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1.
Raj J Sharma NN Prasad S Bhalla TC 《Journal of industrial microbiology & biotechnology》2008,35(1):35-40
The nitrile hydratase (Nhase) induced cells of Rhodococcus rhodochrous PA-34 catalyzed the conversion of acrylonitrile to acrylamide. The cells of R. rhodochrous PA-34 immobilized in 2% (w/v) agar (1.76 mg dcw/ml agar matrix) exhibited maximum Nhase activity (8.25 U/mg dcw) for conversion
of acrylonitrile to acrylamide at 10°C in the reaction mixture containing 0.1 M potassium phosphate buffer (pH 7.5), 8% (w/v)
acrylonitrile and immobilized cells equivalent to 1.12 mg dcw (dry cell weight) per ml. In a partitioned fed batch reaction
at 10°C, using 1.12 g dcw immobilized cells in a final volume of 1 l, a total of 372 g of acrylonitrile was completely hydrated
to acrylamide (498 g) in 24 h. From the above reaction mixture 87% acrylamide (432 g) was recovered through crystallization
at 4°C. By recycling the immobilized biocatalyst (six times), a total of 2,115 g acrylamide was produced. 相似文献
2.
The nitrile hydratase (NHase, EC 3.5.5.1) activity of Rhodococcus rhodochrous PA-34 was explored for the conversion of 3-cyanopyridine to nicotinamide. The NHase activity (∼18 U/mg dry cell weight, dcw)
was observed in 0.1 M phosphate buffer, pH 8.0 containing 1M 3-cyanopyridine as substrate, and 0.75 mg of resting cells (dry
cell weight) per ml reaction mixture at 40°C. However, 25°C was more suitable for prolonged batch reaction at high substrate
(3-cyanopyridine) concentration. In a batch reaction (1 liter), 7M 3-cyanopyridine (729 g) was completely converted to nicotinamide
(855 g) in 12h at 25°C using 9.0 g resting cells (dry cell weight) of R. rhodochrous PA-34. 相似文献
3.
The nitrile hydratase (NHase) of Rhodococcus rhodochrous PA-34 catalyzed the conversion of acrylonitrile to acrylamide. The resting cells (having NHase activity) (8 %; 1 mL corresponds
to 22 mg dry cell mass, DCM) were immobilized in polyacrylamide gel containing 12.5 % acrylamide, 0.6 % bisacrylamide, 0.2
% diammonium persulfate and 0.4 % TEMED. The polyacrylamide entrapped cells (1.12 mg DCM/mL) completely converted acrylonitrile
in 3 h at 10 °C, using 0.1 mol/L potassium phosphate buffer. In a partitioned fed batch reactor, 432 g/L acrylamide was accumulated
after 1 d. The polyacrylamide discs were recycled up to 3×; 405, 210 and 170 g/L acrylamide was produced in 1st, 2nd and 3rd
recycling reactions. In four cycles, a total of 1217 g acrylamide was produced by recycling the same mass of entrapped cells. 相似文献
4.
T. C. Bhalla M. Aoshima S. Misawa R. Muramatsu K. Furuhashi 《Engineering in Life Science》1995,15(3):297-306
The nitrilase of Rhodococcus rhodochrous PA-34 catalyzes the production of optically active amino acids from aminonitriles. The amino acid sequence of the NH2 terminus of the purified nitrilase was determined for the preparation of a synthetic oligonucleotide as a southern hybridization probe. A 9.5-kbp Pst I-fragement, which hybridized with the oligonucleotide probe, was isolated from R. rhodochrous PA-34 genomic libraries constructed in pUC 19. Nucleotide sequence analysis revealed that the nitrilase gene codes for a putative polypeptide of 380 amino acids which correspond to a relative molecular weight of 41, 723. 相似文献
5.
The superiority of the third-generation catalyst,Rhodococcus rhodochrous J1 nitrile hydratase,for industrial production of acrylamide 总被引:7,自引:0,他引:7
Toru Nagasawa Hitoshi Shimizu Hideaki Yamada 《Applied microbiology and biotechnology》1993,40(2-3):189-195
As the third-generation biocatalyst for industrial production of acrylamide, the superiority of Rhodococcus rhodochrous J1 nitrile hydratase was demonstrated in comparison with other acrylamide-producing bacteria. R. rhodochrous J1 enzyme is much more heat stable and more tolerant to a high concentration of acrylonitrile than Pseudomonas chlororaphis B23 and Brevibacterium R312 enzymes. The J1 enzyme is peculiar in its extremely high tolerance to acrylamide. The hydration reaction of acrylonitrile catalysed by J1 cells proceeded even in the presence of 50% (w/v) acrylamide. The tolerance of J1 enzyme to various organic solvents such as n-propanol and isopropanol was prominent. Using R. rhodochrous J1 resting cells, the accumulation reaction was carried out by feeding acrylonitrile to maintain a level of 6%. After 10 h incubation, the accumulation of acrylamide was approximately 65.6% (w/v) at 10°C, 56.7% (w/v) at 15°C, and 56.0 (w/v) at 20°C. The high stability, high catalytic efficiency and other outstanding features of the J1 enzyme are analysed and discussed.
Correspondence to: T. Nagasawa 相似文献
6.
Novel additives that act as substratum for attachment of the yeast cells, increased ethanol production in Saccharomyces cerevisiae. The addition of 2 g rice husk, straw, wood shavings, plastic pieces or silica gel to 100 ml medium enhanced ethanol production by 30–40 (v/v). Six distillery strains showed an average enhancement of 34 from 4.1 (v/v) in control to 5.5 (v/v) on addition of rice husk. The cell wall bound glycogen increased by 40–50 mg g –1 dry yeast while intracellular glycogen decreased by 10–12 mg g–1 dry yeast in cells grown in presence of substratum 相似文献
7.
A propionitrile-induced nitrile hydratase (NHase), a promising biocatalyst for synthesis of organic amides has been purified from cell-free extract of Rhodococcus rhodochrous PA-34. About 11-fold purification of NHase was achieved with 52% yield. The SDS-PAGE of the purified enzyme revealed that it consisted of two subunits of 25.04 kD and 30.6 kD. However, the molecular weight of holoenzyme was speculated to be 86 kD by native-PAGE. This NHase exhibited maximum activity at pH 8.0 and temperature 40°C. Half-life was 2 h at 40°C and 0.5 h at 50°C. The Km and Vmax were 167 mM and 250 μmole/min/mg using 25 mM 3-cyanopyridine as substrate. AgNO3, Pb(CH3COO)2 and HgCl2 inhibited the NHase to extent of 89–100%. 相似文献
8.
Z. I. Finkelstein B. P. Baskunov E. L. Golovlev J. Vervoort I. M. C. M. Rietjens M. A. Baboshin L. A. Golovleva 《Microbiology》2003,72(6):660-665
Of the four investigated Rhodococcus strains (R. rhodochrous172, R. opacus 4a and 557, and R. rhodnii 135), the first three strains were found to be able to completely transform fluorene when it was present in the medium as the sole source of carbon at a concentration of 12–25 mg/l. At a fluorene concentration of 50–100 mg/l in the medium, the rhodococci transformed 50% of the substrate in 14 days. The addition of casamino acids and sucrose (1–5 g/l) stimulated fluorene transformation, so that R. rhodochrous 172 could completely transform it in 2–5 days. Nine intermediates of fluorene transformation were isolated, purified, and structurally characterized. It was found that R. rhodnii 135 and R. opacus strains 4a and 557 hydroxylated fluorene with the formation of 2-hydroxyfluorene and 2,7-dihydroxyfluorene. R. rhodochrous 172 transformed fluorene via two independent pathways to a greater degree than the other rhodococci studied. 相似文献
9.
Biodiesel from microalgae seems to be the only renewable biofuel that has the potential to completely replace the petroleum-derived
transport fuels. Therefore, improving lipid content of microalgal strains could be a cost-effective second generation feedstock
for biodiesel production. Lipid accumulation in Scenedesmus obliquus was studied under various culture conditions. The most significant increase in lipid reached 43% of dry cell weight (dcw),
which was recorded under N-deficiency (against 12.7% under control condition). Under P-deficiency and thiosulphate supplementation
the lipid content also increased up to 30% (dcw). Application of response surface methodology in combination with central
composite rotary design (CCRD) resulted in a lipid yield of 61.3% (against 58.3% obtained experimentally) at 0.04, 0.03, and
1.0 g l−1 of nitrate, phosphate, and sodium thiosulphate, respectively for time culture of 8 days. Scenedesmus cells pre-grown in glucose (1.5%)-supplemented N 11 medium when subjected to the above optimized condition, the lipid accumulation
was boosted up to 2.16 g l−1, the value ~40-fold higher with respect to the control condition. The presence of palmitate and oleate as the major constituents
makes S. obliquus biomass a suitable feedstock for biodiesel production. 相似文献
10.
Shreenath Prasad Anurag Misra Ved Prakash Jangir Abhishek Awasthi Jog Raj Tek Chand Bhalla 《World journal of microbiology & biotechnology》2007,23(3):345-353
Rhodococcus sp. NDB 1165, a nitrile-transforming organism was isolated from temperate forest soil of Himalayas. The nitrilase (EC 3.5.5.2)
activity of this organism had higher substrate specificity toward aromatic nitriles (benzonitrile, 3-cyanopyridine and 4-cyanopyridine)
and unsaturated aliphatic nitrile (acrylonitrile) in comparison to saturated aliphatic nitriles (acetonitrile, propionitrile,
butyronitrile and isobutyronitrile) nitrile and arylacetonitrile (phenylacetonitrile and indole-3-acetonitrile). The nitrilase
of Rhodococcus sp. NDB 1165 was inducible in nature and propionitrile proved to be an efficient inducer. However, the salts of ferrous and
cobalt ions had an inhibitory effect. Under optimized reaction conditions (pH 8.0 and temperature 45°C) the nitrilase activity
of this organism was 2.39 ± 0.07 U/mg dry cell mass (dcm). The half-life of this enzyme was 150 min and 40 min at 45°C and
50°C respectively. However, it was quite stable at 40°C and around 58 % activity was retained even after 6 h at this temperature.
The V
max and K
m value of this nitrilase were 1.67 μmol/ml min and 0.1 M respectively using 3-cyanopyridine as substrate. However, the decrease
in V
max and K
m values (0.56 μmol/ml min and 0.02 M, respectively) were ␣observed at >0.05 M 3-cyanopyridine which revealed that this enzyme
experienced uncompetitive inhibition at higher substrate concentrations. Under optimized reaction conditions, 1.6 M 3-cyanopyridine
was successfully converted in to nicotinic acid using 2.0 mg resting cells (dcm)/ml reaction mixture in 11 h. This is the
highest production of nicotinic acid i.e. 8.95 mg/mg resting cells (dcm)/h as compared to nitrilase systems reported hitherto. 相似文献
11.
Summary Production of poly(3-hydroxybutyric acid) [P(3HB)] by Rhodopseudomonas palustris SP5212 isolated in this laboratory has been optimized under phototrophic microaerophilic conditions. Cells grown in malate medium accumulated 7.7% (w/w) P(3HB) of cellular dry weight at the early stationary phase of growth. The accumulated P(3HB) however, attained 15% (w/w) of cellular dry weight when acetate (1.0%, w/v) was used as the sole carbon source under nitrogen-limiting conditions. Synthesis and accumulation of polymer was favoured by sulphate-free conditions and at a phosphate concentration sub-optimal for growth. The polymer content of cells was increased drastically (34% of cellular dry weight) when the acetate containing medium was supplemented with n-alkanoic acids. Compositional analysis by H1 NMR revealed that these accumulated polymers were composed of 3-hydroxybutyric acid and 3-hydroxyvaleric acid (3HV). The contents of 3HV in these copolymers ranged from 14 to 38 mol%. 相似文献
12.
The cellsof Rhodococcus rhodochrous M33, which produce a nitrile hydratase enzyme, were immobilized in acrylamide-based polymer gels. The optimum pH and temperature
for the activity of nitrile hydratase in both the free and immobilized cells were 7.4 and 45°C, respectively, yet the optinum
temperature for acrylamide production by the immobilized cells was 20°C. The nitrile hydratase of the immobilized cells was
more stable with acrylamide than that of the free cells. Under optimal conditions, the final acrylamide concentration reached
about 400 g/L with a conversion yield of almost 100% after 8 h of reaction when using 150 g/L of immobilized cells corresponding
to a 1.91 g-dry cell weight/L. The enzyme activity of the immobilized cells rapidly decreased with repeated use. However,
the quality of the acrylamide produced by the immobilized cells was much better than that produced by the free cells in terms
of color, salt content, turbidity, and foam formation. The quality of the aqueous acrylamide solution obtained was found to
be of commercial use without further purification. 相似文献
13.
We sought the optimum conditions for the production of benzonitrilase by Rhodococcus rhodochrous J1. The use of isovaleronitrile or isobutyronitrile as an inducer greatly enhanced benzonitrilase formation. When Rhodococcus rhodochrous J1 was cultivated at 28°C for 96 h in a medium consisting of 0.1 ml of isovaleronitrile, 0.5 g of polypeptone, 0.3 g of malt extract, 0.3 g of yeast extract and 1 g of glycerol per 100 ml of tap water (pH 7.2), and isovaleronitrile was fed twice at the concentrations of 0.1% (v/v) and 0.2% (v/v) at 55 h and 77 h, respectively, during the course of cultivation, the enzyme activity in the culture broth reached approximately 3,100-times higher than the initially obtained level. 相似文献
14.
An efficient and reproducible protocol is described for the regeneration of Astragalus melilotoides protoplasts isolated from hypocotyl-derived embryogenic calli. Maximum protoplast yield (11.74±0.6×105/g FW) and viability (87.07±2.8%) were achieved using a mixture of 2% (w/v) Cellulase Onozuka R10, 0.5% (w/v) Cellulase Onozuka RS, 0.5% (w/v) Macerozyme R10, 0.5% (w/v) Hemicellulase, and 1% (w/v) Pectinase, all dissolved in a cell protoplast wash (CPW) salt solution with 13% (w/v) sorbitol. First divisions occurred 3–7 days following culture initiation. The highest division frequency (9.86±0.68%) and plating efficiency (1.68±0.05%) were obtained in solid-liquid medium (KM8P) supplemented with 1.0 mg/l 2,4-dichlorophenoxyacetic acid, 0.5 mg/l 6-benzylaminopurine (BA), 0.2 mg/l kinetin, 0.2 M glucose, 0.3 M mannitol and 500 mg/l casein hydrolysate. Upon transfer to MS medium with 0.5 mg/l -naphthaleneacetic acid and 1-2 mg/l BA, the protoplast-derived calli produced plantlets via somatic embryogenesis (56.3±4.1%) and organogenesis (21.6±0.6%). Somatic embryos or adventitious shoots developed into well-rooted plantlets on MS medium without any plant growth regulators or supplemented with 3.0 mg/l indole-3-butyric acid, respectively. About 81% of the regenerants survived in soil, and all were normal with respect to morphology and growth characters.Abbreviations BA: 6-Benzylaminopurine - CH: Casein hydrolysate - CPW: Cell protoplast wash - 2,4-D: 2,4-Dichlorophenoxyacetic acid - FDA: Fluorescein diacetate - IBA: Indole-3-butyric acid - KIN: Kinetin - MES: 2-(N-morpholino) Ethanesulphonic acid - NAA: -Naphthaleneacetic acidCommunicated by A. Altman 相似文献
15.
The hydrophobic bacterium Rhodococcus rhodochrous NBRC15564 was employed as a whole-cell biocatalyst to examine its potential for bioconversion in solvent-free organic media. The genes encoding two different thermostable alcohol dehydrogenases (ADHTt1 and ADHTt2) of Thermus thermophilus HB27 were expressed in R. rhodochrous cells. To inactivate indigenous mesophilic enzymes in R. rhodochrous, transformant cells were heated at 70 °C for 10 min. Heat-treated hydrophobic wet cells were used for the bioconversion of 2,2,2-trifluoroacetophenone (TFAP) to α-(trifluoromethyl) benzyl alcohol (TFMBA) as a model reaction with ADHTt1. NADH, which was supplied in aqueous solution, was regenerated by converting cyclohexanol to cyclohexanone by ADHTt2. All reactions were performed by suspending heat-treated cells in solvent-free organic media consisting of 3.7 M TFAP and 4.8 M cyclohexanol (1:1, v/v ratio) at 60 °C. When 800 mg heat-treated R. rhodochrous cells were dispersed in 2 mL of solvent-free organic media (400 mg cells/mL), the product concentration reached about 3.6 M TFMBA by 48 h with a total NADH turnover number of approximately 900. The overall productivity was 190 mol TFMBA/kg cells/h. 相似文献
16.
Fiocco D Capozzi V Goffin P Hols P Spano G 《Applied microbiology and biotechnology》2007,77(4):909-915
The effect of overproducing each of the three small heat shock proteins (Hsp; Hsp 18.5, Hsp 18.55, and Hsp 19.3) was investigated
in Lactobacillus plantarum strain WCFS1. Overproduction of the three genes, hsp 18.5, hsp 18.55, and hsp 19.3, translationally fused to the start codon of the ldhL gene yielded a protein of approximately 19 kDa, as estimated from Tricine
sodium dodecyl sulfate–polyacrylamide gel electrophoresis in agreement with the predicted molecular weight of small Hsps.
Small Hsp overproduction alleviated the reduction in growth rate triggered by exposing exponentially growing cells to heat
shock (37 or 40°C) and cold shock (12°C). Moreover, overproduction of Hsp 18.55 and Hsp 19.3 led to an enhanced survival in
the presence of butanol (1% v/v) or ethanol (12% v/v) treatment suggesting a potential role of L. plantarum small Hsps in solvent tolerance. 相似文献
17.
The survival of two different pentachlorophenol (PCP)-degrading bacteria were studied in natural soil. The PCP-degraders Rhodococcus chlorophenolicus and Flavobacterium sp., both able to mineralize PCP into CO2 and chloride in axenic culture, were tested for the capacity to survive and degrade PCP in natural soil. These bacteria were immobilized on polyurethane (PUR) foam and introduced into natural peaty soil to give about 109 cells g-1 of soil (dry weight). R. chlorophenolicus induced PCP-degrading activity in soil remained detectable for 200 days whether or not a carbon source was added (distillery waste or wood chips). Electron microscopic investigation performed almost a year after inoculation, revealed the presence of R. chlorophenolicus-like cells in the PUR foam particles. PCP-degrading activity of Flavobacterium sp. declined within 60 days of burial in the soil without enhancing the PCP removal. R. chlorophenolicus degraded PCP in soil at a mean rate of 3.7 mg of PCP day-1 kg-1 of soil, which corresponds to ca. 5×10-3 pg of PCP degraded per inoculated R. chlorophenolicus cell day-1. The solvent extractable organic chlorine contents of the soil decreased stoichiometrically (>95%) with that of PCP indicating that PCP was essentially mineralized.Abbreviations ATCC
American type culture collection
- DSM
Deutsche Sammlung für Mikroorganismen
- DW
distillery waste
- EM
electron microscopy
- EOX
extractable organic halogen
- GC/ECD
gas chromatograph/electron capture detector
- GC/MS
gas chromatograph/mass spectrometer
- PCP
pentachlorophenol
- WC
wood chips
- d.wt.
dry weight
- w.wt.
wet weight
- d.s.
dry soil
- d.H2O
distilled water
- PCA
polychlorinated aromatics 相似文献
18.
Graves T Narendranath NV Dawson K Power R 《Applied microbiology and biotechnology》2007,73(5):1190-1196
The combined effects of lactic acid and acetic acid on ethanol production by S. cerevisiae in corn mash, as influenced by temperature, were examined. Duplicate full factorial experiments (three lactic acid concentrations
× three acetic acid concentrations) were performed to evaluate the interaction between lactic and acetic acids on the ethanol
production of yeast at each of the three temperatures, 30, 34, and 37°C. Corn mash at 30% dry solids adjusted to pH 4 after
lactic and acetic acid addition was used as the substrate. Ethanol production rates and final ethanol concentrations decreased
(P<0.001) progressively as the concentration of combined lactic and acetic acids in the corn mash increased and the temperature
was raised from 30 to 37°C. At 30°C, essentially no ethanol was produced after 96 h when 0.5% w/v acetic acid was present
in the mash (with 0.5, 2, and 4% w/v lactic acid). At 34 and 37°C, the final concentrations of ethanol produced by the yeast
were noticeably reduced by the presence of 0.3% w/v acetic acid and ≥2% w/v lactic acid. It can be concluded that, as in previous
studies with defined media, lactic acid and acetic acid act synergistically to reduce ethanol production by yeast in corn
mash. In addition, the inhibitory effects of combined lactic and acetic acid in corn mash were more apparent at elevated temperatures. 相似文献
19.
Crude 2,6-naphthalene dicarboxylic acid was purified by Pseudomonas sp. HN-72 which biotransformed the major impurity of 2-formyl-6-naphthoic acid into 2,6-naphthalene dicarboxylic acid. The
biotransformation yield reached 100% when the reaction was performed at 40°C for 1 h, in 200 ml KH2PO4/KOH buffer (50 mM, pH 8.0), with 0.2% (w/v) crude 2,6-naphthalene dicarboxylic acid and 2.5 mg dry cell wt/ml. 相似文献
20.
The biotransformation of racemic 1-phenylethanol (30 mg) with plant cultured cells of basil (Ocimum basilicum cv. Purpurascens, 5 g wet wt) by shaking 120 rpm at 25°C for 7 days in the dark gave (R)-(+)-1-phenylethanol and acetophenone in 34 and 24% yields, respectively. The biotransformation can be applied to other 1-arylethanols
and basil cells oxidized the (S)-alcohols to the corresponding ketones remaining the (R)-alcohols in excellent ee. 相似文献