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The Investigation On Physiology Functional Characteristics Of Bifidobacterium And Its Applications In Foods

Posted on:2003-07-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:X C MengFull Text:PDF
GTID:1100360065460198Subject:Food Science
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Bifidobacterium is important inhabitant in intestinal tracts of people and animals. It has beneficial effects on intestinal health. But its functional mechanisms are not clear. Physiological function, functional mechanisms of Bifidobacterium and its applications in foods were investigated systematically by seven experiments in vitro and in vivo. They were composed of isolation and determination of Bifidobacterium, comparison of growth characteristics, factors influencing survivability, bioantaganism to pathogen, adherence and colonization to mucus membrane, immunomodulation mechanisms on trial animals and development of products containing Bifidobacterium.Growth and acidic ability of two commercial strains (B.adolescentis, Ba; B.infantis, Bi) , two strains isolated from commercial products (B.Iongum, Bl; B. breve, Bbr) and two strains isolated from infant faeces (B.b ifidum, Bb; B.Iongum- 1, Bl-1 ) were compared in TPY medium. The results showed that Bi grown faster than Ba. Acidic ability of Bi was lower than that of Ba. There was not obvious delaying stage in growth curve of Bi. Ba was reverse. There were also not obvious delaying stage in growth curve of BI and Bbr. Absorbance at 600nm of BI and Bbr were 2.348 and 2.162 respectively after 48 hours. Absorbance at 600nm of Bb and Bl-1 were 1.400 and 1.447 respectively after 48 hours. Commercial product strains were better than strains isolated from infant faeces in growth and acidic ability.Characteristics on gastrointestinal (GIT) condition tolerance of Ba, Bi, BI and Bbr were investigated in simulative pH of gastric acid, gastric juice, intestinal juice and intestinal bile salt. Survivability of Ba, Bi, BI and Bbr were 0.14%, 17.86%, 49.09% and 9.53% respectively after 1.5 hours in pH1.5 condition, and were 45.39%, 97.27%, 84.53% and 85.51% respectively after 1.5 hours in simulative gastric juice containing pepsin and were 29.17%, 47.97%, 87.70% and 77.27% respectively after 12 hours in simulative intestinal juice containing pancreatin. The amounts of viable Ba, BI, and Bbr decreased with the concentration of bile salt increased. The survivability were 5.92%, 1 3.96%. and 61.24% respectively after 12 hours in simulative intestinal juice containing 2% bile salt. The growth speed decreased with concentration of bile salt increased. The GIT conditions tolerance ability of Bifidobacterium strains was different. The tolerance of Bi and BI were best among the tested strains.The amounts of Salmonella were below 102cfu/mL after 20 hours in co-culturing with Ba, BI, and Bbr. The amounts of Salmonella were 1.3 X 108cfu/mL after 20 hours in co-culturing with Bi. When four strains supernatants and acetic acid-lactic acid (3:2) of pH4 were added to broth media to culture Salmonella, it was found that the inhibitory ability of acetic acid-lacticacid was the highest, then was that of Ba, Bl and Bbr supernatants, and the inhibitory ability of Bi supernatant was the lowest. When the pH of acid liquid and supernatants was adjusted to 7, there was no influence on growth trend of Salmonella. But the amounts of Salmonella in different growth stage were lower than the corresponding stage of the controlled group.The scan electron micrographs showed that the relationship of intestinal microflora with mucus was close. It was found that the adhesive percent of Ba was 44.6%, that of Bbr was 33.20%, that of Bi and Bl were 18.40% and 11.78% respectively by comparison of the adhesion of radioactively labeled Bifidobacterium strains to the mucus. The adhesive percent of Ba decreased when the tested sugars, colostrums powder and the supernatants of Bi, Bl, Salmonella and E.co//.were added, while the adhesive percent of Ba increased when the supernatants of Ba and Bbr were added.The immunomodulation of Bi and Bl on the specific and non-specific immunity of normal mouse, the prevention and the treatment of Bi and Bl on the mouse model with low immunity were investigated. It was found that two strains had no significant effects on weight, spleen/weight and kidney/weight. Ther...
Keywords/Search Tags:Bifidobacterium, physiological characteristics, growth, pathogen, adherence, immunomodulation, application
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