Background Safety issues of probiotic products have been reported frequently in recent years. Ten bacterial strains isolated from seven commercial probiotic products on market were evaluated for their safety, by whole-genome analysis. Results We found that the bacterial species of three probiotic products were incorrectly labeled. Furthermore, six probiotic product isolates (PPS) contained genes for the production of toxic metabolites, while another three strains contained virulence genes, which might pose a potential health risk. In addition, three of them have drug-resistance genes, among which two strains potentially displayed multidrug resistance. One isolate has in silico predicted transferable genes responsible for toxic metabolite production, and they could potentially transfer to human gut microflora or environmental bacteria. Isolates of Lactobacillus rhamnosus and Bifidobacterium animalis subsp. lactis are associated with low risk for human consumption. Based on a comparative genome analysis, we found that the isolated Enterococcus faecium TK-P5D clustered with a well-defined probiotic strain, while E. faecalis TK-P4B clustered with a pathogenic strain. Conclusions Our work clearly illustrates that whole-genome analysis is a useful method to evaluate the quality and safety of probiotic products. Regulatory quality control and stringent regulations on probiotic products are needed to ensure safe consumption and protect human health.

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The aim of the present study was to comprehensively evaluate the changes in the metabolite profile of breast milk over lactation stages and their relationship with dietary intake in Chinese women by HPLC-QTOFMS based metabolomic analysis. The colostrum, transitional milk and mature milk of thirty healthy lactating women were collected for analysis. Eighty-four differential metabolites over lactation stages were identified, including 12 fatty acyls, 15 glycerolipids, 23 glycerophospholipids, 7 sphingolipids, 7 vitamins, 5 nucleotides-related metabolites, 2 amino acids, 1 amino acid derivate, 9 dipeptides, 1 steroid hormone, 1 energy-related metabolite and 1 amine. Partial least-squares regression analysis indicated that the metabolite profiles of the colostrum, transitional milk and mature milk have a strong relationship with dietary intake (R2 values were 0.92, 0.87 and 0.74, respectively). However, among the 84 differential metabolites over lactation stages, only two showed a strong relationship with dietary intake: 1,24,25-(OH)3 vitamin D3 was positively correlated with the dietary intake of meat and eggs, protein and fat; 11β-hydroxyprogesterone was negatively correlated with the dietary intake of fruit and carbohydrate. After adjusting for dietary intake, the variation trend of all the 84 differential metabolites over lactation stages remained unchanged. In conclusion, 84 differential metabolites in the breast milk of Chinese women over lactation stages were identified, and their variation trend was independent of dietary intake. These metabolites were partially different from those identified in previous metabolomic studies in the Western population. The present study is quite meaningful for understanding the variation of nutritional requirements in Chinese infants at different developmental stages and manufacturing optimal infant formulas for them.

The long-term influence of gestational diabetes mellitus (GDM) on offspring and the effect of omega-3 polyunsaturated fatty acids (n-3 PUFA) on GDM offspring are poorly understood. We studied the long-term diabetic risk in GDM offspring and evaluated the effect of n-3 PUFA intervention. Healthy offspring rats were fed standard diet (soybean oil) after weaning. GDM offspring were divided into three groups: GDM offspring (soybean oil), n-3 PUFA adequate offspring (fish oil), and n-3 PUFA deficient offspring (safflower oil), fed up to 11 months old. The diabetic risk of GDM offspring gradually increased from no change at weaning to obvious impaired glucose and insulin tolerance at 11 months old. N-3 PUFA decreased oxidative stress and inflammation in the liver of older GDM offspring. There was a differential effect of n-3 PUFA and n-6 PUFA on hepatic telomere length in GDM offspring. Non-targeted metabolomics showed that n-3 PUFA played a modulating role in the liver, in which numerous metabolites and metabolic pathways were altered when GDM offspring grew to old age. Many metabolites were related to diabetes risk, such as α-linolenic acid, palmitic acid, ceramide, oxaloacetic acid, tocotrienol, tetrahydro-11-deoxycortisol, andniacinamide. In summary, GDM offspring exhibited obvious diabetes risk at old age, whereas n-3 PUFA decreased this risk.