Electron microscopy of hydrogen producing immobilized E-cloacae IIT-BT 08 on natural polymers

Possibilities of using lignocellulosic agroresidues as solid support matrix for immobilization of E cloacae HT-BT 08 are explored for the production of pollution free gaseous fuel hydrogen. Among the three lignocellulosic carriers used, coir was found to be the best in terms of cell retention (4.4 x 10(11) cells/g dry carrier), packing density (100 g/l reactor volume) and cell loading (44 g dry cell/l reactor volume). Electron microscopic studies showed that the exopolysaccharide secreted by the cells facilitated both aggregation and adsorption of the cells on solid matrix. They also showed that coir had a higher cell density as compared to other support matrices, The immobilized cells showed surface associated growth, compression and binary fission under anaerobic condition. Among the three lignocellulosic carriers used for hydrogen production, coir gave the highest rate of production (62 mmol/l h) as compared to rice straw (44 mmol/l h) and bagasse (52 mmol/l h). In another study the Cu2+ and Zn2+ contents of the anaerobic H-2 producing cells were found to be higher as compared to the aerobic non-H-2 producing cells. (C) 2001 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.