Response of cultures of Propionibacterium to acid and low pH: tolerance and inhibition.
Seventeen Propionibacterium strains were tested for acid production and final pH achieved on glucose, fructose, or maltose as the primary carbon source. On average, strains of Propionibacterium acidipropionici produced more acid and reached lower final pH values than did strains of the other species. Three strains of P. acidipropionici, one Propionibacterium jensenii, and two Propionibacterium thoenii strains were tested further for the ability to survive and/or grow at low pH with lactic, hydrochloric, or propionic acid as acidulant. The organic acids were more inhibitory than hydrochloric acid; propionic acid was most inhibitory. In all cases, the P. jensenii and P. thoenii strains initiated growth and survived at lower pH values than did the p. acidipropionici stains. The ability to produce large amounts of acid or achieve low final pH values did not coincide with the ability to initiate growth or survive in low-pH conditions. Strains could not initiate growth below pH 5.0, but cultures started at neutral pH reached final pH values of less than 4.4. At neutral pH, strains could grow in the presence of increased lactate concentrations (up to 180 mM) or propionate concentrations (150 mM) that were inhibitory at acid pH. attempts to isolate variants able to initiate growth below pH 5.0 were unsuccessful.
Rehberger
J L
JL
Department of Food Science and Human Nutrition, Iowa State University, Ames, 50011, USA.
Glatz
B A
BA
D015169:Colony Count, Microbial; D003470:Culture Media; D006851:Hydrochloric Acid; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid; D011422:Propionates; D011424:Propionibacterium / Q000235:genetics / Q000502:physiology*; D013696:Temperature
D003470:Culture Media; D011422:Propionates; D019344:Lactic Acid; C029658:propionic acid; D006851:Hydrochloric Acid