Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2005
Publication Date: 4/19/2005
Citation: Smith, M.R., Zahnley, J.C. 2005. Production of amylase by arthrobacter psychrolactophilus. Journal of Industrial Microbiology and Biotechnology. 32:277-283:56
Interpretive Summary: Amylases which are active at low or moderate temperatures are needed to reduce costs of producing ethanol from starch or increase efficiency of other processes that require starch hyrdrolysis at ambient temperatures. We described the production of amylase by a cold-tolerant bacterium that can grow at 0 degrees C to determine the type, number and best time to harvest cultures for amylase. Amylase production was transient in cultures on starch, maltose or no added sugars. Glucose inhibited amylase production. A single type of mesophilic alpha amylase was apparently made which had a temperature optimum between 40 and 50 deg. C on soluble starch in 3-hr assays. Purified starch-binding proteins from the cultures had molecular weights of 105 and 26 kDa. This amylase would be useful for processes that operate above 20 degrees C.
Technical Abstract: Arthrobacter psychrolactophilus ATCC 700733 grew with doubling time of 1.5 to 2.3 hrs (22 deg C) and produced up to 0.2 units/ml (soluble starch) of extracellular amylase in Tryptic Soy Broth without dextrose (TSBWD) in cultures containing 0.5% or 1.0% (w/v) soluble starch or maltose as the fermentable substrate. Time-course experiments showed that amylolytic activity appeared within 24 hrs, reached peak levels in 72-96 hrs, and declined rapidly thereafter. Peak levels were highest in TSBWD/1.0% soluble starch. Proteolytic activity appeared at the same time as amylase. Significant amylase was not observed in TSBWD/0.5% glucose or in cultures incubated at 28 deg. C. Native PAGE and in situ staining for activity produced a single band. The amylase bound to raw corn,wheat or potato starch. SDS PAGE revealed two starch-binding proteins. Activity had a temperature optimum of 40-50 deg C.