The addition of anion-exchange resin microparticles into a polyacrylonitrile (PAN) ballooned microsphere layer drastically enhanced the fermentative activity of Trichoderma atroviride AG2755-5NM398 in an extractive liquid-surface immobilization (Ext-LSI) system. The production of 6-pentyl-alpha-pyrone (6PP), a fungicidal secondary metabolite, was 1.92-fold higher than the control (PAN alone). (C) 2012, The Society for Biotechnology, Japan. All rights reserved.