Antibacterial potential of extracts and metabolites isolated from the endophytic fungus Chaetomium cochliodes against phytopathogenic bacteria
Author:
Saad M.M.G.1, Abdelgaleil S.A.M.1
Affiliation:
1. Department of Pesticide Chemistry and Technology , Faculty of Agriculture, El-Shatby, Alexandria University , Alexandria , Egypt .
Abstract
Summary
Five fungal endophytes, Alternaria sp., Aspergillus sp., Chaetomium sp., Rhizopus sp. and Curvularia sp., were isolated from an Egyptian herbaceous plant, Tribulus terrestris, and tested for their antibacterial activity against three phytopathogenic bacteria (Pectobacterium carotovorum subsp. carotovorum, Ralstonia solanacearum, Pseudomonas syringae pv. syringae). Chaetomium sp. showed the highest antibacterial activity. This strain was identified morphologically and molecularly as Chaetomium cochliodes MS03 (MW898133) based on the ITS1-5.8S rRNA-ITS2 genomic region. Chaetomium cochliodes caused 15 and 8 mm inhibition zones of P. carotovorum subsp. carotovorum and R. solanacearum, respectively. Chaetomium cochliodes isolate was fermented and extracted with ethyl acetate. The crude extract of C. cochliodes showed strong antibacterial activity against P. carotovorum subsp. carotovorum (inhibition zone = 27 mm). Bioassay guided isolation of the crude extract using silica gel column chromatography was conducted to isolate bioactive secondary metabolites. Minimum inhibitory concentrations (MICs) were 500, 32 and 4 mg/L for C. cochliodes extract, fraction 14 and fraction 15, respectively, against P. carotovorum subsp. carotovorum. Bioactive fractions were analyzed by GC/MS. The bioactive pure compound was identified as 9,12-octadecadienoic acid (Z,Z) and the chemical structure was confirmed by H1 NMR and C13 NMR spectral analysis. The isolated compound showed a promising antibacterial activity against P. carotovorum subsp. carotovorum with MIC value of 32 mg/L.
Publisher
Walter de Gruyter GmbH
Reference51 articles.
1. Arnold, A.E., Maynard, Z., Gilbert, G.S. Coley, P.D. and Kursar, T.A. 2000. Are tropical fungal endophytes hyper diverse? Ecology Letters, 3: 267-274. 2. Atmosukarto, I., Castillo, U., Hess, W.M., Sears, J. and Strobel, G. 2005. Isolation and characterization of Muscodor albus I-41.3s, a volatile antibiotic producing fungus. Plant Sciences, 169: 854–861. 3. Barnett, H. and Hunter, B. 1998. Illustrated genera of imperfect fungi; A comprehensive resource for recognizing, identifying, and learning various aspects of imperfect fungi (4th ed). St. Pau, MN: APS Press. 4. Blechert, S., Brodschelm, W., Hölder, S., Kammerer, L., Kutchan, T.M., Mueller, M.J., Xia, Z.Q. and Zenk, M.H. 1995. The octadecanoic pathway: Signal molecules for the regulation of secondary pathways. Proceeding of the National Academy of Sciences USA, 92: 4099–4105. 5. Bultreys, A. and Kaluzna, M. 2010. Bacterial cankers caused by Pseudomonas syringae on stone fruit species with special emphasis on the pathovars syringae and morsprunorum race 1 and race 2. Journal of Plant Pathology, 92: 21−33.
|
|