Fungal cells immobilized with ballooned polyacrylonitrile (PAN) microsphere (MS) on an interface between a liquid medium and a hydrophobic organic solvent efficiently catalyze various microbial transformations such as hydrolysis, reduction, hydroxylation, and epoxidation of lipophilic substrates dissolved in the organic phase (liquid-liquid interface bioreactor; L-L IBR). In this study, the electric charge of MS layer in the L-L IBR was modified by mixing 4 kinds of anion-exchange, 2 kinds of cation-exchange or a chelating resin microparticles, and applied to regio- and stereoselective subterminal hydroxylation of n-decane to (-)-4-decanol by Monilliera sp. NAP 00702. In general, the addition of cation-exchange and chelating resin microparticles into a PAN-MS layer led to the strong inhibition of fungal growth and hydroxylation activity. On the other hand, the addition of anion-exchange resin microparticles having moderate total capacity (<= 1.00 meq/g) significantly increased hyphal growth and hydroxylation activity. Especially, the addition of IRA910CT microparticles (total capacity >= 1.00 meq/g) into a PAN-MS layer led to 1.6-fold increase of 4-decanol production. Thus, it was concluded that the moderate addition of anion-exchange resin microparticles into an MS layer in the L-L IBR system was effective to enhancement of fungal growth and hydroxylation activity. (C) 2012 Elsevier Ltd. All rights reserved.