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1.
C. Löser H. Seidel A. Zehnsdorf U. Stottmeister 《Applied microbiology and biotechnology》1998,49(5):631-636
Microbial hydrocarbon degradation in soil was studied during periodical aerobic/anaerobic switching and under purely aerobic
conditions by using a pilot-scale plant with diesel-fuel-contaminated sand. The system worked according to the percolation
principle with controlled circulation of process water and aeration. Periodical switching between 4 h of aerobic and 2 h of
anaerobic conditions was achieved by repeated saturation of the soil with water. Whatever the cultivation mode, less than
50% of the diesel was degraded after 650 h because the hydrocarbons were adsorbed. Contrary to expectations, aerobic/anaerobic
changes neither accelerated the rate of degradation nor reduced the residual hydrocarbon content of the soil. Obviously the
pollutant degradation rate was determined mainly by transport phenomena and less by the efficiency of microbial metabolism.
The total mass of oxygen consumed and carbon dioxide produced was greater under aerobic/anaerobic changing than under aerobic
conditions, although the mass of hydrocarbons degraded was nearly the same. As shown by an overall balance of microbial growth
and by a carbon balance, the growth yield coefficient was smaller during aerobic/anaerobic changes than under aerobic conditions.
Received: 25 November 1997 / Received revision: 15 January 1998 / Accepted: 18 January 1998 相似文献
2.
The fate of thiocyanate (SCN−) and cyanate (OCN−) under methanogenic conditions was investigated at 35 °C. Thiocyanate and cyanate were added to mixed methanogenic cultures
along with an organic mixture. Thiocyanate was stable under these conditions, and had no adverse effect on methanogenesis
at a concentration as high as 2.5 mM. In contrast, cyanate at a concentration as low as 0.3 mM initially inhibited methanogenesis
but, after the complete removal of cyanate, methanogenesis gradually recovered. The inhibitory effect of cyanate on methanogenesis
became more profound with repeated additions of cyanate. The transformation of cyanate followed the hydrolytic route to ammonia
and bicarbonate under anaerobic conditions and its hydrolysis rate was enhanced by microbial activity. Cyanide was not detected
as a cyanate transformation product under the methanogenic conditions of this study.
Received: 13 June 1997 / Received revision: 29 August 1997 / Accepted: 15 September 1997 相似文献
3.
P. Arvidsson K. Nilsson H. Håkanson B. Mattiasson 《Applied microbiology and biotechnology》1998,49(6):677-681
A chemiluminescence detector was used to measure the production of nitric oxide, NO, from the denitrifying bacteria Pseudomonas stutzeri. NO is an intermediate when P. stutzeri converts nitrate into nitrogen gas. The reaction between NO and ozone is selective and sensitive in generating chemiluminescence.
Calibrations were made down to 1 nM, with a signal-to-noise ratio of 3. Bacteria were immobilised in alginate beads. Denitrification
experiments were made in an anaerobic non-growth medium by adding nitrate to a certain concentration in the reactor. The bacteria
were exposed to nitrate in the concentration range 1 pM–5 mM. The lowest concentration to give a measurable NO response was
100 nM.
Received: 16 October 1997 / Received revision: 20 January 1998 / Accepted: 24 January 1998 相似文献
4.
Flavia Nastri Angela Lombardi G. Morelli Carlo Pedone Vincenzo Pavone Geneviève Chottard Pierrette Battioni Daniel Mansuy 《Journal of biological inorganic chemistry》1998,3(6):671-681
The coordination state of Fe(III)- and Fe(II)-mimochrome I, a covalent peptide-deuteroheme sandwich involving two nonapeptides
bearing a histidine residue in a central position, was studied by UV-visible, EPR, and resonance Raman spectroscopy. The ferric
and ferrous states of this new iron species mainly exist, at pH 7, in a low-spin hexacoordinate form with two axial histidine
ligands coming from the peptide chains. A minor amount of high-spin form for the ferric state is also present at pH 7. However,
it is mainly high-spin at pH 2 or in DMSO. Fe(II)-mimochrome I binds CO with an affinity comparable to that of myoglobin and
hemoglobin. Fe(III)-mimochrome I reacts with alkylhydroxylamine and arylhydrazines, leading to the corresponding Fe(II)-nitrosoalkyl
and Fe(III)-σ-aryl complexes, respectively. These reactions were greatly dependent on the solvent used and on the pH, and
were much slower than the corresponding reactions performed by deuterohemin in the presence of excess imidazole. All these
results indicate that the reactivity of iron-mimochrome I is controlled by the binding of the peptide chains to the iron.
The reactivity shown by this complex at neutral pH is intermediate between that observed for iron porphyrins in the presence
of excess imidazole and that of hemoproteins characterized by a strong bis-histidine axial coordination, such as cytochrome
b
5. Fe(III)-mimochrome I is able to catalyze styrene epoxidation by using a [Fe(III)-mimochrome I]/[H2O2]/[stryrene] ratio of 1 : 10 : 2000 in phosphate buffer solution (pH 7.2) containing 2% CTAB both under strictly anaerobic
conditions and in the presence of oxygen, at 0 °C.
Received: 26 May 1998 / Accepted: 20 August 1998 相似文献
5.
A. Yamada M. Miyashita K. Inoue T. Matsunaga 《Applied microbiology and biotechnology》1997,48(3):367-372
A novel purple nonsulfur bacterium strain NKPB030619, which has resistance to over 5 mM selenite, was isolated from a marine
environment. An initial concentration of 1.1 mM selenite, added to the medium, was decreased to under 0.05 mM within 5 days.
The color of the cell suspension turned red within 2 days. The red coloration gradually decreased and black precipitates appeared
during 2 weeks of cultivation. Under these conditions, two main types of deposit were formed extracellularly. These deposits
were thought to contain red amorphous selenium and black vitreous selenium. The selenite reduction to elemental selenium in
this bacterium was induced by the introduction of light and l-malic acid under anaerobic conditions. These results suggest that selenite reduction is coupled with photosynthesis and l-malic acid can serve as the indirect electron donor for its reduction. Phylogenetic analysis based on the 16S rDNA sequence
showed that NKPB0360619 belongs to the α subdivision of Proteobacteria and is classified into the Rhodobacter species. The highest similarity of 86.2% was observed with R. sphaeroides.
Received: 13 August 1996 / Received last revision: 6 May 1997 / Accepted: 11 May 1997 相似文献
6.
The white-rot basidiomycete Phanerochaete chrysosporium BKM-F-1767 was tested for its capacity to degrade dehydroabietic acid (DHA). In anaerobic treatment, this molecule is the
most recalcitrant member of the resin acid group, which is known to cause operational problems to anaerobic reactors treating
pulp and paper industry wastewaters. In this study the effect of DHA on different parameters, such as growth, ligninolytic
enzyme activity, extracellular protein production as well as both glycerol and ammonium consumption by the fungus, was determined.
Although the above parameters were affected by the addition of DHA, the results show that the fungus could still produce significant
titres of ligninolytic enzymes. The fungus removed 47% of the DHA initially present in the static culture, after 10 days of
incubation. Anaerobic toxicity assays showed that the treatment of DHA with P. chrysosporium reduced the methanogenesis and acetogenesis inhibition caused by DHA and allowed improved methane production by the anaerobic
bacteria.
Received: 10 June 1997 / Received revision: 6 January 1998 / Accepted: 24 January 1998 相似文献
7.
The green alga Chlamydomonas reinhardtii Dangeard CW-15 exhibited very low rates of plasma-membrane Fe(III) reductase activity when grown under Fe-sufficient conditions.
After switching the medium to an Fe-free formulation, both ferricyanide reductase and ferric chelate reductase activities
rapidly increased, reaching a maximum after 3 d under iron-free conditions. Both of the Fe(III) reductase activities increased
in parallel over time, they exhibited similar K
m values (approximately 10 μM) with respect to Fe(III), displayed the same pH profile of activity, and both exhibited the same
degree of light stimulation which could be inhibited by 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea (DCMU). Furthermore, ferricyanide
competitively inhibited ferric chelate reduction by iron-limited cells. These results indicate that both Fe(III) reductase
activities were mediated by the same iron-limitation-induced plasma-membrane reductase. No evidence was found for the presence
of Fe(III)-reducing substances in the culture medium, or for the involvement of active oxygen species in the process of Fe(III)
reduction. Chlamydomonas reinhardtii appears to respond to iron limitation in a manner similar to Strategy I higher plants.
Received: 24 June 1997 / Accepted: 2 August 1997 相似文献
8.
J. J. Crawford G. K. Sims R. L. Mulvaney M. Radosevich 《Applied microbiology and biotechnology》1998,49(5):618-623
Anaerobic biodegradation of atrazine by the bacterial isolate M91-3 was characterized with respect to mineralization, metabolite
formation, and denitrification. The ability of the isolate to enhance atrazine biodegradation in anaerobic sediment slurries
was also investigated. The organism utilized atrazine as its sole source of carbon and nitrogen under anoxic conditions in
fixed-film (glass beads) batch column systems. Results of HPLC and TLC radiochromatography suggested that anaerobic biotransformation
of atrazine by microbial isolate M91-3 involved hydroxyatrazine formation. Ring cleavage was demonstrated by 14CO2 evolution. Denitrification was confirmed by detection of 15N2 in headspace samples of K15NO3-amended anaerobic liquid cultures. In aquatic sediments, mineralization of uniformly ring-labeled [14C]atrazine occurred in both M91-3-inoculated and uninoculated sediment. Inoculation of sediments with M91-3 did not significantly
enhance anaerobic mineralization of atrazine as compared to uninoculated sediment, which suggests the presence of indigenous
organisms capable of anaerobic atrazine biodegradation. Results of this study suggest that the use of M91-3 in a fixed-film
bioreactor may have applications in the anaerobic removal of atrazine and nitrate from aqueous media.
Received: 3 September 1997 / Received revision: 4 December 1997 / Accepted: 2 January 1998 相似文献
9.
M. Kunioka 《Applied microbiology and biotechnology》1997,47(5):469-475
The biosynthesis and chemical reactions of poly(amino acid)s produced by microorganisms are reviewed. A large amount of γ-poly(glutamic
acid) (PGA) has been produced by Bacillus strains. ε-Polylysine (PL) has been produced by Streptomyces albulus. As a modification of PGA and PL, pH-sensitive hydrogels have been prepared by means of γ irradiation or the addition of
a crosslinking agent to an aqueous solution of PGA and PL.
Received: 4 September 1996 / Received revision: 27 January 1997 / Accepted: 28 January 1997 相似文献
10.
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
11.
Effects of oxygen on invertase expression in continuous culture of recombinant Saccharomyces cerevisiae containing the SUC2 gene 总被引:2,自引:0,他引:2
The yeast SUC2 gene, cloned on a multicopy plasmid pRB58, was used to study the effect of oxygen on the invertase expression of the recombinant
Saccharomyces cerevisiae. Glucose repression was not the only factor affecting the invertase expression. The results obtained from the single-stage
continuous cultures under microaerobic conditions showed that invertase expression was also strongly dependent on oxygen availability,
and moving from anaerobic to aerobic conditions led to a five-fold increase in specific invertase activity. However, the cell
yields under anaerobic conditions were quite low compared to those under aerobic conditions. These opposite effects of oxygen
on cell growth and gene expression offer a strategy for maximizing invertase productivity by a two-stage continuous culture.
The first stage was operated at a low level of glucose, around 100 mg/l, under aerobic conditions in order to obtain a high
yield of yeast biomass, and the second stage maintained anaerobic conditions with residual glucose levels of 50 mg/l to derepress
and fully induce invertase expression. The two-stage continuous culture resulted in a 2.5-fold increase in invertase productivity
over that of a single-stage continuous culture.
Received: 28 July 1998 / Received revision: 22 September 1998 / Accepted: 7 November 1998 相似文献
12.
Bioreactor selection is important for maximising the productivity of recombinant organisms. In this paper a comparison is
made between growth and recombinant protein synthesis in three types of bioreactor containing a marine Vibrio capable of heterologous expression and secretion of the non-toxic B-subunit pentamer of Escherichia coli heat-labile enterotoxin, EtxB. The heterologous gene was located on the plasmid pMMB68. Resistance to carbenicillin was used
to select for plasmid-containing cells. In batch and continuous culture, volumetric productivities were highest when cells
were grown in the presence of carbenicillin. Without antibiotic selection, the highest volumetric productivity (9.4 mg EtxB−1 h−1) was observed in hollow-fibre bioreactors, and the production phase could be maintained for over 50 h. The highest specific
productivity under these conditions was found in batch culture, but the maximal production phase was only of 5 h duration.
In hollow-fibre reactors the type of fibre used significantly affected productivity, both with regards to the maintenance
of reactor integrity and by allowing passage of the recombinant toxoid through the selectively permeable membrane. Where contamination
of the product with carbenicillin is to be avoided, these bioreactors are superior to batch or continuous culture.
Received: 29 January 1997 / Received revision: 9 April 1997 / Accepted: 13 April 1997 相似文献
13.
D. Naki C. Paech G. Ganshaw V. Schellenberger 《Applied microbiology and biotechnology》1998,49(3):290-294
Mutants that secrete increased amounts of enzyme into a selection medium can be efficiently enriched from large populations
of mutagenized microorganisms during growth in hollow fibers. Under these conditions, each colony grows in its own microenvironment
and cross-feeding between neighboring colonies is limited. We applied the technique to B. subtilis carrying a plasmid-encoded protease gene. The plasmid was subjected to random mutagenesis and clones secreting up to fivefold-increased
amounts of enzyme were selected using a medium containing bovine serum albumin as the sole nitrogen source.
Received: 22 May 1997 / Received revision: 21 October 1997 / Accepted: 7 November 1997 相似文献
14.
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
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.
E. Kostyál E.-L. Nurmiaho-Lassila J. A. Puhakka M. Salkinoja-Salonen 《Applied microbiology and biotechnology》1997,47(6):734-741
This study deals with combining the biologi cal removal of organic halogens with the removal of nitrogen from bleached kraft
pulp mill wastewater in fluidized-bed reactors under nitrifying and denitrifying conditions. Untreated and biotreated bleached
kraft pulp mill wastewaters had no detrimental effect on nitrification or denitrification. The nitrifying biofilm reactor,
pregrown on synthetic inorganic feed with ammonia, removed without a lag phase adsorbable organic halogens [7.2 mg Cl (g biomass
volatile solids)−1day−1] from bleached kraft pulp mill wastewater and selected chlorophenols from synthetic wastewater. Electron microscopical examination
of the biofilm showed that bacteria, morphologically similar to the nitrifying species Nitrosomonas or Nitrobacter, and Nitrosospira were dominant. The denitrifying fluidized-bed reactor, pregrown on nitrate and methanol, denitrified without a lag phase bleached
kraft pulp mill wastewater. Under denitrifying conditions, 35% of the total organic carbon content of untreated bleached kraft
pulp mill waste water was removed. The reducing power delivered by untreated bleached kraft pulp mill wastewater for denitrification
was 2 mmol electrons/mmol carbon mineralized. Dechlorination under denitrifying conditions was negligible.
Received: 21 November 1996 / Received revision: 27 January 1997 / Accepted: 1 February 1997 相似文献
17.
Physiological aspects of continuous lactic acid fermentations at high dilution rates 总被引:1,自引:0,他引:1
U. Kulozik 《Applied microbiology and biotechnology》1998,49(5):506-510
The effects of the substrate conditions on the volumetric productivity of Lactobacillus helveticus at different cell densities up to 60 g l−1 in a continuous stirred-tank reactor with microfiltration to retain the biomass were investigated. At low dilution rates,
D, the steady-state volumetric productivity, r
p, gradually increased to a maximum at D = 1.2–1.5 h−1, because of reduced product inhibition. At higher D values, r
p unexpectedly decreased, although the substrate conditions further improved. The maxima of r
p at different cell densities coincided with a critical specific substrate utilization rate beyond which the cell metabolism
seems to be controlled through a catabolic modulator factor, and r
p decreases.
Received: 8 September 1997 / Received last revision: 31 December 1997 / Accepted: 2 January 1998 相似文献
18.
Solano-Serena F Marchal R Huet T Lebeault JM Vandecasteele JP 《Applied microbiology and biotechnology》2000,54(1):121-125
The biodegradability under aerobic conditions of volatile hydrocarbons (4–6 carbons) contained in gasoline and consisting
of n-alkanes, iso-alkanes, cycloalkanes and alkenes, was investigated. Activated sludge was used as the reference microflora. The biodegradation
test involved the degradation of the volatile fraction of gasoline in closed flasks under optimal conditions. The kinetics
of biodegradation was monitored by CO2 production. Final degradation was determined by gas chromatographic analysis of all measurable hydrocarbons (12 compounds)
in the mixture after sampling the headspace of the flasks. The degradation of individual hydrocarbons was also studied with
the same methodology. When incubated individually, all hydrocarbons used as carbon sources, except 2,2-dimethylbutane and
2,3-dimethylbutane, were completely consumed in 30 days or less with different velocities and initial lag periods. When incubated
together as constituents of the light gasoline fraction, all hydrocarbons were metabolised, often with higher velocities than
for individual compounds. Cometabolism was involved in the degradation of dimethyl isoalkanes.
Received: 19 October 1999 / Received revision: 21 January 2000 / Accepted: 23 January 2000 相似文献
19.
The biodegradation of an oily sludge is facilitated by a microbial tensio-active agent isolated from Pseudomonas aeruginosa USB-CS1. The optimal oil-in-water dispersion conditions are as follows: pH 6.5, temperature 30 °C, agitation 150 rev/min.
The total hydrocarbon content shows that the biodegradation of the oily substrate mediated by the biosurfactant or by the
biosurfactant–P. aeruginosa USB-CS1 complex is significantly higher after 30 days of incubation than that in other experimental conditions, by a mean
of 70%. Substrate fractionation by column chromatography reveals that, if biosurfactant is present, saturated and aromatic
compounds are more susceptible to microbial degradation than they are in other biodegradation systems by an average of 55%
and 40% respectively. These results suggest that the stimulatory effects of the biosurfactant on the biodegradation of the
oily substrate are limited over time by the loss of surface activity of the biosurfactant after 30 days of incubation.
Received : 7 August 1996 / Received revision : 6 December 1996 / Accepted : 4 January 1997 相似文献
20.
Mycobacterium sp. strain 12523 has a para-site-specific hydroxylation activity, which produce para-substituted phenols from various aromatic compounds. However, the activity is unstable and the reactions are inactivated
within 24 h. In order to extend the reaction period, the factors that affected reaction stability were examined. The hydroxylation
activity of the cells incubated in buffer was significantly stabilized by the inclusion of an inducer such as methyl ethyl
ketone. It is suggested that a regulatory mechanism is involved in controlling the activity. This study resulted in the development
of a convenient method to stabilize the hydroxylation activity, involving the addition of an inducer, such as acetone, to
the reaction system. This method permitted the hydroxylation reaction to continue for more than 67 h.
Received: 27 January 1997 / Received revision: 18 March 1997 / Accepted: 13 April 1997 相似文献