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Effects of intrinsic microbial stress factors on viability and physiological condition of yeasts isolated from spontaneously fermented cereal doughs.
Int J Food Microbiol. 2019 Sep 02; 304:75-88.IJ

Abstract

Fermented cereal doughs constitute a predominant part of West African diets. The environment of fermented doughs can be hostile for microbial survival due to high levels of microbial metabolites such as weak carboxylic organic acids and ethanol. In order to get a better understanding of the intrinsic factors affecting the microbial successions of yeasts during dough fermentation, survival and physiological responses of the yeasts associated with West African fermented cereal doughs were investigated at exposure to relevant concentrations of microbial inhibitory compounds. Three strains each of the predominant species, i.e. Saccharomyces cerevisiae, Kluyveromyces marxianus, Pichia kudriavzevii as well as the opportunistic pathogen Candida glabrata were studied. The strains were exposed to individual stress factors of cereal doughs, i.e. (i) pH 3.4, (ii) 3% (v/v) ethanol (EtOHpH3.4), (iii) 285 mM lactic acid (LApH3.4) and (iv) 150 mM acetic acid (AApH3.4) as well as to combinations of these stress factors, i.e. (v) (LA + AA)pH 3.4 and (vi) (LA + AA+EtOH)pH 3.4. Growth and single cell viability were studied by flow cytometry using combined SYTO 13 and propidium iodide (PI) staining. Intracellular pH (pHi), plasma membrane integrity and micro-colony development of stressed cells were studied by fluorescence microscopy using PI and carboxyfluorescein diacetate succinimidyl ester (CFDA-se). Viability of the yeast strains was not affected by pH 3.4 and 3% (v/v) ethanol (EtOHpH3.4). 285 mM lactic acid (LApH3.4) reduced the specific growth rate (μmax) from 0.27-0.41 h-1 to 0.11-0.26 h-1 and the viability from 100% to 2.6-41.7% at 72 h of exposure in most yeast strains, except for two strains of C. glabrata. 150 mM acetic acid (AApH3.4) as well as the combinations (LA + AA)pH 3.4 and (LA + AA+EtOH)pH 3.4 reduced μmax to 0.0 h-1 and induced significant cell death for all the yeast strains. Exposed to (LA + AA+EtOH)pH 3.4, the most resistant yeast strains belonged to S. cerevisiae followed by P. kudriavzevii, whereas C. glabrata and K. marxianus were more sensitive. Strain variations were observed within all four species. When transferred to non-stress conditions, i.e. MYGP, pH 5.6, after exposure to (LA + AA+EtOH)pH 3.4 for 6 h, 45% of the single cells of the most resistant S. cerevisiae strain kept their plasma membrane integrity, recovered their pHi to near physiological range (pHi = 6.1-7.4) and resumed proliferation after 3-24 h of lag phase. The results obtained are valuable in order to change processing conditions of the dough to favor the survival of preferable yeast species, i.e. S. cerevisiae and K. marxianus and inhibit opportunistic pathogen yeast species as C. glabrata.

Authors+Show Affiliations

Laboratoire de Sciences des Aliments, Faculté des Sciences Agronomiques, Université d'Abomey-Calavi, 03 BP 2819, Jéricho, Cotonou, Benin. Electronic address: houngbedjimarcel@gmail.com.Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark.Laboratoire de Sciences des Aliments, Faculté des Sciences Agronomiques, Université d'Abomey-Calavi, 03 BP 2819, Jéricho, Cotonou, Benin.Laboratoire de Sciences des Aliments, Faculté des Sciences Agronomiques, Université d'Abomey-Calavi, 03 BP 2819, Jéricho, Cotonou, Benin.Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark.Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31174038

Citation

Houngbédji, Marcel, et al. "Effects of Intrinsic Microbial Stress Factors On Viability and Physiological Condition of Yeasts Isolated From Spontaneously Fermented Cereal Doughs." International Journal of Food Microbiology, vol. 304, 2019, pp. 75-88.
Houngbédji M, Johansen P, Padonou SW, et al. Effects of intrinsic microbial stress factors on viability and physiological condition of yeasts isolated from spontaneously fermented cereal doughs. Int J Food Microbiol. 2019;304:75-88.
Houngbédji, M., Johansen, P., Padonou, S. W., Hounhouigan, D. J., Siegumfeldt, H., & Jespersen, L. (2019). Effects of intrinsic microbial stress factors on viability and physiological condition of yeasts isolated from spontaneously fermented cereal doughs. International Journal of Food Microbiology, 304, 75-88. https://doi.org/10.1016/j.ijfoodmicro.2019.05.018
Houngbédji M, et al. Effects of Intrinsic Microbial Stress Factors On Viability and Physiological Condition of Yeasts Isolated From Spontaneously Fermented Cereal Doughs. Int J Food Microbiol. 2019 Sep 2;304:75-88. PubMed PMID: 31174038.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of intrinsic microbial stress factors on viability and physiological condition of yeasts isolated from spontaneously fermented cereal doughs. AU - Houngbédji,Marcel, AU - Johansen,Pernille, AU - Padonou,S Wilfrid, AU - Hounhouigan,D Joseph, AU - Siegumfeldt,Henrik, AU - Jespersen,Lene, Y1 - 2019/05/23/ PY - 2019/02/26/received PY - 2019/05/20/revised PY - 2019/05/21/accepted PY - 2019/6/8/pubmed PY - 2019/8/29/medline PY - 2019/6/8/entrez KW - Flow cytometry KW - Fluorescence microscopy KW - Intracellular pH KW - Mawè doughs KW - Plasma membrane integrity KW - Yeast survival SP - 75 EP - 88 JF - International journal of food microbiology JO - Int J Food Microbiol VL - 304 N2 - Fermented cereal doughs constitute a predominant part of West African diets. The environment of fermented doughs can be hostile for microbial survival due to high levels of microbial metabolites such as weak carboxylic organic acids and ethanol. In order to get a better understanding of the intrinsic factors affecting the microbial successions of yeasts during dough fermentation, survival and physiological responses of the yeasts associated with West African fermented cereal doughs were investigated at exposure to relevant concentrations of microbial inhibitory compounds. Three strains each of the predominant species, i.e. Saccharomyces cerevisiae, Kluyveromyces marxianus, Pichia kudriavzevii as well as the opportunistic pathogen Candida glabrata were studied. The strains were exposed to individual stress factors of cereal doughs, i.e. (i) pH 3.4, (ii) 3% (v/v) ethanol (EtOHpH3.4), (iii) 285 mM lactic acid (LApH3.4) and (iv) 150 mM acetic acid (AApH3.4) as well as to combinations of these stress factors, i.e. (v) (LA + AA)pH 3.4 and (vi) (LA + AA+EtOH)pH 3.4. Growth and single cell viability were studied by flow cytometry using combined SYTO 13 and propidium iodide (PI) staining. Intracellular pH (pHi), plasma membrane integrity and micro-colony development of stressed cells were studied by fluorescence microscopy using PI and carboxyfluorescein diacetate succinimidyl ester (CFDA-se). Viability of the yeast strains was not affected by pH 3.4 and 3% (v/v) ethanol (EtOHpH3.4). 285 mM lactic acid (LApH3.4) reduced the specific growth rate (μmax) from 0.27-0.41 h-1 to 0.11-0.26 h-1 and the viability from 100% to 2.6-41.7% at 72 h of exposure in most yeast strains, except for two strains of C. glabrata. 150 mM acetic acid (AApH3.4) as well as the combinations (LA + AA)pH 3.4 and (LA + AA+EtOH)pH 3.4 reduced μmax to 0.0 h-1 and induced significant cell death for all the yeast strains. Exposed to (LA + AA+EtOH)pH 3.4, the most resistant yeast strains belonged to S. cerevisiae followed by P. kudriavzevii, whereas C. glabrata and K. marxianus were more sensitive. Strain variations were observed within all four species. When transferred to non-stress conditions, i.e. MYGP, pH 5.6, after exposure to (LA + AA+EtOH)pH 3.4 for 6 h, 45% of the single cells of the most resistant S. cerevisiae strain kept their plasma membrane integrity, recovered their pHi to near physiological range (pHi = 6.1-7.4) and resumed proliferation after 3-24 h of lag phase. The results obtained are valuable in order to change processing conditions of the dough to favor the survival of preferable yeast species, i.e. S. cerevisiae and K. marxianus and inhibit opportunistic pathogen yeast species as C. glabrata. SN - 1879-3460 UR - https://www.unboundmedicine.com/medline/citation/31174038/Effects_of_intrinsic_microbial_stress_factors_on_viability_and_physiological_condition_of_yeasts_isolated_from_spontaneously_fermented_cereal_doughs_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0168-1605(19)30137-0 DB - PRIME DP - Unbound Medicine ER -