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Summary Gibberellin (GA) production inFusarium moniliforme (Gibberella fujikuroi) is suppresed by adding the plant growth retardant CCC [(2-chloroethyl)trimethylammonium chloride] to the culture medium. A concentration of 0.1 mg/l of CCC causes 50% inhibition whereas 10 mg/l and higher concentrations fully suppress GA production. Dry weight of the mycelium is not, or only slightly reduced in the presence of CCC.Thin-layer chromatography of acidic fractions of CCC-free cultures reveals fluorescent spots at 4 differentR
f
values. No fluorescent spots can be detected on chromatograms of acidic fractions obtained from CCC cultures, thus demonstrating that production of all GA's is inhibited by CCC.If CCC is added to the medium 2 or 3 days after inoculation, further GA production is blocked, but the level of GA present at the time of CCC application is maintained. CCC does not enhance inactivation of GA3 in sterile culture medium, nor in the presence of the fungus. It is therefore concluded that CCC inhibits the biosynthesis of GA in the fungus.Transfer of thoroughly washed mycelium from medium with CCC to fresh medium does not result in GA production because sufficient CCC is carried over in the mycelium to block GA biosynthesis completely. 相似文献
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Elena Alonso-Fernandes Helga Fernández-Llamosas Irene Cano Cristina Serrano-Pelejero Laura Castro Eduardo Díaz Manuel Carmona 《Microbial biotechnology》2023,16(5):915-930
Pollution by metalloids, e.g., tellurite and selenite, is of serious environmental concern and, therefore, there is an increasing interest in searching for ecologically friendly solutions for their elimination. Some microorganisms are able to reduce toxic tellurite/selenite into less toxic elemental tellurium (Te) and selenium (Se). Here, we describe the use of the environmentally relevant β-proteobacterium Aromatoleum sp. CIB as a platform for tellurite elimination. Aromatoleum sp. CIB was shown to tolerate 0.2 and 0.5 mM tellurite at aerobic and anaerobic conditions, respectively. Furthermore, the CIB strain was able to reduce tellurite into elemental Te producing rod-shaped Te nanoparticles (TeNPs) of around 200 nm length. A search in the genome of Aromatoleum sp. CIB revealed the presence of a gene, AzCIB_0135, which encodes a new methyltransferase that methylates tellurite and also selenite. AzCIB_0135 orthologs are widely distributed in bacterial genomes. The overexpression of the AzCIB_0135 gene both in Escherichia coli and Aromatoleum sp. CIB speeds up tellurite and selenite removal, and it enhances the production of rod-shaped TeNPs and spherical Se nanoparticles (SeNPs), respectively. Thus, the overexpression of a methylase becomes a new genetic strategy to optimize bacterial catalysts for tellurite/selenite bioremediation and for the programmed biosynthesis of metallic nanoparticles of biotechnological interest. 相似文献
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The pair correlation function g(r) is an important tool in exploratory data analysis and model choice in point process statistics. In the case of cluster processes, the behaviour of g(r) for small r is particularly interesting. But just these values of g(r) can be estimated with difficulties only. This paper tries to show that kernel estimators yield reliable results. It is useful to work with variable band widths. An example where the points are positions of pines in a forest illustrates the application of the method. 相似文献
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