title: The effect of NaCl substitution with KCl on proteinase activities of cell-free extract and cell-free supernatant at different pH levels and salt concentrations: Lactobacillus acidophilus and Lactobacillus casei.
abstract: The aim of this study was to investigate the effect of substitution of NaCl with KCl at different pH levels and salt concentrations on proteinase activity of cell-free extract and cell-free supernatant of the probiotics Lactobacillus acidophilus and Lactobacillus casei. de Man, Rogosa, and Sharpe broth aliquots were mixed with 2 pure salts (NaCl and KCl) and 2 salt concentrations at 2 concentration levels (5 and 10%), inoculated with Lactobacillus acidophilus or Lactobacillus casei, and incubated aerobically at 37°C for 22 h. The cultures were then centrifuged at 4,000×g for 30 min, and the collected cell pellets were used to prepare cell-wall proteinases and the supernatants used as a source of supernatant (extracellular) proteinases. The proteolytic activity and protein content of both portions were determined. After incubation of both portions with 3 milk caseins (α-, β-, κ-casein), the supernatants were individually subjected to analysis of angiotensin-converting enzyme (ACE)-inhibitory activity and proteolytic activity using the o-phthalaldehyde method. Significant differences were observed in ACE-inhibitory and proteolytic activities between salt substitution treatments of cell-free extract and cell-free supernatant from both probiotic strains at the same salt concentration and pH level.
authors.affiliation: School of Biomedical and Health Sciences, Victoria University, Werribee Campus, PO Box 14428, Melbourne, Victoria 8001, Australia.
authors.forename: M M
authors.initials: MM
authors.lastname: Ayyash
authors.forename: F
authors.initials: F
authors.lastname: Sherkat
authors.forename: N P
authors.initials: NP
authors.lastname: Shah
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000378:metabolism; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D007779:Lactobacillus acidophilus / Q000187:drug effects / Q000378:metabolism*; D007780:Lacticaseibacillus casei / Q000187:drug effects / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000187:drug effects* / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology*; D019936:Probiotics / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D003470:Culture Media; D012965:Sodium Chloride; D011189:Potassium Chloride; D010447:Peptide Hydrolases