Identification of sites of injury in
            <b>
              <i>Lactobacillus bulgaricus</i>
            </b>
            during heat stress

Teixeira, Paula; Castro, H.; Mohácsi-Farkas, Csilla; Kirby, R.

doi:10.1046/j.1365-2672.1997.00221.x

Cited by 159 publications

(88 citation statements)

References 12 publications

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“…The heating menstrum used was heat-treated (90°C, 30 min) 20% (wt/vol) RSM supplemented with 0.5% (wt/vol) yeast extract; an additional 1% (wt/vol) sucrose was added for strain UCC 118. The heating method used was essentially the method described by Teixeira et al (35). Two 50-ml portions of RSM in 100-ml bottles were agitated with magnetic stirrer bars and were placed in a water bath at the following test temperatures: 37°C (for the control and to obtain the initial count) and 55, 58, 59, 60, and 61°C.…”

Section: Methodsmentioning

confidence: 99%

Comparative Survival Rates of Human-Derived Probiotic Lactobacillus paracasei and L. salivarius Strains during Heat Treatment and Spray Drying

Gardiner

O’Sullivan

Kelly

et al. 2000

Appl Environ Microbiol

380

276

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Spray drying of skim milk was evaluated as a means of preserving Lactobacillus paracasei NFBC 338 and Lactobacillus salivarius UCC 118, which are human-derived strains with probiotic potential. Our initial experiments revealed that NFBC 338 is considerably more heat resistant in 20% (wt/vol) skim milk than UCC 118 is; the comparable decimal reduction times were 11.1 and 1.1 min, respectively, at 59°C. An air outlet temperature of 80 to 85°C was optimal for spray drying; these conditions resulted in powders with moisture contents of 4.1 to 4.2% and viable counts of 3.2 ؋ 10 9 CFU/g for NFBC 338 and 5.2 ؋ 10 7 CFU/g for UCC 118. Thus, L. paracasei NFBC 338 survived better than L. salivarius UCC 118 during spray drying; similar results were obtained when we used confocal scanning laser microscopy and LIVE/DEAD BacLight viability staining. In addition, confocal scanning laser microscopy revealed that the probiotic lactobacilli were located primarily in the powder particles. Although both spray-dried cultures appeared to be stressed, as shown by increased sensitivity to NaCl, bacteriocin production by UCC 118 was not affected by the process, nor was the activity of the bacteriocin peptide. The level of survival of NFBC 338 remained constant at ϳ1 ؋ 10 9 CFU/g during 2 months of powder storage at 4°C, while a decline in the level of survival of approximately 1 log (from 7.2 ؋ 10 7 to 9.5 ؋ 10 6 CFU/g) was observed for UCC 118 stored under the same conditions. However, survival of both Lactobacillus strains during powder storage was inversely related to the storage temperature. Our data demonstrate that spray drying may be a cost-effective way to produce large quantities of some probiotic cultures.Given that probiotic microorganisms play a role in promoting and maintaining health (29) has stimulated considerable interest in incorporating these into functional foods and pharmaceutical products. By definition, probiotics are "living microorganisms, which upon ingestion in certain numbers, exert health benefits beyond inherent basic nutrition" (13), and it is recommended that probiotic products contain at least 10 7 live microorganisms per g or per ml (15). Therefore, from a commercial point of view, an inexpensive method for large-scale production of cultures containing high levels of viable probiotic cells in a form suitable for product applications is highly desirable.In previous studies researchers have investigated the production of freeze-dried powders and frozen concentrates of probiotic Bifidobacterium and Lactobacillus spp. (10,12,24). However, there are many disadvantages associated with this approach; freeze-drying is time-consuming and expensive, there are high transport and storage costs associated with frozen concentrated cultures, and the freeze-thaw process is associated with a loss of culture viability. In comparison, spray drying, one of the predominant processing tools used in the dairy industry, can be used to produce large amounts of dairy ingredients relatively inexpensively; it has been estimated th...

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Section: Methodsmentioning

confidence: 99%

Comparative Survival Rates of Human-Derived Probiotic Lactobacillus paracasei and L. salivarius Strains during Heat Treatment and Spray Drying

Gardiner

O’Sullivan

Kelly

et al. 2000

Appl Environ Microbiol

380

276

View full text Add to dashboard Cite

show abstract

“…However, most probiotic strains do not survive well the high temperatures and dehydratation during the spray-drying process. Loss of viability is principally caused by cytoplasmatic membrane damage although the cell wall, ribosomes and DNA are also affected at higher temperatures [74]. It was reported that the stationary phase cultures are more resistant to heat compare to cells in exponential growth phase [61].One approach used by a number of researchers to improve probiotic survival is the addition of protectants to the media prior to drying.…”

Section: Spray-dryingmentioning

confidence: 99%

Encapsulation Technology to Protect Probiotic Bacteria

Chávarri¹,

Marañón²,

Villarán³

2012

Probiotics

117

101

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“…During these processes, bacteria are subjected to adverse conditions, one of the most encountered and drastic stresses being the heat stress. The bestdescribed effects induced by high temperatures concern the protein denaturation [28], but membranes, nucleic acids and certain enzymes have been equally identified as cellular sites of heat injury [25]. Heat stress is also responsible for a disturbance of the transmembrane proton gradient, leading to a decrease of the intracellular pH [21,22,29].…”

Section: Introductionmentioning

confidence: 99%

Lactobacillus delbrueckii ssp. bulgaricus thermotolerance

Gouesbet

Jan

Boyaval

2001

Lait

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-Lactobacillus delbrueckii ssp. bulgaricus is a lactic acid bacterium widely used in the dairy food industry. Since the industrial processes are a succession of constraints, it is essential to understand the behaviour of L. bulgaricus when facing usual stresses. The influence of heat stress was investigated on the viability of L. bulgaricus cells grown in a chemically defined medium. The susceptibility of cells to heat-shock was obvious only above 55 °C. We investigated the acquisition of thermotolerance as a result of exposure to a moderate heat-shock, and the acquisition of a crossstress-tolerance by exposure to a mild osmotic stress. When cells were submitted, before lethal temperature challenge (65 °C), to a heat pre-treatment at 50 °C or to a hyper-osmotic pre-treatment, the viability of cells increased. For the industrial strain RD 546, the addition of glycine betaine (GB) in 0.4 mol . L -1 NaCl during the pre-treatment decreased the acquired thermotolerance, while GB alone enhanced cell viability. The thermotolerance of the type strain was not influenced by GB. We demonstrated that the stress tolerance induced by a moderate heat-shock was dependent on protein synthesis, while the effect of GB on RD 546 thermotolerance was independent of such biosynthesis. Thermotolerance acquired in presence of GB depends on a strain-dependant mechanism that differs from the mechanism involved after a moderate heat-shock.heat-shock response / cross-protection / osmotic stress / betaine / thermoadaptation Résumé -Stress thermique et thermotolérance chez Lactobacillus delbrueckii ssp. bulgaricus. Lactobacillus delbrueckii ssp. bulgaricus est une bactérie lactique largement utilisée en industrie alimentaire. Les procédés industriels étant une succession de contraintes, il est essentiel de connaître le comportement de L. bulgaricus face aux stress rencontrés. L'influence du stress thermique sur la viabilité de 2 souches de L. bulgaricus, cultivées en milieu chimiquement défini, a été étudiée. La viabilité des cellules n'est affectée qu'au-delà de 55 °C. Les cellules acquièrent une thermotolérance vis-à-vis d'un choc thermique à 65 °C durant 10 min, c'est-à-dire une viabilité accrue, après exposition à un prétraitement thermique modéré à 50 °C ou un prétraitement hyperosmotique. Pour la

show abstract

Identification of sites of injury in Lactobacillus bulgaricus during heat stress

Cited by 159 publications

References 12 publications

Comparative Survival Rates of Human-Derived Probiotic Lactobacillus paracasei and L. salivarius Strains during Heat Treatment and Spray Drying

Comparative Survival Rates of Human-Derived Probiotic Lactobacillus paracasei and L. salivarius Strains during Heat Treatment and Spray Drying

Encapsulation Technology to Protect Probiotic Bacteria

Lactobacillus delbrueckii ssp. bulgaricus thermotolerance

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