Production of antimicrobial compounds from endophytic microorganisms of sweetpotato
2007
Tan, J.D. | Sanchez, E.L. Jr., Leyte State Univ., Baybay, Leyte (Philippines). Philippine Root Crop Research and Training Center | Tanaka, M. | Katayama, T. | Azano, K. | Tomita, F., Hokkaido Univ., Sapporo 060 (Japan). Lab. of Applied Microbiology
This study isolated endophytic microorganisms with antimicrobial properties from sweetpotato (SP) grown in the Philippines. Endophytic microorganisms were isolated from surface-sterilized stem cuttings of selected Philippine SP varieties such as BSP-SP-17, BSP-SP-22, and NSIC-SP-25. The isolates were purified and tested for antimicrobial activities by using spot and streak inoculation methods against Lasiodiplodia theobromae (SP rot-causing mold), Colletotrichum gloeosporioides (yam anthracnose-causing mold), Diplodia natalensis (watermelon and citrus stem end rot-causing mold and Bacillus subtilis (potato soft rot-causing bacteria). Twenty-one isolates (12 bacteria and 9 fungi) exhibited antimicrobial activities against one or more indicator microorganisms tested. Through 16S rDNA sequencing analyses, the bacteria were identified as Bacillus megaterium, Bacillus pumilis, Microbacterium arborescens, Micrococcus luteus, and Bacillus subtilis. The fungi were also identified as Phomopsis sp., Aspergillus sp., Penicillium sp., and two belonging to Mycosphaerellaceae and Polyporaceae families, through their partial 26S rDNA and ITS region sequencing analyses. The supernatant of these isolates were further tested against the aforementioned indicator microorganisms and four other types of indicators such as B. subtilis AHU 2035,m A. flavus var. asper AHU 7051, Alternaria sp. S-1, and C. albicans CA14. All identified isolates possessed wide spectrum of activities against the indicator microorganisms. B. subtilis, B. megaterium, Penicillium sp., and one isolate belonging to Mycosphaerellaceae family were able to inhibit six or more of the indicator microorganisms tested.
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