Different effects of pectin and κ-carrageenan on the multiscale structures and in vitro digestibility of extruded rice starch

This study compared the different effects of pectin (PE) and κ-carrageenan (CG) on the multilevel structures (i.e. granule, crystallites, helices, fractals, and short-range order) and in vitro digestibility of extruded rice starch (MERS). The addition of either PE or CG altered the multiscale structures, increased the resistant component (RC) content, and reduced predicted glycemic index (pGI), with CG being more effective especially at a low content. CG led to the growth of molecular aggregates (α), single-helices, and V-type crystals (X). PE resulted in higher contents of double-helices and A + B-type crystals (X) and enhanced the short-range order (R) and particle compactness. Pearson correlation analysis indicates that, for MERS/PE, the slowly-digestible component (SDC) and RC contents were influenced by different factors in the sequence of total crystallinity (X) > X > X > single-helix content > α > R > double-helix content. For MERS/CG, the RC content was affected by X > single-helix content > X

Loop-mediated isothermal amplification assays for screening of bacterial integrons

BACKGROUND: The occurrence and prevalence of integrons in clinical microorganisms and their role played in antimicrobial resistance have been well studied recently. As screening and detection of integrons are concerned, current diagnostic methodologies are restricted by significant drawbacks and novel methods are required for integrons detection. RESULTS: In this study, three loop-mediated isothermal amplification (LAMP) assays targeting on class 1, 2 and 3 integrons were implemented and evaluated. Optimization of these detection assays were performed, including studing on the reaction temperature, volume, time, sensitivity and specificity (both primers and targets). Application of the established LAMP assays were further verified on a total of 1082 isolates (previously identified to be 397 integron-positive and 685 integron-negative strains). According to the results, the indispensability of each primer had been confirmed and the optimal reaction temperature, volume and time were found to be 65°C, 45 min and 25 µL, respectively. As application was concerned, 361, 28 and 8 isolates carrying intI1, intI2 and intI3 yielded positive amplicons, respectively. Other 685 integron-negative bacteria were negative for the integron-screening LAMP assays, totaling the detection rate and specificity to be 100%. CONCLUSIONS: The intI1-, intI2- and intI3-LAMP assays established in this study were demonstrated to be the valid and rapid detection methodologies for the screening of bacterial integrons