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1.
Acetobacter aceti have been grown on ethanol under inhibitory conditions created by high concentrations of phenol. A defined medium with no
vitamin or amino acid supplements has been used such that ethanol was the sole carbon substrate. The culture temperature was
maintained at 30 °C while the pH was manually controlled to fall within the range 4.5–6.0 during ethanol consumption. Growth
on ethanol at a few thousand milligrams per litre (below the known inhibitory level) resulted in a maximum specific growth
rate of 0.16 h−1 with a 95% yield of acetic acid, followed immediately by acetic acid consumption at a growth rate of 0.037 h−1. Phenol was found to inhibit growth by decreasing both the specific growth rate and the biomass yield during ethanol consumption.
On the other hand, the yield of acetic acid during ethanol consumption and the yield of biomass during acetic acid consumption
remained constant, independent of phenol inhibition. A model is presented and is shown to represent the phenol-inhibited growth
behaviour of A. aceti during both ethanol and acetic acid consumption.
Received: 6 November 1998 / Received revision: 8 February 1999 / Accepted: 12 February 1999 相似文献
2.
In order to measure the substrate-oxidizing activity of intact cells of Acetobacter pasteurianus no. 2, a given amount of the bacterial cells was immobilized on a carbon-paste electrode, and the current at the electrode
was measured in a buffer solution. When Fe(CN)3−
6 was added to the buffer solution, an anodic current was observed at 0.5 V (against Ag/AgCl). Further, when ethanol was added
to the solution, the current started to increase to reach a steady-state within 3 min. The electrode had a good response to
acetaldehyde and lactic acid as well as ethanol. Culture conditions affected the current response to various substances; the
response of the electrode modified with the cells grown in static culture was much higher than that of the electrode with
the cells grown in shaking culture, and the electrode with ethanol-grown cells had a high response to ethanol and acetaldehyde
compared with that of the electrode with glucose-grown cells. The increase in the amount of the current after the addition
of ethanol (ΔI
EtOH) was linearly proportional to the total number of immobilized cells per electrode in the range 1.0 × 104–1.0 × 108 cells. The ΔI
EtOH values were measured with the electrode prepared with a fixed volume of the cell suspensions taken from the culture at 6-h
intervals; the dependence of the ΔI
EtOH value on time agreed well with the cell growth measured by colony counting and turbidity in the lag and logarithmic phase.
After the logarithmic phase, the value of ΔI
EtOH sharply decreased, resembling to the growth measured by colony counting, rather than by turbidity.
Received: 30 October 1998 / Received revision: 2 February 1999 / Accepted: 5 February 1999 相似文献
3.
S. Flahaut Abdellah Benachour Jean-Christophe Giard Philippe Boutibonnes Yanick Auffray 《Archives of microbiology》1996,165(5):317-324
Enterococcus faecalis was strongly resistant to high osmotic pressure in complex medium; however, when it was subjected to a moderate osmotic stress
[6.5% (w/v) NaCl or 52% (w/v) sucrose] for 2 h, it showed cross-protection against ethanol (22%), detergents stresses [bile
salts (0.3%) and SDS (0.017%)], hydrogen peroxide challenge (45 mM), and to a minor extent against lethal temperature (62° C).
In response to salt stress [6.5% (w/v) NaCl], E. faecalis induced a large number of stress proteins. In addition, NaCl strongly induced the synthesis of many proteins more than tenfold.
Although the acquired thermotolerance was inhibited markedly by chloramphenicol, the other NaCl-induced cross-tolerances seemed
not to be correlated with de novo protein synthesis. The relationship between the stress protein synthesis and the induction
of different types of cross-protection is discussed.
Received: 7 September 1995 / Accepted: 29 January 1996 相似文献
4.
G.-J. Shen J.-S. Shieh A. J. Grethlein M. K. Jain J. G. Zeikus 《Applied microbiology and biotechnology》1999,51(6):827-832
The biochemical mechanisms for growth tolerance to a 100% CO headspace in cultures, and butanol plus ethanol production from
CO by Butyribacterium methylotrophicum were assessed in the wild-type and CO-adapted strains. The CO-adapted strain grew on glucose or CO under a 100% CO headspace,
whereas, the growth of the wild-type strain was severely inhibited by 100% CO. The CO-adapted strain, unlike the wild-type,
also produced butyrate, from either pyruvate or CO. The CO-adapted strain was a metabolic mutant having higher levels of ferredoxin–NAD
oxidoreductase activity, which was not inhibited by NADH. Consequently, only the CO-adapted strain can grow on CO because
CO oxidation generates reduced ferredoxin which, via the mutated ferredoxin–NAD reductase activity, forms reduced NADH required
for catabolism. When the CO-adapted strain was grown at pH 6.0 it produced butanol (0.33 g/l) and ethanol (0.5 g/l) from CO
and the cells contained the following NAD-linked enzyme activities (μmol min−1 mg protein−1): butyraldehyde dehydrogenase (227), butanol dehydrogenase (686), acetaldehyde dehydrogenase (82) and ethanol dehydrogenase
(129).
Received: 15 September 1998 / Received revision: 12 February 1999 / Accepted: 19 February 1999 相似文献
5.
Pyrophosphate is a source of phosphoryl groups for Escherichia coli protein phosphorylation 总被引:1,自引:0,他引:1
Bertrand Duclos Elisabeth Vaganay Mustapha Dadssi Alain J. Cozzone 《FEMS microbiology letters》1996,145(1):49-54
Abstract Stress tolerance and cross-protection in Enterococcus faecalis ATCC19433 were examined after exposure to bile salts, acid or heat shock. Bile salts and heat adapted cells demonstrated induced homologous tolerance and cross-resistance. No cross-protection of heat adapted cells against acid stress is observed and pretreatment with bile salts even sensitized the cells to this challenge. Whole-cell protein extract analysis revealed that each treatment induced a battery of stress proteins. Some of these polypeptides are induced by more than one treatment. The greatest overlap is observed between bile salts and heat treatments. Eighteen stress proteins, including DnaK and GroEL, are common between these stresses. 相似文献
6.
Industrial 20-m3-scale and laboratory-scale aerobic fed-batch processes with Escherichia coli were compared. In the large-scale process the observed overall biomass yield was reduced by 12% at a cell density of 33 g/l
and formate accumulated to 50 mg/l during the later constant-feeding stage of the process. Though the dissolved oxygen signal
did not show any oxygen limitation, it is proposed that the lowered yield and the formate accumulation are caused by mixed-acid
fermentation in local zones where a high glucose concentration induced oxygen limitation. The hypothesis was further investigated
in a scale-down reactor with a controlled oxygen-limitation compartment. In this scale-down reactor similar results were obtained:
i.e. an observed yield lowered by 12% and formate accumulation to 238 mg/l. The dynamics of glucose uptake and mixed-acid
product formation (acetate, formate, d-lactate, succinate and ethanol) were investigated within the 54 s of passage time through the oxygen-limited compartment.
Of these, all except succinate and ethanol were formed; however, the products were re-assimilated in the oxygen-sufficient
reactor compartment. Formate was less readily assimilated, which accounts for its accumulation. The total volume of the induced-oxygen-limited
zones was estimated to be 10% of the whole liquid volume in the large bioreactor. It is also suggested that repeated excretion
and re-assimilation of mixed-acid products contribute to the reduced yield during scale-up and that formate analysis is useful
for detecting local oxygen deficiency in large-scale E. coli processes.
Received: 7 November 1998 / Received revision: 4 February 1999 / Accepted: 5 February 1999 相似文献
7.
Microorganisms used in food technology and probiotics are exposed to technological and digestive stresses, respectively. Traditionally used as Swiss-type cheese starters, propionibacteria also constitute promising human probiotics. Stress tolerance and cross-protection in Propionibacterium freudenreichii were thus examined after exposure to heat, acid, or bile salts stresses. Adapted cells demonstrated acquired homologous tolerance. Cross-protection between bile salts and heat adaptation was demonstrated. By contrast, bile salts pretreatment sensitized cells to acid challenge and vice versa. Surprisingly, heat and acid responses did not present significant cross-protection in P. freudenreichii. During adaptations, important changes in cellular protein synthesis were observed using two-dimensional electrophoresis. While global protein synthesis decreased, several proteins were overexpressed during stress adaptations. Thirty-four proteins were induced by acid pretreatment, 34 by bile salts pretreatment, and 26 by heat pretreatment. Six proteins are common to all stresses and represent general stress-response components. Among these polypeptides, general stress chaperones, and proteins involved in energetic metabolism, oxidative stress response, or SOS response were identified. These results bring new insight into the tolerance of P. freudenreichii to heat, acid, and bile salts, and should be taken into consideration in the development of probiotic preparations. 相似文献
8.
The esterification reaction between stearic acid and lactic acid using Rhizomucor miehei lipase and porcine pancreas lipase was optimized for maximum esterification using response surface methodology. The formation
of the ester was found to depend on three parameters namely enzyme/substrate ratio, lactic acid (stearic acid) concentration
and incubation period. The maximum esterification predicted by theoretical equations for both lipases matched well with the
observed experimental values. In the case of R. miehei lipase, stearoyl lactic acid ester formation was found to increase with incubation period and lactic acid (stearic acid)
concentrations with maximum esterification of 26.9% at an enzyme/substrate (E/S) ratio of 125 g mol−1. In the case of porcine pancreas lipase, esterification showed a steady increase with increase in incubation period and lactic
acid (stearic acid) concentration independent of the E/S ratios employed. In the case of PPL, a maximum esterification of
18.9% was observed at an E/S ratio of 25 g mol−1 at a lactic acid (stearic acid) concentration of 0.09 M after an incubation period of 72 h.
Received: 12 February 1999 / Received revision: 31 May 1999 / Accepted: 4 June 1999 相似文献
9.
10.
Pseudomonas sp. DJ-12 cells were subjected to mild treatments of stress such as exposure to biphenyl, 4-chlorobiphenyl (4CB), 4-hydroxybenzoate
(4HBA), ethanol, and heat, and then were examined for production of stress-shock proteins and morphological changes. The adapted
cells were then subjected to lethal stress conditions such as 200 mm 4CB, 100 mm biphenyl, 10 mm 4HBA, 20% ethanol, and 46°C
to examine crossly protective responses to the stresses. Several stress-shock proteins including DnaK and GroEL were newly
synthesized in the adapted cells. Some of them were commonly produced by those stresses separately treated. The cells treated
with these aromatic hydrocarbons showed destructive openings on the cell envelopes. On the other hand, those cells treated
with ethanol or heat displayed irregular rod shapes with wrinkled surfaces. The adapted cells to each stress under sublethal
conditions exhibited increased resistance to the same stress of lethal conditions. The cells adapted with 5 mm 4HBA showed
greater protection for survival than those adapted by other stresses. In addition, those adapted cells showed increased resistance
to other stresses as a cross-protection phenomenon. The cells adapted to 42°C exhibited markedly increased resistance to the
lethal stresses of 46°C as well as to 20% ethanol.
Received: 20 December 2000/Accepted: 26 January 2001 相似文献
11.
Kajiwara S Aritomi T Suga K Ohtaguchi K Kobayashi O 《Applied microbiology and biotechnology》2000,53(5):568-574
The fermentation characteristics of Saccharomyces cerevisiae strains which overexpress a constitutive OLE1 gene were studied to clarify the relationship between the fatty acid composition of this yeast and its ethanol productivity.
The growth yield and ethanol productivity of these strains in the medium containing 15% dextrose at 10 °C were greater than
those of the control strains under both aerobic and anaerobic conditions but this difference was not observed under other
culture conditions. During repeated-batch fermentation, moreover, the growth yield and ethanol productivity of the wild-type
S. cerevisiae increased gradually and then were similar to those of the OLE1-overexpressing transformant in the last batch fermentation. However, the unsaturated fatty acid content (77.6%) of the wild-type
cells was lower than that (86.2%) of the OLE1-recombinant cells. These results suggested that other phenomena caused by the overexpression of the OLE1 gene, rather than high unsaturated fatty acid content, are essential to ethanol fermentation by this yeast.
Received: 11 June 1999 / Received last revision: 12 November 1999 / Accepted: 28 November 1999 相似文献
12.
V. Gorenflo A. Steinbüchel S. Marose M. Rieseberg T. Scheper 《Applied microbiology and biotechnology》1999,51(6):765-772
The fluorescence properties of one chemically and seven biologically produced polyhydroxyalkanoic acids were investigated
as film castings and in living cells respectively after staining with Nile red. All these polyesters show a similar fluorescence
behaviour, revealing a clear fluorescence maximum at an excitation wavelength between 540 nm and 560 nm and an emission wavelength
between 570 nm and 605 nm. This could be shown by the use of two-dimensional fluorescence spectroscopy and flow cytometry.
The examination of native poly(3-hydroxybutyric acid), poly(3HB), granules isolated from cells of Ralstonia eutropha H16 showed that the addition of 6.0 μg Nile red is necessary for total staining of 1.0 mg granules. The fluorescence intensity
at an excitation wavelength of 550 nm and an emission wavelength of 600 nm showed high correlation to the poly(3HB) concentration
of grana suspensions at different grana concentrations. These results and the staining of cell suspensions during cultivation
experiments revealed that Nile red has a high potential for the quantitative determination of hydrophobic bacterial polyhydroxyalkanoic
acids.
Received: 13 November 1998 / Received revision: 4 February 1999 / Accepted: 12 February 1999 相似文献
13.
A heat shock following electroporation induces highly efficient transformation of Corynebacterium glutamicum with xenogeneic plasmid DNA 总被引:10,自引:0,他引:10
An improved method for the electrotransformation of wild-type Corynebacterium glutamicum (ATCC 13032) is described. The two crucial alterations to previously developed methods are: cultivation of cells used for
electrotransformation at 18 °C instead of 30 °C, and application of a heat shock immediately following electrotransformation.
Cells cultivated at sub optimal temperature have a 100-fold improved transformation efficiency (108 cfu μg−1) for syngeneic DNA (DNA isolated from the same species). A heat shock applied to these cells following electroporation improved
the transformation efficiency for xenogeneic DNA (DNA isolated from a different species). In combination, low cultivation
temperature and heat shock act synergistically and increased the transformation efficiency by four orders of magnitude to
2.5 × 106 cfu μg−1 xenogeneic DNA. The method was used to generate gene disruptions in C. glutamicum.
Received: 26 March 1999 / Received revision: 9 June 1999 / Accepted: 11 June 1999 相似文献
14.
Fernández MJ Adrio JL Piret JM Wolfe S Ro S Demain AL 《Applied microbiology and biotechnology》1999,52(4):484-488
Growth of Streptomyces clavuligerus NP1 in the presence of methanol or ethanol resulted in a marked increase in production of cephalosporin(s) from penicillin
G by resting cells. The mycelium produced in alcohol-supplemented medium was fragmented and dispersed as compared with growth
in control medium. HPLC analysis showed that at least two products were present in the biotransformation supernatant fluid
after 1 h incubation. One of them has been identified as deacetoxycephalosporin G (DAOG).
Received: 9 December 1998 / Received revision: 29 March 1999 / Accepted: 16 April 1999 相似文献
15.
Chernyavskaya OG Shishkanova NV Il'chenko AP Finogenova TV 《Applied microbiology and biotechnology》2000,53(2):152-158
The ability of yeast to synthesize α-ketoglutaric acid (KGA) from ethanol has been studied. Thiamine-auxotrophic yeasts of
different genera and species may be able to produce KGA; the main condition of synthesis is growth limitation by thiamine.
Using a model culture, mutant Yarrowia lipolytica N 1, the principal conditions affecting KGA oversynthesis were identified. These were: thiamine concentration in medium and
in cells, nitrogen and oxygen concentration in medium, and pH level. A KGA concentration of 49 g/l and a yield from ethanol
consumed of 42% were achieved. Based on the results of the analysis of the activities of the key enzymes participating in
ethanol metabolism and KGA synthesis, a concept of the mechanism of KGA biosynthesis by Y. lipolytica yeast is suggested and discussed.
Received: 1 March 1999 / Received revision: 28 June 1999 / Accepted: 5 June 1999 相似文献
16.
P. Schmitt C. Vasseur V. Phalip D. Q. Huang C. Diviès H. Prévost 《Applied microbiology and biotechnology》1997,47(6):715-718
The co-metabolism of citrate plus xylose by Leuconostoc mesenteroides subsp. mesenteroides results in a growth stimulation, an increase in d-lactate and acetate production and repression of ethanol production. This correlated well with the levels of key enzymes
involved. A partial repression of alcohol dehydrogenase and a marked stimulation of acetate kinase were observed. High citrate
bioconversion yields in diacetyl plus acetoin were obtained at pH 5.2 in batch (11.5%) or in chemostat (up to 17.4%) culture.
In contrast, no diacetyl or acetoin was detected in citrate plus glucose fermentation.
Received: 6 December 1996 / Received revision: 14 February 1997 / Accepted: 14 February 1997 相似文献
17.
A continuously growing callus was obtained from immature endosperm of Morus alba L Cv S-36 cultured on Murashige and Skoog medium containing 5 μm 2,4-dichlorophenoxyacetic acid. Shoot buds were produced
when the callus was subcultured on a medium containing a cytokinin or a cytokinin and 1-naphthaleneacetic acid (NAA). The
maximum number of shoots was formed on the medium containing thidiazuron (1 μM), or benzylaminopurine (5 μM) and NAA (1 μM).
Shoots were multiplied by forced axillary branching and rooted in vitro. Endosperm-derived plants were established in soil.
Each of the ten plants examined cytologically was triploid (3 n=42).
Received:17 February 1999 / Revision received: 4 May 1999 / Accepted: 19 May 1999 相似文献
18.
P. Wahl P. Walser-Volken K. Laumen M. Kittelmann O. Ghisalba 《Applied microbiology and biotechnology》1999,53(1):12-18
Rhodococcus globerulus K1/1 was found to express an inducible (S)-specific N-acetyl-2-amino-1-phenyl-4-pentene amidohydrolase. Optimal bacterial growth and amidohydrolase expression were both observed
at about pH 6.5. Purification of the enzyme to a single band in a Coomassie blue-stained SDS-PAGE gel was achieved by nucleic
acid and ammonium sulfate precipitation of Rhodococcus globerulus K1/1 crude extract and column chromatography on TSK Butyl-650(S) Fractogel and Superose 12HR. The amidohydrolase was purified to a homogeneity leading to a tenfold increase of the specific
activity with a recovery rate of 65%. At pH 7.0 and 23 °C the enzyme showed no loss of activity after 30 days incubation.
The amidohydrolase was stable up to 55 °C. The enzyme was inhibited strongly only by 10 mM Zn2+ among the tested metal cations and was inhibited 100% by 0.01 mM phenylmethanesulfonyl fluoride. The molecular weight of
the native enzyme was estimated to be 92 kDa by gel filtration and 55 kDa by SDS-PAGE, suggesting a homodimeric structure.
Received: 8 February 1999 / Received revision: 3 May 1999 / Accepted: 7 May 1999 相似文献
19.
Two protein bands with strong esterase activity are present in broths of Nocardia lactamdurans MA4213 cultures. One of them shows cephalosporin C acetylhydrolase (CAH) activity. This activity is maximal at 48 h of growth
and shows a pattern of regulation slightly different from that of cephamycin production in medium supplemented with glucose
(166 mM), glycerol (326 mM) or ammonium chloride (60 mM). The CAH activity was purified to homogeneity by DEAE-Sepharose ion-exchange,
Sephadex G-75 gel filtration, and phenyl-Sepharose hydrophobic interaction chromatography. It showed a molecular mass of 72,100 Da.
The N-terminus of the protein was determined and showed the amino acid sequence GGAAPGGPGAHPLWLPAGKD. The enzyme showed K
m values of 7.0 mM and 8.3 mM for cephalosporin C and 7-aminocephalosporanic acid respectively but was not active on cephamycin
C.
Received: 17 December 1999 / Received revision: 22 February 2000 / Accepted: 25 February 2000 相似文献
20.
Riondet C Cachon R Waché Y Sunyol i Bert E Gbaguidi P Alcaraz G Diviès C 《Applied microbiology and biotechnology》2000,53(4):476-479
The combined effect of redox potential (RP) (from −200 to 500 mV) and pH (from 5.0 to 7.0) on the heat resistance and growth
recovery after heat treatment of Escherichia coli was tested. The effect of RP on heat resistance was very different depending on the pH. At pH 6.0, there was no significant
difference, whereas at pH 5.0 and 7.0 maximum resistance was found in oxidizing conditions while it fell in reducing ones.
In sublethally heat-damaged cells, low reducing and acid conditions allowed growth ability to be rapidly regained, but a decrease
in the redox potential and pH brought about a longer lag phase and a slower exponential growth rate, and even led to growth
failure (pH 5.0, ≤−100 mV).
Received: 28 June 1999 / Received revision: 22 October 1999 / Accepted: 22 October 1999 相似文献