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1.
Torres R Ramón F de la Mata I Acebal C Castillón MP 《Applied microbiology and biotechnology》1999,53(1):81-84
At 28 °C, Streptomyces lavendulae produced high levels of penicillin V acylase (178 IU/l of culture) when grown on skim milk as the sole nutrient source for
275 h. The enzyme showed catabolite repression by glucose and was produced in the stationary phase of growth. Penicillin V
was a good inducer of penicillin V acylase formation, while phenoxyacetic acid, the side-chain moiety of penicillin V, did
not alter enzyme production significantly. The enzyme was stable between pH 6 and 11 and at temperatures from 20 °C to 55 °C.
This extracellular enzyme was able to hydrolyse natural penicillins and unable to hydrolyse penicillin G.
Received: 22 March 1999 / Received revision: 16 June 1999 / Accepted: 20 June 1999 相似文献
2.
K. Hofvendahl E. W. J. van Niel B. Hahn-Hägerdal 《Applied microbiology and biotechnology》1999,51(5):669-672
Lactococcus lactis ssp. lactis ATCC 19435 is known to produce mixed acids when grown on maltose. A change in fermentation conditions only, elevated temperatures
(up to 37 °C) and reduced pH values (down to 5.0) resulted in a shift towards homolactic product formation. This was accompanied
by decreased growth rate and cell yield. The results are discussed in terms of redox balance and maintenance, and the regulation
of lactate dehydrogenase and pyruvate formate-lyase.
Received: 14 December 1998 / Received revision: 12 January 1999 / Accepted: 22 January 1999 相似文献
3.
Influence of complex nutrients, temperature and pH on bacteriocin production by Lactobacillus sakei CCUG 42687 总被引:1,自引:0,他引:1
Aasen IM Møretrø T Katla T Axelsson L Storrø I 《Applied microbiology and biotechnology》2000,53(2):159-166
The effects of process conditions and growth kinetics on the production of the bacteriocin sakacin P by Lactobacillus sakei CCUG 42687 have been studied in pH-controlled fermentations. The fermentations could be divided into phases based on the
growth kinetics, phase one being a short period of exponential growth, and three subsequent ones being phases of with decreasing
specific growth rate. Sakacin P production was maximal at 20 °C. At higher temperatures (25–30 °C) the production ceased at
lower cell masses, when less glucose was consumed, resulting in much lower sakacin P concentrations. With similar media and
pH, the maximum sakacin P concentration at 20 °C was seven times higher than that at 30 °C. The growth rate increased with
increasing concentrations of yeast extract, and the maximum concentration and specific production rate of sakacin P increased
concomitantly. Increasing tryptone concentrations also had a positive influence upon sakacin P production, though the effect
was significantly lower than that of yeast extract. The maximum sakacin P concentration obtained in this study was 20.5 mg
l−1. On the basis of the growth and production kinetics, possible metabolic regulation of bacteriocin synthesis is discussed,
e.g. the effects of availability of essential amino acids, other nutrients, and energy.
Received: 7 June 1999 / Received revision: 15 September 1999 / Accepted: 17 September 1999 相似文献
4.
Transient expression and stable transformation of soybean using the jellyfish green fluorescent protein 总被引:13,自引:6,他引:7
Embryogenic soybean [Glycine max (L.) Merrill.] suspension cultures were bombarded with five different gene constructions encoding the jellyfish (Aequorea victoria) green fluorescent protein (GFP). These constructions had altered codon usage compared to the native GFP gene and mutations
that increased the solubility of the protein and/or altered the native chromophore. All of the constructions produced green
fluorescence in soybean cultures upon blue light excitation, although a soluble modified red-shifted GFP (smRS-GFP) was the
easiest to detect based on the brightness and number of foci produced. Expression of smRS-GFP was visible as early as 1.5 h
after bombardment, with peak expression at approximately 6.5 h. Large numbers of smRS-GFP-expressing areas were visible for
48 h postbombardment and declined rapidly thereafter. Stably transformed cultures and plants exhibited variation in the intensity
and location of GFP expression. PCR and Southern hybridization analyses confirmed the presence of introduced GFP genes in
stably transformed cultures.
Received: 23 September 1998 / Revision received: 4 January 1999 / Accepted: 15 January 1999 相似文献
5.
Culture conditions for the fermentative production of β-poly(l-malate) (PMLA) by microplasmodia of Physarum polycephalum were investigated and optimized. Optimal production was achieved in the presence of CaCO3. For 1.5% (w/v) d-glucose, 1% bactotryptone and 1% CaCO3, a maximum of 1.7 g PMLA/l was secreted in 3 days. For 4.5% glucose and otherwise the same conditions, 2.7 g PMLA/l was produced
in 6 days. The contribution of carbonate was inhibited by avidin. PMLA and biomass production were not strictly coupled: PMLA
was also synthesized at the beginning of the stationary phase. At pH 5.5 PMLA production was twice that at pH 4.0, while biomass
was not changed. Optimal temperatures were 24–28 °C.
Received: 12 November 1998 / Received revision: 10 February 1999 / Accepted: 12 February 1999 相似文献
6.
The expression of the Arabidopsis heat shock protein (HSP) 18.2 promoter-β-d-glucuronidase (GUS) chimera gene was investigated in transgenic Nicotiana plumbaginifolia plants during the recovery phase at normal temperatures (20–22 °C) after a heat shock (HS) treatment. GUS activity increased
during the recovery phase after HS at 42 °C for 2 h, and maximal GUS activity was observed after 12 h at normal temperatures,
at levels 50–100 times higher than the activity immediately after HS. After HS at 44 °C, little GUS activity was observed
during the first 20–24 h at normal temperatures, but the activity increased gradually thereafter, to reach a maximum at 40–50 h.
After HS at 45 °C, no GUS activity was observed throughout the experimental period. RT-PCR analysis showed that GUS mRNA
remained for 10 h after a 2-h HS at 42 °C and for 40 h after a 2-h HS at 44 °C. These findings demonstrate that brief HS
treatment, especially at a sublethal temperature, induces a long-term accumulation of HSP-GUS mRNA during the recovery phase.
Received: 31 July 1998 / Revision received: 4 November 1998 / Accepted: 19 February 1999 相似文献
7.
The role of gravity in the autolysis of Bacillus subtilis and Escherichia coli was studied by growing cells on Earth and in microgravity on Space Station Mir. Autolysis analysis was completed by examining
the death phase or exponential decay of cells for approximately 4 months following the stationary phase. Consistent with published
findings, the stationary-phase cell population was 170% and 90% higher in flight B. subtilis and E. coli cultures, respectively, than in ground cultures. Although both flight autolysis curves began at higher cell densities than
control curves, the rate of autolysis in flight cultures was identical to that of their respective ground control rates.
Received: 3 December 1998 / Received revision: 23 February 1999 / Accepted: 14 March 1999 相似文献
8.
Effects of elevated temperature on bacterial community structure and function in bioreactors treating a synthetic wastewater 总被引:1,自引:0,他引:1
T M LaPara A Konopka C H Nakatsu J E Alleman 《Journal of industrial microbiology & biotechnology》2000,24(2):140-145
The impact of elevated temperature on bacterial community structure and function during aerobic biological wastewater treatment
was investigated. Continuous cultures, fed a complex growth medium containing gelatin and α-lactose as the principal carbon
and energy sources, supported mixed bacterial consortia at temperatures ranging from 25–65°C. These temperature- and substrate-acclimated
organisms were then used as inocula for batch growth experiments in which the kinetics of microbial growth and substrate utilization,
efficiency of substrate removal, and mechanism of substrate removal were compared as functions of temperature. Bacterial community
analysis by denaturing gradient gel electrophoresis (DGGE) revealed that distinct bacterial consortia were supported at each
temperature. The efficiency of substrate removal declined at elevated temperatures. Maximum specific growth rates and the
growth yield increased with temperature from 25–45°C, but then decreased with further elevations in temperature. Thus, maximum
specific substrate utilization rates did not vary significantly over the 40°C temperature range (0.64 ± 0.04 mg COD mg−1 dry cell mass h−1). A comparison of the degradation of the protein and carbohydrate portions of the feed medium revealed a lag in α-lactose
uptake at 55°C, whereas both components were utilized simultaneously at 25°C. Journal of Industrial Microbiology & Biotechnology (2000) 24, 140–145.
Received 09 August 1999/ Accepted in revised form 12 November 1999 相似文献
9.
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
10.
The allometry of energy reserve depletion: test of a mechanism for size-dependent winter mortality 总被引:5,自引:0,他引:5
We experimentally tested the hypothesis that energy reserve depletion varies inversely with size in the fish Menidia menidia, an estuarine fish known to exhibit size-dependent winter mortality. Individuals in two size groups were starved at two winter
temperatures (4°and 8°C) and sacrificed at a range of time intervals (up to 127 days). Lipid levels and lean tissue were analyzed
to estimate somatic energy storage. As predicted, energy depletion was greater at high temperatures, and proportionally greater
in small than in large fish. After 60 days of starvation at 4°C, small fish retained an average of 67% of their original energy
reserves (vs 53% at 8°C), while large fish retained an average of 80% (vs 66% at 8°C). At 4°C, fish that were fed depleted
their energy reserves as rapidly as unfed fish, but at 8°C, fish that were fed maintained reserves at higher levels than unfed
fish. A high proportion of unfed fish (56% at 4°C, 27% at 8°C) died before they were to be sacrificed. Survival probability
did not vary with size, nor was it influenced by the amount of energy reserves. The rate of energy depletion (equivalent to
routine metabolic rate) decreased gradually over time, particularly in small fish. Routine metabolism did not conform to a
single scaling relationship. Within each temperature-size group, the routine rate declined more rapidly than metabolically
active mass (lean mass). At 8°C, the difference between size groups in energy depletion rate conformed closely to the expected
allometry exponent of 0.8. In contrast, at 4°C, the estimated allometry exponent increased over the experiment (−0.19 to 2.5).
We conclude that strategies to minimize energy loss may often modify bioenergetic scaling relationships.
Received: 30 September 1998 / Accepted: 10 February 1999 相似文献
11.
C. Suresh A. K. Dubey S. Srikanta S. Umesh Kumar N. G. Karanth 《Applied microbiology and biotechnology》1999,51(5):673-675
A UV-induced mutant strain of Aspergillus niger (CFTRI-1105-U9) overproduced a starch-hydrolysing enzyme with properties characteristically different from the known amylases
of the fungus. The purified enzyme of 4.0 pI had an apparent molecular mass of 125 kDa and it dextrinised starch and then
saccharified the dextrins. Patterns of the enzyme activity on starch, resulting in glucose at 60 °C and glucose, maltose and
maltodextrins at 70 °C as primary products, suggested significant applications for the enzyme in starch-processing industries.
Received: 29 October 1998 / Received revision: 11 January 1999 / Accepted: 19 January 1999 相似文献
12.
Extremophiles as a source of novel enzymes for industrial application 总被引:33,自引:0,他引:33
F. Niehaus C. Bertoldo M. Kähler G. Antranikian 《Applied microbiology and biotechnology》1999,51(6):711-729
Extremophilic microorganisms are adapted to survive in ecological niches such as at high temperatures, extremes of pH, high
salt concentrations and high pressure. These microorganisms produce unique biocatalysts that function under extreme conditions
comparable to those prevailing in various industrial processes. Some of the enzymes from extremophiles have already been purified
and their genes successfully cloned in mesophilic hosts. In this review we will briefly discuss the biotechnological significance
of extreme thermophilic (optimal growth 70–80 °C) and hyperthermophilic (optimal growth 85–100 °C) archaea and bacteria. In
particular, we will focus on selected extracellular-polymer-degrading enzymes, such as amylases, pullulanases, cyclodextrin
glycosyltransferases, cellulases, xylanases, chitinases, proteinases and other enzymes such as esterases, glucose isomerases,
alcohol dehydrogenases and DNA-modifying enzymes with potential use in food, chemical and pharmaceutical industries and in
environmental biotechnology.
Received: 14 August 1998 / Received revision: 17 February 1999 / Accepted: 19 February 1999 相似文献
13.
Towards a reduction in excess sludge production in activated sludge processes: biomass physicochemical treatment and biodegradation 总被引:15,自引:0,他引:15
M. Rocher G. Goma A. Pilas Begue L. Louvel J. L. Rols 《Applied microbiology and biotechnology》1999,51(6):883-890
To decrease activated sludge production, microbial cell lysis can be amplified to enhance cryptic growth (biomass growth
on lysates). Cell breakage techniques (thermal, alkaline, acid) were studied to generate Alcaligenes eutrophus and sludge lysates and to evaluate their biodegradability. Gentle treatment conditions produced the best results. Complete
cell deactivation was obtained for temperatures higher than 55 °C. The release kinetics were similar for temperatures varying
from 60 °C to 100 °C. A 20-min incubation was suitable for reaching 80% of the maximum releasable carbon. In thermal-chemical
hydrolysis, NaOH was the most efficient for inducing cell lysis. Carbon release was a two-step process. First an immediate
release occurred, which was of the same order of magnitude for A. eutrophus and sludge [100–200 mg dissolved organic C (DOC) g total suspended solids (TSS)−1], followed by a post-treatment release. The second step was virtually equivalent to the first for sludge, and weaker for
A. eutrophus (<50 mg DOC g TSS−1). The biodegradability of the soluble fraction, both the immediate and the post-treatment carbon release, was investigated.
The optimal degradation yield, obtained with sludge cells, reached 55% after 48 h of incubation and 80% after 350 h. The most
consistent lysis and biodegradation results occurred at pH 10 and 60 °C after a 20-min incubation.
Received: 30 October 1998 / Received revision: 16 February 1999 / Accepted: 20 February 1999 相似文献
14.
Senescence associated with the over-replication of a mitochondrial retroplasmid in Neurospora crassa
Mitochondrial DNA rearrangements and deletions are a prevailing feature of filamentous fungal cultures that undergo senescence.
In Neurospora spp., strains containing the Mauriceville and Varkud mitochondrial retroplasmids routinely senesce at elevated temperatures,
a process that is initiated by the integration of variant forms of the plasmids into the mitochondrial genome. Here, we describe
a strain that is phenotypically distinguishable from previously characterized senescent strains and show that senescence can
occur in the absence of plasmid integration and associated alterations in mitochondrial DNA. The MS4416 strain contains a
unique variant of the Mauriceville retroplasmid, and undergoes senescence at highly predictable frequencies at 37°, 25° and
18 °C. Decline in vegetative growth rate correlates with increased levels of the variant plasmid and alterations in the synthesis
of mitochondrially encoded proteins, suggesting that plasmid over-replication interferes with mitochondrial translation. We
also report the isolation of a mutant strain that escapes senescence yet still maintains high levels of the variant plasmid.
Its ability to tolerate a growth-suppressive retroplasmid suggests that there are mechanisms in Neurospora which compensate for the deleterious effects that plasmid over-replication has on mitochondrial function.
Received: 12 July 1999 / Accepted: 17 December 1999 相似文献
15.
Regulation of the photosynthetic electron transport chain 总被引:20,自引:1,他引:19
The regulation of electron transport between photosystems II and I was investigated in the plant Silene dioica L. by means of measurement of the kinetics of reduction of P700 following a light-to-dark transition. It was found that, in this species, the rate constant for P700 reduction is sensitive to light intensity and to the availability of CO2. The results indicated that at 25 °C the rate of electron transport is down-regulated by approximately 40–50% relative to
the maximum rate achievable in saturating CO2 and that this down-regulation can be explained by regulation of the electron transport chain itself. Measurements of the
temperature sensitivity of this rate constant indicated that there is a switch in the rate-limiting step that controls electron
transport at around 20 °C: at higher temperatures, CO2 availability is limiting; at lower temperatures some other process regulates electron transport, possibly a diffusion step
within the electron transport chain itself. Regulation of electron transport also occurred in response to drought stress and
sucrose feeding. Measurements of non-photochemical quenching of chlorophyll fluorescence did not support the idea that electron
transport is regulated by the pH gradient across the thylakoid membrane, and the possibility is discussed that the redox potential
of a stromal component may regulate electron transport.
Received: 4 March 1999 / Accepted: 25 May 1999 相似文献
16.
Adaptation and acclimation of growth and photosynthesis of five Antarctic red algae to low temperatures 总被引:2,自引:0,他引:2
Temperature requirements for growth, photosynthesis and dark respiration were determined for five Antarctic red algal species.
After acclimation, the stenothermal species Gigartina skottsbergii and Ballia callitricha grew at 0 or up to 5 °C, respectively; the eurythermal species Kallymenia antarctica, Gymnogongrus antarcticus and Phyllophora ahnfeltioides grew up to 10 °C. The temperature optima of photosynthesis were between 10 and 15 °C in the stenothermal species and between
15 and 25 °C in the eurythermal species, irrespective of the growth temperature. This shows that the temperature optima for
photosynthesis are located well below the optima from species of other biogeographical regions, even from the Arctic. Respiratory
rates rose with increasing temperatures. In contrast to photosynthesis, no temperature optimum was evident between 0 and 25 °C.
Partial acclimation of photosynthetic capacity to growth temperature was found in two species. B. callitricha and Gymnogongrus antarcticus acclimate to 0 °C, and 5 and 0 °C, respectively. But acclimation did in no case lead to an overall shift in the temperature
optimum of photosynthesis. B. callitricha and Gymnogongrus antarcticus showed acclimation of respiration to 5 °C, and P. ahnfeltioides to 5 and 10 °C, resulting in a temperature independence of respiration when measured at growth temperature. With respect
to the acclimation potential of the species, no distinction can be made between the stenothermal versus the eurythermal group.
(Net)photosynthetic capacity:respiration (P:R) ratios showed in all species highest values at 0 °C and decreased continuously to values lower than 1.0 at 25 °C. In turn,
the low P:R ratios at higher temperatures are assumed to determine the upper temperature growth limit of the studied species. Estimated
daily carbon balance reached values between 4.1 and 30.7 mg C g−1 FW day−1 at 0 °C, 16:8 h light/dark cycle, 12–40 μmol m−2 s−1.
Received: 4 November 1999 / Accepted: 7 March 2000 相似文献
17.
The ferrous iron oxidation kinetics of Thiobacillus ferrooxidans in batch cultures was examined, using on-line off-gas analyses to measure the oxygen and carbon dioxide consumption rates
continuously. A cell suspension from continuous cultures at steady state was used as the inoculum. It was observed that a
dynamic phase occurred in the initial phase of the experiment. In this phase the bacterial ferrous iron oxidation and growth
were uncoupled. After about 16 h the bacteria were adapted and achieved a pseudo-steady state, in which the specific growth
rate and oxygen consumption rate were coupled and their relationship was described by the Pirt equation. In pseudo-steady
state, the growth and oxidation kinetics were accurately described by the rate equation for competitive product inhibition.
Bacterial substrate consumption is regarded as the primary process, which is described by the equation for competitive product
inhibition. Subsequently the kinetic equation for the specific growth rate, μ, is derived by applying the Pirt equation for bacterial substrate consumption and growth. The maximum specific growth rate,
μ
max, measured in the batch culture agrees with the dilution rate at which washout occurs in continuous cultures. The maximum
oxygen consumption rate, q
O2,max, of the cell suspension in the batch culture was determined by respiration measurements in a biological oxygen monitor at
excess ferrous iron, and showed changes of up to 20% during the course of the experiment. The kinetic constants determined
in the batch culture slightly differ from those in continuous cultures, such that, at equal ferric to ferrous iron concentration
ratios, biomass-specific rates are up to 1.3 times higher in continuous cultures.
Received: 8 February 1999 / Accepted: 17 February 1999 相似文献
18.
Fibrobacter succinogenes S85 cultures that were cellobiose-limited converted cellobiose to succinate and acetate, produced little glucose or cellotriose,
maintained an intracellular ATP concentration of 4.1 mM and a membrane potential of 140 mV for 24 h, did not lyse at a rapid
rate once they had reached stationary phase, and had a most probable number of viable cells that was greater than 106/ml. When the cellobiose concentration was increased 6-fold (5 mM to 30 mM), ammonia was depleted and the cultures left 10 mM
cellobiose. Cultures provided with excess cellobiose produced succinate and acetate while they were growing, but there was
little increase in fermentation acids after the ammonia was depleted and growth ceased. The stationary-phase, cellobiose-excess
cultures had a lysis rate that was 7-fold faster than that of the cellobiose-limited cultures, and the most probable number
was only 3.3 × 103 cells/ml. The stationary-phase, cellobiose-excess cultures had 2.5 times as much cellular polysaccharide as the cellobiose-limited
cultures, but the intracellular ATP and membrane potential were very low (0.1 mM and 40 mV respectively). Methylglyoxal, a
potentially toxic end-product of carbohydrate fermentation, could not be detected, and fresh inocula grew rapidly in spent
medium that was supplemented with additional ammonia. Stationary-phase, cellobiose-excess cultures converted cellobiose to
glucose and cellotriose, but the apparent K
m of cellotriose formation was 15-fold lower than the K
m of glucose production (0.7 mM compared to 10 mM).
Received: 26 June 1997 / Received revision: 12 August 1997 / Accepted: 29 August 1997 相似文献
19.
Microbial decolorization of azo dyes by Proteus mirabilis 总被引:5,自引:0,他引:5
K-C Chen W-T Huang J-Y Wu J-Y Houng 《Journal of industrial microbiology & biotechnology》1999,23(1):686-690
A bacterium identified as Proteus mirabilis was isolated from acclimated sludge from a dyeing wastewater treatment plant. This strain rapidly decolorized a deep red
azo dye solution (RED RBN). Features of the decolorizing process related to biodegradation and biosorption were also studied.
Although P. mirabilis displayed good growth in shake culture, color removal was best in anoxic static cultures. For color removal, the optimal
pH and temperature were 6.5–7.5 and 30–35°C, respectively. The organism exhibited a remarkable color removal capability, even
at a high concentration of azo dye. More than 95% of azo dye was reduced within 20 h at a dye concentration of 1.0 g L−1. Decolorization appears to proceed primarily by enzymatic reduction associated with a minor portion, 13–17%, of biosorption
to inactivated microbial cells.
Received 06 January 1999/ Accepted in revised form 22 April 1999 相似文献
20.
A Gram-negative bacterium producing a heat-stable nitrilase highly active on aliphatic dinitriles 总被引:8,自引:0,他引:8
J. E. Gavagan R. DiCosimo A. Eisenberg S. K. Fager P. W. Folsom E. C. Hann K. J. Schneider R. D. Fallon 《Applied microbiology and biotechnology》1999,52(5):654-659
A Gram-negative bacterial strain, identified as Acidovorax facilis strain 72W, has been isolated from soil by enrichment using 2-ethylsuccinonitrile as the sole nitrogen source. This strain
grows on a variety of aliphatic mono- and dinitriles. Experiments using various heating regimes indicate that nitrile hydratase,
amidase and nitrilase activities are present. The nitrilase is efficient at hydrolyzing aliphatic dinitriles to cyanoacid
intermediates. It has a strong bias for C3–C6 dinitriles over mononitriles of the same chain length. Whole, resting cell hydrolysis of 2-methylglutaronitrile results in
4-cyanopentanoic acid and 2-methylglutaric acid as the major products. Heating, at least 20 min at 50 °C, eliminates nitrile
hydratase and amidase activities, resulting in greater than 97% selectivity to 4-cyanopentanoic acid. The nitrilase activity
has good heat stability, showing a half-life of 22.7 h at 50 °C and a temperature optimum of at least 65 °C for activity.
The strain has been deposited as ATCC 55746.
Received: 26 January 1999 / Received revision: 10 June 1999 / Accepted: 27 June 1999 相似文献