Citation:Madhushika, D. P. H., Jayasundara, J. M. N. M.,Ratnaweera, P. B.,Williams, D. E.,de Silva, E. D. and Andersen, R. J. (2020). Antibacterial activities of peptaibols, trichocellin A-I and B-II, isolated from the endophytic fungus Trichoderma reesei. In: International conference on Frontiers in Chemical Technology 2020. Institute of Chemistry Ceylon, p.30.
Date:2020
Abstract:
Antibiotics are highly used in chemotherapy for bacterial infections worldwide. However, due to
misuse and overuse of antibiotics pathogenic bacteria have developed and continue to develop
resistance to the existing antibiotics rendering them ineffective. Thus there is an urgent need to
develop new types of antibiotics to counter the spread of these lethal, drug resistant infections.
Endophytic fungi of Cyperaceae plants are a relatively unexplored but a significant resource for the
discovery of new biologically active natural products. Therefore, the main objective of this study
was to isolate bioactive secondary metabolites of the endophytic Trichoderma reesei (GenBank
accession number MT476871) fungus isolated from Cyperus iria in Sri Lanka. Initial screening of
T. reesei showed antibacterial activity against the Gram positive Bacillus cereus and Staphylococcus
aureus at 400 μg/mL. T. reesei was grown in large scale and extracted into ethyl acetate following an
incubation period of 13 days. Solvent-solvent partitioning of the crude extract (1005 mg) led to an
active chloroform fraction (580 mg), which was chromatographed on Sephadex LH20 size exclusion
column chromatography. The active fraction B (143 mg) from the six fractions (A-F) obtained from
size exclusion chromatography was further purified via C18 reversed-phase high performance liquid
chromatography (HPLC) to yield two peptaibols. The structures of the peptaibols were determined
as trichocellin A-I and B-II by nuclear magnetic resonance (NMR) and mass spectral data. Both
peptaibols A-I and B-II were active against the two Gram positive bacteria tested with minimum
inhibitory concentrations (MICs) of 64 and 8 μg/mL for B. cereus and 32 and 16 μg/mL for S. aureus
respectively. The positive control Gentamycin gave a MIC of 2 μg/mL for both bacteria. To the best
of our knowledge this is the first study to isolate trichocellins from an endophytic T. reesei fungus.
The study revealed that the isolated trichocellins from T. reesei are potent antibacterial compounds.
