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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.
The effects of different phenolic compound concentrations on the fatty acid composition of Lactobacillus plantarum isolated from traditional home-made olive brines were determined. Increasing amounts of caffeic and ferulic acids induced
a gradual increase in the amounts of myristic, palmitoleic, stearic and 9,10-methylenehexadecanoic (C17Δ, where Δ represents
the cyclopropane group) acid with a concomitant decrease of lactobacillic acid (C19Δ). On the other hand, the addition of tannins induced an increase in the C19Δ level at the expense of vaccenic acid content. The presence of acidic phenols and tannins also affected bacterial growth,
inducing the most obvious effect with tannin at 1 g l−1.
Received: 1 July 1997 / Received revision: 9 September 1997 / Accepted: 15 September 1997 相似文献
3.
H. Okada T. Sekiya K. Yokoyama H. Tohda H. Kumagai Y. Morikawa 《Applied microbiology and biotechnology》1998,49(3):301-308
A cbh2 cDNA encoding Trichoderma reesei QM9414 cellobiohydrolase II, located on the expression vector whose copy number is controlled by the level of gentamicin,
was successfully expressed under the control of a human cytomegalovirus promoter in the fission yeast, Schizosaccharomyces pombe. The 24-amino-acid leader peptide of the cbh2 gene was recognized by the yeast, enabling the efficient secretion of the heterologous cellobiohydrolase. The transformed
S. pombe strain produced over 115 μg cellobiohydrolase proteins/ml rich medium supplemented with malt extract and 100 μg/ml gentamicin.
The molecular masses of the recombinant cellobiohydrolases, secreted as two molecular species, were estimated to be 70 kDa
and 72 kDa by sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE). Deglycosylation treatments revealed that
the recombinant enzymes were overglycosylated and scarcely susceptible to α-mannosidase. The recombinant enzymes showed no
carboxymethylcellulase activity, but showed similar characteristics to those of a native enzyme purified from T. reesei in their optimum pH and temperature, pH and temperature stabilities, and V
max values toward phosphoric-acid-swollen cellulose as substrate, except that their K
m values were about fourfold higher than that of the native enzyme.
Received: 4 August 1997 / Received revision: 13 October 1997 / Accepted: 31 October 1997 相似文献
4.
Production of flavour compounds by yogurt starter cultures 总被引:5,自引:0,他引:5
D Beshkova E Simova G Frengova Z Simov 《Journal of industrial microbiology & biotechnology》1998,20(3-4):180-186
The present work studied the production of carbonyl compounds and saturated volatile free fatty acids by pure cultures of
Streptococcus thermophilus and Lactobacillus bulgaricus, and by starter cultures for Bulgarian yogurt during cultivation and cooling. The mixed cultures formed volatile aromatic
compounds more actively than the pure cultures. A guiding factor in the preparation of the starter cultures was the biochemical
activity of Lactobacillus bulgaricus in synthesizing the major carbonyl compounds, acetaldehyde, diacetyl and the volatile fatty acids C2–C10. The activity of the yogurt cultures in synthesizing carbonyl compounds was at its highest during milk coagulation and cooling,
up to 7 h. However, maximum concentration was reached by 22–31 h. In the cooled 22–h starter cultures, acetaldehyde predominated
(1415.0–1734.2 μg per 100 g) followed by diacetyl (165.0–202.0 μg per 100 g), acetoin (170.0–221.0 μg per 100 g), acetone
(66.0–75.5 μg per 100 g), ethanol (58.0 μg per 100 g), and butanone-2 (3.6–3.8 μg per 100 g). The thermophilic streptococcus
and lactobacillus cultures, and the starter cultures contained predominantly acetic, butyric and caproic acids.
Received 19 June 1997/ Accepted in revised form 10 January 1998 相似文献
5.
High-cell-density cultivations of Escherichia coli K12 in a dialysis reactor with controlled levels of dissolved oxygen were carried out with different carbon sources: glucose
and glycerol. Extremely high cell concentrations of 190 g/l and 180 g/l dry cell weight were obtained in glucose medium and
in glycerol medium respectively. Different behaviour was observed in the formation of acetic acid in these cultivations. In
glucose medium, acetic acid was formed during the earlier phase of cultivation. However, in glycerol medium, acetic acid formation
started later and was particularly rapid at the end of the cultivation. In order to estimate the influence of acetic acid
during these high-cell-density cultivations, the inhibitory effect of acetic acid on cell growth was investigated under different
culture conditions. It was found that the inhibition of cell growth by acetic acid in the fermentor was much less than that
in a shaker culture. On the basis of the results obtained in these investigations of the inhibitory effect of acetic acid,
and the mathematical predictions of cell growth in a dialysis reactor, the influence of acetic acid on high-cell-density cultivation
is discussed.
Received: 20 May 1997 / Received revision: 12 August 1997 / Accepted: 25 August 1997 相似文献
6.
Production of high yields of arachidonic acid in a fed-batch system by Mortierella alpina ATCC 32222
Of six strains of Mortierella tested, Mortierella alpina ATCC 32222 produced the highest yields of arachidonic acid. Supplementation of soy flour (1% w/v) and vegetable oils (1%
v/v) significantly increased the biomass, lipid content and arachidonic acid level. Replacement of NaNO3 with corn steep liquor (1% w/v) also improved arachidonic acid production. A fed-batch culture system at 25 °C, producing
a high biomass (52.4 g/l) and arachidonic acid content (9.1 g/l) in 8␣days, was developed. A fed-batch system at low temperature
(15 °C) gave even higher arachidonic acid levels (11.1 g/l) in 11 days.
Received: 28 October 1996 / Received revision: 3 March 1997 / Accepted: 7 March 1997 相似文献
7.
Although acetate formation and tolerance are important criteria for various aspects of biotechnological process development,
available studies on acetate tolerance in different species are disparate. We evaluate the response of eight bacterial strains,
including two variants of Escherichia coli, two variants of Staphylococcus capitis, and one each of Acetobacter aceti, Gluconobacter suboxydans, Lactobacillus acetotolerans, and L. bulgaricus, to acetate challenges under identical conditions. Our findings were: (1) wild-type organisms of species that are considered
tolerant of acetate perform only slightly better than E. coli in unadapted shaker cultures; (2) the ability to tolerate acetate is strongly dependent on the carbon source, and is, especially
for E. coli, much greater on glycerol than on glucose; (3) respiration is not as important to acetate tolerance in E. coli and S. capitis as has been reported for the acetic acid bacteria; (4) S. capitis was the least affected by acetate under all conditions and grew at up to 44 g/l acetate without any preconditioning; and
(5) qualitative high-throughput screening of growth characteristics can be achieved with relatively inexpensive multiwell
plate readers.
Received: 29 October 1999 / Received revision: 13 January 2000 / Accepted: 14 January 2000 相似文献
8.
I. K. P. Tan K. Sudesh Kumar M. Theanmalar S. N. Gan B. Gordon III. 《Applied microbiology and biotechnology》1997,47(3):207-211
The synthesis of polyhydroxyalkanoates (PHA) by Pseudomonas putida PGA1, using saponified palm kernel oil (SPKO), was investigated. The PHA produced from SPKO was compared with those produced
by the major free fatty acids found in the palm kernel oil. Owing to the absence of lipase activity in P.␣putida, palm kernel oil did not support cell growth. However, SPKO could support cell growth and produced relatively high yield of
both dry cells and PHA. The polyester produced was similar in properties to those derived from lauric (C12:0) and myristic (C14:0) acids, while oleic acid (C18:1) gave rise to PHA that was sticky and of broader molecular mass distribution. Nuclear magnetic resonance and gas chromatography
showed that these PHA were copolymers consisting mainly of n-alkanoate monomers ranging from C6 to C14, with C8 as the predominant component. PHA derived from SPKO and oleic acid also contained a small amount of unsaturated monomers.
Received: 25 March 1996 / Received last revision: 30 September 1996 / Accepted: 18 October 1996 相似文献
9.
Effects of ethanol concentration and stripping temperature on continuous fermentation rate 总被引:1,自引:0,他引:1
F. Taylor M. J. Kurantz N. Goldberg J. C. Craig Jr. 《Applied microbiology and biotechnology》1997,48(3):311-316
The operation of a pilot plant consisting of a 14-l fermentor, 10-cm packed column and condenser for continuous fermentation
and stripping of ethanol was stable for more than 100 days. The feed consisted of a non-sterile solution of 560 g/l glucose
with 100 g/l corn steep water. Fouling of the packing in the column with attached growth of yeast cells was controlled by
in situ washing at intervals of 3–6 days. A computer simulation of the pilot plant was developed and used to analyze the data.
The productivity of the continuous fermentor varied from 14 g ethanol to 17 g ethanol l−1 h−1. The yield was equal to the maximum theoretically possible: 0.51 g ethanol/g glucose consumed. Results are fit to linear
models for the effects of ethanol concentration on specific growth rate and cell yield, and for the effect of stripping temperature
on specific growth rate.
Received: 16 October 1996 / Received revision: 3 January 1997 / Accepted: 24 January 1997 相似文献
10.
A mixed culture of microorganisms able to utilize 4,6-dinitro-ortho-cresol (DNOC) as the sole source of carbon, nitrogen and energy was isolated from soil contaminated with pesticides and from
activated sludge. DNOC was decomposed aerobically in batch cultures as well as in fixed-bed column reactors. Between 65% and
84% of the substrate nitrogen was released as nitrate into the medium, and 61% of the carbon from uniformly 14C-labelled DNOC was recovered as 14CO2. The mixed microbial culture also decomposed 4-nitrophenol and 2,4-dinitrophenol but not 2,3-dinitrophenol, 2,6-dinitrophenol,
2,4-dinitrotoluene, 2,4-dinitrobenzoic acid or 2-sec-butyl-4,6-dinitrophenol (Dinoseb). Maximal degradation rates for DNOC by the bacterial biofilm immobilized on glass beads
in fixed-bed column reactors were 30 mmol day−1 (l reactor volume)−1, leaving an effluent concentration of less than 5 μg l−1 DNOC in the outflowing medium. The apparent K
s value of the immobilized mixed culture for DNOC was 17 μM. Degradation was inhibited at DNOC concentrations above 30 μM and
it ceased at 340 μM, possibly because of the uncoupling action of the nitroaromatic compound on the cellular energy-transducing
mechanism.
Received: 27 March 1997 / Received revision: 5 June 1997 / Accepted: 7 June 1997 相似文献
11.
Auxin and elicitors reportedly activate phospolipase A. A number of inhibitors known to inhibit animal phospholipase A2 were tested for their ability to inhibit hormone and fusicoccin-induced growth. To this end, growth induced by indolyl-3-acetic
acid and 2,4-dichlorophenoxyacetic acid in hypocotyl segments of etiolated zucchini (Cucurbita pepo L.) seedlings was determined in the presence of the inhibitors nordihydroguajaretic acid (NDGA), aristolochic acid, 5,8,11,14-eicosatetraynoic
acid (ETYA), PBx (a prostaglandin derivative), and oleylethyl phosphocholine. Each chemical proved inhibitory to auxin-induced growth, oleylethyl
phosphocholine being the least effective. The effects of the first three inhibitors were investigated in more detail. Growth
induced by 10 μM 2,4-dichlorophenoxyacetic acid or 1 μM indolyl-3-acetic acid was inhibited 50% by about 30–50 μM NDGA, by
about 25 μM aristolochic acid, and by about 10–20 μM EYTA. Growth inhibition was reversible and became apparent 0.5–1 h after
inhibitor addition. Growth induced by 0.5 or 1 μM fusicoccin was much less inhibited by NDGA and by ETYA, whereas aristolochic
acid was only slightly less effective on fusicoccin-induced than on auxin-induced growth. These three inhibitors were also
tested for their effects on gibberellin-induced growth in light-grown peas (Pisum sativum L.) and on cytokinin-induced expansion growth in excised cotyledons from radish (Raphanus sativum L.) seedlings. In both tests, aristolochic acid had toxic side-effects although gibberellin-induced growth was still apparent.
In the gibberellin test, neither NDGA at up to 100 μM nor ETYA at 80 μM was inhibitory to hormone-induced growth. Moreover,
40 μM ETYA was not inhibitory to kinetin-induced growth. We hypothesize that the selectivity of phospholipase A2 inhibitors for auxin-induced growth implies a different signal transduction pathway for each of the different signal substances
tested, and that auxins might use fatty acid(s) and/or lysophospholipid(s) or their derivatives as the preferred second messengers.
Received: 24 September 1996 / Accepted: 18 January 1997 相似文献
12.
Optimization of compactin fermentation 总被引:3,自引:0,他引:3
A Kónya A Jekkel J Sütő J Salát 《Journal of industrial microbiology & biotechnology》1998,20(3-4):150-152
A compactin producer Penicillium sp strain was isolated from soil in our screening program. The compactin-biosynthesising capacity of the strain was improved
from 5 μg ml−1 to 250 μg ml−1 by mutation-selection method. We investigated the effect of the medium composition on compactin productivity. A central,
orthogonal three-factor experimental design by Box and Wilson was used in the investigation. The results were analysed by
non-linear regression analysis. The composition of the production medium was optimized according to the calculated mathematical
model using the steepest ascent method. The compactin productivity was increased to 400 μg ml−1 by applying this method.
Received 08 October 1997/ Accepted in revised form 04 December 1997 相似文献
13.
Nutrient cost is an important aspect in the fermentation of biomass to ethanol. With a goal of developing a cost-effective
fermentation medium, several industrially available nutrient sources were evaluated for their effectiveness in the simultaneous
saccharification and fermentation of pretreated poplar with Saccharomyces cerevisiae D5A. These studies showed that a low-cost medium containing 0.3% corn steep liquor and 2.5 mM MgSO4 · 7H2O was similar in performance to a nutrient-rich medium. Besides its low cost, this alternative medium consists of components
that are available on a commercial scale, thereby making it industrially relevant.
Received: 14 August 1996 / Received revision: 7 January 1997 / Accepted: 24 January 1997 相似文献
14.
P. Becker I. Abu-Reesh S. Markossian G. Antranikian H. Märkl 《Applied microbiology and biotechnology》1997,48(2):184-190
A thermostable lipase was produced in continuous cultivation of a newly isolated thermophilic Bacillus sp. strain IHI-91 growing optimally at 65 °C. Lipase activity decreased with increasing dilution rate while lipase productivity
showed a maximum of 340 U l−1 h−1 at a dilution rate of 0.4 h−1. Lipase productivity was increased by 50% compared to data from batch fermentations. Up to 70% of the total lipase activity
measured was associated to cells and by-products or residual substrate. Kinetic and stoichiometric parameters for the utilisation
of olive oil were determined. The maximal biomass output method led to a saturation constant K
S of 0.88 g/l. Both batch growth data and a washout experiment yielded a maximal specific growth rate, μmax, of 1.0 h−1. Oxygen uptake rates of up to 2.9 g l−1h−1 were calculated and the yield coefficient, Y
X/O, was determined to be 0.29 g dry cell weight/g O2. From an overall material balance the yield coefficient, Y
X/S, was estimated to be 0.60 g dry cell weight/g olive oil.
Received: 8 January 1997 / Received revision: 30 April 1997 / Accepted: 4 May 1997 相似文献
15.
A. Arai S. Masuda A. Matsuyama S. Murakami M. Nakajima 《Applied microbiology and biotechnology》1998,49(3):272-276
The gene for the thermostable pyruvate kinase of Microbispora thermodiastatica IFO 14046, a moderate thermophilic actinomycete, was cloned in Escherichia coli. This gene consists of an open reading frame of 1422 nucleotides and encodes a protein of 474 amino acids with molecular
mass of 50 805 Da. The open reading frame was confirmed as the pyruvate kinase gene by comparison with the N-terminal amino
acid sequence of the purified pyruvate kinase from M. thermodiastatica.
Received: 19 May 1997 / Received last revision: 22 September 1997 / Accepted: 14 October 1997 相似文献
16.
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
17.
J. Gerritse G. Kloetstra A. Borger G. Dalstra A. Alphenaar J. C. Gottschal 《Applied microbiology and biotechnology》1997,48(4):553-562
Anaerobic tetrachloroethene(C2Cl4)-dechlorinating bacteria were enriched in slurries from chloroethene-contaminated soil. With methanol as electron donor,
C2Cl4 and trichloroethene (C2HCl3) were reductively dechlorinated to cis-1,2-dichloroethene (cis-C2H2Cl2), whereas, with l-lactate or formate, complete dechlorination of C2Cl4 via C2HCl3, cis-C2H2Cl2 and chloroethene (C2H3Cl) to ethene was obtained. In oxic soil slurries with methane as a substrate, complete co-metabolic degradation of cis-C2H2Cl2 was obtained, whereas C2HCl3 was partially degraded. With toluene or phenol both of the above were readily co-metabolized. Complete degradation of C2Cl4 was obtained in sequentially coupled anoxic and oxic chemostats, which were inoculated with the slurry enrichments. Apparent
steady states were obtained at various dilution rates (0.02–0.4 h−1) and influent C2Cl4-concentrations (100–1000 μM). In anoxic chemostats with a mixture␣of␣formate and glucose as the carbon and electron source,
C2Cl4 was transformed at high rates (above␣140 μmol l−1 h−1, corresponding to 145 nmol Cl− min−1 mg protein−1) into cis-C2H2Cl2 and C2H3Cl. Reductive dechlorination was not affected by addition of 5 mM sulphate, but strongly inhibited after addition of 5 mM
nitrate. Our results (high specific dechlorination rates and loss of dechlorination capacity in the absence of C2Cl4) suggest that C2Cl4-dechlorination in the anoxic chemostat was catalysed by specialized dechlorinating bacteria. The partially dechlorinated
intermediates, cis-C2H2Cl2 and C2H3Cl, were further degraded by aerobic phenol-metabolizing bacteria. The maximum capacity for chloroethene (the sum of tri-,
di- and monochloro derivatives removed) degradation in the oxic chemostat was 95 μmol l−1 h−1 (20 nmol min−1 mg protein−1), and that of the combined anoxic → oxic reactor system was 43.4 μmol l−1 h−1. This is significantly higher than reported thus far.
Received: 17 April 1997 / Received revision: 6 June 1997 / Accepted: 7 June 1997 相似文献
18.
A Saccharomyces-cerevisiae-based simultaneous saccharification and fermentation (SSF) of lignocellulosic biomass is limited to an operating temperature
of about 37 °C, and even a small increase in temperature can have a deleterious effect. This points to a need for a more thermotolerant
yeast. To this end, S. cerevisiae D5A and a thermotolerant yeast, Candida acidothermophilum, were tested at 37 °C, 40 °C, and 42 °C using dilute-acid-pretreated poplar as substrate. At 40 °C, C. acidothermophilum produced 80% of the theoretical ethanol yield, which was higher than the yield from S.cerevisiae D5A at either 37 °C or 40 °C. At 42 °C, C. acidothermophilum showed a slight drop in performance. On the basis of preliminary estimates, SSF with C. acidothermophilum at 40 °C can reduce cellulase costs by about 16%. Proportionately greater savings can be realized at higher temperatures
if such a high-temperature SSF is feasible. This demonstrates the advantage of using thermophilic or thermotolerant yeasts.
Received: 20 February 1997 / Received revision: 24 June 1997 / Accepted: 4 July 1997 相似文献
19.
The biodegradation of tributyl phosphate (Bu3-P, TBP), releasing phosphate at a high enough concentration locally to precipitate uranium from solution, was demonstrated
by a mixed culture consisting primarily of pseudomonads. The effect of various parameters on Bu3-P biodegradation by growing cells is described. Growth at the expense of Bu3-P as the carbon and phosphorus source occurred over a pH range from 6.5 to 8, and optimally at pH 7. Bu3-P biodegradation was optimal at 30 °C, reduced at 20 °C and negligible at 4 °C and 37 °C. Incorporation of Cu or Cd inhibited,
and Ni, Co and Mn reduced its degradation. Inorganic phosphate (above 10 mM) and kerosene (up to 1 g/l) reduced Bu3-P biodegradation significantly, but nitrate had no effect. Sulphate (10–100 mM) was inhibitory. When pregrown biomass was used
the fastest rates of tributyl and dibutyl phosphate biodegradation were 25 μmol h−1 mg protein−1 and 37 μmol h−1 mg protein−1 respectively. Microcarrier-immobilised biomass decontaminated uranium-bearing acid mine waste water by uranium phosphate
precipitation at the expense of Bu3-P hydrolysis in the presence of 35 mM SO4
2−. At pH 4.5, 79% of the UO2
2+ was removed at a flow rate of 1.4 ml/h on a 7-ml test column.
Received: 2 June 1997 / Received revision: 15 September 1997 / Accepted: 19 September 1997 相似文献
20.
Xanthomonas campestris pv. translucens IFO13599 could produce xanthan gum (18.5 mg/100 mg, lactose) with lactose as the growth substrate in spite of a low level
of β-galactosidase. This productivity corresponded to one-fifth that with glucose. This strain could also produce ice-nucleating
material having an ice-nucleating temperature, T
50, of −2.8 °C with xanthan gum in the culture broth. We found that this strain produced both materials in whey medium from
which the insoluble components had been removed. The production of xanthan with ice-nucleating material reached a maximum
after cultivation for 168 h under optimum conditions. Furthermore, the xanthan obtained had a low viscosity because of its
variant structure revealed, by TLC and HPLC analyses, to be lacking pyruvic acid. Furthermore, we concluded that this mixture
had considerable potential as a regeneratic agent, when compared to other regeneratic agents such as carboxymethylcellulose.
Received: 29 August 1997 / Received revision: 17 November 1997 / Accepted: 18 November 1997 相似文献