TITLE:
Antifungal Activity of Compounds Isolated from Bamboo Vermicompost against Rhizoctonia solani AG1-IB
AUTHORS:
Xiaodong You, Daigo Wakana, Kazuki Ishikawa, Tomoo Hosoe, Motoaki Tojo
KEYWORDS:
Antifungal Compound, Ergosterol Peroxide, Vermicompost, Rhizoctonia solani AG1-IB
JOURNAL NAME:
Advances in Microbiology,
Vol.9 No.12,
November
27,
2019
ABSTRACT: Vermicompost
has become a promising alternative to chemical pesticide because of its disease
suppression effect during these decades. However, the mechanisms by which vermicompost suppress plant
disease are not well-understood. Antifungal compounds, which
are released by beneficial organisms in the vermicompost, may play an important
role in inhibiting plant pathogens; however, these mechanisms have not been
widely examined. In this study, Sterilized Water Extracts of bamboo vermicompost
(SWE), using a 0.22-μm cellulose acetate filter, significantly (P Rhizoctonia solani AG1-IB
on a Potato Dextrose Agar (PDA) plate. This suggests that antifungal compounds
are present in bamboo vermicompost. The ethanol acetate (EtOAc) crude extracts
of bamboo vermicompost showing antifungal activity were further separated. Two
compounds were isolated from the EtOAc fraction of bamboo vermicompost and characterized as ergosterol peroxide (1)
and (22E, 24R)-5α,8α-epidioxyergosta-6,9(11),22-trien-3β-ol (2). Their chemical structures and mass spectra were
determined by nuclear magnetic resonance and mass spectrometry analyses.
Ergosterol peroxide tested at 150, 300, 600, and 900 μg showed 13%, 22%, 34%,
and 53% mycelial growth inhibition against R. solani AG1-IB, respectively.
Because EtOAc crude extracts of the initial substrate materials of bamboo
vermicompost did not inhibit mycelium growth of R. solani AG1-IB,
antifungal compounds in the vermicompost may be released by microbes but not
from the original substrates during vermicomposting.