Abstract: Reports are not available for immobilization of on α-amylase produced by Bacillus subtilis, Agrobacterium tumefaciens, Escherichia coli, Xanthomonas campestris, Staphylococcus aureus, Aspergillus niger, Aspergillus flavus, Metarhizium anisopliae, Azotobacter chroococcum and Rhizopus oryzae on coconut coir. Hence, an attempt was made in present study to immobilize the free amylase on coconut coir. Cell bound amylase of Bacillus subtilis, Escherichia coli, Xanthomonas campestris, Aspergillus niger, Aspergillus flavus and Rhizopus oryzae were immobilized by entrapment in calcium alginate. The immobilized enzyme on cells showed higher α-amylase production compared to free cells. The enzyme was characterized by Thin Layer Chromatography (TLC) and confirmed as alpha amylase. A simple and inexpensive method for immobilizing α-amylase on coconut fiber was also adopted. Highest amylase activity was observed in X. campestris on immobilized state on coconut fibers (1.708±0.103 U/min/g) and also in alginate matrix (0.948±0.082 U/min/100 beads). Hence, the cells of X. campestris were mutated with UV (for different time intervals: 1, 2, 4 and 8 min) and acridine orange (in different concentrations: 1, 2, 4 and 8 μg mL-1). The immobilized catalyst of mutant strain of X. campestris AO4 on alginate matrix exhibited 66.31% (4.125±0.056 U/min/100 beads) higher than that of the parent strain. It exhibited highest activity, when immobilized on coconut coir. Thus the mutant strain of X. campestris AO4 could be used in industries for the efficient conversion of starch to oligosaccharides.