A Study on the Antimicrobial Potentials of an Endophytic Fungus Fusarium oxysporum NFX 06 Sogra Fathima Musavi and Raj Mohan Balakrishnan National Institute of Technology Karnataka/Department of Chemical Engineering, Mangalore, India Email: fathima.musavi, rajmohanbala @gmail.com Abstract —Endophytes are fungi associated with plants without causing symptoms. They are quite diverse in nature and have enormous potential for production of important secondary metabolites for the pharmaceutical industry. Thus the aim of this work was to isolate an endophytic fungal strain possessing antimicrobial activity against the selected human pathogens. In this study we report for the first time microwave assisted extraction of secondary metabolites from an endophytic fungal strain NFX06 isolated from leaf of Nothapodytes foetida of Agumbe forest, Karnataka. The fungal strain was identified as Fusarium oxysporum NFX06 based on its macroscopical and microscopical characteristics. Further confirmation of the species was done by Internal Transcribed Spacer (ITS) sequencing and the nucleotide sequence was submitted to the GenBank with an accession number KC914432. The highest activity against all the four pathogenic strains [Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922) Pseudomonas aeruginosa (ATCC 27853) and Candida albicans (ATCC 69548)] were exhibited by ethyl acetate extract with a Minimum Bactericidal Concentration (MBC) of about 30μg/mL against Staphylococcus aureus and a Minimum Fungicidal Concentration (MFC) of about 50μg/mL against Candida albicans. Index Terms—endophytic fungi, sequencing, microwave extraction, minimum inhibitory concentration, Nothapodytes foetida I. INTRODUCTION Plants and fungi are the chief source of natural compounds used for medicine, in which medicinal plants and endophytes have attracted considerable interest for their wide variety of bioactive metabolites [1]-[3]. Demain and Sanchez [4] reported that production of bioactive secondary metabolites by medicinal plants and their endophytes have provided countless for therapeutic applications. The discovery of novel antimicrobial metabolites from endophytes is an important alternative to overcome the increasing levels of drug resistance by plant and human pathogens [5], [6].The antimicrobial compounds can be used as drugs and also as food preservatives in the control of food spoilage and food- borne diseases [7]. Bacon and White [8] described endophytes are microbes that colonize living, internal tissues of plants without causing any immediate, overt negative effect. It Manuscript received August 8, 2013; revised October 9, 2013. was estimated there may be as many as 1.5 million different fungal species on our planet [9]. Of these only about 10% have been discovered and nearly 1% is examined for their production of secondary metabolites. Endophytic fungi represent an important and quantifiable component of fungal diversity, with an estimate of at least 1 million species [10]-[12]. They are found in nearly all plant families and have been investigated to be a rich source of novel biological active secondary metabolites such as antibiotics, antimycotics, immunosuppressants, and anticancer compounds [13]. These compounds may have potential for use in modern medicine, agriculture, and industry. Thus endophytic fungi are considered to be rich and reliable source of genetic diversity with novel and undescribed species [14]. In this study an attempt has been made to isolate fungal endophytes of a medicinal plant Nothapodytes foetida (Wights) Sleumer, Syn. N. nimmoniana, Mappia foetida Miers, Premna nimmoniana Graham commonly known as “Amrutha’ a medicinal plant of the family Icacinaceae [15]. It is a small tree distributed in the Western Ghats, a global bio diverse hot spot. As herb it was widely used in Indian traditional medicine for various types of cancers, HIV, malaria and few bacterial infections. Considerable efforts are in progress to map its populations in India since it has been classified as a ‘vulnerable’ species, as reported by Kumar and Ved [16]. Hence the aim of the present study was to screen endophytic fungal isolates possessing antimicrobial activity and also to determine the increase in efficiency of microwave assisted extract of NFX 06 strain. II. MATERIALS AND METHODS A. Collection of Plant Materials Figure 1. Nothapodytes foetida Journal of Medical and Bioengineering Vol. 3, No. 3, September 2014 162 ©2014 Engineering and Technology Publishing doi: 10.12720/jomb.3.3.162-166 Fusarium oxysporum, ITS