| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 106 === The aim of this study is to investigate the composition, yield, prebiotic effect on gut bacteria of Ulva lactuca oligosaccharides (UOS5k). The antimicrobial activity of lactic acid bacteria fermented UOS5k broth against food pathogen bacteria the and effects on the growth of gut bacteria with the combination of UOS5k and phenyllactic acid (Ph-LA) are also evaluated. The proximate composition of Ulva powder were 16.1% of water, 33.7% of ash, 1.08% of crude protein, 0.58% of crude fat, and 48.7% of carbohydrate. The results of the proximate composition of UOS5k were 6.53% of water, 73.2% of ash, 0.35% of crude protein, 0.66% of crude fat, and 19.2% of carbohydrate.The UOS5k were produced by hot acid and enzyme hydrolysis and then separated by ultrafiltration system (< 5 kDa). First, using the artificial sea water medium by adding 0.5% Ulva powder and 0.5% defatted soybean flour. The enzyme activity of amylase induced by P. vesicularis MA103 and A. salmonicida MAEF108 were 0.49 U and 0.94 U, respectively, after 72 hr. And the cellulase activity induced from P. vesicularis MA103 and A. salmonicida MAEF108 were 0.28 U and 0.25 U, respectively
, after 72 hr. Using high performance liquid chromatography (HPLC) and thin layer chromatography (TLC) to analyze the compositon of UOS5k, as comparing with the molecular weight standard oligosaccharides, the main peak UOS5k is approaching to DP4-5, while the molecular weight of major components of UOS5k are approximately 5,473 Da (15.6%), 838 Da (73.0%), and 388 Da (1.2%). In the co-culture of Bifidobacterium adolescentis BCRC14608 + C. perfringens BCRC13019 and Bif. bifidum BCRC14615 + C. perfringens BCRC13019, the viable counts of bifidobacteria grown in basal medium containing 2% UOS5k increased 3.31 and 2.71 Log CFU/mL, as the count of C. perfringens incraesed 0.57 and 1.35 Log CFU/mL, respectively. By using agar well diffusion method, the cell free supertanat (CFS) of strains KP3 and KP4 incubating in added 2% UOS5k MRS broth showed there is no antibacterial activity against food pathogen bacteria. Using HPLC to analyze antimicrobial substances of CFS from glucose MRS broth cultured with strains KP3 or KP4, results indicated that the concentration of LA and Ph-LA were 37.09 and 1.06 mg/mL, 38.49 and 1.08 mg/mL
, respectively. The minimal inhibition concentration (MIC) and minimal bactericidal concentration, (MBC) of extracellular CFS from two lactic acid bacteria strains KP3 and KP4 against to C. perfringens were evaluated as 25 mg/mL as well as 25 mg/ mL
, 25 mg/mL and 50 mg/mL, respectively. In the co-culture test of gut bacteria, the viable counts of Bif. adolescentis BCRC14608 + C. perfringens BCRC13019 and Bif. bifidum BCRC14615 + C. perfringens BCRC13019 grown in basal medium containing 2% UOS5k and extracellular substance of KP3 (25 mg/mL) showed that bifidobacteria increased 2.67 and 1.97 Log CFU/mL, while the cell count of C. perfringens increased 0.39 and 1.83 Log CFU/mL, respectively. While 2% UOS5k and 50 mg/mL of CFS KP4 added basal medium (BM), the viable count of Bif. adolescentis BCRC14608 + C. perfringens BCRC13019 and Bif. bifidum BCRC14615 + C. perfringens BCRC13019 were increased 1.70 and 2.71 Log CFU/mL and C. perfringens bacterial count were increased0.91 and 0.59 Log CFU/mL, respectively. As a conclusion, as Bif. adolescentis BCRC14608 + C. perfringens BCRC13019 incubated with 2% UOS5k and extracellular CFS KP3 (25 mg/mL) added BM the bacterial of showed Bif. adolescentis BCRC14608 increased 2.67 Log CFU/mL, the bacterial count of C. perfringens BCRC13019 increased 0.39 Log CFU/mL.
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