FUNGAL MICROBIOLOGY Antifungal Volatile Organic Compounds from the Endophyte Nodulisporium sp. Strain GS4d2II1a: a Qualitative Change in the Intraspecific and Interspecific Interactions with Pythium aphanidermatum Rosa Elvira Sánchez-Fernández 1 & Daniel Diaz 2 & Georgina Duarte 3 & Patricia Lappe-Oliveras 4 & Sergio Sánchez 5 & Martha Lydia Macías-Rubalcava 1 Received: 15 June 2015 /Accepted: 15 September 2015 /Published online: 26 September 2015 # Springer Science+Business Media New York 2015 Abstract This study demonstrates volatile organic com- pounds (VOCs) production as one of the defense mech- anisms of the antagonistic endophyte Nodulisporium sp. GS4d2II1a, and the volatile changes in two times of the fungal growth; and, as result of its intra and interspe- cific interactions with the plant pathogen Pythium aphanidermatum. The antifungal activity of the volatile and diffusible metabolites was evaluated by means of three types of antagonism bioassays and by organic ex- tract agar dilution. VOCs were obtained by gas chroma- tography coupled to mass spectrometry from 3- and 5- day Nodulisporium sp. cultures, as well as from its in- terspecific in vitro antagonistic interaction with the oomycete P. aphanidermatum, and its intraspecific Nodulisporium sp.–Nodulisporium sp. interaction. The GS4d2II1a strain completely inhibited the growth of two fungi and seven oomycetes by replacing their mycelia in simple antagonism bioassays and by produc- ing in vitro volatile and diffusible metabolites that acted synergistically in multiple antagonism bioassays. Additionally, VOCs inhibited the growth of three oomycetes and one fungus in antagonism bioassays using divided plates. A total of 70 VOCs were detected, mainly including mono and sesquiterpenes, especially eucalyptol and limonene. Multiple correspondence anal- ysis revealed four different volatile profiles, showing that volatiles changed with the fungus age and its intra and interspecific interactions. The metabolites produced by Nodulisporium sp. GS4d2II1a could be useful for biological control of fungal and oomycetes plant patho- gens of economically important crops. Keywords Endophytic fungus . Nodulisporium sp. . Hypoxylon anthochroum . Antifungal . VOCs . Interspecific interaction Introduction Many microorganisms generate a variety of volatile organic compounds (VOCs) with biological activity. Among them, fungi produce volatile compounds with antifungal activity that have potential applications in medicine, industry, and in agri- culture [1]. Endophytic fungi–microorganisms that live inside plant tissues without causing disease symptoms or displaying outward signs of habitation are capable to produce secondary metabolites with antibiotic activity, such as, nonvolatile and volatile compounds [2, 3]. Fungal volatiles mediate ecological relationships such as intra and interspecific communication and as defense compounds [4, 5]. In addition, endophytic * Martha Lydia Macías-Rubalcava mmacias@iquimica.unam.mx 1 Instituto de Química, Departamento de Productos Naturales, Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, Coyoacán, D.F. 04510, Mexico 2 Instituto de Investigaciones Biomédicas, Departamento de Biología Celular y Fisiología, UNAM. Ciudad Universitaria, Coyoacán, D.F. 04510, Mexico 3 Facultad de Química, Unidad de Servicios de Apoyo a la Investigación, UNAM. Ciudad Universitaria, Coyoacán, D.F. 04510, Mexico 4 Instituto de Biología, Departamento de Botánica, UNAM. Ciudad Universitaria, Coyoacán, D.F. 04510, Mexico 5 Instituto de Investigaciones Biomédicas, Departamento de Biología Molecular y Biotecnología, UNAM. Ciudad Universitaria, Coyoacán, D.F. 04510, Mexico Microb Ecol (2016) 71:347–364 DOI 10.1007/s00248-015-0679-3