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1.
An acid α-amylase hyperproducing strain, designated as MIR-61, was isolated in a screening procedure from South American soil samples. MIR-61, a 60°C thermoresistant strain, was identified using 98 biochemical and morphological tests and characterized as Bacillus licheniformis by numerical taxonomy. Batch cultures of B. licheniformis MIR-61 showed extracellular α-amylase and α-glucosidase activities during the exponential growth phase. The production of α-amylase was studied at free and constant pH values at 37 and 45°C. Maximum α-amylase activity (4,767 kU/dm3 in a liquid medium) was detected at 45°C at a constant pH (7.0) in the late exponential phase. The α-amylase production by B. licheniformis MIR-61 is 10 to 300 times higher than the enzyme production reported in strains of the same species. Optimum α-amylase activity was found at 50 to 67°C in an acid pH range from 5.5 to 6.0. These properties would allow its use in starch industry processes. 相似文献
2.
Characterization of thermotolerant Acetobacter pasteurianus strains and their quinoprotein alcohol dehydrogenases 总被引:2,自引:0,他引:2
Watchara Kanchanarach Gunjana Theeragool Toshiharu Yakushi Hirohide Toyama Osao Adachi Kazunobu Matsushita 《Applied microbiology and biotechnology》2010,85(3):741-751
We isolated several thermotolerant Acetobacter species of which MSU10 strain, identified as Acetobacter pasteurianus, could grow well on agar plates at 41°C, tolerate to 1.5% acetic acid or 4% ethanol at 39°C, similarly seen with A. pasteurianus SKU1108 previously isolated. The MSU10 strain showed higher acetic acid productivity in a medium containing 6% ethanol at
37°C than SKU1108 while SKU1108 strain could accumulate more acetic acid in a medium supplemented with 4–5% ethanol at the
same temperature. The fermentation ability at 37°C of these thermotolerant strains was superior to that of mesophilic A. pasteurianus IFO3191 strain having weak growth and very delayed acetic acid production at 37°C even at 4% ethanol. Alcohol dehydrogenases
(ADHs) were purified from MSU10, SKU1108, and IFO3191 strains, and their properties were compared related to the thermotolerance.
ADH of the thermotolerant strains had a little higher optimal temperature and heat stability than that of mesophilic IFO3191.
More critically, ADHs from MSU10 and SKU1108 strains exhibited a higher resistance to ethanol and acetic acid than IFO3191
enzyme at elevated temperature. Furthermore, in this study, the ADH genes were cloned, and the amino acid sequences of ADH
subunit I, subunit II, and subunit III were compared. The difference in the amino acid residues could be seen, seemingly related
to the thermotolerance, between MSU10 or SKU1108 ADH and IFO 3191 ADH. 相似文献
3.
Napatchanok Yuangsaard Wichien Yongmanitchai Mumoru Yamada Savitree Limtong 《Antonie van Leeuwenhoek》2013,103(3):577-588
Pichia kudriavzevii DMKU 3-ET15 was isolated from traditional fermented pork sausage by an enrichment technique in a yeast extract peptone dextrose (YPD) broth, supplemented with 4 % (v/v) ethanol at 40 °C and selected based on its ethanol fermentation ability at 40 °C in YPD broth composed of 16 % glucose, and in a cassava starch hydrolysate medium composed of cassava starch hydrolysate adjusted to 16 % glucose. The strain produced ethanol from cassava starch hydrolysate at a high temperature up to 45 °C, but the optimal temperature for ethanol production was at 40 °C. Ethanol production by this strain using shaking flask cultivation was the highest in a medium containing cassava starch hydrolysate adjusted to 18 % glucose, 0.05 % (NH4)2SO4, 0.09 % yeast extract, 0.05 % KH2PO4, and 0.05 % MgSO4·7H2O, with a pH of 5.0 at 40 °C. The highest ethanol concentration reached 7.86 % (w/v) after 24 h, with productivity of 3.28 g/l/h and yield of 85.4 % of the theoretical yield. At 42 °C, ethanol production by this strain became slightly lower, while at 45 °C only 3.82 % (w/v) of ethanol, 1.27 g/l/h productivity and 41.5 % of the theoretical yield were attained. In a study on ethanol production in a 2.5-l jar fermenter with an agitation speed of 300 rpm and an aeration rate of 0.1 vvm throughout the fermentation, P. kudriavzevii DMKU 3-ET15 yielded a final ethanol concentration of 7.35 % (w/v) after 33 h, a productivity of 2.23 g/l/h and a yield of 79.9 % of the theoretical yield. 相似文献
4.
The fermentation pattern of cassava starch utilization was investigated at 37°C using Rhizopus oligosporus UQM 145 F and eight different media. Depending on the medium used, the addition of zinc or zinc plus iron to a combination of calcium plus manganese switches the fermentation from glucose accumulation to biomass (single cell protein) production. Complete starch hydrolyzation was obtained in both cases, with a complete glucose utilization resulting in 24 g biomass containing 30% true protein per 100 g cassava starch (= 7.45 g SCP/100 g substrate) in 24 hours. In the case of glucose accumulation, biomass was kept low and 15.5 g/l glucose representing 57.3% of starch supplied were obtained in 36 hours. R. oligosporus UQM 145 F grows well between 30° and 45°C. At 45°C and pH 5.0, 7.0 g SCP/100 g substrate were obtained, which rose to 8.6 g if cassava starch is replaced by ground cassava tuber. 相似文献
5.
Chao-Hsun Yang Yu-Chun Huang Cheng-Yu Chen Chia-Ying Wen 《Journal of industrial microbiology & biotechnology》2010,37(9):953-960
A gene encoding the thermostable α-amylase in Thermobifida fusca NTU22 was amplified by PCR, sequenced, and cloned into Yarrowia lipolytica P01g host strain using the vector pYLSC1 allowing constitutive expression and secretion of the protein. Recombinant expression
resulted in high levels of extracellular amylase production, as high as 730 U/l in the Hinton flask culture broth. It is higher
than that observed in P. pastoris expression system and E. coli expression system. The purified amylase showed a single band at about 65 kDa by SDS-polyacrylamide gel electrophoresis and
this agrees with the predicted size based on the nucleotide sequence. About 70% of the original activity remained after heat
treatment at 60°C for 3 h. The optimal pH and temperature of the purified amylase were 7.0 and 60°C, respectively. The purified
amylase exhibited a high level of activity with raw sago starch. After 72-h treatment, the DP
w
of raw sago starch obviously decreased from 830,945 to 237,092. The boiling stable resistant starch content of the sago starch
increased from 8.3 to 18.1%. The starch recovery rate was 71%. 相似文献
6.
Summary The optimum pH for both the rate of production and yield of hyaluronic acid (HA) byStreptococcus zooepidemicus from glucose medium was 6.7±0.2 under anaerobic conditions. High agitation rates (600 rpm) gave superior results compared to 300 rpm. Aeration of the culture (0.3 VVM) improved the HA yield, but not the rate of production and lead to some acetate and CO2 being formed, in addition to lactate and HA. 相似文献
7.
Aspergillus species are increasingly important human pathogens. It is not known whether toxic metabolites of many of these pathogenic
species can act as virulence factors in aspergillosis. We examined isolates of aflatoxin and ochratoxin-producing species
for toxin production in ex vivo conditions. Seven of the 21 aflatoxin-producing isolates screened produced aflatoxin at 35
and 37°C on the general medium yeast extract sucrose agar (YES). However, none of them produced toxin at these temperatures
on brain heart infusion agar (BHA), a medium that mimics human tissue, or on BHA with modified pH or sugar levels. Six of
the 12 ochratoxin-producing isolates examined produced toxin at 35°C on YES. All three isolates of A. alliaceus produced ochratoxin on BHA or modified BHA at 37°C. One strain of A. pseudoelegans produced a minute amount of ochratoxin on modified BHA at 37°C. These data indicate that aflatoxin is an unlikely virulence,
factor but that ochratoxin may be a potential virulence factor in aspergillosis. 相似文献
8.
A thermophilic Bacillus coagulans WCP10-4 with tolerance to high concentration of glucose was isolated from soil and used to produce optically pure l-lactic acid from glucose and starch. In batch fermentation at pH?6.0, 240 g/L of glucose was completely consumed giving 210 g/L of l-lactic acid with a yield of 95 % and a productivity of 3.5 g/L/h. In simultaneous saccharification and fermentation at 50 °C without sterilizing the medium, 200 g/L of corn starch was completely consumed producing 202.0 g/L of l-lactic acid. To the best of our knowledge, this strain shows the highest osmotic tolerance to glucose among the strains ever reported for lactic acid production. This is the first report of simultaneous saccharification and fermentation of starch for lactic acid production under a non-sterilized condition. 相似文献
9.
Li Tan Yue-Qin Tang Hiroto Nishimura Shouta Takei Shigeru Morimura 《Preparative biochemistry & biotechnology》2013,43(7):682-695
Corn stover is the most abundant agricultural residue in China and a valuable reservoir for bioethanol production. In this study, we proposed a process for producing bioethanol from corn stover; the pretreatment prior to presaccharification, followed by simultaneous saccharification and fermentation (SSF) by using a flocculating Saccharomyces cerevisiae strain, was optimized. Pretreatment with acid–alkali combination (1% H2SO4, 150°C, 10 min, followed by 1% NaOH, 80°C, 60 min) resulted in efficient lignin removal and excellent recovery of xylose and glucose. A glucose recovery efficiency of 92.3% was obtained by enzymatic saccharification, when the pretreated solid load was 15%. SSF was carried out at 35°C for 36 hr after presaccharification at 50°C for 24 hr, and an ethanol yield of 88.2% was achieved at a solid load of 15% and an enzyme dosage of 15 FPU/g pretreated corn stover. 相似文献
10.
L-asparaginase synthesis by Escherichia coli B 总被引:2,自引:0,他引:2
We have studied the influence of strain of organism, temperature, and medium on the production of the antileukemic intracellular enzyme L-asparaginase by E. coli B grown in shaken flasks. Five strains of E. coli B exhibited wide differences in their capacities to synthesize the EC-2 form of L-asparaginase active against leukemia. For the most productive strain, when grown in a casein hydrolysate medium, maximal production of L-asparaginase occurred at 25°C. At this temperature, the organism required glycerol, glucose, or other mono-saccharides to synthesize L-asparaginase. Synthesis was stimulated when glycerol was used in place of glucose, but not in its presence. The effect of glycerol on L-asparaginase synthesis was most evident when the cells were grown at 37°C, rather than at 25°C. With 0.25% glucose, cells had a specific activity of 409 I.U./g; with glycerol cells had a specific activity of 553 I.U./g. At 25°C, both cell and L-asparaginase synthesis were increased by the use of 0.25% glycerol resulting in only a slight increase in specific activity of the cells. The addition of zinc, copper, manganese, iron, L-asparagine, L-glutamine, or L-aspartic acid had no effect on L-asparaginase synthesis in the casein hydrolysate medium. L-aspartic acid (10?2 M) enhanced L-asparaginase synthesis in a synthetic medium that lacked these metals or L-asparagine, L-glutamine, or L-aspartic acid; cells grown under these conditions had a specific activity of 90 I.U./g. In the casein hydrolysate medium, cell morphology was correlated with temperature of incubation. 相似文献
11.
A strong fibrin-specific fibrinolytic enzyme was purified from the cell-free spent culture broth of a thermophilic organism,
Streptomyces megasporus SD5. The strain could produce 150 mg crude protein per litre of spent broth, with a specific activity of 80 IU (Plough units)
per milligram, within 18 h of incubation at 55 °C in glucose yeast/extract/peptone (GYP) medium, pH 8.0. For production of
the enzyme, the strain could utilize different carbon and nitrogen sources with a C:N ratio of ∼ 1:2. The enzyme was stable
at a broad range of pH ranging from 5 to 9, and highly thermostable with 50% activity after storage at 60 °C for 6 months.
The enzyme belonged to the serine endopeptidase group. In vitro clot lysis revealed that the enzyme was active at 37 °C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Temperature-sensitive mutants were derived from Brevibacterium lactofermentum strain 2256 in a search for mutants which would produce a large amount of L-glutamic acid in biotin- rich media at the nonpermissive temperature. A total of 159 mutant strains was selected which showed adequate growth at 30°C but showed little or no growth at 37°C on minimal medium. Twenty of these were found to produce glutamic acid in a biotin-rich medium after a temperature shift from 30°C to 37°C, while the wild-type strain 2256 did not produce it under the same cultural condition.One of the typical mutant strains, Ts-88, produced approximately 2g/dl of glutamic acid from beet molasses (the yield > 55%) in the presence of 33 µg/liter of biotin when tempera- , ture was shifted from 30°C to 40°C during the cultivation. It was concluded that, by controlling only temperature during fermentation, glutamic acid production could be realized in media containing biotin-rich natural carbon sources, without any chemical control such as the addition of expensive surface-active agents or antibiotics. Characteristics and merits of the novel fermentation process are discussed. 相似文献
13.
The action of thermostable α-amylase produced by Bacillus licheniformis 44MB82 strain on soluble and insoluble starch, amylose and amylopectin at temperatures 30°C and 90°C was studied. The hydrolysis of soluble starch proceeded rapidly for 10 to 15 minutes after which the maltodextrins thus formed were further dissociated. In the course of 60-minutes enzyme treatment mainly glucose, maltose and maltosugars (from G3 to G6) as low molecular weight products were found and the formation of maltcse and maltotriose was increased by the longer treatment. The hydrolysis of insoluble starch and amylopectin proceeded in the same way while the amylose was hydrolysed slowly. 相似文献
14.
Selection of a cold-adapted bacterium for bioremediation of wastewater at low temperatures 总被引:1,自引:0,他引:1
Emmanuelle Gratia Frédéric Weekers Rosa Margesin Salvino D’Amico Philippe Thonart Georges Feller 《Extremophiles : life under extreme conditions》2009,13(5):763-768
Amongst more than 1000 isolates collected in various cold environments, the strain Arthrobacter psychrolactophilus Sp 31.3 has been selected for its ability to grow and to produce exoenzymes at low temperatures, its inability to grow at
37°C, its non-halophilic character and its growth versatility on various media. This non-pathogenic strain displays a strong
resistance to desiccation and storage at room temperature and is suitable for the production of freeze-dried bacterial starters.
When grown in a synthetic wastewater at 10°C, the strain induces a complete clarification of the turbid medium and efficiently
hydrolyses proteins, starch and lipids in the broth. Furthermore, this strain has a remarkable capacity to improve the biodegradability
of organic compounds in wastewater as indicated by a BOD5/COD ratio of 0.7. 相似文献
15.
Corynebacterium glutamicum is an important microorganism in the industrial production of amino acids. We engineered a strain of C. glutamicum that secretes α-amylase from Streptococcus bovis 148 (AmyA) for the efficient utilization of raw starch. Among the promoters and signal sequences tested, those of cspB from C. glutamicum possessed the highest expression level. The fusion gene was introduced into the homoserine dehydrogenase gene locus on the
chromosome by homologous recombination. L-Lysine fermentation was conducted using C. glutamicum secreting AmyA in the growth medium containing 50 g/l of raw corn starch as the sole carbon source at various temperatures
in the range 30 to 40°C. Efficient L-lysine production and raw starch degradation were achieved at 34 and 37°C, respectively. The α-amylase activity using raw
corn starch was more than 2.5 times higher than that using glucose as the sole carbon source during L-lysine fermentation. AmyA expression under the control of cspB promoter was assumed to be induced when raw starch was used as the sole carbon source. These results indicate that efficient
simultaneous saccharification and fermentation of raw corn starch to L-lysine were achieved by C. glutamicum secreting AmyA using the cspB promoter and signal sequence. 相似文献
16.
Serap Gedikli Gökhan Güngör Yağmur Toptaş Dilber Ece Sezgin Murat Demirbilek Nuray Yazıhan 《Preparative biochemistry & biotechnology》2013,43(7):610-618
AbstractIn the present study, culture conditions of Streptococcus equi was optimized through Box–Behnken experimental design for hyaluronic acid production. About 0.87?gL?1 of hyaluronic acid was produced under the determined conditions and optimal conditions were found as 38.42?°C, 24?hr and 250?rpm. The validity and practicability of this statistical optimization strategy were confirmed relation between predicted and experimental values. The hyaluronic acid obtained under optimal conditions was characterized. The effects of different conditions such as ultraviolet light, temperature and enzymatic degradation on hyaluronic acid produced under optimal conditions were determined. 118?°C for 32?min of autoclaved HA sample included 63.09 µg mL?1 of d-glucuronic acid, which is about two-fold of enzymatic effect. Cytotoxicity of hyaluronic acid on human dermal cells (HUVEC, HaCaT), L929 and THP-1 cells was studied. In vitro effect on pro or anti-inflammatory cytokine release of THP-1 cells was determined. Although it varies depending on the concentration, cytotoxicity of hyaluronic acid is between 5 and 30%. However, it varies depending on the concentration of hyaluronic acid, TNF-α release was not much increased compared to control study. Consequently, purification procedure is necessary to develop and it is worth developing the bacterial hyaluronic acid. 相似文献
17.
Overexpression and characterization of a thermostable trehalose synthase from Meiothermus ruber 总被引:1,自引:0,他引:1
Yueming Zhu Dongsheng Wei Jun Zhang Yufan Wang Hengyi Xu Laijun Xing Mingchun Li 《Extremophiles : life under extreme conditions》2010,14(1):1-8
A thermostable trehalose synthase (TreS) gene from Meiothermus ruber CBS-01 was cloned and overexpressed in Escherichia coli. The purified recombinant TreS could utilize maltose to produce trehalose, and showed an optimum pH and temperature of 6.5
and 50°C, respectively. Kinetic analysis showed that the enzyme had a twofold higher catalytic efficiency (k
cat/K
m) for maltose than for trehalose, indicating maltose as the preferred substrate. The TreS also had a weak hydrolytic property
with glucose as the byproduct, and glucose was a strong competitive inhibitor of the enzyme. The maximum production of trehalose
by the enzyme reached 65% at 20°C. The most importantly the enzyme could maintain very high activity (above 90%) at pH 4.0–8.0
and 60°C 5 h. These results provided that the stable TreS was suitable for the industrial production of trehalose from maltose
in a one-step reaction. 相似文献
18.
Ji-Hee Song Jey -R. S. Ventura Chang-Hee Lee Deokjin Jahng 《Biotechnology and Bioprocess Engineering》2011,16(1):42-49
Butyric acid fermentation by Clostridium tyrobutyricum ATCC 25755 using glucose or brown algae as a carbon source was carried out. Initially, different fermentation modes (batch,
fed-batch, and semi-continuous) at pH 6 and 37°C were compared using a model medium containing glucose as a carbon source.
By feeding the whole medium containing 40 ∼ 50 and 30 g/L of glucose into the fed-batch and semi-continuous fermentations,
very similar butyrate yields (0.274 and 0.252 g butyrate/g glucose, respectively) and productivities (0.362 and 0.355 g/L/h,
respectively) were achieved. The highest butyrate concentration was about 50 g/L, which was observed in the fed-batch fermentation
with whole medium feeding. However, semi-continuous fermentation sustained a longer fermentation cycle than the fed-batch
fermentation due to end-product and metabolic waste inhibition. The established conditions were then applied to the fermentation
using brown algae, Laminaria japonica and Undaria pinnatifida, as substrates for butyric acid fermentation. To hydrolyze brown algae, 7.5 ∼ 10% (w/v) dried brown algae powder was suspended
in 1% (w/v) NaOH or 0.5 ∼ 2.5% (w/v) H2SO4 and then autoclaved at 121°C for 30 ∼ 90 min. The resulting butyrate concentration was about 11 g/L, which was produced from
100 g/L of L. japonica autoclaved for 60 min in 1.5% H2SO4 acid solution. 相似文献
19.
M. S. Madihah A. B. Ariff M. S. Khalil A. A. Suraini M. I. A. Karim 《Folia microbiologica》2001,46(3):197-204
A study of the kinetics and performance of solvent-yielding batch fermentation of individual sugars and their mixture derived
from enzymic hydrolysis of sago starch byClostridium acetobutylicum showed that the use of 30 g/L gelatinized sago starch as the sole carbon source produced 11.2 g/L total solvent,i.e. 1.5–2 times more than with pure maltose or glucose used as carbon sources. Enzymic pretreatment of gelatinized sago starch
yielding maltose and glucose hydrolyzates prior to the fermentation did not improve solvent production as compared to direct
fermentation of gelatinized sago starch. The solvent yield of direct gelatinized sago starch fermentation depended on the
activity and stability of amylolytic enzymes produced during the fermentation. The pH optima for α-amylase and glucoamylase
were found to be at 5.3 and 4.0–4.4, respectively. α-Amylase showed a broad pH stability profile, retaining more than 80%
of its maximum activity at pH 3.0–8.0 after a 1-d incubation at 37°C. SinceC. acetobutylicum α-amylase has a high activity and stability at low pH, this strain can potentially be employed in a one-step direct solvent-yielding
fermentation of sago starch. However, theC. acetobutylicum glucoamylase was only stable at pH 4–5, maintaining more than 90% of its maximum activity after a 1-d incubation at 37°C. 相似文献
20.
An agar-degrading bacterium, Rhodococcus sp. Q5, was isolated from printing and dyeing wastewater using a mineral salts agar plate containing agar as the sole carbon source. The bacterium grew from pH 4.0 to 9.0, from 15 to 35°C, and in NaCl concentrations of 0–5 %; optimal values were pH 6.0, 30°C, and 1 % NaCl. Maximal agarase production was observed at pH 6.0 and 30°C. The bacterium did not require NaCl for growth or agarase production. The agarase secreted by Q5 was inducible by agar and was repressed by all simple sugars tested except lactose. Strain Q5 could hydrolyze starch but not cellulose or carboxymethyl cellulose. Agarase activity could also be detected in the medium when lactose or starch was the sole source of carbon and energy. Strain Q5 could grow in nitrogen-free mineral media; an organic nitrogen source was more effective than inorganic carbon sources for growth and agarase production. Addition of more organic nitrogen (peptone) to the medium corresponded with reduced agarase activity. 相似文献