Stress Resistance and Quorum Sensing Mechanisms

Other acid resistance mechanisms include urease, a nickel-containing oligomeric enzyme that catalyzes the hydrolysis of urea to two molecules of ammonia and one molecule of carbon dioxide (Mobley et al. 1995). The enzyme has maximal activity at pH 7 but loses activity at more extreme acidic pHs, being essentially inactive at pH 4.3. Ureases have been mostly associated with pathogens with the most studied system encoded by the highly urolytic bacteria Helicobacter pylori (Bartnik 

However, urease homologs have been identified in Lact. fermentum (Kakimoto et al. 1990), Lact. brevis ATCC 367 (LVIS 1854), and Leuconostoc mesenteroides subsp. mesenteroides ATCC 8293 (LEUM 2023). Interestingly, Strep, thermophilus is the only member of the food grade LAB to encode a functional urease (Makarova et al. 2006). 

The Impact of Genome Sequencing on Characterization, Taxonomy, and Pan-genome Development of Lactic Acid Bacteria 

Streptococ us thermopi ilus CNRZ1066 1 Lactobacillus delbr leckii subsp. 

LBUL 1232 Lactobacillus lafctis subsp. Isfcais IL1403 1 

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