## 3 Results
### Composition of Microbial Community Analysis  
#### 3.3.1 Relative Abundance  
According to the taxonomic annotation results, the top 10 taxa of each sample or group at each taxonomic rank are selected to form the distribution histogram of the relative abundance of taxa, so as to visually see the taxa with a higher relative abundance and their proportion in different classification levels of each sample [(39; 40)]. The abundance of taxa in the phylum is illustrated on Figure 2a. \begin{table}
\begin{tabular}{c c c c c} \hline  & \multicolumn{2}{c}{**Harmanli**} & \multicolumn{2}{c}{**Yasno Pole**} \\ \hline  & **Thermophilic** & **Mesophilic** & **Thermophilic** & **Mesophilic** \\ \hline Dry weight (\%) & 56.35 & 62.57 & 70.43 & 61.01 \\ Total organic carbon (\%) & 28.01 & 22.19 & 28.58 & 22.85 \\ pH & 8.24 & 8.64 & 7.8 & 7.97 \\ EC (m5-cm\({}^{-1}\)) & 1.363 & 1.516 & 0.972 & 1.02 \\ Total nitrogen (\%) & 1.53 & 1.33 & 1.34 & 1.27 \\ N-NH\({}_{4}\) (mg-kg\({}^{-1}\)) & 210.32 & 120.85 & 199.76 & 175.36 \\ N-NO\({}_{3}\) (mg-kg\({}^{-1}\)) & 62.21 & 90.94 & 74.2 & 94.11 \\ C/N ratio & 18.31 & 16.68 & 21.33 & 17.99 \\ Respiration (mg CO\({}_{2}\cdot\)g\({}^{-1}\cdot\)h\({}^{-1}\)) & 163.10 & 79.32 & 175.73 & 22.82 \\ \hline \end{tabular}
\end{table} 
Table 1: Physicochemical parameters of the compost during sampling in the thermophilic and mesophilic phases of both studied sites: Harmanli and Yasno pole. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Sample Name** & **Raw PE** & **Raw Tags** & **Clean Tags** & **Effective Tags** & **Base** & **AvgLent** & **Q20** & **Q30** & **GC\%** & **Effective\%** \\ \hline A1 & 136,069 & 111,104 & 108,467 & 95,147 & 39,687,497 & 417 & 97.32 & 91.97 & 57.85 & 69.93 \\ A2 & 121,912 & 107,885 & 106,056 & 89,977 & 37,469,369 & 416 & 97.83 & 93.21 & 55.73 & 73.80 \\ B1 & 124,308 & 103,076 & 100,712 & 88,021 & 36,812,995 & 418 & 97.44 & 92.20 & 56.62 & 70.81 \\ B2 & 125,061 & 112,651 & 110,822 & 96,947 & 40,445,191 & 417 & 97.83 & 93.31 & 55.82 & 77.52 \\ \hline \end{tabular}
\end{table} 
Table 2: Summarization of the tags and OTUs number of each sample (A1, thermophilic of Harmanli site; A2, mesophilic of Harmanli site; B1, mesophilic of Yasno pole site; B2, thermophilic of Yasno pole site). _Actinobacteriota_ and _Proteobacteria_ were the predominant phyla in all samples. In thermophilic habitats of Harmanli compost, _Actinobacteriota_ abundance was much higher than _Proteobacteria_, while in rest of the cases, the _Proteobacteria_ was the predominant species (Figure 2a). The relative abundance of _Actinobacteriota_ could comprise up to 52% in the above mentioned, 24% in mesophilic one of Yasno pole, and the abundance decreased in mesophilic of Harmanli and finally in thermophilic compost of Yasno pole. In the mesophilic phase of Harmanli and thermophilic of Yasno pole, the quantity of _Proteobacteria_ was higher than in the rest of the composts. The abundance of _Proteobacteria_ was more significant in the mesophilic phase than in the thermophilic one. The amount of _Acidobacteria_ was relatively constant in compost (15-16%), except for the thermophilic phase of Harmanli compost (8%). At the class level, _Alphaproteobacteriaa_, _Actinobacteria_, _Gammaproteobacteriaa_, and _Thermophilia_ were dominant in the four compost samples in the mesophilic and thermophilic phases, while the relative abundance of _Acidobacteriae_, _Bacteroidia_ and _Verrucomicrobiae_ was much low (Figure 2b). The number of _Alphaproteobacteriaa_ was higher in A2, B1 and B2 (23-25%), while in A1, it was 17%. _Actinobacteria_ were most abundant in thermophilic habitats of Yasno pole compost (around 25%), and the quantity decreased in the rest of the compost samples (9-11%). The phylum _Actinobacteriota_ is a primary eubacterial phylogenetic clade containing diverse Gram-positive bacteria [41] that belong to several classes such as _Acidimicrobijia_, _Actinobacteriae_, and _Thermoophila_.