Digestive enzymes and probiotic properties of four bacteria with high yield catechol siderophore

Abstract:

[Background] Catechol siderophore play an important role in the growth and metabolism of gastrointestinal flora. [Objective] To study various digestive enzymes of four bacteria producing catechol siderophores isolated from healthy adult feces, and to study their probiotic potential. [Methods] Activities of protease, amylase, lipase, cellulase, phytase, lactase and β-glucosidase were analyzed; The number of live bacteria were counted after culturing four strains in simulated gastric and intestinal juice; and then self-agglutination rate, adhesion rate and surface hydrophobicity of four strains were detected; At lost, for intake safety evaluation different dose of four strains were administrated to mice for 7 days, to observe and record the general signs of mice, to calculate the organ index of mice, and conduct bacterial translocation. [Results] E. coli Gut 07 and E. coli Gut 12 didn’t show protease and lipase activity, B. cereus Gut 16 showed no lactase activity, and E. coli Gut 20 was without protease activity. All the enzymes in this study were detectable in the four selected strains. Regard with the probiotic property, the survival rate of the four strains after 6 hours of simulated gastric juice culture was more than 60%, and the number of live bacteria after 24 hours of simulated intestinal juice culture was greater than the initial colony number. Analysis of self-agglutination rate, adhesion rate and surface hydrophobicity showed that the four strains can adhesion and colonization on the gastrointestinal tract (GIT). For safety evaluation, strains were not tolerant to most of the antibiotics. Intragastric administration (4.5×1011 CFU/mL, 20 mL/kg-bw) didn’t show acute toxicity to mice and no translocation of positive strains. [Conclusion] These four bacteria have the potential as probiotics and need further studying on detail function to human diet and safety assessment after that of acute toxicity.