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Characterization of the Growth, Cryotolerance, and Adhesion of Lactic Acid Bacteria in the Presence of Milk Phospholipids

Zhang, Lin
http://orcid.org/0000-0002-8956-2768
http://rave.ohiolink.edu/etdc/view?acc_num=osu1592982895399998

Abstract Details

2020, Master of Science, Ohio State University, Food Science and Technology.
Milk phospholipids (MPLs) are valuable dairy components known for various health benefits, like reducing gastrointestinal infections and supporting neurological development. They are used as functional ingredients for food application and human consumption. Meanwhile, lactic acid bacteria (LAB) are also associated with beneficial effects on human health. They are commonly used in fermented dairy products, and many of them are regarded as probiotics. The possibility of using MPLs and LAB as a combination has great potential benefit and has shown some synergistic effects on the delivery of both ingredients. Little is known about the direct impact of MPLs on LAB, which contributes to the determination of MPLs supplementation strategies and LAB culture selection. Our first objective was to test the influence of MPLs on the growth and cryotolerance of LAB in MRS and acid whey-based dairy (AW) media. We screened 134 strains in our collection and selected 13 LAB strains using 0.5% MPLs supplemented modified minimal medium (MM) and another 14 strains using the AW medium. The growth curves of those 13 LAB in MRS and 0.5% MPLs supplemented MRS media were compared. The cell viability counts and acidification ability of those 14 strains cultivated in AW and 0.5% MPLs supplemented acid whey-based (AWM) media were evaluated using the plate counting method and skim milk fermentation test before and after three cycles of freeze-thawing treatment. We hypothesized that the addition of MPLs would impact the growth of LAB differently in diverse media, and MPLs supplementation could modify the cryotolerance of LAB. Results indicated that the addition of 0.5% MPLs showed a strong inhibitory impact on the growth of LAB in the MRS medium while promoting the growth and enhancing the cryotolerance of LAB significantly in the AWM medium. The second objective was to investigate the adhesion or interaction between MPLs and LAB using the sucrose gradient centrifugation test and further analyze the mechanism of interaction with the analysis of the expression of three surface binding-promoting genes (MapA, Cnb, and CmbA). We categorized the adhesion between MPLs and LAB by observing the density differences of bacteria alone (highest density in our assay) and MPLs alone (lowest density in our assay). Our working hypothesis was that any interaction or adhesion between these two components would yield density differences that are proportional to the amount of bacteria adhered with MPLs. Out of 122 LAB tested, 27% showed what can be characterized as “adhesion”, in which 38% was Lactobacillus reuteri. Further characterization of this adhesion was carried out by the RT-qPCR, which demonstrated that the relative expression level of gene CmbA was positively associated with adhesion. Also, we found out that the supplementation of MPLs caused overexpression of genes MapA and Cnb in L. reuteri OSU-PECh-37A and OSU-PECh-48. Our first study demonstrated that the addition of 0.5% MPLs would inhibit the growth of LAB in the MRS medium but promote their growth and enhance their cryotolerance in the AWM medium. The second study suggests a strain-specific adhesion between MPLs and LAB and that CmbA, which encodes for a surface protein, might be a potential factor of adhesion. A better understanding of the direct influence of MPLs on LAB may contribute to designing new functional products and improve the delivery of both bioactive ingredients to their target site of action.
Rafael Jimenez-Flores (Advisor)
Ahmed Yousef (Committee Member)
Zhongtang Yu (Committee Member)
141 p.
Food Science
lactic acid bacteria; milk phospholipids; acid whey; cryotolerance; adhesion

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Citations

  • Zhang, L. (2020). Characterization of the Growth, Cryotolerance, and Adhesion of Lactic Acid Bacteria in the Presence of Milk Phospholipids [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1592982895399998

    APA Style (7th edition)

  • Zhang, Lin. Characterization of the Growth, Cryotolerance, and Adhesion of Lactic Acid Bacteria in the Presence of Milk Phospholipids. 2020. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1592982895399998.

    MLA Style (8th edition)

  • Zhang, Lin. "Characterization of the Growth, Cryotolerance, and Adhesion of Lactic Acid Bacteria in the Presence of Milk Phospholipids." Master's thesis, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1592982895399998

    Chicago Manual of Style (17th edition)

osu1592982895399998
157
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