients and concentrations were as follows: 40 g l−1 sucrose, 0.19 g l−1 potassium dihydrogen phosphate, 3.1 g l−1 potassium nitrate, and 0.41 g l−1 magnesium sulfate. Concentrations were determined by a central composite design protocol and verified in shake-flask cultivation.
The optimized medium composition yielded a root biomass production of 14.2 g l−1 and azadirachtin accumulation of 5.2 mg g−1, which was equivalent to an overall azadirachtin production of 73.84 mg l−1, 68% more than that obtained under non-optimized conditions. 相似文献
8.
The degradation potential of trichloroethene by the aerobic methane- and ammonia-oxidizing microorganisms naturally associated
with wetland plant (Carex comosa) roots was examined in this study. In bench-scale microcosm experiments with washed (soil free) Carex comosa roots, the activity of root-associated methane- and ammonia-oxidizing microorganisms, which were naturally present on the
root surface and/or embedded within the roots, was investigated. Significant methane and ammonia oxidation were observed reproducibly
in batch reactors with washed roots incubated in growth media, where methane oxidation developed faster (2 weeks) compared
to ammonia oxidation (4 weeks) in live microcosms. After enrichment, the methane oxidizers demonstrated their ability to degrade
150 μg l−1 TCE effectively at 1.9 mg l−1 of aqueous CH4. In contrast, ammonia oxidizers showed a rapid and complete inhibition of ammonia oxidation with 150 μg l−1 TCE at 20 mg l−1 of NH4
+-N, which may be attributed to greater sensitivity of ammonia oxidizers to TCE or its degradation product. No such inhibitory
effect of TCE degradation was detected on methane oxidation at the above experimental conditions. The results presented here
suggest that microorganisms associated with wetland plant roots can assist in the natural attenuation of TCE in contaminated
aquatic environments. 相似文献
9.
Bacterial consortium-AIE2 with a capability of contemporaneous Cr(VI) reduction and azo dye RV5 decolourization was developed
from industrial wastewaters by enrichment culture technique. The 16S rRNA gene based molecular analyses revealed that the
consortium bacterial community structure consisted of four bacterial strains namely, Alcaligenes sp. DMA, Bacillus sp. DMB, Stenotrophomonas sp. DMS and Enterococcus sp. DME. Cumulative mechanism of Cr(VI) reduction by the consortium was determined using in vitro Cr(VI) reduction assays.
Similarly, the complete degradation of Reactive Violet 5 (RV5) dye was confirmed by FTIR spectroscopic analysis. Consortium-AIE2
exhibited simultaneous bioremediation efficiencies of (97.8 ± 1.4) % and (74.1 ± 1.2) % in treatment of both 50 mg l−1 Cr(VI) and RV5 dye concentrations within 48 h of incubation at pH 7 and 37°C in batch systems. Continuous bioreactor systems
achieved simultaneous bioremediation efficiencies of (98.4 ± 1.5) % and (97.5 ± 1.4) % after the onset of steady-state at
50 mg l−1 input Cr(VI) and 25 mg l−1 input RV5 concentrations, respectively, at medium dilution rate (D) of 0.014 h−1. The 16S rRNA gene copy numbers in the continuous bioreactor as determined by real-time PCR assay indicated that Alcaligenes sp. DMA and Bacillus sp. DMB dominated consortium bacterial community during the active continuous bioremediation process. 相似文献
10.
A spiral packed-bed bioreactor inoculated with microorganisms obtained from activated sludge was used to conduct a feasibility
study for phenol removal. The reactor was operated continuously at various phenol loadings ranging from 53 to 201.4 g m−3 h−1, and at different hydraulic retention times (HRT) in the range of 20–180 min to estimate the performance of the device. The
results indicated that phenol removal efficiency ranging from 82.9 to 100% can be reached when the reactor is operated at
an HRT of 1 h and a phenol loading of less than 111.9 g m−3 h−1. At an influent phenol concentration of 201.4 g m−3, the removal efficiency increased from 18.6 to 76.9% with an increase in the HRT (20–120 min). For treatment of phenol in
the reactor, the maximum biodegradation rate (V
m) was 1.82 mg l−1 min−1; the half-saturation constant (K
s), 34.95 mg l−1. 相似文献
11.
Sulfachloropyridazine (SCP), an antibiotic used in aquaculture and in animal husbandry, is a common contaminant in surface
and groundwaters. Two types of microbial reactors were evaluated as methods for removing SCP from flowing water. One type
of reactor evaluated was a nitrogen-limiting biobarrier; the other a slow-sand-filter. Results showed that the soybean oil-fed,
nitrogen-limiting biobarrier was not very effective at removing SCP from flowing water. When supplied with flowing water containing
2.4 mg l−1 SCP the nitrogen-limiting biobarrier removed ~0.6 mg l−1 SCP or about 28% of that present. SCP removal by the nitrogen-limiting biobarrier may not have been biological as abiotic
removal was not ruled out. More efficient biological removal was obtained with the slow-sand-filter which reduced the SCP
levels from 2.35 to 0.048 mg l−1, a removal efficiency of ~98%. High levels of nitrate nitrogen, 50 mg l−1 N, did not interfere with the removal processes of either reactor suggesting that SCP was not being degraded as a microbial
nitrogen source. 相似文献
12.
Anaerobic bacteria that reduce hexavalent chromium [Cr(VI)] to trivalent [Cr(III)] are common in soils and were used to develop
a bioprocess employing a selection strategy. Indigenous Cr(VI)-reducers were enriched from Cr(VI)-contaminated soil under
anaerobic conditions. The mixed culture was then tested for Cr(VI)-reducing activity in a chemostat, followed by transfer
to a 1-L packed-bed bioreactor operated at 30°C for additional study. The support material used in the reactor consisted
of 6-mm porcelain saddles. Cr(VI) concentrations in the liquid ranged from 140–750 mg L−1. Cr(VI)-reducing bacteria were the dominant population with Cr(VI)-reduction rates of approximately 0.71 mg g−1 dry cells h−1 achieved at Cr(VI) concentrations of 750 mg L−1. These results indicate a potential for selecting and maintaining indigenous Cr(VI)-reducers in a bioreactor for Cr(VI)-remediation
of groundwater or soil wash effluents.
Received 09 January 1996/ Accepted in revised form 15 November 1996 相似文献
13.
The tannery industry process involves chromium (Cr) salts as a main constituent of the process. The Cr recovery is a part of the process where other salts are used to achieve separation and recovery for using Cr back in the process. The process steps may contain both forms of Cr [Cr(VI): hexavalent and Cr(III): trivalent]. The recovery of Cr from tannery industry effluent through biological systems is much needed. The diverse physicochemical characteristics of these effluents may limit the growth of microorganisms and hence the limitation towards possible practical application of microorganisms in real industrial effluent conditions. The present study attempted the ability of the Cr-resistant fungus Paecilomyces lilacinus [isolated through an enrichment culture technique at 25 000 mg l−1 of Cr(III)] to grow and remove Cr [Cr(VI) and Cr(III)] from two physicochemically different undiluted tannery industry effluents (tannery effluent and spent chrome effluent) in the presence of cane sugar as a carbon source. Such attempts are made keeping in view the potential integration of biological processes in the overall Cr removal and recovery processes to improve its efficiency and environmental sustainability. The fungus has broad pH tolerance range and can reduce Cr(VI) both in acidic (pH 5.5) and alkaline (pH 8.0) conditions. The fungus showed the ability to remove Cr(VI) (1.24 mg l−1) and total Cr (7.91 mg l−1) from tannery effluent below the detection level within 18 h and 36 h of incubation, respectively, and ability to accumulate 189.13 mg Cr g−1 of dry biomass within 600 h of incubation from spent chrome effluent [containing 3731.4 mg l−1 of initial Cr(III) concentration].At 200 mg l−1 of Cr(VI) in growth media, with 100% detoxification and with only 10.54% of total Cr accumulation in the biomass, P. lilacinus showed Cr(VI) reduction as a major mechanism of Cr(VI) detoxification. The time-course study revealed the log phase of the growth for the maximum specific reduction of Cr(VI) and stationary phase of the growth for its maximum specific accumulation of both the forms of Cr [Cr(III) and Cr(VI)] in its biomass. In growth media at 50 mg l−1 and 200 mg l−1 of Cr(VI), P. lilacinus showed 100% reduction within 36 h and 120 h of incubation, respectively. The high degree of positive correlation and statistically high degree of relationship (r2 = 0.941) between the fungal growth and % Cr(VI) reduction by the fungus support the role of metabolically active cellular growth in Cr(VI) reduction by the fungus. Results indicate that expanded solid (sludge) retention times (SRTs) (stationary phase) can be recommended for the removal of Cr(III) through accumulation. In case of Cr(VI), reduction needs a priority; therefore, a non-expanded SRT is recommended for designing a continuous-flow completely stirred bioreactor so that a log phase of cellular growth can be maintained during the reduction process. This study reveals the strong potential of P. lilacinus fungi for the removal of Cr from tannery effluent and spent chrome effluent. 相似文献
14.
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
15.
Kim YS Lee JH Kim NH Yeom SJ Kim SW Oh DK 《Applied microbiology and biotechnology》2011,90(2):489-497
In the fed-batch culture of glycerol using a metabolically engineered strain of Escherichia coli, supplementation with glucose as an auxiliary carbon source increased lycopene production due to a significant increase in
cell mass, despite a reduction in specific lycopene content. l-Arabinose supplementation increased lycopene production due to increases in cell mass and specific lycopene content. Supplementation
with both glucose and l-arabinose increased lycopene production significantly due to the synergistic effect of the two sugars. Cell growth by the
consumption of carbon sources was related to endogenous metabolism in the host E. coli. Supplementation with l-arabinose stimulated only the mevalonate pathway for lycopene biosynthesis and supplementation with both glucose and l-arabinose stimulated synergistically only the mevalonate pathway. In the fed-batch culture of glycerol with 10 g l−1 glucose and 7.5 g l−1
l-arabinose, the cell mass, lycopene concentration, specific lycopene content, and lycopene productivity after 34 h were 42 g l−1, 1,350 mg l−1, 32 mg g cells−1, and 40 mg l−1 h−1, respectively. These values were 3.9-, 7.1-, 1.9-, and 11.7-fold higher than those without the auxiliary carbon sources,
respectively. This is the highest reported concentration and productivity of lycopene. 相似文献
16.
Summary A tropical white-rot basidiomycete, BDT-14 (DSM 15396) was investigated for its chromium (VI) biosorption potential from an
aqueous solution. Pre-treatment of fungal biomass with acid resulted in 100% metal adsorption compared to only 26.64% adsorption
without any pre-treatment. Chromium adsorption was a rapid process at early exposure resulting in 60% chromium removal within
the first 2 h of exposure. An increase in biomass showed an increase in the total metal ions adsorption but a decrease in
specific uptake of metal ions. The concentrations of chromium had a pronounced effect on the rate of adsorption. The adsorption
efficiency was 100% when the initial Cr (VI) concentration was 100 mg l−1 with 1,000 mg biomass. Only 47.5% adsorption was observed with 500 mg l−1 Cr (VI) concentration. The adsorption data fit well with the Langmuir and Freundlich isotherm models. Comprehensive characterization
of parameters indicates BDT−14 biomass as a promising material for Cr (VI) adsorption. 相似文献
17.
A hexavalent chromium [Cr(VI)] reducing bacterial strain was isolated from chromium-containing slag. It was identified as
Pannonibacter phragmitetus based on physiological, biochemical characteristics and 16S rRNA gene sequence analysis. This bacterium displayed great Cr(VI)
reduction capability. The Cr(VI) could be completely removed in 24 h under anaerobic condition when the initial concentration
was 1,917 mg L−1, with the maximum reduction rate of 562.8 mg L−1 h−1. The Cr(VI) reduction rate increased with the increase of Cr(VI) concentration. P. phragmitetus was able to use many carbon sources such as lactose, fructose, glucose, pyruvate, citrate, formate, lactate, NADPH and NADH
as electron donors, among which the lactate had the greatest power to promote the reduction process. Zn2+, Cd2+ and Ni2+ inhibited, while Cu2+, Pb2+, Mn2+ and Co2+ stimulated the reduction. The optimum pH and temperature for reduction were 9.0 and 30 °C, respectively. The results indicated
that this strain had great potential for application in the bioremediation of chromate-polluted soil and water systems. 相似文献
18.
Mashitha Pise Jaishree Rudra Sunita Bundale Deovrat Begde Nandita Nashikkar Avinash Upadhyay 《In vitro cellular & developmental biology. Plant》2012,48(1):85-91
Asparagus racemosus is an important monocot medicinal plant that is in great demand for its steroidal saponins called shatavarins. This study
was initiated to optimize the conditions for production of shatavarins in cell cultures of A. racemosus in a modified Murashige and Skoog (MS) medium supplemented with six different combinations of growth regulators. Biomass
accumulation was correlated with saponin production over a 30-d culture cycle. Biomass and saponin accumulation patterns were
dependent on combinations of growth regulators and the pH of the medium. Maximum levels of saponin and biomass accumulation
were recorded on day 25 of the culture cycle within a pH range of 3.4 to 5.6. Total saponin produced by the in vitro cultures was 20-fold higher than amounts produced by cultivated plants. Saponin accumulation was not a biomass-associated
phenomenon; cultures which showed the highest biomass accumulation were not the highest saponin accumulators. Maximum biomass
(28.30 ± 0.29 g l−1) and maximum levels of shatavarin IV(11.48 ± 0.61 mg g−1) accumulation was found using a medium containing 2.0 mg l−1 2,4-D, 2 g l−1 casein hydrolysate and 0.005% pectinase. The highest levels of sarsapogenin, secreted and intracellular (4.02 ± 0.09 mg g−1), accumulated using a medium containing 1.0 mg l−1 NAA, 1.0 mg l−1 2,4-D, 0.5 mg l−1 BAP, 2 g l−1 casein hydrolysate and 0.005% pectinase, after 25 d. Shatavarins were secreted into the medium and can be isolated easily
for further purification. 相似文献
19.
Abhinav Grover Jayashankar S. Yadav Ranjita Biswas Choppakatla S. S. Pavan Punita Mishra Virendra S. Bisaria Durai Sundar 《Plant Cell, Tissue and Organ Culture》2012,108(2):323-331
Cell suspension cultures of Camellia sinensis were established in 250 ml shake flasks. Flasks contained 50 ml liquid medium of either Murashige and Skoog (MS), N/5 MS
or Heller medium containing different levels of 6-benzyladenine (BA) (0.05–2 mg l−1), 2,4-dichlorophenoxyacetic acid (2,4-D) (1–10 mg l−1), and sucrose (10–50 g l−1). Moreover, the pH of the medium was varied from 5.2–6.2. In addition, cultures were subjected to light irradiation as well
as to complete darkness. Following optimization of aroma and terpenoid extraction methods, cell cultures were analyzed for
the volatile compounds using GC/MS. A total of 43 compounds were identified using the micro SDE apparatus. Among the major
monoterpenoids obtained were α-terpineol and nerol. Moreover, other high aroma-value compounds, including 2-ethyl hexanol,
benzyl alcohol, benzene acetaldehyde, nonanal and phenylethylalcohol were also detected. The highest levels of these compounds
were obtained from cell suspension cultures grown in MS medium containing 5 mg l−1 2,4-D, 1 mg l−1 BA and 30 g l−1 sucrose at pH of 5.8 with incubation in complete darkness. 相似文献
20.
To provide beneficial guide for the application of the magnetic field in the bio-treatment of the Cr(VI)-contained wastewater,
sludge samples from the control bio-system A (absent of magnetic field) and the contrast bio-system B (present of magnetic
field) were used to adsorb the synthetic wastewater with 100 mg l−1 Cr(VI). Influences of two adsorption modes, single adsorption and once continuous adsorption, on the Cr(VI) adsorption capacities
of both sludge samples were compared. And the influence of regeneration on the Cr(VI) adsorption capacities were also studied.
The results of adsorption experiments showed that the Cr(VI) adsorption capacities of the first single adsorption for sludge
sample A and B were pretty nearly, which were 9.79 and 9.93 mg, respectively. And after 5 single adsorption periods, the total
Cr(VI) adsorption capacity and efficiency of the sample B were 25.88 and 55.66 mg Cr(VI) g−1VSS, while those of the control were 14.95 and 33.98 mg Cr(VI) g−1VSS, respectively. For the sludge sample A and B after a single adsorption, both functions of regeneration were remarkable.
But after 13 cycles of the single adsorption-regeneration, the Cr(VI) adsorption capacity and efficiency of the sample B were
110.15 and 189.91 mg Cr(VI) g−1VSS, while those of the control were 70.89 and 140.38 mg Cr(VI) g−1VSS, respectively. Though the Cr(VI) adsorption capacity of a once continuous adsorption period was more than that of a single
adsorption period obviously, the Cr(VI) removal rates of the sludge sample A and B in the third period of once continuous
adsorption-regeneration were only 8.12 and 33.51%, respectively. It was concluded that the weak magnetic field did improve
the Cr(VI) bio-removal efficiency and the sludge stability, the batch treatment was an ideal operation mode for the bio-treatment
of the Cr(VI)-contained wastewater, as compared with the continuous operation mode, but regeneration and enough sludge content
were two necessary conditions to ensure the efficiency of batch treatment. 相似文献