A novel cold‐adapted pullulanase from Exiguobacterium sp. SH3: Production optimization, purification, and characterization. Issue 3 (23rd August 2013)

• Record Type: Journal Article
• Authors: Rajaei, Sarah; Heidari, Reza; Shahbani Zahiri, Hossein; Sharifzadeh, Sara; Torktaz, Ibrahim; Akbari Noghabi, Kambiz
• Is Part Of: Stärke. Volume 66:Issue 3/4(2014)
• Page Start: 225
• Page End: 234
• Publication Date: 2013-08-23
• Subjects: Starch -- Periodicals; 572.566
• DOI: 10.1002/star.201300030
• Languages: English
• ISSNs: 0038-9056

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="star201300030-sec-0001" sec-type="section"> <p>Cold‐adapted enzymes, elaborated by psychrophiles and psychrotrophs, seem to have potential for current and future applications. In the current study, pullulanase production by the cold‐adapted <italic>Exiguobacterium</italic> sp. SH3 was investigated. The Plackett–Burman design and the response surface methodology were applied to identify and optimize the significant variables affecting the pullulanase production of <italic>Exiguobacterium</italic> sp. SH3. The results showed that temperature, time, and CaCl<sub>2</sub> concentration were significant variables while shaking, starch, yeast extract, tryptone, pH, MnCl<sub>2</sub>, MgCl<sub>2</sub>, and KH<sub>2</sub>PO<sub>4</sub> were not significant. Using statistical analyses and optimizations, the pullulanase production was significantly elevated from 200 ± 18 to 950 ± 27 U/mL (4.75 times) as compared to non‐optimized conditions. A pullulanase of about 70 kDa, designated as Pul‐SH3, was purified 16.2‐folds from the optimized culture, and identified to be an amylopullulanase. The <italic>K</italic><sub>m</sub> and <italic>V</italic><sub>max</sub> of the enzyme were 0.069 mg/mL and 967 U/mL, respectively. The optimum pH and temperature for maximum activity of Pul‐SH3 were 7.5 and 30°C, respectively. As a cold‐adapted enzyme, Pul‐SH3 retained 23% of the maximum activity at 0°C. The biochemical characteristics and N‐terminal amino acid sequence of Pul‐SH3 suggest that the enzyme is a novel cold‐adapted amylopullulanase with remarkably high specific activity at moderate ambient temperature.</p> </sec> </abstract>