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1.
P. S. Apte M. V. Deshpande V. Shankar 《World journal of microbiology & biotechnology》1993,9(2):205-209
A strain of Rhizopus stolonifer produced a high activity of extracellular DNAase when grown on YPG (yeast extract peptone glucose) medium. The source of peptone had a marked effect on the enzyme yield and only one peptone (i.e. from Sarabhai M. Chemicals Ltd, India) supported enzyme production. Maximum enzyme activity (88 U/ml) was obtained after 4 days' growth under submerged conditions in YPG medium containing 100 M Mn2+, Co2+ or Mg2+, and glucose as the sole carbon source. The unpurified enzyme was optimally active at pH 7.5 and 45°C. It had a higher activity with sonicated and heat-denatured DNA than native DNA. 相似文献
2.
Gülnur Birol Z.?lsen Önsan Betül K?rdar Stephen G. Oliver 《Enzyme and microbial technology》1998,22(8):672-677
The production of ethanol from starch has been investigated in three genetically modified Saccharomyces cerevisiae strains (YPG/AB, YPG/MM, and YPB-G). Two of the three strains produce the Aspergillus awamori glucoamylase together with either the Bacillus subtilis (YPG/AB) or the mouse (YPG/MM) α-amylase as separately secreted polypeptides. YPB-G, on the other hand, secretes a bifunctional fusion protein that contains both the B. subtilis α-amylase and the A. awamori glucoamylase activities. Substrate utilization, biomass growth, and ethanol production were all studied in both starch- and glucose-containing media. Much higher growth rates were found when any of the three strains were grown on glucose. YPG/AB showed the most efficient utilization of starch for ethanol production with the lowest levels of reducing sugars accumulating in the medium. The superior performance of YPG/AB as compared to YPB-G was found to correlate with its higher level of α-amylase activity. The ethanol production levels of YPG/AB in starch- and glucose-containing media were found to be comparable. YPB-G, which secretes the bifunctional fusion protein, could produce ethanol in media with starch concentrations above 100 g l−1 while YPG/MM did not produce ethanol from starch because of its negligible secretion of glucoamylase. 相似文献
3.
A thermophilic bacterial strain, Streptomyces thermonitrificans, produced high levels of extracellular deoxyribonuclease (DNase) when grown on NBG medium (containing 1% peptone, 0.3% beef
extract, 1% glucose and 0.5% NaCl). Maximum DNase activity (140 U ml−1) was obtained, in 24 h, when the culture was grown on modified NBG medium (containing 1.3% beef extract, 1% glucose, 0.5%
NaCl and 50 μM Mn2+ at 45°C. The crude enzyme showed higher activity on native DNA than on sonicated and heat denatured DNA. Moreover, addition
of Mn2+ in the assay mixture resulted in a significant stimulation (10–15 fold) of the enzyme activity.
Received 24 November 1998/ Accepted in revised form 25 April 1999 相似文献
4.
Nickel toxicity inhibits ribonuclease and protease activities in rice seedlings: protective effects of proline 总被引:1,自引:0,他引:1
Seedlings of two rice cvs Malviya-36 and Pant-12, when grown under increasing levels of nickel (Ni2+: 200 and 400 μM) in the nutrient medium, showed increased levels of RNA, soluble proteins and free amino acids, especially
proline over a total growth period of 5–20 days. Ribonuclease (RNase) and protease activities decreased in both roots and
shoots due to Ni treatment in situ. Under in vitro conditions, a gradual inhibition of RNase activity was observed with increasing
concentrations of Ni2+ (0–2500 μM) in the assay medium. Artificial desiccation simulated by 40% PEG or the presence of 2.5 mM Ni2+ in the reaction medium resulted in about 52–53% loss of RNase activity. Such a loss could be partially restored by 1 M proline
in the assay medium. The activity staining of RNase revealed seven and four isoforms of RNase in roots and shoots, respectively.
The intensity of most of the bands decreased with increasing levels of Ni2+ treatment in situ. The results suggest that Ni toxicity in rice seedlings suppresses the hydrolysis of RNA and proteins by
inhibiting the activity of RNase and protease, respectively. Proline appears to act as a protectant of the enzyme RNase against
metal- and PEG-induced damages. 相似文献
5.
Curtobacterium luteum, a gram-positive psychrotrophic bacterium, secreting an extracellular protease was isolated from the soil of Gangotri glacier, Western Himalaya. The maximum enzyme production was achieved when isolate was grown in a pH-neutral medium containing skim milk at 15oC over 120 hour. The metal ions such as Zn2+ and Cr2+ enhanced enzyme production. The specific activity of purified enzyme was 8090 u/mg after 34.1 fold purification. The 115 kD enzyme was a metalloprotease (activity inhibited by EDTA and EGTA) and showed maximum activity at 20oC and pH 7. The enzyme was active over a broad pH range and retained 84% of its original activity between pH 6–8. There was no loss in enzyme activity when exposed for 3 hours at 4oC-20oC. However, lost 65% of activity at 30oC, and was almost inactivated at 50oC, but was resistant to repeated freezing and thawing. The enzyme activity was stimulated by manganese ions; however, it was inactivated by copper ions. 相似文献
6.
A microorganism that produces glucose isomerase was isolated from soil and identified as a strain of Streptomyces flavogriseus. The organism produced a large quantity of glucose isomerase when grown on straw hemicellulose, xylan, xylose, and H2SO4 hydrolysate of ryegrass straw. The organism produced glucose isomerase both intra- and extra-cellularly. The highest level of intracellular glucose isomerase (3.5 U/ml) was obtained in about 36 h by a culture grown on straw hemicellulose; the extracellular enzyme (1.5 U/ml) appeared in cultures grown for about 72 h. About equal levels of enzyme were produced in cultures grown on straw hemicellulose, xylan, xylose, and H2SO4 hydrolysate of straw, but production of the enzyme was drastically reduced when the organism was grown on other carbon sources. As a nitrogen source, corn steep liquor produced the best results. Soy flour extract, yeast extract, and various peptones also were adequate substrates for glucose isomerase production. Addition of Mg2+, Mn2+, or Fe2+ to the growth medium significantly enhanced enzyme production. The organism, however, did not require Co2+, which is commonly required by microorganisms used in the production of glucose isomerase. 相似文献
7.
A simple medium enhancing the production of thiaminase I (EC 2.5.1.2) by Bacillus thiaminolyticus was developed. Ca2+ stimulated the enzyme production. The activity of extracellular thiaminase I ranged between 1.29 and 1.33 U/ml medium. 相似文献
8.
Rhizopus oryzae IFO 4697 was found to produce intracellular ribonuclease (RNase), and its growth and activity could be regulated under selected
metal ion stress. The addition of Fe2+, Mg2+ and Zn2+ to the SLSR medium was essential to growth and RNase production. Ca2+ and Mo6+ stimulated RNase production. It is concluded that the addition of 100 mg/ml Ca2+, 5 mg/ml Mo6+, 0.7 mg/ml Zn2+, 2 mg/ml Fe2+, and 49 mg/ml Mg2+ to the SLSR medium was the best condition for producing RNase in high specific activity (3780 U/mg protein). This result
indicates that a metal ion-regulated liquid medium is an efficient culture method for RNase production.
Received: July 19, 2001 / Accepted: April 8, 2002 相似文献
9.
β-Galactosidase was isolated from the cell-free extracts ofLactobacillus crispatus strain ATCC 33820 and the effects of temperature, pH, sugars and monovalent and divalent cations on the activity of the enzyme
were examined.L. crispatus produced the maximum amount of enzyme when grown in MRS medium containing galactose (as carbon source) at 37°C and pH 6.5
for 2 d, addition of glucose repressing enzyme production. Addition of lactose to the growth medium containing galactose inhibited
the enzyme synthesis. The enzyme was active between 20 and 60°C and in the pH range of 4–9. However, the optimum enzyme activity
was at 45°C and pH 6.5. The enzyme was stable up to 45°C when incubated at various temperatures for 15 min at pH 6.5. When
the enzyme was exposed to various pH values at 45°C for 1 h, it retained the original activity over the pH range of 6.0–7.0.
Presence of divalent cations, such as Fe2+ and Mn2+, in the reaction mixture increased enzyme activity, whereas Zn2+ was inhibitory. TheK
m was 1.16 mmol/L for 2-nitrophenyl-β-d-galactopyranose and 14.2 mmol/L for lactose. 相似文献
10.
Effect of cadmium on proline accumulation and ribonuclease activity in rice seedlings: role of proline as a possible enzyme protectant 总被引:2,自引:0,他引:2
When seedlings of two rice (Oryza sativa L.) cultivars Ratna and Jaya were raised under 100 and 500 μM cadmium nitrate in
the medium, a high proline content was noted in Cd2+ stressed seedlings compared to controls. Seedlings grown under 500 μM Cd(NO3)2 maintained increased proline level compared to non-stressed seedlings. Kinetic properties of RNase extracted from control
grown and Cd2+ stressed seedlings showed a marked alteration in Km due to Cd2+ treatment. The RNase isoforms were purified from 15-d-old rice seedlings with a total purification of 22.25 fold and 74.75
% yield using conventional biochemical techniques. Three RNase isoforms, namely I, II and III were eluted from DEAE-Sephacel
column. The isoform RNase II had Km value of 3.2 mg(RNA) cm-3. The in vitro osmotic stress created by incorporation of PEG in the enzyme assay medium led to decreased affinity of enzyme
towards its substrate with increase in Km. This loss in affinity was partially restored by the addition of 1 M proline in
the assay medium, suggesting the possible protective role of proline on RNase under osmotic stress.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Extracellular laccase in cultures of Grifola frondosa grown in liquid culture on a defined medium was first detectable in the early/middle stages of primary growth, and enzyme activity continued to increase even after fungal biomass production had peaked. Laccase production was significantly increased by supplementing cultures with 100–500 μM Cu over the basal level (1.6 μM Cu) and peak levels observed at 300 μM Cu were 7-fold higher than in unsupplemented controls. Decreased laccase activity similar to levels detected in unsupplemented controls, as well as an adverse effect on fungal growth, occurred with further supplementation up to and including 0.9 mM Cu, but higher enzyme titres (2- to 16-fold compared with controls) were induced in cultures supplemented with 1–2 mM Cu2+. SDS-PAGE combined with activity staining revealed the presence of a single protein band (M
r 70 kDa) exhibiting laccase activity in control culture fluids, whereas an additional distinct laccase protein band (M
r 45 kDa) was observed in cultures supplemented with 1–2 mM Cu. Increased levels of extracellular laccase activity, and both laccase isozymes, were also detected in cultures of G. frondosa supplemented with ferulic, vanillic, veratric and 4-hydroxybenzoic acids, and 4-hydroxybenzaldehyde. Using 2,2′-azino-bis(ethylbenzothiazoline-6-sulfonate) (ABTS) as substrate, the optimal temperature and pH values for laccase activity were 65°C and pH 2.2, respectively, and the enzyme was relatively heat stable. In solid-state cultures of G. frondosa grown under conditions adopted for industrial-scale mushroom production, extracellular laccase levels increased during the substrate colonization phase, peaked when the substrate was fully colonized, and then decreased sharply during fruit body development. 相似文献
12.
Kluyveromyces marxianus was grown in submerged culture in a complex medium with several potential inducers of lipolytic activity (triacylglycerols, fatty acids). The highest extracellular lipolytic enzyme production (about 80 U ml–1 in 3 d) was obtained when the medium was supplemented with 2 g urea l–1 plus 5 g tributyrin l–1. Addition of surfactants (1 g l–1) did not improve production. The lipase had a high thermal stability in aqueous solution (73% residual activity after 9 d at 50 °C, 16 min half-life time at 100 °C). It was also stable at acidic pH and showed good tolerance to organic solvents (70% residual activity after 2 d in n-hexane of cyclohexane). 相似文献
13.
S. S. Deshmukh M. V. Deshpande V. Shankar 《World journal of microbiology & biotechnology》1994,10(3):264-267
A thermophilic strain of Streptomyces thermonitrificans produced a high activity of intracellular glucose isomerase (12 U/ml) when grown in a medium containing 1% (w/v) xylose, supplemented with 2% (w/v) sorbitol as the second carbon source, at 50°C for 16 h. Addition of Mg2+ enhanced enzyme production but the organism could grow and produce the enzyme in the absence of Co2+.The authors are with the Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, IndiaNCL Communication No. 5813 相似文献
14.
During the growth of the asporogenous variant ofBacillus megaterium KM in medium containing NO3
− as nitrogen source, the relative rate of extracellular protease synthesis is higher than in the presence of NH4
+. It approaches the relative rate of enzyme synthesis at the incubation of cells in nitrogen-free medium with glucose. This
supports the suggestion that even amino acids which are synthesized endogenously slow down the protease production. In the
postlogarithmic or stationary phase the protease production stops. The interruption of enzyme production does not appear as
a result of insufficient aeration in a dense suspension, or of accumulation of amino acids or their metabolites in cells.
The non-growing cells retain their ability to renew the enzyme synthesis when transferred into a fresh medium, even into a
medium without nitrogen source. In the same way it is possible to “induce” the protease production, if Ca2+ is added to cells in the stationary phase when the population was grown in the Ca2+ free medium. The amount of enzyme produced at the expense of protein turnover by the non-growing populations is sufficient
for the fast hydrolysis of exogenous protein in the medium and for assuring the influx of a sufficient amount of peptides
into the cells. In such a case the growth of the culture is therefore very quickly renewed. 相似文献
15.
Z.T. Xing J.H. Cheng Q. Tan Y.J. Pan 《World journal of microbiology & biotechnology》2006,22(8):799-806
Summary Extracellular laccase in cultures of Grifola frondosa grown in liquid culture on a defined medium was first detectable in the early/middle stages of primary growth, and enzyme activity continued to increase even after fungal biomass production had peaked. Laccase production was significantly increased by supplementing cultures with 100–500 (M Cu over the basal level (1.6 mM Cu) and peak levels observed at 300 mM Cu were ∼
∼7-fold higher than in unsupplemented controls. Decreased laccase activity similar to levels detected in unsupplemented controls, as well as an adverse effect on fungal growth, occurred with further supplementation up to and including 0.9 mM Cu, but higher enzyme titres (2- to 16-fold compared with controls) were induced in cultures supplemented with 1–2 mM Cu2+. SDS-PAGE combined with activity staining revealed the presence of a single protein band (M
r ∼
∼70 kDa) exhibiting laccase activity in control culture fluids, whereas an additional distinct second laccase protein band (M
r␣∼
∼45 kDa) was observed in cultures supplemented with 1–2 mM Cu. Increased levels of extracellular laccase activity, and both laccase isozymes, were also detected in cultures of G. frondosa supplemented with ferulic, vanillic, veratric and 4-hydroxybenzoic acids, and 4-hydroxybenzaldehyde. The optimal temperature and pH values for laccase activity were 65 °C and pH 2.2 (using 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) {ABTS} as substrate), respectively, and the enzyme was relatively heat stable. In solid-state cultures of G. frondosa grown under conditions adopted for industrial-scale mushroom production, extracellular laccase levels increased during the substrate colonization phase, peaked when the substrate was fully colonized, and then decreased sharply during fruit body development. 相似文献
16.
Eirini Kretza Christos P. Papaneophytou Rigini M. Papi Konstantina Karidi Costas Kiparissides Dimitrios A. Kyriakidis 《Biotechnology and Bioprocess Engineering》2012,17(3):512-525
In this study, the lipolytic activity of Thermus thermophilus HB8 was examined. The addition of various oils increased the production of extracellular lipolytic activity, while a combination of olive oil and glucose increased both extracellular and intracellular lipolytic activity. The oxygen transfer rate had a significant influence on both biomass and production of extra- or intra-cellular lipolytic activity. The formation of white halos due to the hydrolysis of oleic acid ester (Tween 80) in agar plates containing Nile Blue and the formation of Ca2+-oleate indicated the secretion of lipase. When the cell-free supernatant of cells grown in basal reach medium or the corresponding intracellular extract were electrophoresed under denatured and renatured conditions, using ??-naphthyl acetate and Fast Blue RR, major bands at 56 kDa or 62 and 32 kDa were observed, respectively. The 56 kDa extracellular enzyme was partial purified and characterized. Its peak of activity occurred at 80°C and pH 7.0, while the T1/2 was 1 h at 100°C. The K m of the partial purified enzyme was 1 mM and the V max was 0.044 U/mL/min when using p-nitrophenyl laurate as substrate. The presence of Ca2+ and Hg2+ stimulated lipase activity, whereas Zn2+, Co2+, or EDTA inhibited lipase activity. The highest activity was observed in the presence of coconut oil and p-nitrophenyl laurate (pNPL). Purified lipase was the most stable in the presence of various organic solvents, such as pentanol, chloroform and n-dodecane. Because of the superior thermostability and stability in the presence of organic solvents of T. thermophilus extracellular lipase, this lipase holds great promise for use in industrial applications. 相似文献
17.
Production and partial purification of naringinase by Penicillium decumbens PTCC 5248 总被引:1,自引:0,他引:1
Norouzian D. Hosseinzadeh A. Inanlou D. Nouri Moazami N. 《World journal of microbiology & biotechnology》2000,16(5):471-473
Penicillium decumbens PTCC 5248 produced naringinase when grown in a medium contained naringin as a source of carbon. Rhamnose also induced production of naringinase. Prunin disappeared as the time of enzymatic reaction increased. On fractionation with isopropanol 24-fold purification was achieved. Optimum pH and temperature for naringinase activity were determined to be 4.5 and 55 °C respectively. The Km value of the enzyme with respect to naringin was found to be 1.7 mM. Citric acid, glucose, Ca2+, Mg2+, Zn2+ all inhibited naringinase activity. 相似文献
18.
Tsutomu Yamaguchi Noriyuki Muroya Masakazu Isobe Mamoru Sugiura 《Bioscience, biotechnology, and biochemistry》2013,77(5):999-1005
Out of some 750 strains of microorganisms, a potent bacterium for lipase production was isolated from soil and was identified as Chromobacterium viscosum.The bacterium accumulates lipase in culture fluid when grown aerobically at 26°C for 3 days in a medium composed of soluble starch, soy bean meal, lard and inorganic salts.Chromobacterium lipase had an optimum pH of 7.0 for activity at 37°C, and an optimal temperature of 65°C at pH 7.0. The enzyme retained 80% of the activity when heated for 10 min at 70°C. This lipase was capable of hydrolyzing a variety of natural fats and oils, and it was more active on lard and butter than on olive oil. The activity was stimulated by Ca2+, Mg2+, Mn2+ and inhibited by Cu2+, Hg2+ and Sn2+. It was not diminished but rather stimulated by a high concentration of bile-salts. 相似文献
19.
Characterization of a Cell Envelope-Associated Proteinase Activity from Streptococcus thermophilus H-Strains
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The production and biochemical properties of cell envelope-associated proteinases from two strains of Streptococcus thermophilus (strains CNRZ 385 and CNRZ 703) were compared. No significant difference in proteinase activity was found for strain CNRZ 385 when cells were grown in skim milk medium and M17 broth. Strain CNRZ 703 exhibited a threefold-higher proteinase activity when cells were grown in low-heat skim milk medium than when grown in M17 broth. Forty-one percent of the total activity of CNRZ 385 was localized on the cell wall. The optimum pH for enzymatic activity at 37°C was around 7.0. Serine proteinase inhibitors, such as phenylmethylsulfonyl fluoride and diisopropylfluorophosphate, inhibited the enzyme activity in both strains. The divalents cations Ca2+, Mg2+, and Mn2+ were activators, while Zn2+ and Cu2+ were inhibitors. β-Casein was hydrolyzed more rapidly than αs1-casein. The results of DNA hybridization and immunoblot studies suggested that the S. thermophilus cell wall proteinase and the lactococcal proteinase are not closely related. 相似文献
20.
Summary Modifications of the ultrastructure of the plant pathogenic bacteriumErwinia amylovora were analyzed according to growth conditions and fixation procedures. Six bacterial strains with various virulence characteristics were examined. Cultures were grown either in Yeast Peptone Glucose medium (YPG) or in a medium containing asparagine (ASP) supplemented with sorbitol (1% or 5% sorbitol). When grown in ASP + 1% sorbitol or in YPG, the strains, structurally similar to each other in ASP + 5% sorbitol, presented different frequencies of small evaginations which were observed arising from the cell surface mainly after an OsO4 fixation step. There was no correlation between the frequency of evaginations and the virulence of the strain. An overnight storage at 4 °C considerably enhanced the frequency of the evaginations. It was suggested that the OsO4 fixation step visualized differences in the bacterial outer membrane structure.List of abbreviations used ASP
synthetic medium containing asparagine (see Materials and Methods)
- CM
cytoplasmic membrane
- EPS
exopolysaccharide
- OM
outer membrane
- RT
room temperature
- YPG
yeast peptone glucose medium (see Materials and Methods) 相似文献