###### Abstract  
The aim of this study was the isolation and characterisation of the fungi and bacteria during the composting process of sewage sludge under a semipermeable membrane system at full scale, in order to find isolates with enzymatic activities of biotechnological interest. A total of 40 fungi were isolated and enzymatically analysed. Fungal culture showed a predominance of members of Ascomycota and Basidiomycota division and some representatives of Mucromycotina subdivision. Some noticeable fungi isolated during the mesophilic and thermophilic phase were _Aspergillus_, _Circinella_, and _Talaromyces_. During the maturation phase, some lignin modifying enzyme producers, like _Purpurerocillium_, _Thielavia_, _Bjerkandera_, or _Dichotomyces_, were found. Within this group, _Thielavia_ and _Bjerkandera_ showed high activity with production of lacases and peroxididases. In the bacterial culturome, a total of 128 strains were selected and enzymatically analysed. Bacillus, Actinomycetesales, Pseudomonas, and Lactobacilluses were the orders most represented in culture-bacteria. _Bacillus pumilus_, _B. stratosphericus_, _B. safensis_, and _Pseudomonas formosensis_ were the species most efficient in enzyme production, particularly peroxididases, polyphenol oxidases ammonifying activity, and amylases. These results showed that sewage sludge composting piles could represent a source of microorganisms which have adapted to adverse conditions. bacteria; composting; enzymes; fungi; sewage sludge +
Footnote †: journal: Applied Soft  
of the compost, on the transformation of organic matter, and on the functional diversity [3; 4; 5; 6]. A wide variety of fungi and bacteria are able to break and oxidise macromolecules using a set of hydrolytic, oxidative lyase, and transferase enzymes [7]. In addition, dehydrogenase, \(\delta\)-glucosidase, proteases, phosphatases, and arylsulfatase are the main enzymes proposed to monitor the activity of microbial communities [8]. The associated microbiota during composting is widely diverse and its ecology is extremely complex. Different microbial activities occur depending on the physical-chemical and nutritional conditions prevailing at each moment and throughout the process the microorganisms themselves change the physical-chemical properties. The conditions of the process, like the autochthonous microbiota, temperature, and moisture, or the composition of the sewage sludge, make the pile an interesting ecosystem and a singular environment to search for microorganisms with abilities to produce enzymes with biotechnological applications. Among them, the ones that stand out are those that can be applied in the biosynthesis processes, food industry, biorefineries, and textile industries, like hemicelllases, pectinases, oxidoreductasetases, lacases, and peroxididases. Previous studies on microbial diversity have shown that many of the predominant taxa in the different phases of composting possess high capacity to produce enzymes. The study performed by [PERSON] et al. [9].reported that genera like _Alternaria_, _Cladosporium_, _Penicillium_, _Acremonium_, _Fusarium_, and _Scopulariopsis_ for fungi and _Bacillus_, _Brevibacillus_, _Pseudomonas_, _Streptomyces_, and _Cellulosinicrobium_ for bacteria, isolated from lignocellulosic waste composting, were microorganisms with a high potential for enzyme production [9]. However, as far as we know, there have been no studies about the potential of enzyme production in microorganisms isolated from sewage sludge composting. In this context, the aim of this study was to isolate fungi and bacteria from different phases of the sewage sludge composting pile built at full-scale and with a semipermeable membrane system, in order to assess the capacity of these isolates as candidates in the production of extracellular enzymes with biotechnological applications. This preliminary study could provide the first step in an interesting approach to find microorganisms with metabolic abilities to degrade micropollutants present in sewage sludge.