## 4 Discussion  
Temperature is an important environmental factor affecting the degradation of organic matter in biowaste, as well as in the composting process, including biological activity and the final product quality [46]. Composting technology also has a significant impact since, in open composting, the process is affected by the temperature of the environment, which in most cases is significantly lower than that of the pile. The temperature of the Yasno Pole composting piles increased significantly as early as the third and fourth day and entered the thermophilic stage, unlike the other in Harmanli, in which the thermophilic phase was reached by the twenty-fifth day. This happened due to differences in ambient temperatures and composting technology at the two sites. It is likely that unique microbial communities also play an important role. These results are in line with the results obtained by [PERSON] and collaborators [28]. At the same time, pile turning leads to a change in these conditions in the habitats, which is in line with what other scientists have found [47; 48]. Our research is aimed at answering questions related to the taxonomic diversity of prokaryotes in the phases of composting, but under different climatic conditions at the two sites at Yasno Pole and Harmanli. The main question we pose in the study is related to the selection of taxonomic groups of bacteria performing the same function in the respective microbial communities. This issue also has a practical aspect related to the optimal conversion of organic substances under different conditions, which is not the subject of the present study. We found that _Actinobacteria_ and _Proteobacteria_ were the major phyla in all samples. These results were in accordance with [PERSON] and his research team [49], who found that the abundance of _Proteobacteria_ declined in the thermophilic phase of composting, which indicated that the high-temperature environment was unconducive to its growth. Similar to the results of [PERSON] et al. [50], the abundance of _Proteobacteria_ was significantly greater in the mesophilic phase than in the thermophilic phase, concerning the Yasno pole compost. The above results are often reported in the scientific literature concerning the most abundant phyla found in composting processes [46; 47]. We found that _Thermoleofila_ are dominant class of prokaryotes in thermophilic habitats of compost in Harmanli (together with _Actinobacteria_), but in the rest of the samples, they were significantly represented (Figure 1B). According to [PERSON] and [PERSON], [51] and [PERSON] and collaborators [52], this is essential for the cycling of major elements in the soil. As saprophytes, they produce a range of extracellular hydrolytic enzymes that can degrade animal and plant polymers, including lignin, cellulose, chitin, and other organic compounds [29; 53]. The temperature fluctuations are significant for developing microbial activity and biomass during composting [50]. Those findings have also been highlighted by previous studies [54; 55]. _Actinobacteria_ commonly proliferate during periods with comparatively low temperatures [52]. Contrarily, [PERSON] et al. reported in their review that _Streptomyces_ are found in a wide variety of compots, such as from solid waste, agricultural waste or in the soil after compost application, which is in line with our findings [56]. [PERSON] and [PERSON] isolated more than 140 cellulolytic thermophilic actinomycete strains from medium-like compots, or soils, among others [57]. There were even strains with a high yield of endo- and exoglucanase, and \(\beta\)-glucosidase. Revealing the diversity of prokaryotes at the genus level, we may say that the most abundant genera in both studied sites (_Sphingobacterium_, _Sphingomonas_, _Paracoccus_, _Pseudomonas_, and _Halomonas_) are found in other recent studies [19; 58].