The review deals with phytase-producing microorganisms along with optimum conditions for its production. Various methods used for purifying phytases and their characteristics are discussed. Heterologous gene expression, cost-effective large-scale phytase production, and various biotechnological applications of the enzyme in animal feed and food industries are also discussed.

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Glucoamylase is one of the oldest and widely used biocatalysts in food industry. The major application of glucoamylase is the saccharification of partially processed starch/dextrin to glucose, which is an essential substrate for numerous fermentation processes and a range of food and beverage industries. Glucoamylase for commercial purposes has traditionally been produced employing filamentous fungi, although a diverse group of microorganisms is reported to produce glucoamylase, since they secrete large quantities of the enzyme extracellularly. The commercially used fungal glucoamylases have certain limitations such as moderate thermostability, acidic pH requirement, and slow catalytic activity that increase the process cost. Consequently, the search for newer glucoamylases and protein engineering to improve pH and temperature optima leading to amelioration in catalytic efficiency of existing enzymes have been the major areas of research over the years. The present review focuses attention on the recent advances in molecular biology and protein engineering of glucoamylase to improve its production and functional properties including the so far success achieved in isolating mutants with enhanced thermostability and selectivity, higher pH optimum and improved catalytic activity. A comprehensive account is included on the diversity, regulation of production, classification, purification and properties, and potential applications of microbial glucoamylases to provide an overview on all the important aspects of the enzyme.

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Microbes belonging to the phylum Actinobacteria are prolific sources of antibiotics, clinically useful bioactive compounds and industrially important enzymes. The focus of the current review is on the diversity and potential applications of thermophilic and alkaliphilic actinobacteria, which are highly diverse in their taxonomy and morphology with a variety of adaptations for surviving and thriving in hostile environments. The specific metabolic pathways in these actinobacteria are activated for elaborating pharmaceutically, agriculturally, and biotechnologically relevant biomolecules/bioactive compounds, which find multifarious applications.

Industrial enzyme market has been projected to reach US$ 6.2 billion by 2020. Major reasons for continuous rise in the global sales of microbial enzymes are because of increase in the demand for consumer goods and biofuels. Among major industrial enzymes that find applications in baking, alcohol, detergent, and textile industries are α-amylases. These are produced by a variety of microbes, which randomly cleave α-1,4-glycosidic linkages in starch leading to the formation of limit dextrins. α-Amylases from different microbial sources vary in their properties, thus, suit specific applications. This review focuses on the native and recombinant α-amylases from bacteria and archaea, their production and the advancements in the molecular biology, protein engineering and structural studies, which aid in ameliorating their properties to suit the targeted industrial applications.

Aim: An investigation was carried out on the production of a-amylase by Bacillus thermooleovorans NP54, its partial puri®cation and characterization. Methods and Results: The thermophilic bacterium was grown in shake¯asks and a laboratory fermenter containing 2% soluble starch, 0Á3% tryptone, 0Á3% yeast extract and 0Á1% K 2 HPO 4 at 70 C and pH 7Á0, agitated at 200 rev min À1 with 6-h-old inoculum (2% v/v) for 12 h. When the enzyme was partially puri®ed using acetone (80% [v/v] saturation), a 43Á7% recovery of enzyme with 6Á2-fold puri®cation was recorded. The K M and V max (soluble starch) values were 0Á83 mg ml À1 and 250 mmol mg À1 protein min À1 , respectively. The enzyme was optimally active at 100 C and pH 8Á0 with a half-life of 3 h at 100 C. Both a-amylase activity and production were Ca 2 independent. Conclusions: Bacillus thermooleovorans NP54 produced calcium-independent and thermostable a-amylase. Signi®cance and Impact of the Study: The calcium-independent and thermostable aamylase of B. thermooleovorans NP54 will be extremely useful in starch sacchari®cation since the a-amylases used in the starch industry are calcium dependent. The use of this enzyme in starch hydrolysis eliminates the use of calcium in starch liquefaction and subsequent removal by ion exchange.

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