Whole cells of Teredinobacter turnirae were immobilized onto different sizes of porous sintered glass SIRAN. Production of alkaline protease by the immobilized whole cells was attempted in a batch system. Alkaline protease activity produced by immobilized whole cells was about 2.3 times higher than that produced by freely suspended cells under the same cultivation conditions. The reusability of the immobilized and freely suspended cells was examined. The activity of alkaline protease produced by freely suspended cells decreased with increasing use cycles while the activity of immobilized cells increased gradually and reached a steady state after 4 cycles. T turnirae cells immobilized on different matrices were observed by scanning electron microscopy and the distribution of the cells on each matrix used either in and/or on the internal pores observed. (C) 2003 Elsevier Science Ltd. All rights reserved.