## 4 Possibility of Application of SRB Bacteriophages in Practice  
Using bacteriophages as an antibacterial method has some advantages. Due to specific absorption to only certain receptors on the cell surface, they attack only the genus, species, and sometimes only one particular bacterial strain. Therefore, unlike antibiotics, they do not destroy other microorganisms in the body that may be useful to organisms. At the same time, the virus consists only of proteins and nucleic acids, which thus does not cause side effects after degradation [127]. The development of new biotechnology and pharmaceutical products is possible with the use of bacteriophage particles. Bacteriophage therapy as the antimicrobial treatment, especially against resistant bacterial infections had been known before, recently has been rediscovered again, since phage-based vaccination represents one of the most promising preventive strategies. That is the reason and necessity for the constant discussions and research studies concerning the biological nature of phages, including phage therapy, drug delivery, tissue engineering, food biopreservation and safety, biocontrol of plant pathogens, vaccines and vaccine carriers, biofilm and bacterial growth control, surface disinfection, corrosion control, and other important fields of phages impact [128]. On the other hand, recent achievements in nanotechnology are improving the possibilities for phage manipulation. The essentials for the new science field, such as bio-nanomedicine, are of crucial importance to control the physical, chemical, and biological properties of materials. Phages, similar to viruses, represent a promising nanomaterial that can be manipulated with great precision, since phage particles are formed according to the genetic information (in protein shells), and their sizes and shapes are precisely defined. Genetic engineering and chemical modification allow the control of the composition and surface properties of phage particles. These modifications can lead to the improvement and better quality of human health [129]. It is certain that new phage therapies will have to solve problems, such as potential phage toxin elimination, inadequate phage purification, and the limited knowledge of relations between humans and phages. Control clinical studies are necessary for the application of new phage therapies; these studies are always costly and time consuming, but they are regulated by states' laws. The researches and systematic reviews about phages represent steps toward better understanding of phages interactions with host cells [130]. Another disadvantage of phage therapies is a lack of systematic studies about phage pharmacokinetic data. According to animal studies, phages end most often in the liver, although there is some trapping in the spleen [131]. It is possible to choose some phage strains that are capable of remaining in the circulation and act constantly against bacterial infections [132, 133], the same as strains with a reduced immunogenicity (the reduction of phage adverse reactions). So-called \"platform\" phages and \"dual\" specificity phages would be necessary to be developed or engineered, free of antibiotic-resistant genes and toxins [130, 134]. Phages also act locally at the site of host bacteria. The phage particle produces over a hundred new virions in a single cycle, these viruses again attack neighboring bacteria, and the number of phages destroying bacteria increases exponentially. The use of phages with antibiotics also reduces the chances of creating bacterial resistance to both [135]. However, phage therapy has its drawbacks. One of its greatest weaknesses is its high specificity. In order to initiate therapy, it is necessary to know the pathogen that caused the infection. In acute cases, it is excluded. In these cases, the application of a phage cocktail or polyvalent phage may be considered, but antibiotic formulations have superiority in the rate of action [136].