## 3 SRB Impact on Environments and Humans
### Research in the Field of SRB Bacteriophages  
All of the above negative effects associated with H\({}_{2}\)S production lead to considerations of how to suppress SRB metabolic activities [106; 107; 108; 109; 110; 111; 112; 113]. Alternatively, it may be possible to combat the nuisance of SRB through the use of bacteriophages [10; 65; 66; 70]. Superinfection (SI) exclusion systems are complexes of proteins in the membrane that prevent viral DNA from penetrating to the cell. These proteins are often encoded by prophage genes and are intended to counteract the body's superinfection, preventing the bacterium from being infected with the same or a similar virus several times, thereby reducing the viability of an already infected bacterium [76]. Viruses in total are the most abundant group of \"organisms\" in the world with the amount measured microscopically in aquatic systems present, e.g., at \(10^{7}\) per milliliter [114], which is somewhat higher in sediments [115]. The total population is estimated to be \(10^{31}\) entities [116]. Given the great abundance of bacteria, most of these viruses are thought to be bacteriophages. Bacteriophages can be divided in two main groups [117]: tailed and tailless. They can also be distinguished into a number of different infection types [118]: lytic phage, chronic phage, and latent phage. Lysogenic cycles are associated with what are known as temperate phages [67], while phages that are unable to display lysogenic cycles, but instead only lytic cycles, can be described as strictly or obligately lytic. Temperate phages are of interest especially due to their ability to modify bacterial hosts both genetically and phenotypically [70; 71; 68; 72], whereas strictly lytic phages ideally are what is employed for phage-mediated biocontrol and phage therapy. It is thought that most phages are lytic (whether strictly lytic or instead temperate); in nature, both types of phages serve as natural antagonists of bacteria. Since H\({}_{2}\)S is produced by SRB and it represents the harmful compound in the environment, phages represent an important factor for the elimination of SRB genera. The main sulfide-producing bacteria (SPB) phages belong to families of _Siphoviridae_ and _Myoviridae_. Phage activities toward SPB are the most effective at 30 \({}^{\circ}\)C and less effective at 20 \({}^{\circ}\)C [119]. The lysogenic bacteriophage belonging to _Styloviridae_ (_Siphoviridae_ is a new name according to the ICTV (International Committee on Taxonomy of Viruses)) lyses salt-requiring SRB, _Desulfovibrio salerigens_[70]. Bacteriophages are responsible for 60-70% of all problems occurring during the fermentation of different food commodities (bacteriophages can delay and inhibit fermentation processes) [120]. Spontaneous fermentation is changed with starter cultures due to more controlled processes. _Lactobacillus plantarum_ strains (mainly used in vegetable fermentation) were found to be 25% sensitive to bacteriophages [121]. However, there is a difference in phage infection rate. Phage infection rate is considered fast if bacterial lysis occurs within 2 h after infection [122]. Bacteriophages found during fermentation processes are usually eliminated after 30 min treatment at 80 \({}^{\circ}\)C and 90 \({}^{\circ}\)C (they can survive the time and temperature used in standard food pasteurization). It means that they are resistant to the environments during food fermentation, especially because it was found that bacteriophages grow under broad pH values [123]. When phages titer increases over 10\({}^{6}\) PFU/mL, the fermentation is usually inhibited [124]. As outlined in previous sections, a number of taxa include members that are sulfate reducing, and these bacteria can be found within a variety of contexts, where in some of those contexts, they can be problematic, e.g., such as due to negative impacts on infrastructure (e.g., pipes) or health (e.g., the human intestine).