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Category: Environmental Microbiology; Applied and Industrial Microbiology
Screening for Bioactivity, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817770/9781555812676_Chap30-1.gif /docserver/preview/fulltext/10.1128/9781555817770/9781555812676_Chap30-2.gifAbstract:
The present situation in the screening for bioactive compounds is determined by the nearly unlimited capacity in the throughput of assays. The assays include classical antibacterial assays, classical antifungal assays, antitumor assays, enzyme inhibititory assays, antiparasitic assays, herbicidal assays, and algicidal assays. Alexander Fleming was one of the first scientists who used the agar plate diffusion assay to detect antibacterial activity. Most assays are focused on the inhibition of the polysaccharide network of the cell wall of many fungi, which consists of β-1,3-glucan, chitin, and mannan. One of the most promising new antifungals that were detected as glucan synthase inhibitors is the echinocandin lipopeptide group. Antitumor assays for high-throughput screening are mainly based on the specific inhibition of factors belonging to regulatory cascades. Such assays include the inhibition of protein-tyrosin phosphatases, which control the cell cycle or the inhibition of protein-tyrosin kinases. Chemical screening is focused on the chemical diversity produced by microorganisms and on the assumption that each secondary metabolite produced has or had a biological function in the producing organism. Zahner and coworkers modified the method with regard to staining reagents, sample preparation, and variation of culture conditions of the microorganisms, and his group described numerous secondary metabolites having antibacterial, antifungal, antitumor, enzyme inhibitory, or insecticidal activities.
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Agar plate diffusion assay using Bacillus subtilis as the test organism and agar pieces from actinomycetes cultures. Reprinted from Zahner (1965) by permission of Springer-Verlag.
Agar plate diffusion assay using Bacillus subtilis as the test organism and agar pieces from actinomycetes cultures. Reprinted from Zahner (1965) by permission of Springer-Verlag.
Agar plate diffusion assay using Streptomyces viridochromogenes as the test organism. Test solutions are applied on filter disks.
Agar plate diffusion assay using Streptomyces viridochromogenes as the test organism. Test solutions are applied on filter disks.
Structure of rifampin, a semisynthetic therapeutic agent against tuberculosis.
Structure of rifampin, a semisynthetic therapeutic agent against tuberculosis.
Thienamycin, a broad-spectrum antibacterial beta-lactam antibiotic produced by Streptomyces cattleya.
Thienamycin, a broad-spectrum antibacterial beta-lactam antibiotic produced by Streptomyces cattleya.
Bulging or curling effect caused by inhibitors of the fungal cell wall biosynthesis on the hyphae of Botrytis cinerea; (a) normal hyphae, (b) abnormal hyphae.
Bulging or curling effect caused by inhibitors of the fungal cell wall biosynthesis on the hyphae of Botrytis cinerea; (a) normal hyphae, (b) abnormal hyphae.
Structure of bleomycin, an antitumor antibiotic produced by Streptomyces verticillatus.
Structure of bleomycin, an antitumor antibiotic produced by Streptomyces verticillatus.
HMG-CoA reductase inhibitors of the compactin type (statins), isolated from various fungi.
HMG-CoA reductase inhibitors of the compactin type (statins), isolated from various fungi.
Structures of anthelminthic avermectins produced by Streptomyces avermitilis.
Structures of anthelminthic avermectins produced by Streptomyces avermitilis.
Structure of simocyclinones (antibacterial and antitumor antibiotics), inhibitors of gyrase and protein kinase, produced by Streptomyces antibioticus Tü 6040.
Structure of simocyclinones (antibacterial and antitumor antibiotics), inhibitors of gyrase and protein kinase, produced by Streptomyces antibioticus Tü 6040.