Antibacterial Activities of Endophytic Fungi from Capsicum annuum L. (Siling labuyo) leaves and fruits

Abstract

Endophytic fungi were isolated from Capsicum annuum (siling labuyo) from three ecological zones in the province of Albay, Philippines and were identified through morpho-cultural characteristics and by molecular analysis of the internal transcribed spacer (ITS) region of the 18S ribosomal DNA. Eight fungal endophytes were isolated from the leaves and fruits. Seven were identified as Colletotrichum gloeosporioides, Lasiodiplodia pseudotheobromae, Nigrospora sphaerica, Guignardia mangiferae, Coprinopsis cinerea, Colletotrichum siamense and Colletotrichum truncatum while one remained unidentified. The extracted metabolites from the isolates were then screened for their antibacterial activities at 1,000 µg/mL. Among the fungal isolates, C. cinerea was found to be the most active against Staphylococcus aureus and Escherichia coli with zones of inhibition (ZOI) of 16.00 ± 1.00 and 17.00 ± 1.53 mm, respectively. Phytochemical screening showed that C. cinerea produced a variety of secondary metabolites such as flavonoids, alkaloids, terpenoids and quinones. The other fungal endophytes were also found to synthesize various secondary compounds that may be responsible for their antibacterial activities.