Partial Characterization of Bacteriocins Produced by Two New Enterococcus faecium Isolated from Human Intestine

International audienceThis study aimed at characterizing two novel bacteriocin-producing enterococcal strains isolated from human intestine. A total of 200 lactic acid bacteria were isolated from a woman stool sample. Two of them were selected for characterization due to their high antimicrobial activity against five strains of Listeria monocytogenes. The selected bacteria were identified as two different strains of Enterococcus faecium and designated MT 104 and MT 162. The bacteriocins produced by MT 104 and MT 162 were stable at different pH ranging from 2 to 11 and were active after different treatments such as heat, enzymes, detergents, and γ-irradiation. The two isolated strains exhibited some probiotic properties such as survival in simulated gastric fluid and intestinal fluid, lack of expression of bile salt hydrolase or hemolytic activity, adhesion to Caco-2 cells efficiently, and sensitivity to clinical antimicrobial agents. Thus, the two isolated strains of E. faecium could become new probiotic bacteria and their bacteriocins could be used for controlling L. monocytogenes in combination with irradiation for food preservatio

Synergistic antimicrobial effect of combined bacteriocins against food pathogens and spoilage bacteria

ABSTRACT This study was conducted to determine the possible synergistic antimicrobial activity of four bacteriocins (nisin, pediocin, enterocinMT104b and enterocinMT162b) against foodborne and food spoilage bacteria. Microbroth dilution assay was used to determine Minimum Inhibitory Concentration (MIC) of each bacteriocin and checkerboard technique was applied to determine the possible synergistic antibacterial effects among four bacteriocins. The combination of nisin with MT104b caused a synergistic effect on the elimination of Staphylococcus aureus whereas the combination of nisin plus pediocin, nisin plus MT162b, pediocin plus MT104b, and pediocin plus MT162b caused a synergistic effect against Lactobacillus sakei. Nisin caused an additive effect against Listeria monocytogenes when it was combined with pediocin. Thus, the combinations of different bacteriocins could act synergistically or additively to eliminate serious foodborne pathogens and food spoilage bacteria

High-Density 4T SRAM Bitcell in 14-nm 3-D CoolCube Technology Exploiting Assist Techniques

International audienceIn this paper, we present a high-density four-transistor (4T) static random access memory (SRAM) bitcell design for 3-D CoolCube technology platform based on 14-nm fully depleted-silicon on insulator MOS transistors to show the compatibility between the 4T SRAM and the 3-D design and the considerable density gain that they can achieve when combined. The 4T SRAM bitcell has been characterized to investigate the critical operations in terms of stability (retention and read) taking into account the post-layout parasitic elements. Thus, failure mechanisms are exposed and explained. Based on this paper, a data-dependent dynamic back-biasing scheme improving the bitcell stability is developed. A specific read-assist circuit is also proposed in order to enable a large number of bitcells per column in a memory array. Finally, the designed bitcell offers up to 30% area gain compared to a planar six-transistor SRAM bitcell in the same technology node