By: Lisangan MM1,2, Syarief R1, Rahayu WP1,Dharmaputra OS3,4
1 Faculty of Agricultural Engineering and Technology, Bogor Agricultural University
2 Faculty of Agricultural and Agricultural Technology, The State University of Papua
3 Faculty of Mathematics and Natural Sciences, Bogor Agricultural University
4Southeast Asian Regional Centre for Tropical Biology (SEAMEO BIOTROP)- Indonesia
The objective of this study was to investigate the chemical composition and antifungal activity of kebar grass polar extract and its effect on the mycelial growth, conidiation and morphological structure of two isolates of aflatoxigenic Aspergillus flavus, i.e. isolates BCCF0219 and AF1. A total of 64 components were identified using pyrolysis/gas chromatography/mass spectrometry (Py/GC/MS), consisting of a class of carboxylic acids (7.81%), amina (1.56%), phenolics (26.56%), terpenes (15.60%), alcohols (10.94%), hydrocarbons compounds (20.3 %), benzene derivatives (6.25%), carbohydrate derivatives (4.69%), steroidal saponin (1.56%), haloalkane (1.56%), and sterols (3.13%).In the bioassay, the two isolates of A. flavus were cultured on three types of model media, i.e. fat-enriched medium, protein-enriched medium and carbohydrate-enriched medium containing five concentrations (12, 14, 16, 18, and 20 mg/mL) of kebar grass polar extract. The changes of hyphae structure and conidiation were observed usingScanning Electron Microscopy (SEM). The results showed that the percentage of growth inhibition of A. flavus isolate BCCF0219 caused by kebar grass polar extracts at a concentration of 14 mg/mL was 95.5% (in fat-enriched medium), whereas at a concentration of 12 mg / mL was 95.7% (in carbohydrate-enriched medium) and a concentration of 14 mg/mL was 91.0% (in protein-enriched medium). The percentage of growth inhibition of A. flavusisolate AF1 caused by the extract at a concentration of 16 mg/mL was 100% (in fat-enriched medium),while at a concentration of 12 mg / mL was 91.4% (in carbohydrate-enriched medium) and at a concentration of 16 mg/mL was 94.3% (in protein-enriched medium). A marked retardation in conidial production of the fungus was noticed in relation to the inhibition of mycelial growth. Under scanning electron microscopy, deformation of hyphae tips, formation of short branches, thinner hyphae, folded hyphae and collapse of entire hyphae were the major changes observed. Morphological alterations might be due to the effect on cell permeability through the direct interaction between kebar grass extract and the fungal plasma membrane. These findings indicate the potential of kebar grass leaf extract in preventing aflatoxigenic A. flavus infection and minimize aflatoxin contaminationin stored food and feedstuff.
Keywords: Aspergillus flavus, Biophytum petersianum, growth inhibitor, morphological structure, Scanning Electron Microscopy
Presented at International Symposium on Tropical Fungi, Mikoina. Bogor 10-11 September 2013