| Both selenium(Se) and chromium(Cr) are essential trace elementes which are of important for the health of human and animal. In vivo, Se can be combinded to some specific proteins to form selenoproteins or selenoenzymes which have pervasive biological functions including anti-oxidation, enhance immunity, enhance fertility, detoxification against some heavy metals, and prevention from some local epidemic diseases. It is revealed that Cr is the essential part of Glucose Tolence Factor(GTF), which can regulate the metabolism of glucose, further the metabolism of lipid, protein, and nucleic acid. By now, the additive essential trace elements that used in the food are mostly in the form of inorganic, Se is sodium selenite and Cr is chromium trichloride, which is of low bioavailability, high toxicity and posed potential polution on the environment, and some goverments are trying to replace the essential trace elements in food or feed additive that of inoganic form with organic ones.Host can benefit from the probiotics, which refer to non-pathogenicity bacteria i.e. some species of yeast and most of lactic acid bacteria, when they are ingested. Bacteria has short-term growth cycle, can reproduce itself qucikly and adapt itselt with high level of heavy metal, and it is often served as the vector of essential trace elements, which include both the bio-functions of probiotics and essential trace elements.The culture conditions of Se-and Cr-enriched probiotics were optimized in the present study, and thus the Se-and Cr-enriched probiotics was prepared. Further, the lipid-lowing effects of probiotics was evaluated, and the Se-and Cr-enriched probiotics on the high fat fed mice, which provides some basic information with the lipid-lowing effects of Se-and Cr-enriched probiotics.Experiment 1 The present study was undertaken to check in vitro characteristics of four probiotic strains, which can convert inorganic Se into organic Se. The characteristics studied including acid and bile tolerance, tolerance and removal of lipids(CHO and TG), and maintenance of the native microbial populationes of gastro-intestinal under high-lipids condition. The results showed that all strains were able to survive in pH 3.0 and adapt to 0.3% oxgall media. The concentration of CHO and TG higher than 0.6% and 9.0%, respectively, could significantly restrained the growth of all four strains(P<0.05). Each of those four probiotic strains could remove CHO and TG from media ranging from 6.77-25.78μg·mL-1,3.80-10.25μg·mL-1, respectively, and ease the native microbial populationes of gastro-intestinal of their stress under high-lipids condition. Among the four strains, La, which could remove more than 10μg·mL-1 and 20μg·mL-1 CHO and TG from media, may be promising candidate of lipids tolerance and removal strain.Experiment 2 Single-factor tests were conducted to investigate the effects of cultural conditions including initial pH, culture duration, temperature, inoculum volume and chromium(III) concentration on the growth states of probiotics. Then, the conditions were optimized by orthogonal test and the best result came out to be:initial pH was 6.0, culture duration was 36 h, temperature was 34℃, inoculum volume was 8% and the metal concentration was 20μg·mL-1. Under the conditions, the number of all those four probiotics could reach 108-109cfu·mL-1,89.32% inorganic-Cr was converted into organic form, and the Cr in organic form reached as high as 17.86μg·mL-1.Experiment 3 Based on the results of the EXPERIMENT TWO, the present research was carried out to evaluate the effects of different leveles of Se combing with different leveles of Cr on the growth performance of the four probiotic strains. Further, four leveles of Se and Cr were selected respectively to evaluate the effects of the combination of both two trace elements on the growth performance of the four probiotic strains, the convet rate of organi Se and Cr by those four probiotic strains, and the total amount of organic Se and Cr contained by those four probiotic strains. The results showed that the convet rate of organi Se and Cr by those four probiotic strains could reach upto 70%, the the total amount of organic Se and Cr contained by those four probiotic strains could reach upto 5.53μg·mL-1 and 7.02μg·mL-1, and the CFU of the four probiotic strains could reach upto 8 when the concentration of Se and Cr was 7.5μg·mL-1 and 10μg·mL-1, respectively.Experiment 4 The present study was conducted to evaluated the the effects of Se-and Cr-enriched probiotics on the lipid metabolism of HFD-fed ICR mice. Fourty ICR male mice were randomly divided into four groups, including NC (normal contral group), HFD (hyperlipidemia model group), ISC (probiotics plus inorganic Se and Cr group), OSC (Se and Cr-enriched probiotics group). The animals of NC group were give normal diet, while the other three groups were give high-fat diet. The general situations were observed, and changes of serum glucose and lipips and the lipips in both liver and feces were tested. After 10 weeks, the levels of serum glucose and lipips of HFD group were significant higher than that of the NC group. The levels of serum glucose and lipips of the two treated groups were significant lower than that of HFD group, however,the lipips in feces were of opposite. There were no significant difference of the levels of serum glucose and lipips and fecal lipids betweet ISC and OSC, while the hepatic lipids of OSC were significant lower than that of ISC. The results showed that both the mixture of probiotics, inorganic Se and Cr and Se and Cr-enriched probiotics were capable of reducing the serum glucose and lipids and hepatic lipips, and increasing the amount of lipids excreted with feces in high-fat diet fed ICR mice. However, Se and Cr-enriched probiotics was a better candidate than the mixture of probiotics, inorganic Se and Cr. |
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