Induction of acid resistance in Bifidobacterium: a mechanism for improving desirable traits of potentially probiotic strains

• Published in: Journal of Applied Microbiology Vol. 103; no. 4; pp. 1147 - 1157
• Main Authors: Collado, M.C, Sanz, Y
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.10.2007; Blackwell Publishing Ltd; Blackwell Science
• Subjects: acid resistance; acid tolerance; Adaptation, Physiological; Adaptation, Physiological - drug effects; Adult; antibiotics; Bifidobacterium; Bifidobacterium - drug effects; Bifidobacterium - genetics; Bifidobacterium - growth & development; Bifidobacterium - physiology; Bifidobacterium catenulatum; Bifidobacterium longum; Bile Acids and Salts; Bile Acids and Salts - pharmacology; bile salts; Biological and medical sciences; Colony Count, Microbial; drug effects; Drug Resistance, Microbial; enzyme activity; feces; Feces - microbiology; Fermentation; Fundamental and applied biological sciences. Psychology; Gastric Juice; Gastric Juice - microbiology; gastrointestinal transit; genetics; growth & development; Humans; Hydrochloric Acid; Hydrochloric Acid - pharmacology; Hydrogen-Ion Concentration; metabolism; methods; Microbial Sensitivity Tests; Microbiology; pharmacology; phenotype; physiology; probiotics; Probiotics - metabolism; Random Amplified Polymorphic DNA Technique; Random Amplified Polymorphic DNA Technique - methods; sodium chloride; Sodium Chloride - pharmacology; stress; stress tolerance; temperature; viability; Probiotic; Lactic acid bacteria; Bifidobacterium; Actinomycetaceae; Induction; Applied microbiology; Mechanism; Stress; Actinomycetales; Acid resistance; Bacteria; Actinomycetes; Viability; probiotics
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2007.03342.x

To generate stable acid-resistant Bifidobacterium strains isolated from human subjects and characterize the phenotypic changes of the acid-resistant derivatives. The ability of 20 Bifidobacterium strains isolated from human faeces to survive to simulated gastrointestinal transit was evaluated, showing major reductions in viability (0·25-5·8 logarithmic units) because of gastric stress conditions. Six acid-sensitive strains belonging to the species Bifidobacterium longum and Bifidobacterium catenulatum were submitted to prolonged incubation at pH 2·0 to generate acid-resistant strains. The acid-sensitive and acid-resistant derivative strains were characterized to determine the changes associated with the acquisition of an acid-tolerant phenotype. The acid-resistant derivatives showed better ability to grow in the presence of bile salt (1-3%) and NaCl (6-10%) and higher resistance at elevated temperatures (60-70°C, 10 min) than the parental strains. The acid-resistant derivatives displayed higher fermentative ability, and enzymatic activities. These strains also showed higher sensitivity to most of the tested antibiotics than the parental strains. The stress tolerance of B. longum and B. catenulatum strains was improved by prolonged exposure to acid stress conditions. Some of the generated strains also seemed to have enhanced metabolic properties of relevance for probiotic applications. The successful use of prolonged exposures to acid stress to improve the stability of human bifidobacteria indicates that this strategy could be useful for the production of robust probiotic strains, but involves other phenotypic changes that required an individual characterization.