Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/13477
Title: Genetic studies on a soil streptomyces sp. that produces an antifungal compoud
Authors: NACHAMMA SOCKALINGAM
Keywords: Antifungal, Complex polyketides, PKS I gene cluster, Modules, Gene disruption and Internal fragments
Issue Date: 6-Feb-2004
Source: NACHAMMA SOCKALINGAM (2004-02-06). Genetic studies on a soil streptomyces sp. that produces an antifungal compoud. ScholarBank@NUS Repository.
Abstract: In an effort to identify novel antifungal compounds, soil isolates from different parts of Singapore were screened and several isolates had been identified in an earlier study. One such isolate was 98- 62. The aim of the current study is to study the genes responsible for the biosynthesis of the antifungal compound produced by the soil isolate 98-62. As several of the antifungal compounds synthesized by bacterial strains are encoded by PKS I genes, it was postulated that the antifungal compound produced by the soil isolate 98-62 could also be encoded by PKS I genes. When the genomic DNA of the soil isolate 98- 62 was probed with PKS I specific genes, strong multiple hybridizing bands were observed as is characteristic of PKS I genes. Furthermore, thin layer chromatography separation of the antifungal compound produced by the soil isolate 98-62 compared to the Rf values of complex polyketides rapamycin and FK506. Complex polyketides are encoded by PKS I genes. By homology based approach, a total of 11.6 kb of contiguous PKS I genes were then cloned from the soil isolate 98- 62 and characterized. Sequence analysis of the cloned genes confirmed that a partial cluster of PKS I genes, spanning 2 partial open reading frames, encompassing one complete and two partial modules of PKS I genes had been cloned. To prove the functional involvement of the cloned PKS I genes in the biosynthesis of the antifungal compound, gene disruption using four different gene fragments of the cloned PKS I genes were carried out. Gene disruption experiment using internal fragments of the cloned PKS I genes abolished the antifungal compound production. This work provides functional evidence that the antifungal compound produced by the soil isolate 98- 62 is encoded by the cloned partial PKS I cluster of genes.
URI: http://scholarbank.nus.edu.sg/handle/10635/13477
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