Extracellular Polysaccharide Extraction from Streptococcus thermophilus in Fermented Milk.

Simple item page
dc.citation.issue2
dc.citation.volume10
dc.contributor.authorWa Y
dc.contributor.authorChanyi RM
dc.contributor.authorNguyen HTH
dc.contributor.authorGu R
dc.contributor.authorDay L
dc.contributor.authorAltermann E
dc.contributor.editorCocolin L
dc.coverage.spatialUnited States
dc.date.accessioned2024-07-31T02:50:37Z
dc.date.available2024-07-31T02:50:37Z
dc.date.issued2022-04-27
dc.description.abstractLactic acid bacteria such as Streptococcus thermophilus are known to produce extracellular polysaccharide (EPS) in fermented foods that enhance the creaminess and mouthfeel of the product, such as yogurt. Strains producing larger amounts of EPS are highly sought-after, and therefore, robust and accurate quantification methodologies are important. This study found that two commonly used methodologies significantly underestimated the amount of EPS produced as measured using a milk matrix. To this end, a proteolytic step was implemented prior to EPS extraction (Method C). An initial proteolytic step using xanthan gum-spiked milk significantly increased recovery yield to 64%, compared to 27.8% for Method A and 34.3% for Method B. Method C showed no improvement when assessed using a chemically defined medium. Method C was further validated using three strains of S. thermophilus with varying EPS-production capabilities (STLOW, STMID, STHIGH). Overall, Method C demonstrated significant improvements in the EPS extraction yield for all three S. thermophilus strains in fermented milk. On average, Method C improved isolation yield by ∼3- to 6-fold compared with Method A and by ∼2- to 3-fold compared with method B. There were no significant differences between samples when they were grown in a chemically defined medium, highlighting the importance of a proteolytic step specifically for fermented milk samples. In commercial applications, accurate quantification of EPS-production is an important aspect when finding new strains. IMPORTANCE Extracellular polysaccharide (EPS) production by milk-fermenting microorganisms is a highly sought-after trait in improving the perceived thickness, creaminess, and mouthfeel of yogurt. Streptococcus thermophilus are commonly isolated and their EPS production is quantified in the search for higher-producing strains. In this study, we demonstrated that two commonly used methods for isolating EPS from milk samples significantly underestimated the true amount of EPS present. We demonstrated that the addition of a proteolytic step prior to EPS extraction isolated over 2-fold more EPS than identical samples processed using the traditional protocols. We further validated this method in fermented milk samples from three strains of S. thermophilus that included a low-, mid-, and high-EPS producing strain. Again, we showed significant improvements in EPS isolation using a proteolytic step. In the search for new S. thermophilus strains with enhanced EPS production, accurate quantification in an optimal medium is essential.
dc.description.confidentialfalse
dc.edition.editionApril 2022
dc.format.paginatione0228021-
dc.identifier.author-urlhttps://www.ncbi.nlm.nih.gov/pubmed/35343770
dc.identifier.citationWa Y, Chanyi RM, Nguyen HTH, Gu R, Day L, Altermann E. (2022). Extracellular Polysaccharide Extraction from Streptococcus thermophilus in Fermented Milk.. Microbiol Spectr. 10. 2. (pp. e0228021-).
dc.identifier.doi10.1128/spectrum.02280-21
dc.identifier.eissn2165-0497
dc.identifier.elements-typejournal-article
dc.identifier.issn2165-0497
dc.identifier.numbere0228021
dc.identifier.urihttps://mro.massey.ac.nz/handle/10179/71169
dc.languageeng
dc.publisherAmerican Society for Microbiology
dc.publisher.urihttps://journals.asm.org/doi/10.1128/spectrum.02280-21
dc.relation.isPartOfMicrobiol Spectr
dc.rights(c) 2022 The Author/s
dc.rightsCC BY 4.0
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectStreptococcus thermophilus
dc.subjectdairy
dc.subjectextracellular polysaccharide
dc.subjectfermentation
dc.subjectAnimals
dc.subjectDietary Carbohydrates
dc.subjectFermentation
dc.subjectMilk
dc.subjectPolysaccharides, Bacterial
dc.subjectStreptococcus thermophilus
dc.subjectYogurt
dc.titleExtracellular Polysaccharide Extraction from Streptococcus thermophilus in Fermented Milk.
dc.typeJournal article
pubs.elements-id454157
pubs.organisational-groupOther
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