## 1 Introduction  
The evolution of waste quantity closely follows the development of society. Also, waste that in the past was essentially organic (effluents from animal husbandry, food waste, plant residues, etc.) today contains a very heterogeneous range of products (green waste, food waste, livestock and industrial waste, paper, plastic and metal packaging, etc.). This increased diversity of waste encourages researchers to find a solution to treat and recover it [1]. Over the last decades, the increased affluence of the production industry has resulted in greater quantities of waste produced yearly. One of the most challenging environmental tasks for scientists is definitely the correct management and discarding of industrial solid waste. Presently, the textile industry is considered to be the one of the industries generating a large amount of solid waste, which is disposed directly into the environment without any treatment [2]. Furthermore, the abundant organic fraction in textile waste can be bio-converted into a useful end-product called bio-fertilizer, which could be utilized as a supplement to the soil on farm lands [3]. Composing is a biotransformation process in which a solid organic fraction turns into mature and stabilized material by means of microbial action in aerobic conditions [4]. Compost is a noteworthy soil amendment, with its application as an organic fertilizer improving the level of soil organic matter, long-term soil fertility, and productivity [5]. Several studies have been devoted to the characterization of the composing process in order to follow its progress. Among the most useful parameters for assessing compost maturity are the percentage of total organic carbon (TOC), total nitrogen level, C/N ratio, heavy metals, and enzymatic activities [6]. As the composing process is a biological process, microorganisms play a key role. Furthermore, most of the transformations that organic matter undergoes during the bio-oxidative stage are ascribable to the action of microbes and their enzymatic activities [4]. Several investigations concerning the characterization of the composing microbiot a have been published previously [7]. Furthermore, diversity studies regarding composing substrate are limited, since most reports are focused only on the valorization of solid wastes [4]. In this context, there is a paucity of reports depicting complete biochemical characterization of the microbiota involved in the composing. Many authors have revealed specific microbial communities [7], others elucidated only the enzymatic evolution [8]. In fact, the metabolic abilities of microorganisms in relation to organic waste transformation, along with the nature of the residual material, affect the enzymatic features in biodegradation reactions. An assessment of the dynamics of microbes during composing provides a better understanding of the evolution of the process from a microbiological perspective and an overview of the connections between biotic and abiotic factors. In this context, to identify the microbiota involved in the composing, a metagenomic approach has been widely used [9]. Direct Deoxyribonucleic acid (DNA) sequencing techniques have been emerging recently, increasing the capacity and rate of discovery of previously unknown genes and functional sequences of previously unknown microorganisms [10], allowing the detection of more complete biodiversity in a given environment. They also allow studies of the metabolic pathways of microbiota. High-throughput sequencing (next-generation sequencing (NGS)) is one of the most advanced, rapid, efficient, and accurate technologies used in metagenomics studies [11]. Therefore, the main purpose of this work was to study the dynamics of the microbiota according to its metabolic ability profile during the composing of textile waste.