We report on a rapid method for the detection of Salmonella O8. It does not require an enrichment step but rather uses an aptamer as a probe that was selected by system evolution of ligands by exponential enrichment (SELEX) assay. Firstly, aptamer against Salmonella O8 was selected from a 78 bp random DNA library that was prepared in-vitro. The binding ability of the aptamers to target bacterium was examined by aptamer-linked immobilized sorbent assay. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. Next, this high affinity aptamer B10 was used to recognize Salmonella O8 via fluorescence microscopy. The selected aptamer has a high specificity and high affinity against its target. We believe that the resulting fluorescence in-situ labeling assay is a potentially useful alternative in rapid screening and detection of foodborne pathogens.
This study aimed to analyse the physicochemical properties of Polygonatum cyrtonema polysaccharide (PCP) and evaluated its effects in a high‐fat diet (HFD)‐induced obese mice. Experimentally, PCP was established as a homogeneous heteropolysaccharide with both α‐ and β‐configurations, and its estimated average molecular weight was ˜5.1 kDa. Besides, we discovered its major monosaccharides, including galactose, mannose, rhamnose, galacturonic acid and glucose. PCP markedly decreased obesity‐related parameters, improved serum lipid profile, fasting blood glucose, and leptin levels and reversed insulin resistance. It also reduced the hepatic infiltration of lipid droplets and the size of adipocytes in adipose tissues. Finally, PCP simulation significantly downregulated the mRNA expression of CCAAT/enhancer‐binding protein‐α (C/EBPα), peroxisome proliferator‐activated receptor‐γ (PPARγ), sterol regulatory element‐binding protein‐1c (SREBP‐1c) and fatty acid synthase (FAS). On the contrary, it increased carnitine palmitoyltransferase (CPT1) and uncoupling protein 2 (UCP2) levels closely related to thermogenesis and glucolipid metabolism. Taken together, these findings have provided evidence that PCP could be a potential anti‐obesity ingredient in preventing diet‐induced obesity.
Fresh Dendrobium officinale possessed higher activities compared with the dried ones. High‐pressure processing (HPP) could effectively enhance the content and activities of Dendrobium officinale polysaccharides (DOPS) which is the main active ingredients of fresh Dendrobium officinale juice (FDOJ). Pressure, temperature, and holding time were optimized using response surface methodology to enhance DOPS content. The DOPS molecular weights (Mw) compositions and antioxidantive activities of FDOJ under the optimal HPP conditions (HDOJ) and FDOJ samples were also determined. The result indicated that under the optimal conditions, the highest (DOPS) content obtained was 315.4 mg/100 mL, which represented 37.7% more than that in FDOJ. The high‐performance gel permeation chromatography (HPGPC) result found that Mw compositions of the FDOJ and HDOJ samples were different. Both the in vitro and in vivo results revealed that the antioxidant activities of the HDOJ samples were significantly superior to that of the FDOJ samples.
Practical applications
As we know, HPP has been an attractive way to replace conventional heat treatments for the preservation of foods. This research investigated the utility of HPP for FDOJ. Results showed that, much more than prolonged shelf life of FDOJ, HPP could also enhance the content of DOPS which was the most important active ingredient and therefore improve the antioxidant activities of FDOJ. The results of this study could both expand the application of HPP in the development of the fresh Dendrobium officinale and related products and help to facilitate further development of fresh Dendrobium officinale industries.
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