An overview presentation is made on current global status of microbial isoamylase, a potent enzyme used in food industries, their production, properties and applications. Although few microbial sources were reported to produce extra cellular isoamylase, the Pseudomonas isoamylases were mostly studied. Microbial isoamylases in general showed affinity mostly towards glycogen and amylopectin but not towards pullulan. The end products were maltotriose and malto oligosaccharides often with maltose and glucose. The purified enzymes showed the molecular weight 60-120 kDa and activity was shown only by the monomers. The isoamylases showed varied temperature and pH optima. Adsorbability onto raw starch by the enzyme made its purification more convenient. Saccharification potential of isoamylases was employed in food industries for preparation of high glucose syrup from starch. The isoamylase gene from Pseudomonas amyloderamosa and Flavobacterium odoratum KU was cloned into Saccharomyces cerevisiae and in E. coli, respectively. Further studies are going on gene sequencing and characterization of the isoamylase produced mainly from bacterial sources.