Probiotic characteristics of Lactobacillus plantarum E680 and its effect on Hypercholesterolemic mice.

BACKGROUND: Probiotics have been reported to reduce total cholesterol levels in vitro, but more evidence is needed to determine the clinical relevance of this activity. Chinese traditional fermented pickles are a good source of lactic acid bacteria. Therefore, pickle samples were collected for screening lactic acid bacteria based on their ability to survive stresses encountered during gastrointestinal passage and cholesterol reducing potency. RESULTS: Seventy five lactic acid bacteria strains were isolated from 22 fermented pickles. From these bacteria, Lactobacillus plantarum E680, showed the highest acid (85.25%) and bile tolerance (80.79%). It was sensitive to five of the eight antibiotics tested, inhibited the growth of four pathogenic bacteria, and reduced the total cholesterol level by 66.84% in broth culture. In vivo testing using hypercholesterolemic mice fed high-fat emulsion, independent of food intake, found that L. plantarum E680 suppressed body weight gain and reduced total cholesterol and low-density lipoprotein cholesterol levels, with no effect on high-density lipoprotein cholesterol. CONCLUSIONS: Chinese traditional fermented pickles are a good source for probiotics. L. plantarum E680, isolated from pickles, was acid and bile tolerant, sensitive to antibiotics, and reduced cholesterol levels both in vitro and in vivo. Based on these results, L. plantarum E680 may have potential as a novel probiotic for the development of cholesterol-lowering functional food.

Systematic study of the quality and safety of chilled pork from wet markets, supermarkets, and online markets in China.

BACKGROUND: With increasing media coverage of food safety incidents, such as that of clenbuterol residues in pork, food safety has become a major public health concern in China. Rapidly developing online markets attract increasing numbers of Chinese consumers to purchase food on the Internet. However, the quality and safety of food sold online are uncertain and are less reported on. OBJECTIVE: This research aimed to systematically study the quality and safety of chilled pork from wet markets, supermarkets, and online markets in China. RESULTS: The chilled pork samples from online markets were fresher than those from wet markets and supermarkets based on the surface redness (a* value). Chilled pork contained high levels of nutritional elements, especially the magnesium and phosphorus levels in samples from online markets. The levels of heavy metal element residues and veterinary drug residues in all chilled pork samples were within the standards limits. In addition, huge differences existed in the quality and freshness of the chilled pork samples from online markets according to principal component analysis (PCA). CONCLUSIONS: Most chilled pork sold in Chinese markets was qualified and safe. It is necessary to establish an effective online market supervision system for chilled pork.

Effect of culturing conditions on the expression of key enzymes in the proteolytic system of Lactobacillus bulgaricus.

The proteolytic system of Lactobacillus bulgaricus breaks down milk proteins into peptides and amino acids, which are essential for the growth of the bacteria. The aim of this study was to determine the expressions of seven key genes in the proteolytic system under different culturing conditions (different phases, initial pH values, temperatures, and nitrogen sources) using real-time polymerase chain reaction (RT-PCR). The transcriptions of the seven genes were reduced by 30-fold on average in the stationary phase compared with the exponential growth phase. The transcriptions of the seven genes were reduced by 62.5-, 15.0-, and 59.0-fold in the strains KLDS 08006, KLDS 08007, and KLDS 08012, respectively, indicating that the expressions of the seven genes were significantly different among strains. In addition, the expressions of the seven genes were repressed in the MRS medium containing casein peptone. The effect of peptone supply on PepX transcription was the weakest compared with the other six genes, and the impact on OppD transcription was the strongest. Moreover, the expressions of the seven genes were significantly different among different strains (P<0.05). All these results indicated that the culturing conditions affected the expression of the proteolytic system genes in Lactobacillus bulgaricus at the transcription level.