Interactions between propionic acid bacteria and thermophilic lactic acid bacteria

Abstract

-The growth of propionic acid bacteria was directly dependent on the concentration of free amino acids in cheese, regardless of the strains of lactobacilli contained in the raw mixed cultures, suggesting that the growth of these bacteria was mainly dependent on the proteolytic activity of lactic acid bacteria. The stimulating effect of S. thermophilus was poor probably because this species produces only low amounts of amino acids in milk or cheese. Lactobacilli, which undergo cell Iysis shortly after cheese manufacture, produce large amounts of amino acids. Facultatively heterofermentative lactobacilli were shown to reduce the risk of secondary fermentation in Emmental cheese. This interaction was not due to their production of diacetyl, formate or acetate. Propionibacteria able to grow at 14 "C have a greater tendency to induce secondary fermentation compared to those unable to grow at this temperature. © InralElsevier, Paris.propionic acid bacteria / lactic acid bacteria / facultatively heterofermentative Iactobacilli / interaction / secondary fermentation Résumé -Interaction entre les bactéries propioniques et les bactéries lactiques thermophiles. L'étude présentée a porté sur l'interaction entre les bactéries propioniques (BP) et 23 levains lactiques, 30 de leurs souches isolées, 36 souches isolées de produits laitiers fabriqués hors de la Suisse, une culture de S. thermophilus ainsi que la flore naturelle de deux laits de mélange. La croissance des bactéries lactiques a été réalisée dans des expériences de simulation de fabrication fromagère dans du lait UHT, dont le pH a été maintenu au niveau de celui du fromage par l'ajout de carbonate de calcium. Les lactosérums obtenus ont été utilisés comme source d'azote pour la croissance des BP. Les résul-tats ont montré que l'intensité de la croissance des BP variait en fonction du lactosérum utilisé. Toutefois, les différences observées ne dépendaient pas spécifiquement de la souche des bactéries lactiques, mais uniquement de la concentration en acides aminés. Les différences entre les intensités de croissance ont pu être supprimées en uniformisant la concentration des acides aminés ajoutés, ce qui suggère que la croissance des BP dépend essentiellement de l'activité protéolytique des bactéries lactiques. L'effet stimulant de S. thermophilus sur la croissance des BP a été peu prononcé à cause de la faible concentration des acides aminés libérés. Par contre, les lactobacilles, dont la lyse cellulaire apparaît rapidement après la fabrication du fromage, produisent de grandes quantités d'acides aminés qui stimulent la croissance des BP. Il a été démontré que l'addition de lactobacilles hétérofermentaires Oral communication at the 2nd Symposium on Propionibacteria, Cork, Ireland, June 25-27, 1998.

Propionibacterium freudenreichii strains quantitatively affect production of volatile compounds in Swiss cheese

“…These time periods were not affected by PAB strain but significantly (P < 0.05) depended on the lactic starter, with a mean time in the warm room of 9.3, 11.3, and 14.8 d in the presence of starters LH100, LH77, and LH56-LL57, respectively. This result is in agreement with the observed effect of lactic starters on PAB growth in the present study, and with previous works showing that lactobacilli can induce marked differences in kinetics of propionate formation in Swiss cheese [2,9,16]. As expected from the sampling procedure, the concentrations of propionic and acetic acids did not differ significantly at the end of the warm room ripening (Tab.…”

“…The influence of lactobacilli was the same regardless of the strain of PAB used, which is in accordance with the absence of statistical PABlactobacilli interactions. The influence of thermophilic lactobacilli on PAB in cheese has been previously reported [2,9,16]. As a consequence of the influence of lactobacilli strains on propionic fermentation, using the same ripening period for cheeses containing different lactic strains can result in a bias of the results if the abilities of PAB strains to produce flavour compounds are to be compared.…”

“…Moreover, lactic acid bacteria are also capable of forming various volatile compounds, and in particular, significant amounts of carbonyl compounds [17,19,35,48,51]. PAB have been known for a long time to contribute to the development of Swiss cheese flavour and cheese opening, achieved through the fermentation of lactic acid into propionic acid, acetic acid and CO 2 [6,18,40]. More recently, PAB were shown to play a prominent role in the formation of free fatty acids (FFA) and of short BC acids that result from triglyceride hydrolysis and from leucine/ isoleucine catabolism, respectively [10,41,45].…”

“…The authors showed the contribution of this strain to the formation of a variety of volatiles, such as alcohols, esters and ketones, which were present at significantly greater concentrations in the presence of PAB than in the control cheeses without PAB. No data are available regarding the possible influence of LAB on PAB activity, although the existence of lactobacilli-PAB interactions in cheese has been reported [2,9,16,31].…”

Technological, microbiological and chemical characteristics of Pannerone, a traditional Italian raw milk cheese

“…4.2 ± 1.2 g·kg −1 when calculated on its moisture basis) was lower than that of ripened Swiss cheese (4.0-6.0 g·kg −1 of cheese on moisture basis) [4] or Emmental Grand Cru cheeses (8.0 g·kg −1 in the extracted aqueous phase). This level is similar to that of Comté cheese (4.9 g·kg −1 in the extracted aqueous phase), but higher than that produced by PAB in some industrial French Emmental (1.0-2.0 g·kg −1 in the extracted aqueous phase) [28].…”