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1.
Yoshida T Horinouchi M Ayabe Y Yamaguchi T Shibuya N Habe H Nojiri H Yamane H Omori T 《Applied microbiology and biotechnology》2000,54(3):341-347
A CH3OH-utilizing bacterium that has the ability to produce extracellular polysaccharide (EPS) was isolated from a soil sample,
and was identified as the obligate methylotroph Methylobacillus sp. strain 12S on the basis of its 16S rDNA sequence and growth-substrate specificity. The EPS produced by strain 12S was
purified and the sugar composition was analysed by GC-MS and HPLC to reveal that the EPS was a heteropolymer composed of glucosyl,
galactosyl, and mannosyl residues in the molar ratio 3:1:1. In order to produce mono- and/or oligosaccharides by single-step
fermentation from CH3OH, stain 12S was mutagenized by transposon 5. Among eleven EPS-deficient mutants, three strains were found to accumulate significant amounts of reducing sugars in the
media. The amounts of the reducing sugars produced by the mutants (>ca. 700 mg glucose equivalent/l) were >11–22 times higher
than those produced by the wild-type strain (<ca. 60 mg glucose equivalent/l). The GC-MS analysis showed that all the mutants
accumulated glucose, erythrose, threose and a disaccharide-like compound in the media.
Received: 25 August 1999 / Received revision: 15 March 2000 / Accepted: 24 March 2000 相似文献
2.
Ant-aphid mutualisms: the impact of honeydew production and honeydew sugar composition on ant preferences 总被引:5,自引:0,他引:5
Wolfgang Völkl Joseph Woodring Melanie Fischer Matthias W. Lorenz Klaus H. Hoffmann 《Oecologia》1999,118(4):483-491
The honeydew composition and production of four aphid species feeding on Tanacetum vulgare, and mutualistic relationships with the ant Lasius niger were studied. In honeydew of Metopeurum fuscoviride and Brachycaudus cardui, xylose, glucose, fructose, sucrose, maltose, melezitose, and raffinose were detected. The proportion of trisaccharides (melezitose,
raffinose) ranged between 20% and 35%. No trisaccharides were found in honeydew of Aphis fabae, and honeydew of Macrosiphoniella tanacetaria consisted of only xylose, glucose and sucrose. M. fuscoviride produced by far the largest amounts of honeydew per time unit (880 μg/aphid per hour), followed by B. cardui (223 μg/aphid per hour), A. fabae (133 μg/aphid per hour) and M. tanacetaria (46 μg/aphid per hour). The qualitative and quantitative honeydew production of the aphid species corresponded well with
the observed attendance by L. niger. L. niger workers preferred trisaccharides over disaccharides and monosaccharides when these sugars were offered in choice tests. The
results are consistent with the ants' preference for M. fuscoviride, which produced the largest amount of honeydew including a considerable proportion of the trisaccharides melezitose and raffinose.
The preference of L. niger for B. cardui over A. fabae, both producing similar amounts of honeydew, may be explained by the presence of trisaccharides and the higher total sugar
concentration in B. cardui honeydew. M. tanacetaria, which produced only low quantities of honeydew with no trisaccharides was not attended at all by L. niger.
Received: 2 March 1998 / Accepted: 16 November 1998 相似文献
3.
J. Dynesen H. P. Smits L. Olsson J. Nielsen 《Applied microbiology and biotechnology》1998,50(5):579-582
When Saccharomyces cerevisiae are grown on a mixture of glucose and another fermentable sugar such as sucrose, maltose or galactose, the metabolism is
diauxic, i.e. glucose is metabolized first, whereas the other sugars are metabolized when glucose is exhausted. This phenomenon
is a consequence of glucose repression, or more generally, catabolite repression. Besides glucose, the hexoses fructose and
mannose are generally also believed to trigger catabolite repression. In this study, batch fermentations of S. cerevisiae in mixtures of sucrose and either glucose, fructose or mannose were performed. It was found that the utilization of sucrose
is inhibited by concentrations of either glucose or fructose higher than 5 g/l, and thus that glucose and fructose are equally
capable of exerting catabolite repression. However, sucrose was found to be hydrolyzed to glucose and fructose, even when
the mannose concentration was as high as 17 g/l, indicating, that mannose is not a repressing sugar. It is suggested that
the capability to trigger catabolite repression is connected to hexokinase PII, which is involved in the in vivo phosphorylation
of glucose and fructose.
Received: 5 May 1998 / Received revision: 3 August 1998 / Accepted: 8 August 1998 相似文献
4.
Exopolysaccharide (EPS) production was compared among three strains of lactobacilli. Lactobacillus rhamnosus strain 9595M can be classified among the highest EPS-producing strains of lactic acid bacteria reported to date with a maximum
EPS production of 1275 mg L−1. Under controlled pH, no significant differences in the quantity of EPS produced could be detected between carbon source
(glucose or lactose) or fermentation temperature (32 or 37°C). In milk, strains ATCC 9595M and R produced more than 280 mg L−1 EPS whereas strain Type V produced less than 80 mg L−1 EPS. Journal of Industrial Microbiology & Biotechnology (2000) 24, 251–255.
Received 10 September 1999/ Accepted in revised form 22 December 1999 相似文献
5.
An expression system based on the Staphylococcus aureus protein A gene (spa) was developed to allow the production and export of proteins in Lactobacillus. Plasmid shuttle vectors were constructed that carried the eZZ gene, a synthetic gene based on the Protein A gene (spa) but lacking the carboxy-terminal membrane-anchoring region. A gene fusion was created between the eZZ gene and the VD4 region
of a chlamydial major outer-membrane protein gene. Expression studies demonstrated the recognition of the spa regulatory signals by several Lactobacillus, with the recombinant protein being expressed (from 0.1 μg of EZZVD4 fusion protein per ml in L. plantarum up to 10 μg of EZZ protein per ml in L. fermentum) and exported (levels up to 20% in L. fermentum) in several Lactobacillus strains.
Received: 27 August 1996 / Received revision: 27 November 1996 / Accepted: 29 November 1996 相似文献
6.
S. Guillouet J. H. Choi C. K. Rha A. J. Sinskey 《Applied microbiology and biotechnology》1999,51(2):235-240
Although many studies have examined the influence of culture conditions on the production and composition of polysaccharides,
little is known about the factors influencing the quality of exopolysaccharides (EPS). In this work we studied the effect
of yeast extract on the production, composition and molecular weight of the EPS zooglan produced by Zoogloea ramigera 115SLR. This bacterium was grown on a new completely defined synthetic medium and on a medium containing yeast extract. Growth
and polysaccharide production performances were comparable on the two media with a glucose to exopolysaccharide conversion
yield of 35% (g/g). The polysaccharides produced on these two media have an identical composition but a different molecular
weight and molecular weight distribution. The yeast extract medium leads to a more homogeneous polysaccharide solution.
Received: 12 June 1998 / Received revision: 19 September 1998 / Accepted: 11 October 1998 相似文献
7.
C. Abate D. Callieri Emilio Rodríguez Oscar Garro 《Applied microbiology and biotechnology》1996,45(5):580-583
Pure and mixed cultures of Zymomonas mobilis and Saccharomyces sp. were tested for the production of ethanol using sucrose as the carbon source. Both strains, isolated from spontaneously
fermenting sugar-cane juice, are flocculent and alcohol-tolerant. The best results were obtained using a mixed culture, with
a yield of 0.5 g ethanol/g sugar consumed and a volumetric productivity of 1.5 g ethanol l-1 h-1. No levan was produced even if a sucrose-based medium was used.
Received: 20 April 1995/Received revision: 26 July 1995/Accepted: 13 September 1995 相似文献
8.
C Calvo F Martinez-Checa A Mota V Bejar E Quesada 《Journal of industrial microbiology & biotechnology》1998,20(3-4):205-209
The effects of monovalent and divalent cations on the rheological behavior of Halomonas eurihalina exopolysaccharide (EPS) were studied. Sodium, potassium, magnesium and calcium were added and the relative abilities to increase
viscosity were as follows: KCl > NaCl > MgCl2 > CaCl2. The highest viscosity value was measured in acidic 10−4 M KCl, in which a gel formed. A loss of sulfate content seemed to correlate with the increase of viscosity. H. eurihalina produced EPS in all growth media. Addition of hydrophobic substrates to culture media produced changes in chemical
composition and emulsifying activity of the EPS. Xylene was the most effectively emulsified substance and the EPS produced
on tetradecane and on corn oil the most active emulsifier.
Received 25 July 1997/ Accepted in revised form 30 January 1998 相似文献
9.
Xylitol and riboflavin accumulation in xylose-grown cultures of Pichia guilliermondii 总被引:1,自引:0,他引:1
Seven strains of Pichia guilliermondii (Candida guilliermondii, asexual state) from diverse isolation sources were examined for the production of xylitol and riboflavin in xylose-grown
cultures. Under the conditions tested, all strains produced xylitol from xylose; conversion efficiencies varied, on a strain-specific
basis, from 7% to 36% of the initial substrate. Four of seven strains metabolized xylitol immediately as xylose levels became
depleted. The remaining three strains metabolized xylitol slowly and incompletely. Surprisingly, utilization of xylitol showed
an apparent relationship with riboflavin production. Strains that readily metabolized xylitol produced at least threefold
greater levels of riboflavin than did strains that used xylitol slowly. Moreover, riboflavin accumulation took place during
xylitol consumption. P. guilliermondii strains that produced the highest levels of riboflavin on xylose produced significantly less riboflavin when grown on glucose
or directly on xylitol.
Received: 24 April 1996 / Received revision: 29 July 1996 / Accepted: 24 August 1996 相似文献
10.
P. Kontula J. Jaskari L. Nollet I. De Smet A. von Wright K. Poutanen T. Mattila-Sandholm 《Applied microbiology and biotechnology》1998,50(2):246-252
The effects of Lactobacillus-GG-fermented oat bran product on the microbiota and its metabolic activity in the human gut were investigated, using a simulator
of the human intestinal microbial ecosystem (SHIME), by analysing the bacterial population, short-chain fatty acids and gas
production. In addition, the effects of fermented oat bran supernatant and supernatant samples from reactors 4, 5 and 6 (large
intestine) on the growth of Escherichia coli IHE 13047, Enterococcus faecalis VTT E-93203, Lactobacillus rhamnosus VTT E-94522 (Lactobacillus GG) and Lactococcus lactis subsp. lactis VTT E-90414 were monitored to ascertain possible stimulatory/inhibitory effects by an in vitro turbidometric method. Our
experiments showed that Lactobacillus GG colonized the SHIME reactor and this colonization could be maintained for several weeks without extra supplementation.
Oat bran feeding also favoured the growth of bifidobacteria and caused an increase in the production of acetic, propionic
and butyric acid as well as CH4 and CO2. However, the effects of oat bran, either on bacterial populations or on their metabolic activity, were not directly dose-dependent.
In turbidometric measurements, the supernatant of fermented oat bran exerted an inhibitory effect of Lactobacillus GG, but stimulated the growth of enterococci.
Received: 19 January 1998 / Received revision: 6 April 1998 / Accepted: 13 April 1998 相似文献
11.
A color-variant strain of Aureobasidium pullulans (NRRL Y-12974) produced α-L-arabinofuranosidase (α-L-AFase) when grown in liquid culture on sugar beet arabinan, wheat arabinoxylan,
L-arabinose, L-arabitol, xylose, xylitol, oat spelt xylan, corn fiber, or arabinogalactan. L-Arabinose was most effective
for production of both whole-broth and extracellular α-L-AFase activity, followed by L-arabitol. Oat spelt xylan, sugar beet
arabinan, xylose, xylitol, and wheat arabinoxylan were intermediate in their ability to support α-L-AFase production. Lower
amounts of enzyme activity were detected in corn fiber- and arabinogalactan-grown cultures.
Received: 16 April 1998 / Accepted: 17 June 1998 相似文献
12.
K. P. Hebbar R. D. Lumsden S. M. Poch J. A. Lewis 《Applied microbiology and biotechnology》1997,48(6):714-719
Conditions for optimizing spore production, especially chlamydospores, by host-specific mycoherbicidal strains of Fusarium oxysporum causing vascular wilts in coca (Erythroxylum coca) and poppy (Papaver somniferum) were studied in 2.5-1 fermentors. The fermentor dissolved oxygen and pH had significant effects on the growth characteristics
of F. oxysporum strains. The effect of the fungal strain, however was not significant for most of the variables studied except for chlamydospore
formation. After 14 days of fermentation, the spore types produced were microconidia and chlamydospores, with very little
production of macroconidia. While the total viable counts were significantly higher under high than under low dissolved O2, the chlamydospore counts were significantly higher under low than under high dissolved O2. The percentage of chlamydospores obtained, as a proportion of total viable was significantly higher when the fermentor pH
was increased, than when it was not. Scaling-up the liquid fermentation to 20 l, yielded log10
c = 6.8 (where c = chlamydospores ml−1) after 14 days' fermentation, with biomass viable counts of log10
v∼8.0 (where v = viable counts g−1 air-dried biomass). A single-step liquid fermentation reported in this study increased chlamydospore yields and reduced the
time required for their production with techniques currently available from 5 weeks to less than 2 weeks.
Received: 24 April 1997 / Received revision: 6 August 1997 / Accepted: 29 August 1997 相似文献
13.
Cryopreservation of in vitro-grown shoot-tips of hop (Humulus lupulus L.) using encapsulation/dehydration 总被引:4,自引:0,他引:4
A cryopreservation procedure using encapsulation/dehydration was established for shoot-tips obtained from in vitro-grown shoots of hop. After dissection, shoot-tips were encapsulated in medium with alginate and 0.5 M sucrose. Optimal conditions consisted of preculture for 2 days in solid medium with 0.75 M sucrose, or in increasing sucrose concentrations, desiccation for 4 h with silicagel in a flow cabinet (16% water content)
followed by rapid freezing and slow thawing. Shoot recovery after freezing 60 min in liquid nitrogen was around 80%. No phenotypical
changes were observed in the recovered plants from cryopreserved shoot-tips growing in the field.
Received: 20 April 1997 / Revised: 20 February 1998 / Accepted: 1 Dezember 1998 相似文献
14.
I-Y Lee W T Seo G J Kim M K Kim C S Park Y H Park 《Journal of industrial microbiology & biotechnology》1997,18(4):255-259
Maltose and sucrose were efficient carbon sources for the production of curdlan by a strain of Agrobacterium sp. A two-step, fed-batch operation was designed in which biomass was first produced, followed by curdlan production which
was stimulated by nitrogen limitation. There exists an optimal timing for nitrogen limitation for curdlan production in the
two-step, fed-batch operation. Maximum curdlan production (60 g L−1) was obtained from sucrose with a productivity of 0.2 g L−1 h−1 when nitrogen was limited at a cell concentration of 16.0 g L−1. It was also noted that the curdlan yield from sucrose was as high as 0.45 g curdlan g−1 sucrose, and the highest specific production rate was 1.0 g curdlan g−1 cells h−1 right after nitrogen limitation. Of particular importance was the use of molasses as a cheap carbon source to produce curdlan
in the two-step, fed-batch cultivation. As high as 42 g L−1 of curdlan with a yield of 0.35 g curdlan g−1 total sugar was obtained after 120 h of fed-batch cultivation.
Received 20 August 1996/ Accepted in revised form 26 November 1996 相似文献
15.
S. Nakotte S. Schaffer M. Böhringer P. Dürre 《Applied microbiology and biotechnology》1998,50(5):564-567
Procedures have been developed allowing recombinant DNA work with Clostridium acetobutylicum DSM 792. Electroporation was used to introduce plasmid DNA into exponentially growing clostridial cells and 6 × 102 transformants/μg DNA could be obtained at a time constant of 5.5 ms, 1.8 kV, 50 μF, and 600 Ω. The method also allowed the
taxonomic group IV strain NI-4082 to be transformed (101 transformants/μg DNA). Plasmid preparation from recombinant clostridia was optimal when a modification of the alkaline lysis
method was employed. It was also important to use cells from the mid-logarithmic growth phase. Recombinant strains could be
easily preserved as spore suspensions; under all conditions tested plasmids were maintained.
Received: 17 March 1998 / Received revision: 17 August 1998 / Accepted: 26 August 1998 相似文献
16.
T. Potrawfke T.-H. Löhnert K. N. Timmis R.-M. Wittich 《Applied microbiology and biotechnology》1998,50(4):440-446
The biphenyl-mineralizing bacterium Burkholderia sp. strain LB400 also utilized 3-chloro-, 4-chloro-, 2,3′-dichloro- and 2,4′-dichlorobiphenyl for growth. By the attack of the initial enzyme a chlorine was eliminated dioxygenolytically
from position 2 of one of the aromatic rings when hydrogens of both were substituted by chlorine. The strain mineralized 3-chloro-
and 2,3′-dichlorobiphenyl via the central intermediate 3-chlorobenzoate through its chlorocatechol pathway enzymes, but excreted
stoichiometric amounts of 4-chlorobenzoate from 4-chloro- and 2,4′-dichlorobiphenyl. These two compounds were mineralized by a co-culture of strain LB400 and a derivative of the (methyl-)
benzoate-degrading strain Pseudomonas putida mt-2 (TOL). The complete degradation was achieved upon transfer of a cluster of at least five genes, encoding the regulated
chlorocatechol pathway operon, from strain LB400 to strain mt-2. This transfer was demonstrated by the polymerase chain reaction.
Received: 15 April 1998 / Received revision: 12 June 1998 / Accepted: 19 June 1998 相似文献
17.
Chu-Ting Liu I-Ting Hsu Cheng-Chun Chou Pei-Ren Lo Roch-Chui Yu 《World journal of microbiology & biotechnology》2009,25(5):883-890
In the present study, the production of exopolysaccharides (EPS) by 13 strains of Lactobacillus and 6 strains of Bifidobacterium in a chemical defined medium (CDM) supplemented with 30 g lactose/l was first compared. The highest EPS production of the
Lactobacillus strains was found in L. salivarius BCRC 14759 while among the Bifidobacterium strains examined, B. bifidum BCRC 14615 showed the highest EPS production. Analyzes of the effect of lactose concentration and cultivation temperature
on EPS production revealed that L. salivarius produced the highest amount of EPS (45.3 mg/l) in CDM supplemented with 5 g lactose/l at 40°C while B. bifidum produced the highest EPS (17.0 mg/l) in CDM supplemented with 40 g lactose/l at 35°C. α-Phosphoglucomutase, UDP-glucose pyrophosphorylase
and UDP-galactose-4-epimerase exhibited a markedly notable activity compared with other enzymes examined in the cell extract
of both test organisms. This indicates their possible involvement in the biosynthesis of EPS. 相似文献
18.
Strains of the fission yeast Schizosaccharomyces pombe have been constructed containing single or multiple chromosomally integrated copies of an expression cassette for production
of human gastric lipase. Integrant strains of S. pombe secrete active lipase and are stable for lipase production over a minimum of 50 generations in non-selective media. Lipase
activity levels for integrant strains containing up to three tandem copies of the expression cassette are strongly correlated
with copy number of the cassette in both complete and minimal media. Lipase activity is higher in complete medium than in
minimal medium. Strains carrying three chromosomally integrated expression cassette copies can be grown without selection
in complete medium and are capable of significantly higher lipase activities than strains containing the expression cassette
on a multicopy plasmid.
Received: 27 March 1997 / Received revision: 13 August 1997 / Accepted: 25 August 1997 相似文献
19.
This is the first report describing the gene structure and the enzymatic properties of a β-fructosidase of a hyperthermophilic
organism. The bfrA gene of the ancestral bacterium Thermotoga maritima MSB8 codes for a 432-residue, polypeptide of about 50 kDa, with significant sequence similarity to other β-fructosidases.
On the basis of its primary structure, BfrA can be assigned to glycosyl hydrolase family 32. The bfrA gene was expressed in Escherichia coli and the recombinant enzyme was purified and characterised. BfrA was specific for the fructose moiety and the β-anomeric configuration
of the glycosidic linkages of its substrates. The enzyme released fructose from sucrose and raffinose, and the fructose polymer
inulin was hydrolysed quantitatively in an exo-type fashion. BfrA displayed similar catalytic efficiencies for the hydrolysis
of sucrose and inulin with k
cat/K
m values (at 75 °C, pH 5.5) of about 4.1 × 104 M−1s−1 and 3.1 × 104 M−1s−1 respectively. BfrA had an optimum temperature of 90–95 °C (10-min assay) and was extremely insensitive to thermo-inactivation.
During 5 h at temperatures up to 80 °C at pH 7, the enzyme retained at least 85% of its initial activity. Thus, BfrA is the
most thermostable β-fructosidase and also the most thermostable inulinase described to date. In conclusion, the T. maritima enzyme can be classified as an exo-β-d-fructofuranosidase (EC 3.2.1.26) with invertase and inulinase activity. Its catalytic properties along with the extreme thermostability
recommend it for use in biotechnology.
Received: 28 August 1997 / Received revision: 19 January 1998 / Accepted: 24 January 1998 相似文献
20.
An extracellular enzyme with glucose dehydrogenase activity was purified from liquid cultures of the basidiomycete Agaricus bisporus after growth with d-cellobiose or d-glucose as carbon source. The molecular mass was measured as 57 kDa by gel filtration and 55 kDa by sodiumdodecyl sulphate/polyacrylamide
gel electrophoresis, while the isoelectric point was at pH 3.6. By analysis of 1H-NMR spectra in D2O, the product of d-glucose oxidation was identified as 3-ketoglucose. The substrates oxidized included d-cellobiose, l-arabinose, d-xylose and sucrose, but the specificity parameter (k
cat/K
m) was highest for d-glucose. Two electron acceptors were identified, namely 2,6-dichloroindophenol and p-benzoquinone, but reduction of dioxygen, ferricyanide or cytochrome c was not detectable. The selective C-3 oxidation of d-glucose is well-characterized for Agrobacterium and Flavobacterium, but this is the first report for a fungus.
Received: 19 June 1998 / Received revision: 15 September 1998 / Accepted: 17 September 1998 相似文献