7-60: Identification of novel xylanase genes from fungi in wood and beetle guts in Indonesia

Xylanases are one target for improvement of commercial cellulase preparations. From 2009 to 2011, we isolated over 1500 microbes from the rain forest in Sulawesi, Indonesia, including filamentous fungi from the guts of wood-feeding beetle larvae (Scarabidae, Lucanidae, Passalidae, Buprestidae, Brentidae and others), beetle galleries in wood, and decaying wood. Filamentous fungi were identified by ribosomal sequencing, and included Fusarium, Trichoderma/Hypocrea, Lasiodiplodia, Nectria, Neonectria, Penicillium, and other genera. Xylanase and arabinase activities were detected using AZCL-conjugated substrates. Most filamentous fungi were able to digest xylan. Homologs of known xylanase gene fragments were amplified using degenerate PCR primers. A variety of xylanase sequences were detected, which either clustered with previously known sequences or in new clades. Stability of xylanase activity in culture supernatants belonging to various sequence clades was evaluated after exposure to industrially-relevant conditions such as elevated temperature, acid, base, and solvents. Fungi collected from tropical wood-feeding beetles and decaying wood frequently expressed xylanase that is stable at low pH but not high pH, and active after exposure to 40^oC but rarely 60^oC. The search continues, using samples recently collected at hot springs in Sulawesi, Indonesia.