Identification and characterization of two glucoamylases from Thermoanaerobacter ethanolicus and Saccharophagus degradans.

WAYLLACE, NATAEL M.; HEDÍN, NICOLAS; BUSI, MARIA VICTORIA; DIEGO FABIAN GOMEZ CASATI

Smolenice

Congreso; 8th Symposium on the alpha-amylase family, ALAMY_8th; 2022

Slovak Academy of Sciences

We identified two newglucoamylases: TeGA, from Thermoanaerobacter ethanolicus, a thermophilicanaerobic bacterium and SdGA, from Saccharophagus degradans, a marine bacterium which degrades different complexpolysaccharides at high rate. Both enzymes belong from the family 15 of glycosylhydrolases (GH15). TeGA and SdGA wereexpressed and purified in E. coli BL21 cells and their structure,function and regulation were characterized. TeGA showed a high optimum temperature of 75°C. It also showed one ofthe highest specific activities reported for a bacterial glucoamylase (75.3U/mg) and was also stable in a wide pH range (3.0 to 10.0). Although the enzymewas preferentially active with maltose, it was also able to hydrolyze differentsoluble starches such as those from potato, corn or rice. In addition, TeGAshowed a high thermostability up to around 70°C.  Although SdGA has a maximum activity at 39°Cand pH 6.0, it also shows high activity in a wide range, from low to mildtemperatures, like cold-adapted enzymes. Furthermore, SdGA has a higher contentof flexible residues and a larger CD due to various amino acid insertionscompared to other thermostable GAs. Wepropose that TeGA could be used in different industrial processes such asbiofuel production and food processing, whereas SdGA, is a cold-adaptedenzyme that might be suitable for use in processes that require enzymes whichact at low or medium temperatures.