The evolution of lactic acid bacteria community during the development of mature sourdough

Abstract

In order to follow the composition and changes in lactic acid bacteria (LAB) population of rye flour sourdough that was continuously propagated by a repeated inoculation, sixty-two strains of LAB were isolated and characterized. The LAB were the only bacteria detected, both at the end of the second propagation step and in the stage of mature sourdough (after two weeks of continuous daily refreshment). The stable ecological system in rye sourdough could be established from the second propagation step onward. The predominant genera of LAB during the development of sourdough were lactobacilli, which were grouped in eight clusters. Heterofermentative lactobacilli were in majority in both propagation step two and a mature sourdough participating 56% and 70% of total bacterial count, respectively. The identification based on a phenotypic characterization that was carried out by using a set of 36 tests, showed that the lactobacilli contained in the two sourdough steps did not clearly belong to any known species of the genus Lactobacillus. In addition, the structure of the bacterial population were monitored by two statistical techniques (Hierachical Cluster Analysis and Principal Component Analysis), being applied to phenotypical characteristics of the isolates

Sourdough Microbiome Comparison and Benefits

“…Weckx et al [ 83 ] who studied rye sourdough reported that it took shorter time to reach maturity as compared to wheat and spelt sourdough, possibly due to the different rates of enzymatic activities. In mature sourdough, a range between 10 7 and 10 8 colony-forming units (cfu) g −1 [ 103 ] or sometimes more than 10 8 cfu g −1 [ 4 , 56 , 87 ] of LAB can be found. Therefore, it can be said that LAB population increases as pH reduces and finally both reach a plateau when sourdough mature [ 12 ].…”