Isolation of pullulanase-producing microorganisms of biotechnological interest

CASTILLO DE LAS MERCEDES JULIETA; CAMINATA LANDRIEL, SOLEDAD; BERTONERI,AGOSTINA; ANSELMO, RICARDO; COSTA, HERNÁN

Congreso; LIV Reunión Anual de la SAIB; 2018

Microorganismsare essential for obtaining enzymes due to their low cost of production and geneticengineering possibilities. There is strong biotechnological interest inmicrobial enzymes applicable in food processing, agriculture, pharmaceuticalindustry and molecular biology. Bioprospecting describes theprocedure of exploration, extraction, screening and trading of new productsusing biological diversity as source. Different enzymes are involved in processesrelated to the synthesis and degradation of α-glycosidicbonds. Pullulanases are a type of glycoside hydrolase debranching enzymes,which act on α-1,6 bonds of starch and other α-glucans like pullulan, consistingessentially of maltotriosyl units connected by α-1,6 bonds.Pullulanases are widely used in the saccharification process to obtain useful productssuch as maltose, amylose and glucose by debranching starch; so, they are highly employed in the production ofhigh-fructose corn syrup and in the starch processing industry. The aim ofthis work was to explore, isolate and identify aerobic bacteria producing enzymesacting on pullulan. By bioprospecting samples of soil and highstarch-containing vegetables, 40 bacterial isolates were obtained, of which 3secreted pullulan-hydrolytic enzymes. Bacteria were identified as Bacillus firmus, Alcaligenes faecalis and Micrococcusluteus. HPLC analysis of the products of hydrolysedpullulan with isolated enzymes showed maltotriose as the main product.Accordingly, these enzymes were classified as pullulanases. In particular, pullulanaseisolated from B. firmus produced thehighest debranching activity.