University of SaskatchewanHARVEST
  • Login
  • Submit Your Work
  • About
    • About HARVEST
    • Guidelines
    • Browse
      • All of HARVEST
      • Communities & Collections
      • By Issue Date
      • Authors
      • Titles
      • Subjects
      • This Collection
      • By Issue Date
      • Authors
      • Titles
      • Subjects
    • My Account
      • Login
      JavaScript is disabled for your browser. Some features of this site may not work without it.
      View Item 
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item
      • HARVEST
      • Electronic Theses and Dissertations
      • Graduate Theses and Dissertations
      • View Item

      Characterization and encapsulation of probiotic bacteria using a Pea-protein Alginate matrix

      Thumbnail
      View/Open
      Thesis.pdf (4.192Mb)
      Date
      2009-07
      Author
      Kotikalapudi, Bhagya Lakshmi
      Type
      Thesis
      Degree Level
      Masters
      Metadata
      Show full item record
      Abstract
      Research was undertaken to examine different in vitro characteristics of probiotic bacteria, including Lactobacillus acidophilus ATCC® 11975™, Bifidobacterium infantis ATCC 15697D, Bifidobacterium catenulatum ATCC® 27675 and Bifidobacterium adolescentis ATCC® 15703™ in order to identify suitable strain(s) for encapsulation. Under simulated gastric conditions (pH 2.0), L. acidophilus was the most acid-tolerant strain (D-value 10.2 ± 0.8 min), and was able to survive for 30 min; whereas, the other tested probiotics underwent a rapid (within the first 5 min at pH 2.0) 4-5 log colony forming units (cfu)/mL loss in viability. All probiotics tested were able to survive 5 h exposure to 0.3% Oxgall bile at pH 5.8. The relative ranking of probiotic adherence to Caco-2 cells was determined to be: L. acidophilus > B. catenulatum > B. adolescentis > B. infantis, which correlated with 4.5 104, 3.1 103, 2.6 101, and 1.5 101 cfu/mL associated with Caco-2 cell monolayers, respectively. The most hydrophobic probiotics included L. acidophilus (46.5 ± 6.1%) and B. catenulatum (65.5 ± 5.2%); their hydrophobicity were positively correlated with auto-aggregation ability. Addition of divalent cations, EDTA, and bile salts were found to affect hydrophobicity as well; for example, 0.5 mM MgCl2 resulted in a 20% increase in cell surface hydrophobicity of L. acidophilus from baseline levels; whereas, the addition of 0.1 and 0.5% bile salts decreased L. acidophilus hydrophobicity from control levels by 60 and 90%, respectively. Cell free culture supernatant of L. acidophilus effectively inhibited the growth of Escherichia coli O157:H7, and Clostridium sordelli. Bactericidal activity of L. acidophilus cell-free supernatant (the lethal factor was determined to be both heat and trypsin-resistant) against Escherichia coli O157:H7 and Clostridium sordelli ATCC 9714 over 24 h resulted in reductions of 5.5 and 3.5 log cfu/mL, respectively. Further examination of probiotics revealed varying degrees of resistance to the iv antimicrobial agents ciprofloxacin (4 ìg/mL), naladixic acid (32 ìg/mL), kanamycin (64 ìg/mL) and sulfisoxazone (256 ìg/mL). Determination of carbon source utilization patterns indicated that B. catenulatum utilized a number of carbohydrates including -methyl-D-glucoside, D-xylose, D-cellobiose, and -D-lactose; whereas,L. acidophilus, B. infantis, and B. adolescentis utilized D-xylose. Lactobacillus acidophilus was ultimately selected for encapsulation in a 3 mm diameter pea protein-alginate matrix followed by in vitro challenge to simulated gastric conditions (pH 2.0). Encapsulation of L. acidophilus demonstrated a significant (P < 0.05) protective effect during the 2 h exposure to simulated acidic stomach conditions; within capsules, there was approximately 1 log cfu/mL loss in cell viability, whereas unprotected cells experienced > 6 log/mL loss in cell viability over the same period.
      Degree
      Master of Science (M.Sc.)
      Department
      College of Agriculture
      Program
      College of Agriculture
      Supervisor
      Korber, Darren R.
      Committee
      Low, Nicholas H.; Nickerson, Michael; Shand, Phyllis
      Copyright Date
      July 2009
      URI
      http://hdl.handle.net/10388/etd-08282009-170854
      Subject
      Survival studies
      Encapsulation
      Caco cell line
      Bifidobacterium
      Lactobacillus
      bacteria
      Pea-protein matrix
      Culture
      Statistics
      Collections
      • Graduate Theses and Dissertations
      University of Saskatchewan

      University Library

      © University of Saskatchewan
      Contact Us | Disclaimer | Privacy