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Using filtration enrichment techniques, an Aspergillus terreus arginine auxotrophic strain which contains a mutation that abolishes ornithine transcarbamylase (OTCase) activity has been isolated. This mutant has been genetically transformed with the cloned Aspergillus nidulans OTCase gene. Prototrophic transformants arose at a frequency of about 50 transformants per microgram of plasmid DNA. Southern blot analysis of DNA from the transformants showed that the transforming DNA was ectopically integrated at different locations in the A. terreus genome, often in multiple tandem copies. The transformants were phenotypically stable for several mitotic divisions and retained their capacity to produce extracellular enzymes. 相似文献
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Varicuothiols A and B,New Fungal Metabolites from Aspergillus versicolor with Anti‐Inflammatory Activities 下载免费PDF全文
《化学与生物多样性》2018,15(1)
Chemical examination of a coral‐associated fungus Aspergillus versicolor LZD‐44‐03 resulted in the isolation of two new compounds with the trivial names of varicuothiols A ( 1 ) and B ( 2 ) as a unique scaffold. Their structures were determined through extensive spectroscopic analyses in association with the modified Mosher's method and chemical conversion. Both 1 and 2 exhibited significant inhibition against LPS‐induced RAW24.7 cell proliferation, in association with the down regulation of nitrite production and cytokines (MCP‐1, IL‐6, and TNF‐α). 相似文献
5.
Microbial phytase is used to reduce the environmental loading of phosphorus from animal production facilities. The limiting
factors in the use of this enzyme in animal feeds can be overcome by solid-state fermentation (SSF), which is a promising
technology for commercial enzyme production with lower production costs. Inoculum quality and the influence of inoculum quality
on phytase production are important factors which need in-depth investigation before scaling-up of high-yielding fermentation
process. A full factorial experimental design for 240 h with sampling at every 24 h was used to determine the effects of the
treatments, inoculum age (plate and liquid culture), media composition and the duration of SSF on the production of fungal
biomass and phytase in SSF systems using Aspergillus niger. The optimal treatment combination for maximal phytase production was determined by statistically comparing all treatments
at each sampling time. Both 7- and 14-day plate cultures and M1+ medium composition with 72-h-old liquid inoculum treatments
resulted in optimal phytase production at 144 h of SSF, which was the shortest duration observed for maximal phytase production.
This resulted in maximal phytase production with a mean of 884±121 U/g substrate, while the maximal phytase production observed
at 216 h of SSF (mean phytase activity of 1008±121 U/g substrate), with the same treatment combinations, was not statistically
significant from that at 144 h of SSF. Phytase production was strongly growth-associated with younger inocula. The significant
treatment variables, age of liquid inoculum and the duration of SSF, were used to predict the system response for phytase
production using response surface methodology. From the response surface model, the optimal response of the experiment was
predicted and the reliability of the prediction was checked with the verification experiment. Journal of Industrial Microbiology & Biotechnology (2001) 26, 161–170.
Received 06 June 2000/ Accepted in revised form 14 October 2000 相似文献
6.
ABSTRACT. Gynes and males of Lasius flavus Fab. were taken from the nest as they eclosed, and at intervals thereafter until the mating flight, and their respiration was measured. After the mating flight respiration was measured in gynes at various stages of colony foundation. Respiration in gynes rose rapidly to a peak as they began to accumulate food reserves for colony foundation. Subsequently, the respiratory rate declined and remained at a low level until the mating flight and during the claustral phase of colony foundation. Once the colony was well established and the queen actively laying, the respiratory rate returned to that at the beginning of maturation. Males showed smaller changes in their respiratory rates, which were generally higher than those of the gynes. The variation in respiration in males seemed to be due to increasing restlessness as the time of the mating flight approached. 相似文献
7.
Pyruvate carboxylase has been found in the mitochondrial fraction of two strains of Aspergillus niger along with the marker enzymes of citrate synthase and cytochrome c oxidase. The location of pyruvate carboxylase in A. nidulans was, however, confirmed to be in the cytosolic fraction. The enzyme from the former sources was dependent upon the presence of acetyl-CoA for full activity; the enzyme from A. nidulans was unaffected by the presence or absence of acetyl-CoA. 相似文献
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The uvsC gene of Aspergillus nidulans is a homolog of the RAD51 gene of Saccharomyces cerevisiae. However, with respect to its effects on UV mutagenesis, it differs from the yeast gene, since it seems to be required for
UV mutagenesis; however, this conclusion is based only on data from resting conidia. To further clarify the functional role
of the uvsC gene, we tested the UV mutability of strains bearing a uvsC mutation in resting as well as in germinating conidia, by the p-fluoro-phenyl-alanine resistance test. We also evaluated the mutability of the uvsE mutant which belongs to the same epistatic group. Our results show that the uvsC and uvsE genes do not have a significant role in the mutagenic UV-repair pathway.
Received: 20 January 1998 / Accepted: 22 April 1998 相似文献
10.
Urea, added at 2 to 20 mg/g in solid bran medium supporting growth of Aspergillus oryzae and Rhizopus oligosporus, led to a higher concentration of NH4
+ and pH but a decrease in biomass production.The authors are with the Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 61000 Ljubljana, Slovenia. 相似文献