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1.
Thermomucor indicae-seudaticae was immobilized in alginate, κ-carrageenan, agarose, agar, polyacrylamide and loofah (Luffa cylindrica) sponge (as such or coated with alginate/starch/Emerson YpSs agar), and used for the production of glucoamylase in submerged
fermentation. The mycelium developed from alginate-immobilized sporangiospores secreted higher glucoamylase titres (22.7 U ml−1) than those immobilized in other gel matrices and the freely growing mycelial pellets (18.5 U ml−1). Loofah network provided a good support for mycelial growth, but the enzyme production was lower than that attained with
alginate beads. Glucoamylase production increased with inoculum density and the optimum levels were achieved when 40 calcium
alginate beads (∼5 × 106 immobilized spores) were used to inoculate 50 ml production medium. The alginate bead inoculum displayed high storage stability
at 4°C and produced comparable enzyme titres up to 120 days. The glucoamylase production by hyphae emerged from the immobilized
sporangiospores was almost stable over eight batches of repeated fermentation. Scanning electron micrographs of alginate beads,
after batch fermentation, revealed extensive mycelial growth inside and around the beads. 相似文献
2.
Jung-Soo Kim Manish Kumar Tiwari Hee-Jung Moon Marimuthu Jeya Thangadurai Ramu Deok-Kun Oh In-Won Kim Jung-Kul Lee 《Applied microbiology and biotechnology》2009,83(2):273-283
Nitrile groups are catabolized to the corresponding acid and ammonia through one-step reaction involving a nitrilase. Here,
we report the use of bioinformatic and biochemical tools to identify and characterize the nitrilase (NitPf5) from Pseudomonas fluorescens Pf-5. The nitPf5 gene was identified via sequence analysis of the whole genome of P. fluorescens Pf-5 and subsequently cloned and overexpressed in Escherichia coli. DNA sequence analysis revealed an open-reading frame of 921 bp, capable of encoding a polypeptide of 307 amino acids residues
with a calculated isoelectric point of pH 5.4. The enzyme had an optimal pH and temperature of 7.0°C and 45°C, respectively,
with a specific activity of 1.7 and 1.9 μmol min−1 mg protein−1 for succinonitrile and fumaronitrile, respectively. The molecular weight of the nitrilase as determined by sodium dodecyl
sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography was 33,000 and 138,000 Da, respectively, suggesting
that the enzyme is homotetrameric. Among various nitriles, dinitriles were the preferred substrate of NitPf5 with a K
m = 17.9 mM and k
cat/K
m = 0.5 mM−1 s−1 for succinonitrile. Homology modeling and docking studies of dinitrile and mononitrile substrate into the active site of
NitPf5 shed light on the substrate specificity of NitPf5. Although nitrilases have been characterized from several other sources,
P. fluorescens Pf-5 nitrilase NitPf5 is distinguished from other nitrilases by its high specific activity toward dinitriles, which make
P. fluorescens NitPf5 useful for industrial applications, including enzymatic synthesis of various cyanocarboxylic acids. 相似文献
3.
The fadBA operon in the fatty acid β-oxidation pathway of P. putida KCTC1639 was blocked to induce a metabolic flux of the intermediates to the biosynthesis of medium chain-length PHA (mcl-PHA).
Succinate at 150 mg l−1 stimulated cell growth and also the biosynthesis of medium chain-length-polyhydroxyalkanoate. pH-stat fed-batch cultivation
of the fadA knockout mutant P. putida KCTC1639 was carried out for 60 h, in which mcl-PHA reached 8 g l−1 with a cell dry weight of 10.3 g l−1. 相似文献
4.
Domínguez-Bocanegra AR Ponce-Noyola T Torres-Muñoz JA 《Applied microbiology and biotechnology》2007,75(4):783-791
Phaffia rhodozyma (now Xanthophyllomyces dendrorhous) and Haematococcus pluvialis are known as the major prominent microorganisms able to synthesize astaxanthin natural pigment. Important research efforts
have been made to determine optimal conditions for astaxanthin synthesis. When the focus is on astaxanthin production, the
maximal reported value of 9.2 mg/g cell is obtained within H. pluvialis grown on BAR medium, under continuous illumination (345 μmol photon m−2 s−1) and without aeration. Whereas fermentation by mutated R1 yeast grown on coconut milk produced 1,850 μg/g yeast. However,
when looking at astaxanthin productivity, the picture is slightly different. The figures obtained with P. rhodozyma are rather similar to those of H. pluvialis. Maximal reported values are 170 μg/g yeast per day with a wild yeast strain and 370 μg/g yeast per day with mutated R1 yeast.
In the case of H. pluvialis, maximal values ranged from 290 to 428 μg/g cell per day depending on the media (BG-11 or BAR), light intensity (177 μmol
photon m−2 s−1), aeration, etc. The main aim of this work was to examine how astaxanthin synthesis, by P. rhodozyma and H. pluvialis, could be compared. The study is based on previous works by the authors where pigment productions have been reported. 相似文献
5.
Wen Liu Xuesen Chen Guanjun Liu Qing Liang Tianming He Jianrong Feng 《Plant Cell, Tissue and Organ Culture》2007,88(3):289-299
Embryo rescue technique was used successfully to produce interspecific hybrids by crossing peach (P. persica) as a female parent with apricot (P. armeniaca) and plum (P. salicica). In those crosses that had ‘Yuhualu’ or ‘Zhonghuashoutao’ as female parents, hybrid embryos aborted from the 7th or 8th
week after pollination mainly due to post-pollination incompatibility. An embryo rescue protocol was established to rescue
such embryos and recover hybrid plants. Modified half-strength MS medium containing 4 mg l−1 6-BA and 0.5 mg l−1 IBA produced up to 90% germination in the embryos. Modified MS medium with 1.0 mg l−1 6-BA and 1.0 mg l−1 IBA gave the highest bud induction and multiplication whereas modified MS medium containing 0.5 mg l−1 IAA and 0.2 mg l−1 NAA gave the best rooting percentage. All the hybrids obtained using this embryo rescue technique were verified using simple
sequence repeat (SSR) markers. A series of pollen treatments were carried out to partially overcome pre-pollination incompatibility,
and it was found accidentally that pollen treatment with electrostatic field not only improved pollen germination but also
increased the multiplication coefficient of embryo-induced shoots. 相似文献
6.
T. Zhang 《In vitro cellular & developmental biology. Plant》2007,43(2):91-94
This study investigated the factors affecting in vitro flowering of Perilla frutescens. The shoots regenerated from cotyledonary and hypocotyl explants cultured on Murashige and Skoog (MS) medium supplemented
with benzyladenine (BA) and indole-3-acetic acid, each at 0.5 mg l−1, were excised and transferred to MS medium containing 30 g l−1 of sucrose, 8.25 g l−1 of ammonium nitrate, and 1.0 mg l−1 of BA. After 40 d of culture, 86.2% of shoots flowered and most of which self-fertilized in vitro and produced mature fruits with viable seeds. These seeds were germinated and plants were grown to maturity and flowered
in soil under greenhouse conditions. The in vitro flowering system reported in this study may facilitate rapid breeding of P. frutescens and offers a model system for studying the physiological mechanism of flowering. 相似文献
7.
Qingxin Zhao Sheng Yuan Yuling Zhang Hong Zhu Chuanchao Dai Fang Yang Fengmin Han 《World journal of microbiology & biotechnology》2007,23(8):1057-1064
Pectate lyase A (PelA) of Aspergillus nidulans was successfully expressed in Escherichia coli and effectively purified using a Ni2+-nitrilotriacetate-agarose column. Enzyme activity of the recombinant PelA could reach 360 U ml−1 medium. The expressed PelA exhibited its optimum level of activity over the range of pH 7.5–10 at 50°C. Mn2+, Ca2+, Fe2+, Mg2+ and Fe3+ ions stimulated the pectate lyase activity, but Cu2+ and Zn2+ inhibited it. The recombinant PelA had a V
max of 77 μmol min−1 mg−1 and an apparent K
m of 0.50 mg ml−1 for polygalacturonic acid. Low-esterified pectin was the optimum substrate for the PelA, whereas higher-esterified pectin
was hardly cleaved by it. PelA efficiently macerated mung bean hypocotyls and potato tuber tissues into single cells. 相似文献
8.
Pseudomonas putida and Pseudomonas fluorescens present as a coculture were studied for their abilities to degrade benzene, toluene, ethylbenzene, and xylenes (collectively known as BTEX) under various growth conditions. The coculture effectively degraded various concentrations of BTEX as sole carbon sources. However, all BTEX compounds showed substrate inhibition to the bacteria, in terms of specific growth, degradation rate, and cell net yield. Cell growth was completely inhibited at 500mgl–1 of benzene, 600mgl–1 of o-xylene, and 1000mgl–1 of toluene. Without aeration, aerobic biodegradation of BTEX required additional oxygen provided as hydrogen peroxide in the medium. Under hypoxic conditions, however, nitrate could be used as an alternative electron acceptor for BTEX biodegradation when oxygen was limited and denitrification took place in the culture. The carbon mass balance study confirmed that benzene and toluene were completely mineralized to CO2 and H2O without producing any identifiable intermediate metabolites. 相似文献
9.
An N-acetylglucosaminidase produced by Streptomyces cerradoensis was partially purified giving, by SDS-PAGE analysis, two main protein bands with Mr of 58.9 and 56.4 kDa. The Km and Vmax values for the enzyme using p-nitrophenyl-β-N-acetylglucosaminide as substrate were of 0.13 mM and 1.95 U mg−1 protein, respectively. The enzyme was optimally activity at pH 5.5 and at 50 °C when assayed over 10 min. Enzyme activity
was strongly inhibited by Cu2+ and Hg2+ at 10 mM, and was specific to substrates containing acetamide groups such as p-nitrophenyl-β-N-acetylglucosaminide and p-nitrophenyl-β-D-N,N′-diacetylchitobiose. 相似文献
10.
11.
Two new effective microbial producers of inulinases were isolated from Jerusalem artichoke tubers grown in Thailand and identified
as Aspergillus niger TISTR 3570 and Candida
guilliermondii TISTR 5844. The inulinases produced by both these microorganisms were appropriate for hydrolysing inulin to fructose as the
principal product. An initial inulin concentration of ∼100 g l−1 and the enzyme concentration of 0.2 U g−1 of substrate, yielded 37.5 g l−1 of fructose in 20 h at 40°C when A. niger TISTR 3570 inulinase was the biocatalyst. The yield of fructose on inulin was 0.39 g g−1. Under identical conditions, the yeast inulinase afforded 35.3 g l−1 of fructose in 25 h. The fructose yield was 0.35 g g−1 of substrate. The fructose productivities were 1.9 g l−1 h−1 and 1.4 g l−1 h−1 for the mold and yeast enzymes, respectively. After 20 h of reaction, the mold enzyme hydrolysate contained 53% fructose
and more than 41% of initial inulin had been hydrolysed. Using the yeast enzymes, the hydrolysate contained nearly 38% fructose
at 25 h and nearly 36% of initial inulin had been hydrolysed. The A. niger TISTR 3570 inulinases exhibited both endo-inulinase and exo-inulinase activities. In contrast, the yeast inulinases displayed
mainly exo-inulinase activity. The mold and yeast crude inulinases mixed in the activity ratio of 5:1 proved superior to individual
crude inulinases in hydrolysing inulin to fructose. The enzyme mixture provided a better combination of endo- and exo-inulinase
activities than did the crude extracts of either the mold or the yeast individually. 相似文献
12.
José Miguel Müller Ranulfo Monte Alegre 《World journal of microbiology & biotechnology》2007,23(5):691-695
In this study alginate production by Pseudomonas mendocina in a laboratory-scale fermenter was investigated. In the experiments the effect of temperature (25–31°C) and agitation (500–620 rev min−1) at a constant air flow of 10 v/v/h were evaluated in relation to the rate of glucose bioconversion to alginate using response
surface methodology (RSM). The fermenter configuration was also adapted to a system with a screw mixer and draft tube, due
to the change in rheological characteristics of the fermentation broth. The adjusted model indicates a temperature of 29.1°C
and agitation of 553 rev min−1 for optimum alginate synthesis. In this fermentation system a Y
p/s
of 44.8% was achieved. The alginate synthesized by P. mendocina showed a partially acetylated pattern as previously reported for alginates obtained from other Pseudomonas spp and Azotobacter vinelandii. 相似文献
13.
Orlita A Sidwa-Gorycka M Malinski E Czerwicka M Kumirska J Golebiowski M Lojkowska E Stepnowski P 《Biotechnology letters》2008,30(3):541-545
Growth of Ruta graveolens shoots was induced when Bacillus sp. cell lysates were added to the culture medium. Elicitation of coumarin by this lysate was also very effective; the concentrations
of isopimpinelin, xanthotoxin and bergapten increased to 610, 2120 and 1460 μg g−1 dry wt, respectively. It also had a significant effect on the production of psoralen and rutamarin (680 and 380 μg g−1 dry wt) and induced the biosynthesis of chalepin, which was not detected in the control sample, up to 47 μg g−1 dry wt With lysates of the Pectobacterium
atrosepticum, their effect on growth was not so significant and had no effect on the induction of coumarin accumulation. But elicitation
with this lysate was much more effective for inducing the production of furoquinolone alkaloids; the concentrations of γ-fagarine,
skimmianine, dictamnine and kokusaginine rose to 99, 680, 172 and 480 μg g−1 dry wt, respectively. 相似文献
14.
Meiru Li Hongqing Li Huawu Jiang Guojiang Wu 《Plant Cell, Tissue and Organ Culture》2008,93(3):249-255
Broussonetia papyrifera is well-known for its bark fibers, which are used for making paper, cloth, rope etc. This is the first report of a successful
genetic transformation protocol for B. papyrifera using Agrobacterium tumefaciens. Callus was initiated at a frequency of about 100% for both leaf and petiole explants. Shoots formed on these calli with
a success rate of almost 100%, with 14.08 and 8.36 shoots regenerating from leave-derived and petiole-derived callus, respectively.
For genetic transformation, leaf explants of B. papyrifera were incubated with A. tumefaciens strain LBA4404 harboring the binary vector pCAMBIA 1301 which contains the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene (gus-int) as a reporter gene. Following co-cultivation, leaf explants were cultured on Murashige and Skoog (Physiol Plant 15:473,
1962) (MS) medium supplemented with 1.5 mg l−1 benzyladenine (BA) and 0.05 mg l−1 indole-3-butyric acid (IBA) (CI medium) containing 5 mg l−1 hygromycin and 500 mg l−1 cefotaxime, in the dark. Hygromycin-resistant calli were induced from leaf explants 3 weeks thereafter. Regenerating shoots
were obtained after transfer of the calli onto MS medium supplemented with 1.5 mg l−1 BA, 0.05 mg l−1 IBA, and 0.5 mg l−1 gibberellic acid (GA3) (SI medium), 5 mg l−1 hygromycin and 250 mg l−1 cefotaxime under fluorescent light. Finally, shoots were rooted on half strength MS medium (1/2 MS) supplemented with 10 mg l−1 hygromycin. Transgene incorporation and expression was confirmed by PCR, Southern hybridisation and histochemical GUS assay.
Using this protocol, transgenic B. papyrifera plants containing desirable new genes can be obtained in approximately 3 months with a transformation frequency as high as
44%. 相似文献
15.
Durban MA Silbersack J Schweder T Schauer F Bornscheuer UT 《Applied microbiology and biotechnology》2007,74(3):634-639
Twenty-two Bacillus cereus strains were screened for phospholipase C (PLC, EC 3.1.4.3) activity using p-nitrophenyl phosphorylcholine as a substrate. Two strains (B. cereus SBUG 318 and SBUG 516) showed high activity at elevated temperatures (>70°C) at acidic pH (pH 3.5–6) and were selected for
cloning and functional expression using Bacillus subtilis. The genes were amplified from B. cereus DNA using primers based on a known PLC sequence and cloned into the expression vector pMSE3 followed by transformation into
B. subtilis WB800. On the amino acid level, one protein (PLC318) was identical to a PLC described from B. cereus, whereas PLC516 contained an amino acid substitution (E173D). PLC production using the recombinant strains was performed
by an acetoin-controlled expression system. For PLC516, 13.7 U g−1 wet cell weight was determined in the culture supernatant after 30 h cultivation time. Three purification steps resulted
in pure PLC516 with a specific activity of 13,190 U mg−1 protein. 相似文献
16.
Prabhu P Tiwari MK Jeya M Gunasekaran P Kim IW Lee JK 《Applied microbiology and biotechnology》2008,81(2):283-290
Based on analysis of the genome sequence of Bacillus licheniformis ATCC 14580, an isomerase-encoding gene (araA) was proposed as an l-arabinose isomerase (L-AI). The identified araA gene was cloned from B. licheniformis and overexpressed in Escherichia coli. DNA sequence analysis revealed an open reading frame of 1,422 bp, capable of encoding a polypeptide of 474 amino acid residues
with a calculated isoelectric point of pH 4.8 and a molecular mass of 53,500 Da. The gene was overexpressed in E. coli, and the protein was purified as an active soluble form using Ni–NTA chromatography. The molecular mass of the purified enzyme
was estimated to be ~53 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and 113 kDa by gel filtration chromatography,
suggesting that the enzyme is a homodimer. The enzyme required a divalent metal ion, either Mn2+or Co2+, for enzymatic activity. The enzyme had an optimal pH and temperature of 7.5 and 50°C, respectively, with a k
cat of 12,455 min−1 and a k
cat/K
m of 34 min−1 mM−1 for l-arabinose, respectively. Although L-AIs have been characterized from several other sources, B. licheniformis L-AI is distinguished from other L-AIs by its wide pH range, high substrate specificity, and catalytic efficiency for l-arabinose, making B. licheniformis L-AI the ideal choice for industrial applications, including enzymatic synthesis of l-ribulose. This work describes one of the most catalytically efficient L-AIs characterized thus far. 相似文献
17.
Dimitris Petroutsos Petros Katapodis Paul Christakopoulos Dimitris Kekos 《Journal of applied phycology》2007,19(5):485-490
The ability of Tetraselmis marina, a green coastal microalga, to remove chlorophenols under photoautotrophic conditions was investigated. T.marina was able to grow in the presence of 20 mg L−1 of the phenolic compounds tested. The EC50 (growth rate) value of p-chlorophenol (p-CP) to T.marina was found to be 25.5 mg L−1. The microalga was able to remove chlorophenols, showing higher efficiency for p-CP. The effect of photoregime and NaHCO3 concentration on p-CP removal was investigated. Under continuous illumination with 1 g L−1 NaHCO3 initial concentration T.marina removed 65% of 20 mg L−1 in a 10-day cultivation period. 相似文献
18.
Thellungiella halophila is a salt-tolerant close relative of Arabidopsis, which is adopted as a halophytic model for stress tolerance research. We established an Agrobacterium tumefaciens-mediated transformation procedure for T. halophila. Leaf explants of T. halophila were incubated with A. tumefaciens strain EHA105 containing a binary vector pCAMBIA1301 with the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene as a reporter gene. Following
co-cultivation, leaf explants were cultured on selective medium containing 10 mg l−1 hygromycin and 500 mg l−1 cefotaxime. Hygromycin-resistant calluses were induced from the leaf explants after 3 weeks. Shoot regeneration was achieved
after transferring the calluses onto fresh medium of the same composition. Finally, the shoots were rooted on half strength
MS basal medium supplemented with 10 mg l−1 hygromycin. Incorporation and expression of the transgenes were confirmed by PCR, Southern blot analysis and GUS histochemical
assay. Using this protocol, transgenic T. halophila plants can be obtained in approximately 2 months with a high transformation frequency of 26%. 相似文献
19.
Xiaohuan Wang Zhenhua Gao Yunzhen Wang Ray A. Bressan Stephen C. Weller Xia Li 《In vitro cellular & developmental biology. Plant》2009,45(4):435-440
An in vitro regeneration system with a 100% efficiency rate was developed in peppermint [Mentha x piperita] using 5- to 7-mm-long second internode stem segments of 3-wk-old stock plants. Shoots developed at sites of excision on
stem fragments either directly from the cells or via primary calluses. The optimal medium for maximum shoot initiation and
regeneration contained Murashige and Skoog (MS) salts, B5 vitamins, thidiazuron (TDZ, 11.35 μM), ZT (4.54 μM), 10% coconut
water (CW), 20 g l−1 sucrose, 0.75% agar, adjusted to pH 5.8. A frequency of 100% shoot initiation was achieved, with an average of 39 shoots
per explant. This regeneration system is highly reproducible. The regenerated plants developed normally and were phenotypically
similar to Black Mitcham parents. 相似文献
20.
Zahir Ahmad Zahir Usman Ghani Muhammad Naveed Sajid Mahmood Nadeem Hafiz Naeem Asghar 《Archives of microbiology》2009,191(5):415-424
Ethylene synthesis is accelerated in response to various environmental stresses like salinity. Ten rhizobacterial strains
isolated from wheat rhizosphere taken from different salt affected areas were screened for growth promotion of wheat under
axenic conditions at 1, 5, 10 and 15 dS m−1. Three strains, i.e., Pseudomonas putida (N21), Pseudomonas aeruginosa (N39) and Serratia proteamaculans (M35) showing promising performance under axenic conditions were selected for a pot trial at 1.63 (original), 5, 10 and 15 dS m−1. Results showed that inoculation was effective even in the presence of higher salinity levels. P. putida was the most efficient strain compared to the other strains and significantly increased the plant height, root length, grain
yield, 100-grain weight and straw yield up to 52, 60, 76, 19 and 67%, respectively, over uninoculated control at 15 dS m−1. Similarly, chlorophyll content and K+/Na+ of leaves also increased by P. putida over control. It is highly likely that under salinity stress, 1-aminocyclopropane-1-carboxylic acid-deaminase activity of
these microbial strains might have caused reduction in the synthesis of stress (salt)-induced inhibitory levels of ethylene.
The results suggested that these strains could be employed for salinity tolerance in wheat; however, P. putida may have better prospects in stress alleviation/reduction. 相似文献