Antifungal activity of lactic acid bacteria isolated from fermented catfish (Clarias gariepinus) as biocontrol of sclerotium rolfsii infecting chili plants

Abstract

Sclerotium rolfsii is one of the most destructive soil-borne pathogen of chili plant (Capsicum annum) causing damping-off, stem rot, root rot, southern blight and wilt diseases. Severely infected chili plant diseases could reduce the quality and quantity of chili produce resulting in economic loss. Lactic Acid Bacteria (LAB) are reported to have antifungal activity. However, very little information is known on antifungal activity against S. rolfsii. Hence, the objectives of this study were to identify the LAB species isolated from fermented catfish and to determine antifungal activities of the isolated LAB against S. rolfsii. Identification of LAB from fermented catfish was done by API 50 CHL and 16S rRNA gene sequencing. The identified isolates were Lactobacillus plantarum with different strains name such as JCM 1149, WCFS1 strain WCFS1 and strain NRRL B-14678. In this study, nine cultures of Cell Free Supernatant (CFS-LAB) were tested for antifungal activity on Potato Dextrose Agar (PDA). Results showed that four of Lb. plantarum strains from fermented catfish showed greater inhibitory activity (60% to 64.7%) against S. rolfsii after incubation at 28�C for three days compared with the control treatment (S. rolfsii growth in PDA without CFS-LAB). Active compound present in the crude supernatant was partially purified using ammonium sulphate precipitation method were tested at different temperatures, pH and enzymes. The proteins of LAB bacteriocins were analysed by electrophoresis and band of interest were identified by Mass Spectrometry (LC-MS/MS) based on peptide sequencing. Findings of study confirmed that the antifungal activity of Lb. plantarum was chitin-binding protein and was effectively acted as biocontrol agent against fungal infection in chili plant. � 2018, Malaysian Society of Applied Biology. All rights reserved.