Optimisation of batch culture conditions for cyclodextrin glucanotransferase production from Bacillus circulans DF 9RReportar como inadecuado




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Microbial Cell Factories

, 1:3

First Online: 12 September 2002Received: 12 July 2002Accepted: 12 September 2002

Abstract

BackgroundThe extracellular enzyme cyclodextrin glucanotransferase CGTase synthesizes cyclic malto-oligosaccharides called cyclodextrins CDs from starch and related α-1,4-glucans. CGTases are produced by a variety of bacteria, mainly Bacillus species, by submerged culture in complex medium. CGTases differ in the amount and types of CDs produced. In addition, CGTase production is highly dependent on the strain, medium composition and culture conditions. Therefore we undertook this study with a newly isolated strain of Bacillus circulans.

ResultsCGTase activity produced from Bacillus circulans DF 9R was optimised in shake flasks using a combination of conventional sequential techniques and statistical experimental design. Effects of nutrients, including several carbon, nitrogen and mineral sources, were assayed. The selected minimal medium consisted of 1.5 % cassava starch, 0.4 % ammonium sulphate, 0.1 M phosphate buffer, 0.002 % MgSO4 and 0.002 % FeSO4. The optimal concentrations of carbon and nitrogen sources were determined using a central composite design. Maximum CGTase activity obtained in supernatants was 5.8 U-mL in 48 h of incubation. Optimal conditions for enzyme production also included an initial pH of 8.3 and 37°C as the incubation temperature.

Cell growth and CGTase production profile were not linked to each other, suggesting that enzyme production-secretion is not growth–associated but mainly a late-log phase event.

ConclusionWe have screened conditions for optimal CGTase production. The selected minimal medium contained starch, ammonium, Mg and Fe as essential nutrients. As an additional advantage, this medium does not require complex nitrogen sources with varying and unknown composition.

Electronic supplementary materialThe online version of this article doi:10.1186-1475-2859-1-3 contains supplementary material, which is available to authorized users.

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Autor: Adriana M Rosso - Susana A Ferrarotti - Norberto Krymkiewicz - Bclara Nudel

Fuente: https://link.springer.com/



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