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Food spoilage which makes food unsuitable for human consumption is one of the major concerns in the food industry. Although various chemical additives are being used commercially for food preservation to prevent spoilage, but these chemically synthesized preservatives cause severe ill-effects on human health. The increasing awareness of health hazards caused due to them among the consumers has led to a demand for availability of chemical-free food in the market. This in turn has created the need to look for new alternatives, which are natural but efficient and do not pose any health issues. In this context, naturally occurring, non-pathogenic lactic acid bacteria, or bacteriocins produced by them have attracted a lot of attention in the scientific community. Bacteriocins are ribosomally synthesized active proteins which show bactericidal mode of action against food spoiling bacteria and are considered to be safe additives for food preservation. However, several hurdles such as sensitivity to proteolytic enzymes, restricted antimicrobial spectrum, high dosage requirement and low yield limit the use of bacteriocins as efficient food preservatives. To combat some of these limitations, more recently bacteriocin-nanoconjugates have emerged as a promising solution. This review focuses on the limitations of bacteriocins in restricting the growth of food-borne pathogens and the potential of nanotechnology in enhancing the antimicrobial activity of bacteriocins.

Upsurge in the instances of antibiotic-resistant uropathogenic Escherichia .coli (UPECs) strains has repositioned the attention of researchers towards a century old antimicrobial approach popularly known as phage therapy. Rise of extended spectrum beta lactamase (ESBL) and biofilm producing strains has added another step of hurdle in treatment of uropathogens with conventional antibiotics, thus providing a further impetus for search for exploring new therapeutic measures. In this direction, bacteriophages, commonly called phages, are recently being considered as potential alternatives for treatment of UPECs. Phages are the tiniest form of viruses which are ubiquitous in nature and highly specific for their host. This review discusses the possible ways of using natural phages, genetically engineered phages, and phage lytic enzymes (PLEs) as an alternative antimicrobial treatment for urinary tract infections. The review also sheds light on the synergistic use of conventional antibiotics with phages or PLEs for treatment of uropathogens. These methods of using phages and their derivatives, alone or in combination with antibiotics, have proved fruitful so far in in vitro studies. However, in vivo studies are required to make them accessible for human use. The present review is a concerted effort towards putting together all the information available on the subject.

An ever-growing demand for food products with minimal chemical additives has generated a necessity for exploring new alternatives for food preservation. In this context, more recently, bacteriocins, the peptides having antimicrobial property, synthesized ribosomally by numerous bacteria have been attracting a lot of attention. They are known to possess the potential to restrict the growth of microorganisms causing food spoilage without causing any harm to the bacteria themselves owing to the presence of self-defensive proteins. In particular, the bacteriocins of lactic acid bacteria have been considered harmless and safe for consumption and are indicated to evade the development of unwanted bacteria. Use of bacteriocins as biopreservatives has been studied in various food industries, and they have been established to elevate the shelf life of minimally processed food items by exerting killing mechanism. They restrict the growth of undesirable bacteria by breaking the target cell membrane and finally resulting into pore formation. The current article provides an insight on bacteriocins of lactic acid bacteria, their biosynthesis, mechanism of action, and promising applications of these antimicrobial peptides in the food sector.

The complete genome sequence of the unique virulent bacteriophage BRock, isolated from compost on Streptomyces sp. strain SFB5A, was determined. BRock is a myovirus with a 112,523-bp genome containing a GC content of 52.3%. There were 188 protein-coding genes predicted, including structural and enzymatic proteins, but none predicted for lysogeny. Twenty-nine tRNAs were predicted. School of Integrated Sciences at James Madison University; Harry G. M. Jopson Endowed Chair Fund at Bridgewater College; Fulbright We thank the School of Integrated Sciences at James Madison University for support. The research was also financed through the Harry G. M. Jopson Endowed Chair Fund at Bridgewater College to S.F.B.; Annotation was performed at Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Haryana, India, by undergraduate and MS students in a program funded by Fulbright to L.M.

Bacteriocins produced by lactic acid bacteria are safer alternatives to the more popularly used chemical preservatives which exhibit several adverse effects. The bacteriocins have an advantage of being efficient in controlling food pathogens without possessing any side-effects. However, the bacteriocins have a limitation of exhibiting a narrow antimicrobial spectrum and having a high-dosage requirement. With an aim to combat these limitations, the present study involved the biosynthesis of bacteriocin-capped nanoparticles, using two bacteriocins (Bac4463 and Bac22) extracted and purified from Lactobacillus strains. Nanoconjugates synthesised at optimum conditions were characterized using various physico-chemical techniques. The interaction of bacteriocin-capped silver nanoparticles with the pathogenic bacteria was observed using scanning electron microscopy, wherein the deformed and elongated cells were clearly visible. In vitro antimicrobial efficacy of both Bac4463-capped silver nanoparticles and Bac22-capped silver nanoparticles against different food pathogens was observed to be enhanced in comparison to the antimicrobial activity of bacteriocins alone. Minimum inhibitory concentration was observed to be as low as 8 μg/ml for Bac4463-capped silver nanoparticles against Staphylococcus aureus, and 2 μg/ml for Bac22-capped silver nanoparticles against Shigella flexneri. This study, therefore, recommends the use of bacteriocin-capped nanoparticles as food preservatives to control the growth of food spoiling bacteria.

The present research was designed with an aim to attempt enhancement of antimicrobial efficacy of bacteriocins against food-borne pathogens. Bacteriocin Bac23 was extracted from a lactic acid bacterium which was isolated from raw milk, and identified as Lactobacillus plantarum using 16S rRNA gene sequencing. The purified Bac23 was found to be stable over a broad temperature (20 °C - 100 °C) and pH (2–12) range, its molecular weight was estimated as 5.1 kDa using SDS-PAGE, and the amino acid sequence determined using LCMS/MS identified it as plantaricin. Bac23 exhibited antimicrobial response against only three (S.flexneri, S.aureus, and P.aeruginosa) out of a total of six test food-borne pathogens. The purified Bac23 was further used for green synthesis of bacteriocin-capped silver nanoparticles (SNPs), which displayed a particle size of 31 nm and a hydrodynamic diameter of 79.19 nm. The capped SNPs exhibited an antibacterial response against all the six test food-borne pathogens displaying MIC value as low as 4 μg/ml for S.flexneri and P.aeruginosa; thus, resulting into an almost 50% increase in the antimicrobial spectrum when compared with the antimicrobial activity of Bac23 alone. The present study therefore reports that the capping of a bacteriocin onto silver nanoparticles can enhance its antimicrobial response; hence aiding in combating food-borne pathogens.

Nanoscience deals with the structural and functional aspects of materials with a size range of 1–100 nm. Such small size range offers a high surface to volume ratio which in turn proves advantageous over macromolecules of similar chemical compositions. Contributing to their unique properties and biocompatibility with human cells is the possibility of their biogenic synthesis, which further makes them an attractive alternative option for use in human medicine. Nanostructures of various shapes, sizes, and configurations have been facing extensive investigation since the last few decades. Initially, nanoparticles were majorly researched for the inspection of their antimicrobial properties, but as the field expanded, it has further extended to uncovering their potential applications in therapeutics, drug delivery, and nanomedicine. The present chapter aims at discussing the potential of metallic nanoparticles as antimicrobial and therapeutic agents, the major focus being on the various proposed mechanisms used by nanoparticles for the inhibition of microbial cells and the various applications of nanoparticles in the field of therapeutics and drug discovery. Besides the potential benefits of nanoparticles, there is a mounting apprehension about the risk associated with their use on living beings and environment. There is a tremendous need to study their toxic effects before using them as routine therapeutic agents. Hence, the studies related to the toxic effects of nanoparticles on nontarget population which are essential for their implementation as therapeutic agents have also been reviewed.