In recent years, a wide range of microbial metabolites have been used for industrial production world wide for human welfare. Pullulan is one of the important microbial metabolite produced by Aureobasidium pullulans , a polymorphic fungus, all over the world. Pullulan is a linear homopolymer composed of maltotriose subunits interconnected with glycosidic linkages. This polymer is being exploited in food, cosmetic, medical and pharmaceutical industries including manufacture of biodegradable plastics. This work aims at improvement of Aureobasidium pullulans strain through mutation as well as immobilization for increased production of pullulan in fermentation system. The book will shed some light on current industrial aspects of microbiology especially fermentation technology and will be of great use to students as well as all those interested in the subject.