## 3 Mycobacteriumophages--General Characteristics and Overview  
Bacteriophages (phages) are viruses that infect and lyse bacterial cells. They are considered the most abundant and diverse biological entities on the planet, with an estimated \(10^{31}\) viral particles and over \(10^{8}\) distinct genotypes [15; 16; 17]. Phages inhabit virtually all environments containing bacteria, including soil, water, wastewater, and clinical specimens [18; 19]. The existence of bacteriophages was first observed in the late 19 th and early 20 th centuries by researchers such as [PERSON], [PERSON], and [PERSON], the latter of whom formally introduced the concept of \"bacteriophages\" and pioneered early therapeutic use [20; 21; 22; 23]. While phage therapy saw some application in the 1930s and 1940s, its popularity waned with the rise in antibiotics. However, due to growing antibiotic resistance, interest in phages has resurged, particularly because of their species- or even strain-specific lytic activity and minimal disruption to host microbiota [24; 25; 26; 27]. Bacteriophage classification is governed by the International Committee on Taxonomy of Viruses (ICTV), which groups phages based on genome type (DNA or RNA), strandedness (single or double), capsid morphology, and presence or absence of a lipid envelope [28; 29; 30]. Detailed information on the general classification of bacteriophages is provided in Table 1. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Family**} & **Nucleic Acid** & **Representative** & **Characteristic** & **Typical Host** & **Application** & **Year/Author of** **Classification** \\  & **Type** & **Phase** & **Features** & **[Reference]** \\ \hline \multirow{3}{*}{_Mycoviridae_} & \multirow{3}{*}{dsDNA, linear} & \multirow{3}{*}{TM4} & Complex structure, & \multirow{3}{*}{_Mycobacterium_ sp.} & a genetic tool and & \multirow{3}{*}{1944/[PERSON]} \\  & & & contractile tail & & & \\ \cline{1-1} \cline{6-6}  & & & & & & \\ \cline{1-1} \cline{6-6}  & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: General classification of bacteriophages. Mycobacteriophages were first isolated in 1946 from environmental samples containing _Mycobacterium smgematis_, a fast-growing, nonpathogenic species often used as a model organism [40]. In 1954, phages infecting _Mycobacterium tuberculosis_ were identified, highlighting the potential of these viruses in tuberculosis research and treatment [41]. Mycobacteriophages have since been recovered from a wide range of ecological sources, including soil, freshwater, marine environments, and clinical materials [17; 41]. Structurally, mycobacteriaiophages typically consist of an icosahedral head and a tail apparatus that facilitates host recognition and DNA injection (Figure 1). The head, formed by dozens of capsomere subunits, contains the viral genome, while the tail--ranging in length from several nanometers to over 800 nm--often includes specialized fibers or basplates essential for the adsorption to the bacterial cell wall [42; 43; 44]. Most mycobacteriophages belong to the order _Caudovirales_ and possess linear double-stranded DNA genomes [45; 46; 47; 48]. These phages exhibit either long, flexible non-contractile tails (family _Siphoviridae_) or contractile tails (family _Mycoviridae_) [45; 46; 47; 48]. Due to their specificity, diversity, and ease of genetic manipulation, mycobacteriaiophages are not only important in fundamental microbiological  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Family**} & \multirow{2}{*}{**Nucleic Acid Type**} & \multirow{2}{*}{**Representative Phage**} & \multirow{2}{*}{**Characteristic Features**} & \multirow{2}{*}{**Typical Host**} & \multirow{2}{*}{**Application**} & \multicolumn{2}{c}{**Year/Author of Classification**} \\  & & & & & & & **[Reference]** \\ \hline \multirow{2}{*}{_Siphoviridae_} & \multirow{2}{*}{dsDNA, linear} & \multirow{2}{*}{L5} & Complex structure, long flexible tail & \multirow{2}{*}{_Mycobacterium_ sp.}