Molecular Characterization of L-Arabinose Isomerase from Lactococcus lactis KF147 and the development of a novel method for D-tagatose detection


Arranz Fíguls, Clara  


Dtagatose is regarded as one of most valuable rare sugars in the current market and hence its production routes are a topic of interest nowadays. As a ketohexose, Dtagatose has low caloric value but its sweetness is very similar to that of sucrose. Due to its distinct properties and benefits on human health it has received great attention and has currently the Generally Recognised as Safe (GRAS) status by the U.S. Food and Drug Administration (USFDA) since 2010. Due to scarcity in nature, production of Dtagatose either by chemical or biological methods is a much discussed topic in the field. In order to overcome the drawbacks that the chemical processes present, biological methods using Larabinose isomerase (AIs) for converting Dgalactose to Dtagatose have emerged as a cheap, ecofriendly and most efficient alternative for tagatose synthesis. Due to the growing need for this enzyme’s characterization and for the huge interest that this sugar presents, its detection methods are as well a subject of interest. For now the two most used methods are HPLC and a colorimetric assay that involves strong acids. They both present setbacks regarding laborious sampling or results accuracy. In this bachelor thesis, the AI from Lactococcus lactis KF147 has been characterized by cloning its gene in Lactococcus lactis MG1363 strain and its activity has been tested in range of different temperatures and pH. AI from Bacillus coagulans, a well characterized enzyme has been used as a reference. Moreover, a novel method for the detection of tagatose which involves the reduction of a a watersoluble tetrazolium salt (WST8) by this sugar has been studied showing linear correlation in a wider range than other colorimetric assays and has also shown negligible interference with other reducing sugars. Both works are still and will be under study after the defense of this thesis.



Fornaguera Puigvert, Cristina
Salinas, Yolanda 


IQS SE - Undergraduate Program in Biotechnology