In Vitro Fermentation Of Neutro Garlic Fructan By Human Faecal Bacteria

Garlic fructan, which was confirmed to have similar structure with inulin fructooligosaccharide, is the main component of garlic essential oil production byproduct. There are no research reported about its'effect on gut microbiology. Effects of neutro garlic fructan of different average degrees of polymerization (DP 11,14,16,21, respectively) on short chain fatty acids (SCFA) production, as well as the change of human faecal microflora were investigated via an in vitro anaerobic batch culture system which contained the garlic fructan as unique carbon source and inoculated with human feacal bacteria. Glucose, Inulin and no extra carbon groups were also conducted as controls.①CFU of total anaerobes, Enterococci, Bacteroides, Clostridium, Bifidobacterium, Lactobacillus were analyzed by plate counting with selective culture plates after fermenting for 24 hours. Results suggested that the utilization of garlic fructan of DP 16 (sample c),21 (sample d) were more efficiently utilized by human faecal bacteria. Growth of Bifidobacterium can be significantly stimulated about 2.2-4.1 orders of magnitude by the four garlic fructans, while the samples of DP 16 and DP 21 shown better stimulatory effects, the highest bacterial counts up to 7.74 logcfu/mL fermentation broth. CFU of Bacteroides, Enterococci and Clostridium were all significantly decreased about 0.36～1.05 orders of magnitude after garlic fructans fermentation.②Microflora of the cultures after 24h in vitro fermentation were also analyzed by terminal restriction fragment length polymorphism (T-RFLP) technique. Results showed that Lactobacillus were rapidly stimulated in the fermentation broth, which was added with garlic fructan sample c (DP 16) and sample d (DP 21). Lactobacillus, with the relative percentage of 27.68% and 34.15%, were the dominant species in the fermentation broth communities, and its proportion was higher than other faecal flora. Bifidobacterium growed well, with the proportion 11.31%,5.4%,7.56%,7.67%, respectively in the inulin, garlic fructan sample a (DP 11), c (DP 16) and d (DP 21) fermentation culture and was significantly stimulated compared with feacal samples and negative control.③The culture broths were removed at 0,4,8,12, and 24 hours for acetate, propionate, butyrate ④and lactate analysis. It was found out that except negative control, all samples produced highest total SCFA concentration at 12h. The concentration of total SCFA in garlic fructan culture were sample a> sample b> sample c> sample d, and sample a produced the highest total SCFA concentration 86.38μmol/mL. The concentration and molar ratios of lactate and butyrate in the culture broths is higher than acetate and propionate. And for garlic fructan sample a, the molar ratio of butyrate was significantly higher than other groups. And the molar ratio of acetate:propionate:butyrate:lactate in sample c was 14:11:45:30.