Effect of protective agents, freezing temperature, rehydration media on viability of malolactic bacteria subjected to freeze-drying

Zhao, Guanglei; Zhang, G.

doi:10.1111/j.1365-2672.2005.02587.x

Cited by 127 publications

(91 citation statements)

References 32 publications

(38 reference statements)

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“…The maximum viability after freeze-drying of Lb. brevis and O. oeni in yeast extract and sodium glutamate was 68 and 54%, respectively [37]. Lb.…”

Section: Resultsmentioning

confidence: 94%

Impact of fermentation pH and temperature on freeze-drying survival and membrane lipid composition of Lactobacillus coryniformis Si3

Schoug¹,

Fischer²,

Heipieper³

et al. 2007

J Ind Microbiol Biotechnol

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During the industrial stabilization process, lactic acid bacteria are subjected to several stressful conditions. Tolerance to dehydration differs among lactic acid bacteria and the determining factors remain largely unknown. Lactobacillus coryniformis Si3 prevents spoilage by mold due to production of acids and specific antifungal compounds. This strain could be added as a biopreservative in feed systems, e.g. silage. We studied the survival of Lb. coryniformis Si3 after freeze-drying in a 10% skim milk and 5% sucrose formulation following different fermentation pH values and temperatures. Initially, a response surface methodology was employed to optimize final cell density and growth rate. At optimal pH and temperature (pH 5.5 and 34 degrees C), the freeze-drying survival of Lb. coryniformis Si3 was 67% (+/-6%). The influence of temperature or pH stress in late logarithmic phase was dependent upon the nature of the stress applied. Heat stress (42 degrees C) did not influence freeze-drying survival, whereas mild cold- (26 degrees C), base- (pH 6.5), and acid- (pH 4.5) stress significantly reduced survival. Freeze-drying survival rates varied fourfold, with the lowest survival following mild cold stress (26 degrees C) prior to freeze-drying and the highest survival after optimal growth or after mild heat (42 degrees C) stress. Levels of different membrane fatty acids were analyzed to determine the adaptive response in this strain. Fatty acids changed with altered fermentation conditions and the degree of membrane lipid saturation decreased when the cells were subjected to stress. This study shows the importance of selecting appropriate fermentation conditions to maximize freeze-drying viability of Lb. coryniformis as well as the effects of various unfavorable conditions during growth on freeze-drying survival.

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“…The maximum viability after freeze-drying of Lb. brevis and O. oeni in yeast extract and sodium glutamate was 68 and 54%, respectively [37]. Lb.…”

Section: Resultsmentioning

confidence: 94%

Impact of fermentation pH and temperature on freeze-drying survival and membrane lipid composition of Lactobacillus coryniformis Si3

Schoug¹,

Fischer²,

Heipieper³

et al. 2007

J Ind Microbiol Biotechnol

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“…Interestingly, for both strains, Ϫ20°C appeared significantly more bactericidal than Ϫ70°C, a pattern also observed for other lactobacilli (51). It is possible that L. salivarius UCC118 derivatives are more susceptible to damage by external osmotic stress to the cell, a characteristic of slow cooling as opposed to intracellular ice crystal formation, a consequence of fast cooling, a pattern also observed for other lactobacilli (51,56). The improved viability of UCC118-BetL ϩ , most likely reflects the cryoprotective properties of accumulated betaine which stabilizes protein structure and function, while also maintaining membrane fluidity (1,41,49).…”

Section: Vol 72 2006 Betl Expression In Lactobacillus Salivarius 2173mentioning

confidence: 92%

Heterologous Expression of BetL, a Betaine Uptake System, Enhances the Stress Tolerance ofLactobacillus salivariusUCC118

Sheehan

Sleator

Fitzgerald

et al. 2006

Appl Environ Microbiol

116

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Given the increasing commercial and clinical relevance of probiotic cultures, improving the technological robustness of what are often process-sensitive cultures is an important biological goal. The nisin-controlled expression system was used to direct the heterologous expression of the listerial betaine uptake system BetL in the probiotic strain Lactobacillus salivarius UCC118. Following nisin induction, strains expressing betL exhibited a significant increase in resistance to several stresses, including elevated osmo-, cryo-, baro-, and chill tolerance, as well as increased resistance to spray-and freeze-drying. The ability to confer additional stress tolerance on a probiotic culture may be an important step in delivering viable cultures for maximal efficacy.

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“…However, recovery from freeze-drying without appropriate pre-incubation and pre-and post-treatments of the freeze-dried culture is poor, relating to freeze-drying process conditions, storage conditions and appropriate recovery medium. 76 Although starter culture technology increases the prospect of rapid and reliable MLF, the process is often delayed and failures, though rare, can still occur, because the fermentation depends upon the growth of the bacterial cells inoculated into the wine, which is typically of poor nutrient quality, high acidity and high ethanol concentration. Also, the condition of the cells at the time of inoculation and the properties of the wine will affect the growth of the MLF microbes and thus the success of the biotransformation.…”

Section: Starter Culturesmentioning

confidence: 99%

Strategies for enhanced malolactic fermentation in wine and cider maturation

Zhang

Lovitt

2006

J of Chemical Tech & Biotech

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Malolactic fermentation (the conversion of malate to lactate) has been recognised as a desired process in wine and cider making and is being progressively developed. It not only concerns the conversion of malate but also involves flavour-related biotransformations catalysed by malolactic fermentation bacteria. This review considers strategies to improve the reliability and performance of malolactic fermentation and documents the development of cell propagation systems and maturation processes, especially in relation to the physiology and biochemistry of malolactic fermentation bacteria. This includes the use of starter cultures and high cell concentrations for propagation and biotransformation, the types of bioreactors and their operational modes, especially those associated with the process of malolactic fermentation. Oenococcus oeni, the predominant organism associated with malolactic fermentation, is an acidophilic bacterium and is able to grow in wine at pH 3.5 or lower in the presence of ethanol and sulphite. As malolactic fermentation takes place in a highly alcoholic (up to 13% v/v) and highly acidic (pH 3.5 or lower) environment, slow growth and poor yields are frequently encountered when starter cultures are used. As a result, it requires several weeks or even months in such conditions to achieve full maturation. The malolactic fermentation process is also affected by temperature, malate concentration, nutrient composition and cell concentration. With an improved understanding of malolactic fermentation and the use of high cell concentrations, appropriate bioreactor designs and various operational modes, process innovation involving the separation of cell propagation from the maturation process now looks feasible. The review assesses the performance of malolactic fermentation systems and the relative benefits of high-cell-concentration biotransformation systems (free cells, immobilised cells or membrane bioreactor) to achieve malolactic fermentation with high productivity. INTRODUCTIONMalolactic fermentation (MLF) refers to the conversion of L-malate into L-lactate and CO 2 normally catalysed by lactic acid bacteria (LAB). The conversion of L-malate into L-lactate and CO 2 is a decarboxylation and leads to a natural decrease in acidity together with an enhancement in the bacterial stability and flavour of wine.1 -5 MLF has been progressively recognised and developed in wine making. A number of reviews of MLF and its associated LAB in wine have been published in the past two decades.

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Effect of protective agents, freezing temperature, rehydration media on viability of malolactic bacteria subjected to freeze-drying

Cited by 127 publications

References 32 publications

Impact of fermentation pH and temperature on freeze-drying survival and membrane lipid composition of Lactobacillus coryniformis Si3

Impact of fermentation pH and temperature on freeze-drying survival and membrane lipid composition of Lactobacillus coryniformis Si3

Heterologous Expression of BetL, a Betaine Uptake System, Enhances the Stress Tolerance ofLactobacillus salivariusUCC118

Strategies for enhanced malolactic fermentation in wine and cider maturation

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