Chapter 28 : Putting Microorganisms to Work

Abstract:

By isolating the first glutamine and glutamate auxotrophs of Klebsiella aerogenes, the author's research group discovered that the glutamate dehydrogenase activity could be eliminated without major consequence to cell growth. They showed that an additional mutation was needed to inactivate a second enzyme, glutamate synthase, to create a glutamate requirement. Recombinant DNA methods changed more than our ability to unravel the mysteries of microbial genetics. Microorganisms were used to make a panoply of products from interleukins for treating cancer to phenylalanine for manufacturing the sweetener aspartame to enzymes for cleaning drains. The study of cold-active enzymes could lend insight into the basic features that set an enzyme's thermostat for activity. Some isolates belong to previously undiscovered bacterial genera and species based on their physiological properties and 16S ribosomal RNA gene sequences. The group screened the isolates for cold-active enzymes such as glycosidases, phosphatases, and proteases. In one case, three different genes were cloned, each encoding an unusual β-galactosidase, from one Arthrobacter isolate. The study of psychrophilic organisms is just one example of an understudied but important area just waiting for future microbiologists to probe. Discoveries through basic research of unique lifestyles continually amaze us, and new biotechnology products await adventurers with the skill to develop them.