Detection and Expression of Biosynthetic Genes in Actinobacteria ...

BERVANAKIS, G.Chapter 3: RESULTSTable 50: Fermentation analysis, depicting the antimicrobial activities for supernatantand mycelial extracts of the Cerylid environmental actinobacterial isolates.IsolateZones of Inhibition*Optimal OptimalNumberSupernatantMycelial ExtractFermentation FermentationS. aureus M. luteus C. albicans S. aureus M. luteus C. albicans Medium~ Time (hr)A0350 ++ +++ + ++ +++ + Dextrin 240A1113 ++ +++ ++ +++ +++ ++ 153 240A2381 ++ +++ ++ +++ +++ +++ Dextrin 240A3675 N/D N/D + N/D N/D 21.5 153m 168A0347 N/D ++ N/D N/D ++ N/D IM25 240A2707 N/D ++ N/D N/D ++ N/D IM25 240* Zones of Inhibition: + 8 – 15 mm, ++ 16 – 25 mm, +++ >25 mm, - no inhibitionN/D: no zones of inhibition detected~ ingredients for fermentation media described in the materials and methods (Table 28)The optimal fermentation time was determined by taking samples of the medium at24 hour intervals and analyzing the broth supernatant and mycelial extract in welltype antibacterial assays (section 2.7.2). The different types of liquid productionmedia influenced the chemical expression of metabolites (Table 50). Fermentationproduction media which showed enhanced or induced antimicrobial activitiesincluded Dextrin, 153 and IM25. In other cases where the same culture wasinoculated into different liquid production media antimicrobial activity was reducedor not detectable. This effect was observed in SI and 153m liquid media.3.2.3 Improving Antimicrobial Metabolite Productionin Low Yielding Actinobacteria Cultures3.2.3.1 Solid-Substrate Fermentations (SSF)Actinobacterial cultures exhibiting low antimicrobial activity in liquid mediafermentations were also subjected to solid-substrate fermentations, to determine if theproductivity of metabolites could be enhanced. Table 51 indicates that inoculating lowyielding actinobacterial cultures into solid state media either suppressed or enhancedantimicrobial activities depending on the fermentation conditions. Only isolate A2707culture showed an increased antimicrobial effect due to the solid substrate._____________________________________________________________________99