Stationary-phase acid and heat treatments for improvement of the viability of probiotic lactobacilli and bifidobacteria

Abstract

Aims: To investigate whether sublethal treatments of stationary-phase probiotic cultures enhance their survival during lethal treatments and to adapt these treatments to the fermenter-scale production of probiotic cultures. Methods and Results: Conditions for acid and heat pretreatments were screened for three Lactobacillus and two Bifidobacterium strains. Strains were sublethally treated both at laboratory scale and at fermenter scale in a strain-specific manner and exposed to a subsequent lethal treatment. At laboratory scale viability improvement was detected in each strain. However, improvement was more pronounced in the Lactobacillus than in the Bifidobacterium strains. At fermenter scale three strains were tested: for the two Lactobacillus strains a marked improvement in viability was obtained whereas for the Bifidobacterium strain the improvement was either minor or not detected. Conclusions: Development of treatments for viability enhancement of probiotic strains is feasible, but strainspecific optimization is necessary to obtain notable improvements. Significance and Impact of the Study: Strain-specific treatments were developed for the viability enhancement of stationary-phase probiotic cells both at laboratory and fermenter scale. These results can be utilised in the production of probiotic cultures with improved viability.

Technology and potential applications of probiotic encapsulation in fermented milk products

“…For instance, it has been reported that stationary phase cells of L. rhamnosus yielded the highest recovery rate after drying (31-50 % survival), but early log-phase cells exhibited only14% survival and lag phase cells showed the highest susceptibility, with only a 2 % cell survival under similar conditions of drying (Corcoran et al, 2004). Saarela et al (2004) reported that freeze drying and storage stability performance of B. animalis subsp. lactis cells grown to a late-logarithmic growth phase (15 h) or to an early stationary phase.…”

Influence of lyophilization, fluidized bed drying, addition of protectants, and storage on the viability of lactic acid bacteria

“…By exhibiting stress conditions (pH, temperature, osmotic pressure etc) adaptive response can be provoked resulting in more desiccation-resistant bacterial cells (Abee and Wouters 1999;Baati et al 2000;Conrad et al 2000;Kim et al 2001;Saarela et al 2004;Morgan et al 2006). Response surface methodologies were reported to be particularly suitable to detect interactions and co-dependencies between the individual parameters mentioned (Schoug et al 2006).…”

Low-pH Adaptation and the Acid Tolerance Response of Bifidobacterium longum Biotype longum

“…For instance, the acid tolerance response has been evidenced in Bifidobacterium longum and B. animalis (32,41) and in other gram-positive bacteria such as Listeria monocytogenes (13), Enterococcus faecalis (16), or Lactococcus lactis (37). Mechanisms underlying acid tolerance used by gram-positive bacteria include not only proton pumping via the F 1 F o -ATPase but also changes in the cell membrane and regulatory mechanisms, alterations in different metabolic pathways, and amino acid decarboxylation (12).…”