title: Mg2+improves the thermotolerance of probiotic Lactobacillus rhamnosus GG, Lactobacillus casei Zhang and Lactobacillus plantarum P-8.
abstract: Food-related carbohydrates and proteins are often used as thermoprotectants for probiotic lactobacilli during industrial production and processing. However, the effect of inorganic salts is rarely reported. Magnesium is the second-most abundant cation in bacteria, and commonly found in various foods. Mg2+homeostasis is important in Salmonella and has been reported to play a critical role in their thermotolerance. However, the role of Mg2+in thermotolerance of other bacteria, in particular probiotic bacteria, still remains a hypothesis. In this study, the effect of Mg2+on thermotolerance of probiotic lactobacilli was investigated in three well-documented probiotic strains, Lactobacillus rhamnosus GG, Lactobacillus casei Zhang and Lactobacillus plantarum P-8, in comparison with Zn2+and Na+. Concentrations of Mg2+between 10 and 50 mmol l-1were found to increase the bacterial survival upon heat challenge. Remarkably, Mg2+addition at 20 mmol l-1led to a 100-fold higher survival of L. rhamnosus GG upon heat challenge. This preliminary study also showed that Mg2+shortened the heat-induced extended lag time of bacteria, which indicated the improvement in bacterial recovery from thermal injury.
  
  
  CONCLUSIONS
  In order to improve the productivity and stability of live probiotics, extensive investigations have been carried out to improve thermotolerance of probiotics. However, most of these studies focused on the effects of carbohydrates, proteins or amino acids. The roles of inorganic salts in various food materials, which have rarely been reported, should be considered when incorporating probiotics into these foods. In this study, Mg2+was found to play a significant role in the thermotolerance of probiotic lactobacilli. A novel strategy may be available in the near future by employing magnesium salts as protective agents of probiotics during manufacturing process.
authors.affiliation: Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen City, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Suzhou Key Lab of Green Chemical Engineering, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, China.|STLO, Agrocampus Ouest, INRA, Rennes, France.
authors.forename: S
authors.initials: S
authors.lastname: Huang
authors.affiliation: Suzhou Key Lab of Green Chemical Engineering, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, China.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.affiliation: STLO, Agrocampus Ouest, INRA, Rennes, France.
authors.forename: G
authors.initials: G
authors.lastname: Jan
authors.affiliation: STLO, Agrocampus Ouest, INRA, Rennes, France.
authors.forename: R
authors.initials: R
authors.lastname: Jeantet
authors.affiliation: Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen City, China.|Suzhou Key Lab of Green Chemical Engineering, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, China.
authors.forename: X D
authors.initials: XD
authors.lastname: Chen
mesh_terms: D007780:Lacticaseibacillus casei / Q000187:drug effects* / Q000502:physiology; D048191:Lactiplantibacillus plantarum / Q000187:drug effects* / Q000502:physiology; D052201:Lacticaseibacillus rhamnosus / Q000187:drug effects* / Q000502:physiology; D008274:Magnesium / Q000494:pharmacology*; D019936:Probiotics; D000071436:Thermotolerance / Q000187:drug effects*
chemical_list: D008274:Magnesium
keywords: inorganic salts; magnesium; probiotics; recovery; thermotolerance