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In this study, lactic acid bacteria (LAB) fermentation and β-galactosidase catalysis methods were combined to increase the lactulose concentration and reduce the galactose and lactose content in a hot-alkaline-based system. The optimal conditions for chemical isomerization were 70 °C for 50 min for lactulose production, in which the concentration of lactulose was 31.3 ± 1.2%. Then, the selection and identification of LAB, which can utilize lactose and cannot affect lactulose content, were determined from 451 strains in the laboratory. It was found that Lactobacillus salivarius TM-2–8 had weak lactulose utilization and more robust lactose utilization. Lactobacillus rhamnosus grx.21 was weak in terms of lactulose utilization and strong in terms of galactose utilization. These two strains fermented the chemical isomerization system of lactulose to reduce the content of lactose and galactose. The results showed that the lactose concentration was 48.96 ± 2.92 g/L and the lactulose concentration was 59.73 ± 1. 8 g/L for fermentation lasting 18 h. The β-galactosidase was used to increase the content of lactulose in the fermented system at this time. The highest concentration of 74.89 ± 1.68 g/L lactulose was obtained at an enzymatic concentration of 3 U/mL and catalyzed at 50 °C for 3 h by β-galactosidase. [ABSTRACT FROM AUTHOR]

Traditional fermented products and human intestines are rich sources of Lactobacillus strains which may have remarkable probiotic properties. In the present study, the probiotic properties of 40 Lactobacillus strains isolated from intestinal tracts of longevity population and traditional fermented food in China were determined, including the survival rates in simulated gastric acid and bile salt, aggregation, hydrophobicity, adhesion rate, antioxidant ability (ferric reducing antioxidant power), and antimicrobial ability. The differences between human strains and nonhuman strains were compared via t‐test and principal component analysis (PCA). The significant differences were found in the survival rate at 0.3% bile salt, adhesion ability of the strains, and antioxidant ability of the fermentation broth (p <.05). The results of PCA showed that the first principal component (PC1) score of human strains was significantly higher than that of nonhuman strains (p <.01). And some probiotic Lactobacillus were selected for further application based on the unsupervised clustering algorithm, heat‐map analysis, and K‐means algorithm. Four strains, CS128, CS39, CS01, and CS1301, along with Lactobacillus rhamnosus GG (LGG) were divided into cluster I. The four strains, all isolated from human tracts, have been selected. Thus, human Lactobacillus has better probiotic potential and application prospects than strains from the nonhuman source. PCA, the unsupervised clustering algorithm, and heat‐map analysis can be used to analyze and select Lactobacillus visually and effectively. [ABSTRACT FROM AUTHOR]

Obesity is a prevalent chronic disease worldwide. In this study, we screened lactic acid bacteria (LAB) suitable for fermenting Shenheling extract (SHLE) to enhance its anti-obesity efficacy and improve flavor. Using SHLE as the medium, a single strain was inoculated and the lactic acid bacteria suitable for growth in SHLE were preliminarily screened through a growth curve. The growth of the initially screened LAB was characterized in detail by the pH value, titration acidity and viable bacteria count. At the same time, appropriate LAB were selected with the lipase activity inhibition rate, α-glucosidase activity inhibition rate and a sensory evaluation as the response indicators. As a result, 6 of the 12 strains of lactic acid bacteria grew well in SHLE. The fermentation of five representative LAB could significantly improve the inhibition rate of the lipase activity of SHLE and maintain the inhibition rate of the α-glucosidase activity at a high level. In addition, fermentation removed the original flavors of SHLE such as grass, bitterness and cassia and added a sour taste, fruity aroma and cool taste. Among them, Lactobacillus fermentum grx08 and Lactobacillus rhamnosus hsryfm1301 gave SHLE a soft sour taste after fermentation. L. fermentum grx08, L. rhamnosus grx10 and hsryfm1301 imparted a moderately fruity aroma to SHLE after fermentation. In summary, L. fermentum grx08 and L. rhamnosus hsryfm1301 were the candidate strains for fermenting SHLE to produce good-flavored slimming functional drinks. [ABSTRACT FROM AUTHOR]

Objective: Fermented milk is the optimal vehicle for delivering probiotic bacteria. However, the viable count of probiotic bacteria such as some lactic acid bacteria and the post-acidification of fermented milk are a contradiction. The objective of this study was to restrict the post-acidification of the fermented milk containing living Lactobacillus rhamnosus hsryfm 1301. Results: Mild heat stress treatment (46 °C, 1 h) was chosen to help control the post-acidification caused by L. rhamnosus hsryfm 1301. When fermented milk was produced by single L. rhamnosus hsryfm 1301, the heat stress treatment reduced the post-acidification from 0.39 to 0.11% lactic acid, and the viable cells were maintained above 2.0 × 108 CFU mL−1 during 21 days of storage. Although the post-acidification limitation of heat treatment was relatively weak in fermented milk produced by L. rhamnosus hsryfm 1301 and S. thermophilus grx02 (from 0.26 to 0.10% lactic acid), this treatment was still effective. Furthermore, no whey separation in the fermented milk was caused by the treatment. Conclusions: Mild heat stress treatment could limit the post-acidification caused by L. rhamnosus hsryfm 1301 by decreasing its metabolism and proliferation. This treatment is a promising strategy to improve the shelf life of probiotic fermented milk. [ABSTRACT FROM AUTHOR]

Objective: To investigate the aerotolerance of Lactobacillus rhamnosus hsryfm 1301 and its influencing factors.Results: The growth rate of L. rhamnosus hsryfm 1301 weakened noticeably when the concentration of supplemented H2O2 reached 1 mM, and only 2% of all L. rhamnosus hsryfm 1301 cells survived in MRS broth supplemented with 2 mM H2O2 for 1 h. After pretreatment with 0.5 mM H2O2, the surviving cells of L. rhamnosus hsryfm 1301 in the presence of 5 mM H2O2 for 1 h increased from 3.7 to 7.8 log CFU. Acid stress, osmotic stress, and heat stress at 46 °C also enhanced its aerotolerance, while heat stress at 50 °C reduced the tolerance of L. rhamnosus hsryfm 1301 to oxidative stress. Moreover, treatment with 0.5 mM H2O2 increased the heat stress tolerance of L. rhamnosus hsryfm 1301 by approximately 150-fold.Conclusions: Lactobacillus rhamnosus hsryfm 1301 possesses a stress-inducible defense system against oxidative stress, and the cross-adaptation to different stresses is a promising target to increase the stress tolerance of L. rhamnosus hsryfm 1301 during probiotic food and starter culture production. [ABSTRACT FROM AUTHOR]

A growing stream of research suggests that probiotic fermented milk has a good effect on nonalcoholic fatty liver disease. This work aimed to study the beneficial effects of Lactobacillus rhamnosus hsryfm 1301 fermented milk (fermented milk) on rats with nonalcoholic fatty liver disease induced by a high-fat diet. The results showed that the body weight and the serum levels of total cholesterol, total glyceride, low-density lipoprotein, alanine transaminase, aspartate aminotransferase, free fatty acid, and reactive oxygen species were significantly increased in rats fed a high-fat diet (M) for 8 wk, whereas high-density lipoprotein cholesterol and superoxide dismutase were significantly decreased. However, the body weight and the serum levels of total cholesterol, total glyceride, alanine transaminase, aspartate aminotransferase, free fatty acid, reactive oxygen species, interleukin-8, tumor necrosis factor-α, and interleukin-6 were significantly decreased with fermented milk (T) for 8 wk, and the number of fat vacuoles in hepatocytes was lower than that in the M group. There were significant differences in 19 metabolites in serum between the M group and the C group (administration of nonfermented milk) and in 17 metabolites between the T group and the M group. The contents of 7 different metabolites, glycine, glycerophosphocholine, 1,2-dioleoyl-sn-glycero-3-phosphocholine, thioetheramide-PC, d -aspartic acid, oleic acid, and l -glutamate, were significantly increased in the M group rat serum, and l-palmitoyl carnitine, N6-methyl-l-lysine, thymine, and 2-oxadipic acid were significantly decreased. In the T group rat serum, the contents of 8 different metabolites—1-O-(cis -9-octadecenyl)-2-O-acetyl-sn-glycero-3-phosphocholine, acetylcarnitine, glycine, glycerophosphocholine, 1,2-dioleoyl-sn-glycero-3-phosphocholine, d -aspartic acid, oleic acid, and l -glutamate were significantly decreased, whereas creatinine and thymine were significantly increased. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that 50 metabolic pathways were enriched in the M/C group and T/M group rat serum, of which 12 metabolic pathways were significantly different, mainly distributed in lipid metabolism, amino acid, and endocrine system metabolic pathways. Fermented milk ameliorated inflammation, oxygenation, and hepatocyte injury by regulating lipid metabolism, amino acid metabolic pathways, and related metabolites in the serum of rats with nonalcoholic fatty liver disease. [ABSTRACT FROM AUTHOR]

Because the probiotic and growth characteristics of probiotics are strain-specific features, it is crucial to be able to distinguish the probiotic strains from the other strains in the same species. To rapidly identify Lactobacillus rhamnosus at the strain level through PCR, a method for searching for several strain-specific sequences in the genome of a strain was investigated. The whole genomes of L. rhamnosus hsryfm 1301 and L. rhamnosus LV108 were sequenced, and gene family analysis was performed with using L. rhamnosus GG and L. rhamnosus Lc705 as reference strains. Thirty-one and 19 strain-specific open reading frames (ORFs) were found in L. rhamnosus hsryfm 1301 and L. rhamnosus LV108, respectively. Thus, strain-specific primer pairs could be designed in a more rational and controllable manner. Concatenation of several strain-specific primer pairs designed from the strain-specific ORFs (and their adjacent regions) were able to distinguish L. rhamnosus LV108 (primer pairs V2, V4, V5, and V9) or L. rhamnosus hsryfm 1301 (primer pairs H1, H2, H3, and H4) from 12 other L. rhamnosus strains. This strain-specific identification method was determined to be accurate, rapid, economical, reproducible and easy to perform. • 31 and 19 strain-specific open reading frames were found in hsryfm 1301 and LV108. • Fore strain-specific primer pairs were designed for hsryfm 1301 and LV108. • Several strain-specific primer pairs made the identification results more reliable. • L. rhamnosus strains were identified rapidly at the strain level by PCR. • This method is easy to perform, fast, economical, reproducible and accurate. [ABSTRACT FROM AUTHOR]