Detection and Expression of Biosynthetic Genes in Actinobacteria ...
Detection and Expression of Biosynthetic Genes in Actinobacteria ...
Detection and Expression of Biosynthetic Genes in Actinobacteria ...
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BERVANAKIS, G.Chapter 4: DISCUSSIONglycerol favour antimicrobial activity, whereas liquid media supplemented withvarious ref<strong>in</strong>ed oils enhanced antimicrobial activity. Solid substrate fermentationswere found to <strong>in</strong>crease the heterogeneity <strong>of</strong> metabolites expressed as well as <strong>in</strong>creaseantibacterial activity. It was established that a general fermentation medium for SMscreen<strong>in</strong>g could not be identified, as <strong>in</strong>dividual isolates had preferred cultivationconditions.The correlation between antimicrobial activity <strong>and</strong> TLC b<strong>and</strong>s was successfullyperformed us<strong>in</strong>g bioautography. UV-Vis spectroscopic studies were useful <strong>in</strong> partiallyidentify<strong>in</strong>g similar chemical species present <strong>in</strong> the organic extracts. RP-HPLC wasused to separate the chemical species present <strong>in</strong> the microbial extracts it was shownthat extracts A1113 <strong>and</strong> A0350 conta<strong>in</strong>ed identical chromatograms, with two majorpeaks adjacent to one another conta<strong>in</strong><strong>in</strong>g the same chromaphore <strong>in</strong>dicat<strong>in</strong>g thepresence <strong>of</strong> one compound. LC/MS analysis <strong>of</strong> organic extracts A0350 <strong>and</strong> A1113showed identical chromatograms with molecular ions at m/z 1253 to 1255. Based onthe molecular weights <strong>and</strong> UV spectrum <strong>of</strong> the compounds, <strong>and</strong> the visible color <strong>of</strong>the extracts, the active compounds <strong>in</strong> both extracts appear to belong to act<strong>in</strong>omyc<strong>in</strong> Dor one <strong>of</strong> it’s isomers. Evaluation <strong>of</strong> A2381 organic extract by RP-HPLC <strong>in</strong>dicated thepresence <strong>of</strong> a number <strong>of</strong> non-polar compounds which may have been responsible forthe antibacterial activity. Two major compounds with molecular ions at m/z 425.5 <strong>and</strong>385.3 were identified by LC/MS analysis, these compounds could represent a number<strong>of</strong> compounds such as the act<strong>in</strong>opyrones, Antibiotic YL 01869P, Antibiotic WP 3688-5 or derivatives <strong>of</strong> trichostat<strong>in</strong>. HPLC comb<strong>in</strong>ed screen<strong>in</strong>g <strong>of</strong> UV-Visible <strong>and</strong> massspectrometric detection <strong>of</strong>fers a accurate analysis <strong>of</strong> constituents <strong>in</strong> organic extracts<strong>and</strong> partially characteris<strong>in</strong>g compounds. The active compounds identified as a result<strong>of</strong> chemical screen<strong>in</strong>g would need to be produced <strong>in</strong> larger quantities <strong>in</strong> order toelucidate the chemical structures._____________________________________________________________________133
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