Konthorn Kachanuban. Characterization of bioactive compounds produced by actinobacteria isolated from mangrove forest soil samples in Thailand. Master's Degree(Fishery Science and Technology). Kasetsart University. Office of the University Library. : Kasetsart University, 2022.
Characterization of bioactive compounds produced by actinobacteria isolated from mangrove forest soil samples in Thailand
Abstract:
The recent lack of discovery of novel antibiotics and the increase of antibiotic-resistant microorganisms present significant problems in infectious disease therapy. The mangrove forest ecosystem is an important natural source of novel organisms that have high potential to produce bioactive compounds. This study focuses on screening and identification of antimicrobial compound-producing actinobacteria from mangrove sediment samples, determination of some optimal parameters for antimicrobial compound production, as well as characterization of the antimicrobial compounds produced. Among a total of 22 isolates isolated from seven sediment samples, Streptomyces iconiensis OUCMDZ-5511, which was identified by colony morphology and 16S rRNA gene sequence, displayed the broadest antimicrobial spectrum against eight target indicator bacteria. An ethyl acetate (EtOAc) extract from culture broth of S. iconiensis OUCMDZ-5511 had the highest antibacterial activity against B. subtilis ATCC 6051, determined by agar well diffusion method, when this strain was cultured in A1 broth with initial pH of 9.0 and 0% NaCl. According to bioassay-guided chromatography, three interesting antimicrobial compounds, namely 2(3H)-benzothiazolone, indole-3-acetic acid and lumichrome were obtained from culture broth EtOAc extract of S. iconiensis OUCMDZ-5511 after purification by HPLC and structure identification by ESI-MS and NMR. However, only lumichrome showed broad-spectrum antibacterial activity against S. Weltevreden, S. aureus, B. subtilis, M. luteus and E coli, with MIC and MBC values ranging from 0.125 to 0.5 mg/mL and 0.25 to 1.0 mg/mL, respectively. Notably, this study is the pioneer report on identification of 2(3H)-benzothiazolone, indole-3-acetic acid, and lumichrome in EtOAc extract from culture broth of S. iconiensis.
Kasetsart University. Office of the University Library