共查询到20条相似文献,搜索用时 343 毫秒
1.
X. Chen C. P. Romaine M. D. Ospina-Giraldo D. J. Royse 《Applied microbiology and biotechnology》1999,52(2):246-250
We describe a polymerase chain reaction (PCR)-based test that is specific for the pathogenic European biotype 2 (Th2) and
North American biotype 4 (Th4) of Trichoderma harzianum, responsible for the green mold epidemic in the cultivated mushroom, Agaricus bisporus. A PCR primer pair was designed that targets a 444-bp arbitrary sequence in the genome of Th4. The primers also amplified
the same product with Th2, but showed no reactivity with other biotypes of T. harzianum, several biocontrol Trichoderma, or with 31 other genera and species of fungi. The PCR-based test should have application in disease management programs,
and in the evaluation of biocontrol Trichoderma for potential pathogenicity on mushrooms.
Received: 23 November 1998 / Received revision: 19 February 1999 / Accepted: 5 March 1999 相似文献
2.
F. Laborda I. F. Monistrol N. Luna M. Fernández 《Applied microbiology and biotechnology》1999,52(1):49-56
Several fundamental aspects of microbial coal liquefaction/solubilization were studied. The liquefied/solubilized products
from coal by microorganisms were analysed. The liquid products analysed by IR titration and UV/visible spectrometry showed
some alterations with regard to the original coal. Humic acids extracted from the liquefied lignite showed a reduction in
the average molecular weight and a increase in the condensation index, probably due to depolymerization caused by microorganisms.
The mechanisms implicated in coal biosolubilization by two fungal strains, M2 (Trichoderma sp.) and M4 (Penicillium sp.) were also studied. Extracellular peroxidase, esterase and phenoloxidase enzymes appear to be involved in coal solubilization.
Received: 15 June 1998 / Received revision: 23 November 1998 / Accepted: 29 November 1998 相似文献
3.
Extracellular lignin peroxidase (LiP) was not detected during decoloration of the azo dye, Amaranth, by Trametes versicolor. Approximately twice as much laccase and manganese peroxidase (MnP) was produced by decolorizing cultures compared to when
no dye was added. At a low Mn2+ concentration (3 M), N-limited (1.2 mM NH4
+) cultures decolorized eight successive additions of Amaranth with no visible sorption to the mycelial biomass. At higher
Mn2+ concentrations (200 M), production of MnP increased and that of laccase decreased, but the rate or number of successive Amaranth
decolorations was unaffected. There was always a 6-h to 8-h lag prior to decoloration of the first aliquot of Amaranth, regardless
of MnP and laccase concentrations. Although nitrogen-rich (12 mM NH4
+) cultures at an initial concentration of 200 M Mn2+ produced high laccase and MnP levels, only three additions of Amaranth were decolorized, and substantial mycelial sorption
of the dye occurred. While the results did not preclude roles for MnP and laccase, extracellular MnP and laccase alone were
insufficient for decoloration. The cell-free supernatant did not decolorize Amaranth, but the mycelial biomass separated from
the whole broth and resuspended in fresh medium did. This indicates the involvement of a mycelial-bound, lignolytic enzyme
or a H2O2-generating mechanism in the cell wall. Nitrogen limitation was required for the expression of this activity.
Received: 19 May 1998 / Received revision: 22 October 1998 / Accepted: 7 November 1998 相似文献
4.
More than 70% of n-hexadecane-grown cells of Cladosporium resinae ATCC 22711 were converted to spheroplasts when they were treated with chitinase and lytic enzyme from Trichoderma harziamum. The light mitochondrial fraction, containing microbodies, mitochondria and vacuoles, was isolated from spheroplasts. Vacuoles
in cells were demonstrated by the inability of acridine orange to stain organelles previously treated with 2.5 μM Bafilomycin
A1, a vacuolar ATPase inhibitor. Microbodies, mitochondria and vacuoles were separated from the light mitochondrial fraction
by self-generated density-gradient ultracentrifugation using iodixanol as gradient medium. NADH-dependent n-alkane monooxygenase activity and fatty alcohol oxidase activity were located in the cytoplasm and mitochondrial fractions
respectively.
Received: 21 September 1998 / Received revision: 21 January 1999 / Accepted: 31 January 1999 相似文献
5.
B. C. Okeke A. Paterson J. E. Smith I. A. Watson-Craik 《Applied microbiology and biotechnology》1997,48(4):563-569
Sterilised and non-sterilised soils contaminated with pentachlorophenol (PCP) were inoculated with solid substrate cultures
of Lentinula edodes LE2 (“shiitake” mushroom) to simulate monoculture bioremediation treatments and treatments in which the fungus competes with
natural microflora. With monocultures of L. edodes, rates of PCP depletion were rapid for the initial 4 weeks and, although thereafter the rate decreased, 99% biotransformation
was obtained in 10 weeks. In mixed culture, PCP biotransformation by L.␣edodes was markedly slower and only 42% of the PCP was depleted after 10 weeks. Maximal rates of PCP transformation, biomass (ergosterol)
accumulation and oxidative enzymes (phenol oxidase and manganese-peroxidase) production were observed after 2 weeks of incubation.
In monocultures, phenol oxidase activity was 195.5 U g−1 and Mn-peroxidase 138.4 U g−1. In mixed cultures, fungal enzyme activities were markedly lower: 70.33 U g−1 for phenol oxidase and 85.0 g−1 for Mn-peroxidase. Analyses of soil metabolites after 10 weeks revealed that monocultures of L.edodes had eliminated both PCP and pentachloroanisole. Pentachloroanisole, however, was detected in soils with the mixed microflora.
Both dechlorination and mineralisation of the xenobiotic compound were effected by L. edodes LE2.
Received: 7 April 1997 / Accepted: 14 June 1997 相似文献
6.
M. Wenk T. Baumgartner J. Dobovšek T. Fuchs J. Kucsera J. Zopfi G. Stucki 《Applied microbiology and biotechnology》1998,49(5):624-630
The evaluation of pesticide-mineralising microorganisms to clean-up contaminated soils was studied with the widely applied
and easily detectable compound atrazine, which is rapidly mineralised by several microorganisms including the Pseudomonas sp. strain Yaya 6. The rate of atrazine removal was proportional to the water content of the soil and the amount of bacteria
added to the soil. In soil slurry, 6 mg atrazine kg soil−1 was eliminated within 1 day after application of 0.3 g dry weight inoculant biomass kg soil−1 and within 5 days when 0.003 g kg soil−1 was used. In partially saturated soil (60% of the maximal water-holding capacity) 15 mg atrazine kg soil−1 was eliminated within 2 days by 1 g biomass kg soil−1 and within 25 days when 0.01 g biomass kg soil−1 was used. In unsaturated soil, about 60% [U-ring-14C]atrazine was converted to 14CO2 within 14 days. Atrazine was very efficiently removed by the inoculant biomass, not only in soil that was freshly contaminated
but also in soil aged with atrazine for up to 260 days. The bacteria exposed to atrazine in unsaturated sterile soil were
still active after a starvation period of 240 days: 15 mg newly added atrazine kg soil−1 was eliminated within 5 days.
Received: 31 October 1997 / Received revision: 16 January 1998 / Accepted: 18 January 1998 相似文献
7.
H. Mulder A. M. Breure D. van Honschooten J. T. C. Grotenhuis J. G. van Andel W. H. Rulkens 《Applied microbiology and biotechnology》1998,50(2):277-283
The effect of biofilm formation by Pseudomonas 8909N (DSM no. 11634) on the dissolution and biodegradation rates of solid naphthalene was quantified. Biofilms were cultivated
on solid naphthalene as a model polycyclic aromatic hydrocarbon in continuous cultures. After different periods of incubation,
the dissolution rate of naphthalene was determined by batch dissolution tests with active or inactivated biofilms and without
biofilms. Results show that the naphthalene dissolution rate to the bulk liquid phase was reduced by over 90% after 7 days
of biofilm formation. The degradation of naphthalene in the biofilm proved to be insignificant compared to the decrease in
the bulk liquid conversion of naphthalene, and the overall biodegradation rate of the solid naphthalene decreased.
Received: 26 January 1998 / Received revision: 16 April 1998 / Accepted: 19 April 1998 相似文献
8.
《Molecular & general genetics : MGG》1998,260(2-3):218-225
The mycoparasite Trichoderma harzianum has been extensively used in the biocontrol of a wide range of phytopathogenic fungi. Hydrolytic enzymes secreted by the
parasite have been directly implicated in the lysis of the host. Dual cultures of Trichoderma and a host, with and without contact, were used as means to study the mycoparasitic response in Trichoderma. Northern analysis showed high-level expression of genes encoding a proteinase (prb1) and an endochitinase (ech42) in dual cultures even if contact with the host was prevented by using cellophane membranes. Neither gene was induced during
the interaction of Trichoderma with lectin-coated nylon fibres, which are known to induce hyphal coiling and appressorium formation. Thus, the signal involved
in triggering the production of these hydrolytic enzymes by T. harzianum during the parasitic response is independent of the recognition mediated by this lectin-carbohydrate interaction. The results
showed that induction of prb1 and ech42 is contact-independent, and a diffusible molecule produced by the host is the signal that triggers expression of both genes
in vivo. Furthermore, a molecule that is resistant to heat and protease treatment, obtained from Rhizoctonia solani cell walls induces expression of both genes. Thus, this molecule is involved in the regulation of the expression of hydrolytic enzymes during mycoparasitism by T. harzianum.
Received: 8 June 1998 / Accepted: 28 July 1998 相似文献
9.
Thiobacillus ferrooxidans was able to grow under anaerobic conditions on copper sulphide with ferric ion as the electron acceptor. The dissolution of
covellite under these conditions (68% after 35 days) was higher than values observed aerobically in cultures with similar
media composition and almost as high as under aerobic conditions without iron. From these results we propose a mechanism for
anaerobic bioleaching of covellite in the presence of ferric iron and speculate that it may occur in leach dumps where the
oxygen concentration is, as reported elsewhere, very low.
Received: 3 September 1996 / Received revision: 13 January 1997 / Accepted: 24 January 1997 相似文献
10.
The majority of lignin-degrading basidiomycetes are able to depolymerize humic acids. In this presentation the relationship
and possible similarities between enzymes involved in lignin degradation and humic acid depolymerization were examined on
the genetic level. We have cloned fragments of the gene encoding the extracellular ligninolytic enzyme laccase from Clitocybula dusenii, Nematoloma frowardii and a fungal strain designated i63-2, and compared the three sequences with those of several other published laccase genes.
The sequenced fragments displayed a high homology both on the DNA (97%–77%) and amino acid (100%–85%) level. Furthermore,
the expression of this gene in the above-mentioned fungi was demonstrated by a nested polymerase chain reaction with cDNA
as template.
Received: 3 February 1998 / Received revision: 31 August 1998 / Accepted: 3 September 1998 相似文献
11.
Production of ligninolytic enzymes and synthetic lignin mineralization by the bird's nest fungus Cyathus stercoreus 总被引:3,自引:0,他引:3
Production of ligninolytic enzymes and degradation of 14C-ring labeled synthetic lignin by the white-rot fungus Cyathus stercoreus ATCC 36910 were determined under a variety of conditions. The highest mineralization rate for 14C dehydrogenative polymerizates (DHP; 38% 14CO2 after 30 days) occurred with 1 mM ammonium tartrate as nitrogen source and 1% glucose as additional carbon source, but levels
of extracellular laccase and manganese peroxidase (MnP) were low. In contrast, 10 mM ammonium tartrate with 1% glucose gave
low mineralization rates (10% 14CO2 after 30 days) but higher levels of laccase and manganese peroxidase. Lignin peroxidase was not produced by C. stercoreus under any of the studied conditions. Mn(II) at 11 ppm gave a higher rate of 14C DHP mineralization than 0.3 or 40 ppm, but the highest manganese peroxidase level was obtained with Mn(II) at 40 ppm. Cultivation
in aerated static flasks gave rise to higher levels of both laccase and manganese peroxidase compared to the levels in shake
cultures. 3,4-Dimethoxycinnamic acid at 500 μM concentration was the most effective inducer of laccase of those tested. The
purified laccase was a monomeric glycoprotein having an apparent molecular mass of 70 kDa, as determined by calibrated gel
filtration chromatography. The pH optimum and isoelectric point of the purified laccase were 4.8 and 3.5, respectively. The
N-terminal amino acid sequence of C. stercoreus laccase showed close homology to the N-terminal sequences determined from other basidiomycete laccases. Information on C. stercoreus, whose habitat and physiological requirements for lignin degradation differ from many other white-rot fungi, expands the
possibilities for industrial application of biological systems for lignin degradation and removal in biopulping and biobleaching
processes.
Received: 29 January 1999 / Received revision: 5 July 1999 / Accepted: 9 July 1999 相似文献
12.
Evaluation of solid substrates for enzyme production by Coriolus versicolor, for use in bioremediation of chlorophenols in aqueous effluents 总被引:1,自引:0,他引:1
In the development of a system for the removal of chlorophenols from aqueous effluents, a range of solid substrates for the
growth of Coriolus versicolor were investigated. Substrates included wood chips, cereal grain, wheat husk and wheat bran. Suitability for transformation
of chlorophenols depended on laccase production by the fungus. The greatest amount of laccase (<25 Units g−1 substrate) was produced on wheat husk and wheat bran over 30 days colonisation. Aqueous extracts of laccase from wheat husk
and wheat bran cultures removed 100% of 2,4-dichlorophenol (50 ppm) from solution within 5 h and 75–80% of pentachlorophenol
(50 ppm) within 24 h. Wheat bran was formulated into pellets with biscuit flour to provide a compact substrate for fungal
immobilisation. Addition of 8–12% yeast extract to the pellets increased laccase production five-fold. Colonised pellets were
added to chlorophenol solutions in 200–4000-ml bioreactors, resulting in >90% removal of chlorophenols within 100 min.
Received: 10 April 2000 / Received revision: 4 July 2000 / Accepted: 10 July 2000 相似文献
13.
Pseudomonas sp. D7-4 and Pseudomonas sp. B13 FR1(pFRC20P) degraded mixtures of chloro- and methyl-substituted benzoates exclusively via an extended ortho pathway, whereas in Pseudomonas putida WR201 both ortho and meta fission were induced by mixtures of 3-chloro- and 3-methylbenzoate or even by 3-chlorobenzoate alone. The competition behaviour
of these strains was compared in batch and in chemostat cultures. Despite misrouting of metabolites, strain WR201 was competitive,
in a lot of the competition experiments, with mixtures of these substrates. Only in a narrow range of the mixing ratio of
chloro- and methylbenzoate was the presence of both the meta and ortho pathways a disadvantage for competitiveness. Outside these ranges other attributes, such as high growth rates or short lag
periods, of a respective strain were even more essential for one strain to outcompete another.
Received: 13 February 1998 / Received revision: 28 April 1998 / Accepted: 30 April 1998 相似文献
14.
Kacena MA Merrell GA Manfredi B Smith EE Klaus DM Todd P 《Applied microbiology and biotechnology》1999,51(2):229-234
Previous investigations have reported that bacterial suspension cultures grow to higher stationary concentrations in space
flight than on Earth; however, none of these investigations included extensive ground controls under varied inertial conditions.
This study includes extensive controls and cell-growth data taken at several times during lag phase, log phase, and stationary
phase of Escherichia coli and Bacillus subtilis. The Marquardt-Levenberg, least-squares fitting algorithm was used to calculate kinetic growth parameters from the logistic
bacterial growth equations for space-flight and control growth curves. Space-flight cultures grew to higher stationary-phase
concentrations and had shorter lag-phase durations. Also, evidence was found for increased exponential growth rate in space.
Received: 27 February 1998 / Received revision: 21 August 1998 / Accepted: 3 September 1998 相似文献
15.
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
16.
U. Mukundan V. Bhide G. Singh W. R. Curtis 《Applied microbiology and biotechnology》1998,50(2):241-245
Brief exposure of Beta vulgaris root cultures to acidic medium resulted in release of betalain pigments while the capability for regrowth and continued pigment
accumulation was retained. A 10-min exposure to pH 2 followed by return to standard growth medium (pH 5.5, 1.1 mM PO4) resulted in release of 0.59 mg pigment/g dry weight over the subsequent 24-h period. The released pigment corresponds to
36.8% of the total pigments. Further improvement in culture productivity was achieved through phosphate limitation. Specific
pigment productivity increased fivefold for cultures grown in phosphate-free medium as compared to cultures grown in control
medium (1.1 mM PO4). A maximum total pigment production of 25.2 mg/l was observed at an initial medium phosphate level 0.3 mM. When combined
with phosphate limitation, low pH facilitated the release of 3.03 mg pigment/g dry weight, which corresponds to 50% of the
total pigment. The permeabilized roots were capable of regrowth and continued pigment accumulation. A cytochemical assay for
respiratory activity revealed that the basis of regrowth was lateral root initials that were unaffected during the acidic
pH treatment.
Received: 16 December 1997 / Received revision: 7 May 1998 / Accepted: 16 May 1998 相似文献
17.
High-level expression of an endoxylanase gene from Bacillus sp. in Bacillus subtilis DB104 for the production of xylobiose from xylan 总被引:1,自引:0,他引:1
K. J. Jeong I. Y. Park M. S. Kim S. C. Kim 《Applied microbiology and biotechnology》1998,50(1):113-118
To produce xylobiose from xylan, high-level expression of an endoxylanase gene from Bacillus sp. was carried out in Bacillus subtilis DB104. A 1.62-kb SmaI DNA fragment, coding for an endoxylanase of Bacillus sp., was ligated into the Escherichia coli/B. subtilis shuttle vector pJH27Δ88, producing pJHKJ4, which was subsequently transformed into B. subtilis DB104. A maximum endoxylanase activity of 105 U/ml was obtained from the supernatant of B. subtilis DB104 harboring pJHKJ4. The endoxylanase was purified to homogeneity by ion-exchange chromatography and the production profile
of xylooligosaccharides from xylan by the endoxylanase was examined by HPLC with a carbohydrate analysis column. Xylobiose
was the major product from xylan at 40 °C and its proportion in the xylan hydrolyzates increased with the reaction time; at
12 h, over 60% of the reaction products was xylobiose. These results suggest that xylobiose, which has a stimulatory effect
on the selective growth of the intestinal bacterium Bifidobacterium, can be mass-produced effectively by the endoxylanase of Bacillus sp. cloned in B. subtilis.
Received: 2 January 1998 / Received revision: 4 March 1998 / Accepted: 4 March 1998 相似文献
18.
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
19.
Lignite (brown coal) can be liquefied/solubilized with several fungi by different mechanisms. When applied industrially,
only catalytic mechanisms can compete with chemical methods. The well-known fungal ligninolytic peroxidases are at a disadvantage,
in that the relatively expensive hydrogen peroxide must be used as a cofactor. Comparing several fungal strains, we observed
that the fungus Trametes versicolor is able to decolorize coal-derived humic acids, producing a considerable amount of laccase in the process. During this reaction
the amount of humic acids decreases whilst that of fulvic acids increases; this was verified by optical density measurement
and GPC after the two substance classes had been separated.
Received: 27 August 1998 / Received revision: 4 November 1998 / Accepted: 7 November 1998 相似文献
20.
The production of ligninolytic enzymes was studied in surface cultures of the South American white-rot fungus Nematoloma frowardii b19 and four other strains of this ecophysiological group (Clitocybula dusenii b11, Auricularia sp. m37a, wood isolates u39 and u45), which are able to depolymerize low-rank-coal-derived humic acids with the formation
of fulvic-acid-like compounds. The fungi produced the three crucial enzymes of lignin degradation – lignin peroxidase, manganese
peroxidase and laccase. In the case of N. frowardii b19, laccase and the two peroxidases could be stimulated by veratryl alcohol. Manganese (II) ions (Mn2+) caused a rapid increase of Mn peroxidase activity accompanied by the complete repression of lignin peroxidase. Under nitrogen-limited
conditions the growth as well as the production of ligninolytic enzymes was partly repressed. During the depolymerization
process of coal humic acids using solid agar media, gradients of ligninolytic enzyme activities toward 2,2′-azinobis(3-ethylbenzthiazoline-6-sulphonate)
and syringaldazine were detectable inside the agar medium.
Received: 5 August 1996 / Received revision: 13 November 1996 / Accepted: 15 November 1996 相似文献