共查询到20条相似文献,搜索用时 31 毫秒
1.
This paper describes the effect of different nutrients on the production of pyrazoloisoquinolinone antibiotics (APHE) by
Streptomyces griseocarneus. In a chemically defined medium with glucose as carbon and l-lysine as nitrogen source all APHE antibiotics (APHE-1 to -3) are produced, APHE-3 being the most abundant. Propionate and
butyrate used as precursors with glucose as main carbon source increased the production of APHE-1 and -2, respectively. The
presence of propionate or butyrate reduced the production of APHE-3. Results obtained in minimal medium supplemented with
l-valine and l-histidine indicate a relationship between these amino acids and APHE biosynthesis. These data, together with those obtained
in the presence of precursors of fatty acids, also show possible links with fatty acid biosynthesis. Different nutritional
requirements were found for APHE-3 production in comparison with APHE-1 and APHE-2.
Received: 15 April 1999 / Received revision: 21 June 1999 / Accepted: 27 June 1999 相似文献
2.
The fate of nuclear envelope proteins during the pachytene/metaphase I transition was investigated in rat spermatocytes cultured
in vitro in the presence of the phosphatase inhibitor okadaic acid (OA). Under these experimental conditions lamin B1 and
the lamina-associated proteins 2 (LAPs2) behave as already described in other cell types. In contrast to these results, meiotic
lamin C2 appears to be degraded after addition of OA to the spermatocyte culture medium as this lamin was no longer detectable
by immunofluorescence microscopy or by immunoblotting. Taking into account the peculiarities of the lamin C2 primary structure,
it is tempting to speculate that degradation of this protein represents a critical step in the process of disassembly of the
spermatocyte nuclear envelope.
Received: 22 September 1999; in revised form: 25 October 1999 / Accepted: 29 October 1999 相似文献
3.
Wunderwald U Kreisel G Braun M Schulz M Jäger C Hofrichter M 《Applied microbiology and biotechnology》2000,53(4):441-446
A synthetic fluorinated humic acid (FHA) was prepared by the spontaneous oxidative polymerization of 3-fluorocatechol. The
13C-solid-state NMR spectrum showed signals in the region for aromatic carbons with different substituents (aryl-H, aryl-C,
aryl-O carbons) and for carboxyl-carbon. The latter indicated the formation of carboxylic groups, probably caused by ring
cleavages during the polymerization process. An indication of the formation of carboxylic groups was also found in the infrared
spectrum (band at 1715 cm−1). The dissolved FHA was degraded with active mycelium of the agaric white-rot fungus Nematoloma frowardii as well as with its isolated manganese peroxidase. In both cases, decolorization of the brownish FHA solution and partial
defluorination (45–60%) took place. Degradation proceeded via formation of lower-molecular-mass fulvic acid-like substances.
The results demonstrate that halogenated humic substances, e.g., resulting from the humification of xenobiotic compounds (bound
residues), can in principle be eliminated by ligninolytic fungi (e.g., soil colonizing litter decomposers) and their manganese
peroxidase system.
Received: 28 June 1999 / Received revision: 14 October 1999 / Accepted: 16 October 1999 相似文献
4.
The genetics and biochemistry of daunorubicin and doxorubicin production by Streptomyces peucetius is reviewed, with a focus on how such information can be used for the genetic engineering of strains having improved titers
of these two antitumor antibiotics.
Received 23 February 1999/ Accepted in revised form 22 March 1999 相似文献
5.
The agaric basidiomycete Clitocybula dusenii was used for the production of the extracellular ligninolytic enzyme, manganese (Mn) peroxidase. An immobilization technique
is described using cellulose and polypropylene as carrier for the fungal mycelium. High amounts of Mn peroxidase were obtained
with agitated cultures of immobilized fungus (up to 3,000 U l−1) while the biomass was recovered and used for further production cycles. Purification of Mn peroxidase revealed the existence
of two forms: MnP1 (molecular mass 43 kDa, pI 4.5) and MnP2 (42 kDa, pI 3.8).
Received: 30 July 1999 / Received revision: 1 December 1999 / Accepted: 3 December 1999 相似文献
6.
Polygalacturonases (PG) have evolved in the past years from a pectinase “simply” being used for food processing to an important
parameter in plant–fungal interaction. PG-inhibiting proteins (PGIP) that are synthesised in plants as a specific response
to PGs of pathogenic fungi, have become a focus as a possible target in resistance breeding, and PGIPs are also a concern
as an inhibiting factor in food processing. Plant PGs have been identified as a major factor in fruit ripening, and PG-deficient
transgenic plants have been bred. Mainly fungal PGs are used in industrial processes for juice clarification and the range
of enzymes is being extended through new recombinant and non-recombinant fungal strains. Finally, novel fields of application
can be envisaged for PGs in the production of oligogalacturonides as functional food components. Here we aim to highlight
the various fields where PGs are encountered and where they are of biological or technological importance.
Received: 22 June 1999 / Received revision: 4 October 1999 / Accepted: 10 October 1999 相似文献
7.
Spatiotemporal Patterns of Laccase Activity in Interacting Mycelia of Wood-Decaying Basidiomycete Fungi 总被引:3,自引:0,他引:3
Abstract
Interspecific fungal interactions are important ecological processes, whereas their physiological mechanisms are little understood.
The aim of this work was to study how activity of fungal extracellular laccase was changed across mycelia during interactions
between white- and brown-rot basidiomycetes from different wood decay stages. Qualitative assay of eight species interacting
with each other in all combinations showed four spatial patterns of laccase activity: (I) laccase activity present both in
contact zone and mycelium, (II) laccase activity only in contact zone, (III) laccase activity in mycelium but not in contact
zone, (IV) no laccase activity. Presence of laccase activity only in the contact zone was more frequent than expected from
random samples associated with mycelia that replaced other ones. On the other hand, the presence of laccase activity in the
mycelium but not in the contact zone was only attributed to fungal species that were replaced by their antagonists. After
one month, laccase activity was distributed over mycelia more homogeneously than after 6 days of interactions. In interacting
mycelia, laccase activity was higher than in control and increasing with time. Saprotrophic fungi from late successional stages
of wood decay generally had higher laccase activity than early succession saprotrophic and pathogenic fungi. The qualitative
assays were confirmed by quantitative assay of total laccase activity. Significance of the results in antagonistic fungal
interactions as well as in the processes of hyphal tip growth and mycelium senescence is discussed.
Received: 6 October 1999; Accepted: 1 February 2000; Online Publication: 5 May 2000 相似文献
8.
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
9.
Vanderberg LA Krieger-Grumbine R Taylor MN 《Applied microbiology and biotechnology》2000,53(4):447-452
Rhodococcus rhodochrous strain OFS grew on toluene as a sole source of carbon and energy with a maximum growth rate of 0.011 h−1. Initial reaction products were extracted, derivatized and identified by GC-MS. Oxygen consumption studies indicated that
OFS grown on an aliphatic substrate required an induction period before oxidizing toluene. OFS grown on toluene transformed
an array of aromatic ground water pollutants including styrene, ethylbenzene and chlorobenzene. Products of these transformations
were identified. The sole product of chlorobenzene biotransformation was 4-chlorophenol. Products from toluene oxidation included
3- and 4-methylcatechol as well as benzyl alcohol, p-cresol and cis-toluene dihydrodiol. The identification of these and the products of other aromatic substrate conversions affirm that oxidation
occurred on the functional group as well as directly on the aromatic nucleus.
Received: 23 July 1999 / Received revision: 4 October 1999 / Accepted: 16 October 1999 相似文献
10.
Keppler C Achterhold K Ostermann A van Bürck U Chumakov AI Rüffer R Sturhahn W Alp EE Parak FG 《European biophysics journal : EBJ》2000,29(2):146-152
Nuclear forward scattering of synchrotron radiation is used to determine the quadrupole splitting and the mean square displacement
of the iron atom in deoxymyoglobin in the temperature range between 50 K and 243 K. Above 200 K an abnormally fast decay of
the forward scattered intensity at short times after the synchrotron flash is observed, which is caused by protein-specific
motions. The results strongly support the picture that protein dynamics seen at the position of the iron can be understood
by harmonic motions in the low temperature regime while in the physiological regime diffusive motions in limited space are
present. The shape of the resonance broadening function is investigated. An inhomogeneous broadening with a Lorentzian distribution
indicating dipole interactions results in a better agreement with the experimental data than the common Gaussian distribution.
Received: 30 August 1999 / Revised version: 22 October 1999 / Accepted: 6 December 1999 相似文献
11.
Phylogenetic hypotheses of muscle actin evolution are significantly different when a sea urchin is used as a representative
echinoderm than when a sea star is used. While sea urchin muscle actins support an echinoderm–chordate sister relationship,
sea star sequences suggest that echinoderm muscle actins are convergent with chordate muscle actins. Our results suggest that
gene conversion in the sea star muscle actin may be responsible for these discordant results.
Received: 19 July 1999 / Accepted: 1 October 1999 相似文献
12.
Fernández MJ Adrio JL Piret JM Wolfe S Ro S Demain AL 《Applied microbiology and biotechnology》1999,52(4):484-488
Growth of Streptomyces clavuligerus NP1 in the presence of methanol or ethanol resulted in a marked increase in production of cephalosporin(s) from penicillin
G by resting cells. The mycelium produced in alcohol-supplemented medium was fragmented and dispersed as compared with growth
in control medium. HPLC analysis showed that at least two products were present in the biotransformation supernatant fluid
after 1 h incubation. One of them has been identified as deacetoxycephalosporin G (DAOG).
Received: 9 December 1998 / Received revision: 29 March 1999 / Accepted: 16 April 1999 相似文献
13.
Handedness in humans is possibly maintained by a frequency-dependent advantage during aggressive interactions. To contribute
to relevant data related to this idea, functional handedness has been measured in a traditional ethnic group (Ntumu) from
southern Cameroon, and confronted to the level of aggressive behavior. Functional handedness was measured by the hand holding
the machete, an asymmetric tool used every day. Aggressive behavior was assessed by the frequency of occurrence of the traditional
tribunal for solving internal conflicts. There was a low percentage of left-handers (8.1%), with no significant sex differences,
although females below 50 year old displayed a significant increase of left-handedness with age. The level of aggressive behavior
was low, as the traditional tribunal took place only seven times during the last five years. Results are discussed in the
context of the evolution of handedness and the possible recent societal changes following European colonisation.
Received: 20 August 1999 / Received in revised form: 22 October 1999 / Accepted: 6 November 1999 相似文献
14.
Microsporogenesis in Lilium longiflorum Thunb. is a naturally synchronous process and affords a system in which to study stage-specific events of meiosis and anther
development. Zymogram gel analyses were conducted with extracts from a variety of stages of anther development to identify
proteinases which likely play roles in anther metabolism. These experiments revealed that several proteinases are present
at different stages of anther development, and class-specific inhibitors were used to classify these enzymes. Proteolytic
activities increased as anther development proceeded and these activities were temporally correlated with the apoptotic events
which precede dehiscence, as well as with events crucial for the maturation of viable pollen.
Received: 12 October 1999 / Accepted: 13 November 1999 相似文献
15.
The cyt1Aa gene of Bacillus thuringiensis subsp. israelensis and binary toxin gene of Bacillus sphaericus C3-41 were introduced into an acrystalliferous strain of B. thuringiensis independently and in combination by using shuttle vector pBU4. SDS-PAGE and Western blot analysis proved that cyt1Aa and binary toxin genes coexpressed during the sporulation of the recombinant. Transformant strain expressing the Cyt1Aa and
binary toxin proteins in combination was more toxic to susceptible and resistant Culex pipiens quinquefasciatus than the transformants expressing Cyt1Aa protein or binary toxin proteins independently. It was suggested that large amount
of production of Cyt1Aa protein and binary toxin proteins possibly interacted synergistically, thereby increasing its mosquitocidal
toxicity significantly.
Received: 22 October 1999 / Accepted: 22 November 1999 相似文献
16.
Ligninolytic basidiomycetes were screened for their ability to reduce aryl acids to the corresponding aldehydes and alcohols.
Seven fungal strains converted p-anisic acid in high molar yields to the reduced products. The white-rot fungus Bjerkandera sp. strain BOS55 was one of the best reducing strains and was highly tolerant towards high concentrations of different aromatic acids. It
was tested for the reduction of p-anisic, veratric, 3-chloro-4-methoxybenzoic, 3,5-dichloro-4-methoxybenzoic, 3,4-dichlorobenzoic, 4-fluorobenzoic, and 3-nitrobenzoic
acids. All of these compounds were reduced to their corresponding aldehydes and alcohols.
Received: 22 March 1999 / Received revision: 12 July 1999 / Accepted: 1 August 1999 相似文献
17.
Pharmaceutically active secondary metabolites of microorganisms 总被引:23,自引:0,他引:23
Demain AL 《Applied microbiology and biotechnology》1999,52(4):455-463
The antibiotics have been useful in our battles against infectious bacteria and fungi for over 50 years. However, many antibiotics
are used commercially, or are potentially useful, in medicine for activities other than their antibiotic action. They are
used as antitumor agents, immunosuppressive agents, hypocholesterolemic agents, enzyme inhibitors, antimigraine agents, and
antiparasitic agents. A number of these products were first discovered as antibiotics which failed in their development as
such, or as mycotoxins. In addition to the above alternative applications, new powerful antibiotics have been discovered and
commercialized in recent years and others are in clinical testing at the moment. A few successful secondary metabolites appear
to have no antibiotic activity. The recently increased development of resistance to older antibacterial and antifungal drugs
is being met with the use or clinical testing of older, underutilized or previously nondeveloped narrow-spectrum antibacterial
products as well as powerful semisynthetic antifungal agents.
Received: 28 December 1998 / Received revision: 26 April 1999 / Accepted: 1 May 1999 相似文献
18.
Local therapy with interleukin-2 (IL-2) and other cytokines may be a very effective way to treat cancer. This was the theme
of the First Symposium on Local Cytokine Therapy of Cancer: Interleukin-2, Interferons and Related Cytokines, in Hamburg,
29 April–1 May 1999. The abstracts are published in Anticancer Research 19: 1995–2016 (1999) [1]. Here we present a report.
Received: 28 October 1999 / Accepted: 2 December 1999 相似文献
19.
Although studies in plant and animal cell culture systems indicate farnesylation is required for normal cell cycle progression,
how this lipid modification of select proteins translates into whole-organism developmental decisions involving cell proliferation
or differentiation is largely unknown. The era1 mutant of the higher plant Arabidopsis thaliana (L.) Heynh. offers a unique opportunity to understand the role farnesylation may play in regulating various processes during
the development of a multicellular organism. Loss of farnesylation affects many aspects of Arabidopsis growth and development. In particular, apical and axillary meristem development is altered and these phenotypes are contingent
on the growth conditions.
Received: 25 October 1999 / Accepted: 22 December 1999 相似文献
20.
Cloning of the cyclodextrin glucanotransferase gene from alkalophilic Bacillus sp. A2-5a and analysis of the raw starch-binding domain 总被引:2,自引:0,他引:2
The cyclodextrin glucanotransferase (CGTase) gene of alkalophilic Bacillus sp. A2-5a was cloned and expressed in Bacillus subtilis ANA-1 as a host. The DNA region included an open reading frame encoding a 704-amino-acid polypeptide with a typical raw starch-binding
motif in its C-terminal region. The CGTase purified from Bacillus sp. A2-5a bound to raw starch as strongly as porcine pancreas α-amylase, as expected from the sequence motif. A chromosomal
region (a DNA fragment of about 14.1 kbp) including the CGTase gene was also cloned and the nucleotide sequence was determined.
Possible cyclodextrinase and putative cyclodextrin-binding protein genes were found in the flanking region of the CGTase gene,
which implied that the novel starch-degradation pathway postulated for a gram-negative bacterium [Klebsiella oxytoca; Fiedler et al. (1996) J Mol Biol 256: 279–291] also exists in a gram-positive bacterium i.e. Bacillus.
Received: 6 August 1999 / Received last revision: 8 October 1999 / Accepted: 22 October 1999 相似文献