Abstract
Abstract Pozol is a beverage made with maize dough that is prepared after boiling the kernels in limewater, causing a decrease in soluble sugars, with starch being the main fermentable carbohydrate in the dough. Previously, Streptococcus infantarius ssp. infantarius 25124 (Sii-25124) was identified as the most amylolytic bacteria isolated in this product. Analysis of Sii-25124 amylolytic enzymes revealed two amylases, a cytoplasmic α-amylase of 55.7 kDa and an extracellular amylopullulanase of 246.3 kDa, with two catalytic domains, one typical of an α-amylase and another typical of a pullulanase/glycogen debranching enzyme. Characterization of the joint activity of both enzymes using Sii-25124 cell lysate supernatant demonstrated stability between 30 °C and 45°C, and pH stability in a range between 6.8 and 8.0. The joint activity of Sii-25124 amylases showed a fast production of reducing sugars when starch was used as the substrate. In contrast, reducing sugar production from amylopectin was lower, but it steadily increased throughout the reaction time. The amylopullulanase produced by Sii-25124 hydrolyzes the starch in the dough to produce low molecular weight oligosaccharides, which may be transported into Sii-25124 cells, so that intracellular α-amylase hydrolyzes them to mono- and disaccharides. Amylopullulanase production by Sii-25124 could be an example of a specialized enzyme that successfully dominates starchy food fermentation.
Highlights
Pozol is an acidic, non-alcoholic fermented maize beverage that has been highly consumed in south-eastern Mexico since pre-Hispanic times
Pozol has been reported as a diverse and dynamic source of Amylolytic lactic acid bacteria (ALAB) and non-ALAB, with Streptococcus being the genus that prevails during the whole fermentation process and S. infantarius ssp. infantarius 25124 (Sii-25124), the most amylolytic bacteria isolated from this product
Low amylolytic activity is observed it presents a high specific growth rate when grown on starch, suggesting that the observed activity, low, is enough for Sii25124 to be dominant in pozol fermentation [7]
Summary
Non-alcoholic fermented maize beverage that has been highly consumed in south-eastern Mexico since pre-Hispanic times. To prepare this drink, maize kernels are nixtamalized, where corn is cooked with 1-3% dry maize weight lime [commercial Ca(OH)2] for 50-90 min and soaked for 14-18 h in its own cooking solution, which is removed. Infantarius 25124 (Sii-25124), the most amylolytic bacteria isolated from this product In this bacterium, low amylolytic activity is observed it presents a high specific growth rate when grown on starch, suggesting that the observed activity, low, is enough for Sii25124 to be dominant in pozol fermentation [7]
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