ISSN 2736-1756
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (3), pp. 001-006, March, 2019. © International Scholars Journals
Full Length Research Paper
The antifungal mechanism of Bacillus subtilis against Pestalotiopsis eugeniae and its development for commercial applications against wax apple infection
Hsiu Fen Lin1, Tsang Hai Chen2, and Shan Da Liu3*
1Graduate Institute of Bioresources, National Pingtung University of Science and Technology, Pingtung 912, Taiwan, Republic of China.
2Department of Plant Medicine, National Pingtung University of Science and Technology, Pingtung 912, Taiwan, Republic of China.
3Graduate Institute of Health and Biotechnology Industry, Meiho University, Pingtung 912, Taiwan, Republic of China.
Accepted 16 February, 2019
Abstract
The inhibition zones of three Bacillus subtilis isolates, BS-99, BS-23857 and BS-33608 against Pestalotiopsis eugeniae were, 13.5, 0, and 0 mm, respectively. BS-99 showed the strongest inhibitory activity, whereas, no inhibitory activity was reported for BS-23857 or BS-33608. The spore germination rates of P. eugeniae were not significantly inhibited by n-hexane, ethyl acetate (EtOAc), or methanol (MeOH) extracts of the fermentation broths of BS-99, BS-23857, and BS-33608. However, the hyphae of P. eugeniae became swollen and malformed after 12 h and stopped growing after 30 h of treatment with the MeOH extract of the BS-99 fermentation broth. Analysis by polymerase chain reaction (PCR), blood agar test plates, and high performance liquid chromatography (HPLC) indicated that, BS-99 produced the antibiotics, iturin A and surfactin, whereas, BS-23857 and BS-33608 only produced surfactin. These data suggest that, the antifungal activity of the B. subtilis BS-99 isolate against P. eugeniae is activated only when both iturin A and surfactin are present and not by surfactin alone. Unveiling the antifungal mechanism of B. subtilis, BS-99 could promote its commercial development and application as a biofungicide for controlling P. eugeniae infections of the wax apple, which is a highly valued fruit in Taiwan.
Key words: Bacillus subtilis, iturin A, solvent extract, surfactin.