Plasmids for Optimizing Expression of Recombinant Proteins in <em>E. coli</em>

Plasmids are important vectors for the transfer of genetic material among microbes. The transfer of plasmids causes transmission of genes involved in pathogenesis and survival, to the host bacteria leading to their evolution and adaptation to diverse environmental conditions. A large number of plasmids of varying sizes have been discovered and isolated from various microorganisms. Plasmids are also valuable tools to genetically manipulate microbes for various purposes including production of recombinant proteins. Escherichia coli is the most preferred microbe for production of recombinant proteins, due to rapid growth rate, cost-effectiveness, high yield of the recombinant proteins and easy scale-up process. Several plasmids have been designed to optimize the expression of heterologous proteins in E. coli. In order to circumvent the issues of protein refolding, the codon usage in E. coli, the absence of post-translational modifications, such as glycosylation and low recovery of functionally active recombinant proteins, various plasmids have been designed and constructed. This chapter summarizes the recent technological advancements that have extended the use of the E. coli expression system to produce more complex proteins, including glycosylated recombinant proteins and therapeutic antibodies

Bacteriocins as promising antimicrobial peptides, definition, classification, and their potential applications in cheeses

Abstract There is increased importance to finding alternative solutions to antibiotic resistance which require more research, bacteriocins are promising antimicrobial peptides with inhibitory and bactericidal activities that might be one of these solutions. Bacteriocins are small antimicrobial peptides synthesized by bacterial ribosomes, active against the bacterial pathogen, multidrug-resistant bacteria, and cancer therapy. Lactic acid bacteria (LAB) are one of the most used bacteria to produce bacteriocins and dairy products (i.e. cheeses) consider rich sources of LAB isolates. Enterococcus faecalis, Lactobacillus fermentum, L. plantarum, L. helveticus, L. pentosus, L. paracasei subsp. paracasei, L. rhamnosus I, and L. delbrueckii subsp. lactis are strong strains in bacteriocins production. Several applications were applied to control bacterial pathogens spread in cheeses, one of them is using bacteriocins and bacteriocins-like inhibitory substances (BLIS). To reduce foodborne pathogens and spoilage bacteria in cheese, bacteriocins can be applied in several means such as inoculating cheese with bacteriocin-producer strain and adding purified or semi-purified bacteriocin as a food additive. This review is focused on bacteriocins and BLIS classification, mechanism, and applications in dairy products i.e. cheeses