Cloning and starch degradation profile of maltotriose-producing amylases from Streptomyces species
The end products from starch hydrolysis by amylases have important applications in various industries. Here, two amylases derived from two Streptomyces species that hydrolyze soluble starch from potato produced maltotriose as the primary maltooligosaccharide product. The genes, annotated as putative glycoside hydrolases, were cloned and expressed in Streptomyces lividans. These amylases displayed hydrolysis activity from pH 3 to 9.5 and were not affected by Ca2+. Optimal production of maltotriose was between 20 and 30 °C at pH 6.5. At the optimal temperature, both amylases produced maltotriose-rich end products rather than either maltose or maltotetraose.
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There is much interest in the study and production of nondigestible oligosaccharides (NDOs), due to their bioactivities and beneficial effects to the human health. The main approach in the production of NDOs relies on the action of glycosidases performing hydrolysis or transglycosylation of polysaccharides and sugars. In this chapter, a description of the main microbial glycosidases used for NDOs production, their sources, their principal properties, and a description of the production processes with the better results obtained are discussed.
Contractor Failure: Analysis
The possibility exists for any construction contractor to fail to filfill the contract requirements associated with a facility. Contractor failure occurs when a contractor is unable to perform his/her contractual duties, thus requiring the facility owner to invoke the contract's nonperformance clause. This paper provides aggregate contractor business failure statistics and outlines potential causes for failure. A framework to identify and quantify the associated costs is also introduced. Several case studies are presented to examine the cause and cost of failure and the means by which the facilities were completed. Alternatives available for project completion when contractor failure occurs are discussed. Recommendations to identify and monitor contractors at high risk for failure are outlined as well. This paper provides facility owners with a greater awareness of the possibility of contractor failure, how to quantify costs of contractor failure, and avoidance techniques.