## 4 Possibility of Application of SRB Bacteriophages in Practice
Certain criteria for a suitable phage preparation must be followed to avoid unwanted side effects of therapy. It is necessary to identify and classify the phage according to the ICTV system, using mainly DNA sequences or electron microscopy. Therapeutic phages should be able to reproduce by lytic life cycle. The effect of lytic phages is faster, because they always destroy cells directly, and also, there is less chance of transduction. Propagates that become part of the genome may inaccurately cleave to lytic cycle and transfer bacterial genes (such as antibiotic resistance) to another individual [137]. Despite the praised ability of phages to attack and destroy unwanted bacteria, this method has its negative side, too. These viruses develop concurrently with their hosts as part of evolutionary dynamics. While the chances of developing bacterial resistance to antibiotics are higher than those of bacteriophages, this chance still exists, since bacteria have different ways of dealing with viruses. An important industry where phage phenomena are often declining against SRB is the oil industry. Against biocorrosion, which causes enormous damage to the infrastructure of the oil processing industry, chemical biocidal agents are often used, which are inserted into oil pipelines to destroy harmful microorganisms. However, these preparations have low efficacy against bacteria in biofilms, where the extracellular matrix produced by the cells often protects them from damage [138]. However, bacteriophages may have the ability to break down the polysaccharide complexes and, consequently, to lyse the cells. The biocorrosion phage control procedure was patented in America in 2009 [139]. First, corrosion agents in pipes and other equipment are to be identified and isolated. Subsequently, mixtures of lytic bacteriophages will be formed, which will inhibit the growth of (not only) SRB. Existing isolates as well as those newly obtained from industrial and environmental samples can be used. As an ideal environment, the text mentions water sediments, taking into account the physicochemical properties of sediments. The exact procedure should be based on the known characteristics of the species identified at the corrosion site. Thereafter, the effectiveness of the phage isolate against the sample originating from the damaged sites is tested. Then, the bacteriophage lysate will be optimized, for example by mutagenesis and targeted selection or genetic engineering. The targeted creation of new phages is also not excluded. The patent proposes using \"pigging\" to transport the product to the site. This procedure uses a cylindrical device, known as a \"pig\", to inspect and clean the tubes without stopping the flow of products therein. In this case, the \"pig\" is intended to release virus-containing fluid or gel in the tubes. For example, phages can be injected into the surrounding sediment to treat the outer surface of the tubes [140]. It also offers a similar approach to solving the problem of \"acid\" oil. For the identified SRB producing H\({}_{2}\)S, a first mix of phages against this population should be created. At the same time, a second mixture is produced, designed, and adapted to the bacteria in the water, which will flood the site to maintain the pressure and extraction efficiency. In doing so, it seeks to combat two originally separate populations of bacteria that degrade oil [140]. Two years later, the scientists have isolated two bacteriophages from marine black sediment, where _Desulfovibrio_ and _Haloaneraobium_ formed a synergistic culture [141; 142]. The authors of this technological procedure based their method on the phases with a lytic cycle, to which it is suggested to add the use of biocides to achieve the greatest effect [138]. Another option is to use prophages. In many _Desulfovibrio_ species, several prophage elements are present in the genome. In these viruses, the transition to the virulent phase can be induced by stressing the bacterial cells with, for example, UV radiation or antibiotics.