Response of lactic acid bacteria to the digestive environment.
ABSTRACT This article reviews several studies regarding adaptation to the digestive environment by lactic acid bacteria. The behavior of lactic acid bacteria in the digestive tract is worth investigating, and bacterial physiologic changes remain to be examined.
A genetic approach based on the fusion of bacterial promoters with genes of the reporter protein luciferase is described to screen for functions that lactic acid bacteria may suppress or activate in the digestive environment.
Variations in luciferase expression from different promoters were observed in the digestive tract of mice models. In some cases, the promoter could be activated in response to an inducer provided with the diet.
These data suggest that lactic acid bacteria are metabolically active in the digestive tract and can synthesize proteins to adapt to the digestive environment.
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ABSTRACT: The high mechanical properties in 7xxx aluminum alloy are obtained by controlling the precipitation hardening microstructure. In this work, the relationship between the microstructures and mechanical properties of 7A04 (Al-Zn-Mg-Cu) aluminum alloy during isothermal aging at 140 degrees C after different quenching rates has been studied in order to find its useful hardening conditions. The as-extruded samples were solution heat treated at 480 degrees C and cooled in air, 70 degrees C water, 40 degrees C water and 0 degrees C ice water. Tensile test were performed and the ultimate tensile strength and percentage of elongation were obtained. The difference in the amount of precipitates is known by DSC and the morphology of the precipitates is characterized by TEM. The results indicate that the artificial age hardening response is strongly dependent on the quenching rate. Lower quenching rate results in lower tensile strength but higher percentage of elongation in the peak age condition, and this corresponds to the difference in the size and number density of the precipitates. It is concluded that the highest ultimate tensile strength is obtained in the fastest quenching rate in 0 degrees C ice water (up to 870Ks(-1)) while stable and high percentage of elongation is achieved in the intermediate quenching rate (about 226 Ks(-1)).Advanced Materials Research 01/2010; 89-91:347-352. DOI:10.4028/www.scientific.net/AMR.89-91.347
09/2005; 24(1/2). DOI:10.4102/satnt.v24i1/2.161
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ABSTRACT: Today, sufficient consistent data are available to reinforce the interest of the use of Lactic Acic Bacteria (LAB), particularly lactococci and lactobacilli strains, to develop novel mucosal vaccination strategies. LAB are Gram positive bacteria exploited since the highest Antiquity by humans to produce fermented foods. They are thus good candidates to develop novel oral vectors and constitute attractive alternatives to vaccinal strategies based on attenuated pathogens which could induce healthy risks. Here, we summarized the most recent researches performed on the use of LAB as live vaccine delivery vectors.Revue Francophone des Laboratoires 12/2009; 2009(417):79-89. DOI:10.1016/S1773-035X(09)70312-0