Thermostable α-amylase production by Bacillus licheniformis cells immobilized on polyacrylates with cyclic carbonate groups in the side chain

A considerable increase (up to 35%) of thermostable alpha-amylase yield was achieved by Bacillus licheniformis cells, immobilized on polymers containing cyclic carbonate groups in comparison to the synthesis by free cells. The increase of enzyme production was dependent on the manner of cell immobilization and on the kind of polymers used. The alpha-amylase yield by immobilized "growing" cells was higher than that reached by immobilized "washed" cells. The homopolymer poly [(2-oxo-1,3-dioxolan-4-yl) methyl 2-propenoate] and especially its methyl derivative were found to be more suitable for bacterial cell immobilization than the copolymer N-vinyl-pyrrolydone poly [(2-oxo-1,3-dioxolan-4-yl) methyl 2-propenoate]. After 576 h (4 cycles) of repeated batch fermentations, all biocatalysts used showed approximately equal alpha-amylase activity (2000 U/ml), corresponding to 60-80% residual activity depending on the kind of the biocatalyst.