This study aimed to investigate the effects of temperature on the quality of vermicompost and microbial profiles of dewatered sludge during vermicomposting. To do this, fresh sludge was separately vermicomposted with the earthworm Eisenia fetida under different temperature regimes, specifically, 15 • C, 20 • C, and 25 • C. The results showed that the growth rate of earthworms increased with temperature. Moreover, the lowest organic matter content along with the highest electrical conductivity, ammonia, and nitrate content in sludge were recorded for 25 • C indicating that increasing temperature significantly accelerated decomposition, mineralization, and nitrification. In addition, higher temperature significantly enhanced microbial activity in the first 30 days of vermicomposting, also exhibiting the fastest stabilization at 25 • C. High throughput sequencing results further revealed that the alpha diversity of the bacterial community was enhanced with increasing temperature resulting in distinct bacterial genera in each vermicompost. This study suggests that quality of vermicompost and dominant bacterial community are strongly influenced by the contrasting temperature during vermicomposting of sludge, with the optimal performance at 25 • C. one of the most critical factors affecting the growth and reproduction of earthworms [9,10]. For instance, Eisenia fetida as a ubiquitous epigenetic species capable of vermicomposting exhibited wide tolerance to a broad temperature range (15-25 • C) for their growth [11]. Previous studies also indicate high variability in the temperature used for vermicomposting with most using room temperature, also suggesting a wide range of temperature useful for treating sludge [6,12,13]. Only a few publications clearly reported that 20 • C was the optimal temperature condition for treating activated sludge [14]. Given that the growth of earthworms is strongly associated with temperature, different regimes may also affect the quality of the vermicomposting product and its agricultural value. Hence, understanding the optimal temperature condition to operate vermicomposting of sludge is vital to drive the development of the vermicomposting industry.Although the use of earthworms is popular in vermicomposting systems, microorganisms also play important roles in decomposing and converting the organic matter present in sludge [8,15]. In addition, the dewatered sludge is mainly characterized by active microbes and debris from dead cells and particulate matter [1]. Consequently, the activity, abundance, and community composition of microbes in sludge may be strongly associated with the vermicomposting efficiency and sludge quality [8,13]. For other sludge biodegradation systems, the impact of temperature on microbial profiles has been well-investigated, such as on anaerobic digestion [16,17], composting [18,19], and vermifiltration [20]. Even in soil systems, temperature also showed an intensive effect on microbial growth, activity, and community structuring within a short period, and thus affe...