AUTHOR=Li Jingjing , Sang Moli , Jiang Yutong , Wei Jianhua , Shen Yulong , Huang Qihong , Li Yaoyao , Ni Jinfeng 

TITLE=Polyene-Producing Streptomyces spp. From the Fungus-Growing Termite Macrotermes barneyi Exhibit High Inhibitory Activity Against the Antagonistic Fungus Xylaria

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.649962

DOI=10.3389/fmicb.2021.649962

ISSN=1664-302X

ABSTRACT=<p>Fungus-growing termites are engaged in a tripartite mutualism with intestinal microbes and a monocultivar (<italic>Termitomyces</italic> sp.) in the fungus garden. The termites are often plagued by entomopathogen (<italic>Metarhizium anisopliae</italic>) and fungus garden is always threatened by competitors (<italic>Xylaria</italic> spp.). Here, we aim to understand the defensive role of intestinal microbes, the actinomycetes which were isolated from the gut of <italic>Macrotermes barneyi</italic>. We obtained 44 antifungal isolates, which showed moderate to strong inhibition to <italic>Xylaria</italic> sp. HPLC analysis indicated that different types of polyenes (tetraene, pentene, and heptaene) existed in the metabolites of 10 strong antifungal <italic>Streptomyces</italic> strains. Two pentene macrolides (pentamycin and 1′14-dihydroxyisochainin) were firstly purified from <italic>Streptomyces</italic> strain HF10, both exhibiting higher activity against <italic>Xylaria</italic> sp. and <italic>M. anisopliae</italic> than cultivar <italic>Termitomyces</italic>. Subsequently, tetraene and heptaene related gene disruption assay showed that the mutant strains lost the ability to produce corresponding polyenes, and they also had significantly decreased activities against <italic>Xylaria</italic> sp. and <italic>M. anisopliae</italic> compared to that of wild type strains. These results indicate that polyene-producing <italic>Streptomyces</italic> from the guts of <italic>M. barneyi</italic> have strong inhibition to competitor fungus and polyenes contribute to inhibitory effects on <italic>Xylaria</italic> sp.</p>