1.Viability of Listeria monocytogenes on Boneless, Water-Added Hams, Commercially Prepared with and without Food-Grade Chemicals, during Extended Storage at 4 and/or -2.2°C.
Luchansky JB1, Campano SG2, Shoyer BA3, Porto-Fett AC3. J Food Prot. 2016 Apr;79(4):613-9. doi: 10.4315/0362-028X.JFP-15-431.
Viability of Listeria monocytogenes was monitored during refrigerated (4°C) and/or frozen (i.e., deep chilling at -2.2°C) storage on casing-cooked hams that were commercially prepared with and without potassium lactate and sodium diacetate (1.6%), buffered vinegar (2.2%), buffered vinegar and potassium lactate (1.7%), or a blend of potassium lactate, potassium acetate, and sodium diacetate (1.7%). A portion of these hams were subsequently surface treated with lauric arginate ester (LAE; 44 ppm). In phase I, hams (ca. 3.5 kg each) were sliced (ca. 0.7 cm thick, ca. 100 g), inoculated (ca. 4.0 log CFU per slice), surface treated with LAE, and stored at either 4°C for 120 days or at -2.2°C for 90 days and then at 4°C for an additional 120 days. In phase I, without antimicrobials, the population of L. monocytogenes increased by ca. 5.9 log CFU per slice within 120 days at 4°C; however, pathogen levels increased only slightly (ca. 0.45 log CFU per slice) for hams formulated with potassium lactate and sodium diacetate and decreased by ca.
2.Antimony film sensor for sensitive rare earth metal analysis in environmental samples.
Makombe M1,2,3, van der Horst C1,2, Silwana B1,2, Iwuoha E1, Somerset V2. J Environ Sci Health A Tox Hazard Subst Environ Eng. 2016 Apr 11:1-10. [Epub ahead of print]
A sensor for the adsorptive stripping voltammetric determination of rare earth elements has been developed. The electrochemical procedure is based on the oxidation of the rare earth elements complexed with alizarin complexone at a glassy carbon electrode that was in situ modified with an antimony film, during an anodic scan from -0.2 V to 1.1 V (vs. Ag/AgCl) and deposition potential of -0.1 V (vs. Ag/AgCl). The factors influencing the adsorptive stripping capability were optimised, including the complexing agent concentration, plating concentration of antimony and deposition time. The detection of rare earth elements (La, Ce and Pr) were realised in 0.08 M sodium acetate (pH = 5.8) solution as supporting electrolyte, with 2 × 10-6 M alizarin complexone and 1.0 mg L-1 antimony solution. Under the optimised conditions, a deposition time of 360 s was obtained and a linear response was observed between 1 and 25 µg L-1. The reproducibility of the voltammetric measurements was found to be within 5.
3.Dissipation kinetics of oxytetracycline, tetracycline, and chlortetracycline residues in soil.
Li Y1, Wang H2, Liu X3, Zhao G1, Sun Y4. Environ Sci Pollut Res Int. 2016 Apr 13. [Epub ahead of print]
The dissipation of different residual states of tetracycline antibiotics (TCs) including oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) laboratory microcosm systems was investigated in this study. The residues were fractionated by stepwise extractions into aqueous state (KCl solution extracts), organic state (MeOH extracts), residual state I (citric acid-sodium citrate buffer and ethyl acetate extracts) and residual state II (acetonitrile-EDTA-McIlvaine buffer extracts) for accurate evaluation of TCs pollution. The antibiotics in the aqueous state were hardly detected, whereas the antibiotics in the organic state dissipated relatively fast (not detectable within 15 days after application) and followed simple first-order kinetics (SFOK) (R 2 from 0.929 to 0.990). While first-order double-exponential decay model (FODED) (R 2 from 0.840 to 0.999) and availability-adjusted first-order model (AAFO) (R 2 from 0.939 to 0.
4.Impact of lactic acid and hydrogen ion on the simultaneous fermentation of glucose and xylose by the carbon catabolite derepressed Lactobacillus brevis ATCC 14869.
Jeong KH1, Israr B1, Shoemaker SP2, Mills DA2,3, Kim J1. J Microbiol Biotechnol. 2016 Apr 8. doi: 10.4014/jmb.1512.12038. [Epub ahead of print]
Lactobacillus brevis ATCC 14869 exhibited a carbon catabolite de-repressed (CCR) phenotype which has ability to consume fermentable sugar simultaneously with glucose. To evaluate this unusual phenotype under harsh conditions during fermentation, the effect of lactic acid and hydrogen ion concentrations on L. brevis ATCC 14869 were examined. Kinetic equations describing the relationship between specific cell growth rate and lactic acid or hydrogen ion concentration has been reduced. The change of substrate utilization and product formation according to lactic acid and hydrogen ion concentration in the media were quantitatively described. Moreover; utilization of other compounds were also observed along with hydrogen ion and lactic acid concentration simultaneously. It has been found that substrate preference changes significantly regarding to utilization of compounds in media. That could result into formation of two-carbon products. In particular, acetic acid present in the media as sodium acetate were consumed instead of one i.