D Rao, A Swamy, G SivaRamaKrishna
amylases, beta amylases, bioprocess technology and production, gluco amylases
D Rao, A Swamy, G SivaRamaKrishna. Bioprocess technology Strategies, Production and Purification of Amylases: An overview. The Internet Journal of Genomics and Proteomics. 2006 Volume 2 Number 2.
The Present paper deals with bioprocess strategies involved in the production of Amylases from different microbial sources. Amylases purification and different sources sub categories of amylase production discussed in detailed .The paper also deals with Glucoamylase, Molecular Biology of Amylases , and application of commercially available enzymes.
Amylases are among the most important enzymes and are of great significance in present-day biotechnology. Although they can be derived from several sources, such as plants, animals and microorganisms, the enzymes from microbial sources generally meet industrial demands. Microbial amylases could be potentially useful in the pharmaceutical and fine-chemical industries if enzymes with suitable properties could be prepared. Interestingly, the first enzymes produced industrially were an amylase from a fungal source in 1894, which was used as a pharmaceutical aid for the treatment of digestive disorders . With the advent of new frontiers in biotechnology, the spectrum of amylase application has widened in many other fields, such as clinical, medicinal and analytical chemistries, as well as their widespread application in starch analytical chemistries, as well as their widespread application in starch saccharification and in the textile, food ,brewing and distilling industries. Some of the applications of commercial available enzymes available enzymes are summarized in Table1.
Amylases have most widely been reported to occur in microorganisms, although they are also found in plants and animals. Two major classes of amylases have been identified in microorganisms, namely ? -Amylase and Glucoamylase. In addition, ? -amylase and, which is generally of plant origin, has also been reported from a few microbial sources. ? -Amylases (endo-1,4-?--D-glucan glucohydrolase,EC 220.127.116.11) are extra cellular enzymes that randomly cleave the 1,4- ? -D-glucosidic linkages between adjacent glucose units in the linear amylase chain. These are endozymes that split the substrate in the interior of the molecules and are classified according to their action and properties. For examples, amylases that produce free sugars are termed ‘saccharogenic' and those that liquefy starch without producing free sugars are known as ‘starch-liquefying' . ? Amylases (?-1,4-glucan maltohydrolase,EC 18.104.22.168) is usually of plant origin, but a few microbial strains are also known to produce it. It is an exoacting enzymes that cleaves non-reducing chain ends of amylase, amylopectin and glycogen molecules. It hydrolyses alternate glycosidic linkages, yielding glycosidc linkages maltose (? meric form).Since ? amylase is unable to by pass -1,6-glycosidic ? linkages in amylopectin, it results in incomplete degradation of the molecule, yielding 50-60% maltose and limit dextrin. Glucoamylase (synonym amyloglucosidasse, ‘glucanogenic enzymes','starch glucogenase' and ‘Y-amylase'; exo-1,4
α -Amylase may be derived from several bacteria, yeasts and fungi. Bacterial amylase, however, is generally reefed over fungal amylase due to several characteristic advantages that it offers. Strain of
Unlike other members of the amylase family, only a few attempts have been made to study β amylases of microbial origin a few attempts have been made to study β amylase have generally been obtained from plant sources. Bacterial strains belonging to
They can be derived from a number of sources, such as plants , animals and microorganisms. Commercial need, however, is met by glucoamylase obtained from microbial sources. Filamentous fungi apparently constitute the major source of glucoamylase among all microbes.
Production of Amylases
Although several microorganisms can produce amylases, it remains a challenging task to obtain a strain is the most significant factor in the amylase production process. Sometimes a single strain can produce more than one enzyme, i.e. alpha-amylase as well as glucoamylase. For example, the strains of
Production of α-Amylase
The cell- immobilization technique has also been employed for α-amylase production. Lvanova
Production of β-Amylase
β-amylase are usually of plant origin, and not much work has been done on the production of β-amylase using microorganisms. Some of the microorganisms reported to produce β-amylase include
Production of Glucoamylase
Extensive work has been carried out on the production of glucoamylases in solid cultures using
Purification of amylases
Enzyme application in pharmaceutical and clinical sectors requires high purity amylases. Thus, it is significant to developed economic process for their purification to obtain chemically pure enzymes with maximum specific activity. Traditionally the purification of amylases from fermentation media has been done in several steps, which include centrifugation of the culture (a step of extraction may be required for solid media), selective concentration of the supernatant usually by ultra filtration, and selective precipitation of the enzyme by ammonium sulphate or organic solvents such as ethanol in the cold. Then the crude enzyme is subjected to chromatography (usually affinity or ion-exchange chromatography) and gel filtration.
Molecular Biology of Amylases
Genetic engineering has been used extensively for cloning of amylase producing strains, mainly α-amylase and GA, in order to achieve desirable characteristics in the cloned host. The purpose of gene cloning can be, amongst other, the expression of thermostable enzymes, higher enzyme productivity and co-expression of two enzyme by the same organism. A great deal of work has been done on the cloning of α-amylase genes in different microbes, mostly in
Dr.D.Muralidhara Rao Asst.Professor Department of Biotechnology Srikrishnadevaraya University Anantapur 515003 A.P. India email@example.com http://www.sku-biotech.org