## 1 Introduction  
The attraction of bacterial cellulose (BC) as a natural biopolymer, produced by microorganisms, arises from its main functional properties and subsequent applications, especially in the biomedical, food, and engineering fields [1; 2; 3]. Bacteria able to synthesize cellulose can be considered ubiquitous since they have been found to inhabit different ecosystems. They can be isolated from environmental sources (such as soil and plants), from insects, humans, and from food sources [4].  
Within the family _Aectobacteraceae_, the genus _Komagataeibacter_ includes species, such as _K. xylinus_, _K. europaeus_ and _K. hansenii_, that have been described as cellulose producing organisms [5]. The main studied strains belong to the _K. xylinus_ species, which is recognized as the model organism for studying the mechanism of BC synthesis [6; 7].  
One of the most important reservoirs in which it is possible to detect strains belonging to the _Komagataeibacter_ genus is kombucha tea, a fermented beverage traditionally produced in Asia, probably originating from the northeast of China [8]. Kombucha tea is characterized by a microbial community in which different microbial groups, mainly yeasts and bacteria, live in a symbiotic lifestyle [9]. Among bacteria groups, acetic acid bacteria are the main functional organisms, although lactic acid bacteria are also found; moreover, among yeasts, strains of the genera _Saccharomyces_ and _Zygosaccharomyces_ have been described [10]. Kombucha tea production consists of two fermentation reactions operated by yeasts and acetic acid bacteria [11]. The symbiotic relation between yeast and bacteria is established during the fermentation process, in which the yeasts are capable of hydrolysing sucrose, the main substrate for kombucha tea production, into glucose and fructose, and then ethanol. Acetic acid bacteria use glucose, fructose and ethanol to produce gluconic acid, glucuronic acid, acetic acid, and BC [12; 13].  
Kombucha tea can be considered as a dynamic environment, rapidly changing its composition, acting as an copysiological reservoir of very specialized organisms. Considering the occurrence and function of acetic acid bacteria within kombucha, previous studies have described _K. xylinus_ as the main species.  
The ability of _K. xylinus_ strains to produce BC is highly variable, making the selection of the best ones a crucial step in order to obtain candidate strains for large scale BC production. In fact, the availability of selected organisms in producing BC is a requirement for exploiting them as industrial machinery. The production of BC is mainly influenced by two factors. The first one is represented by the carbon sources used in the medium [14; 15]; pure carbon sources could increase the production cost, making the process unsustainable. The second issue is related to the ability of the organism to grow and produce BC in the selected conditions [16]. Some studies have described the abilities of strains belonging to the _Komagatebacter_ genus for producing BC at different yields [5].  
In this work, acetic acid bacteria were collected from liquid and pellicle fraction of kombucha tea samples. In total, 46 isolates were screened for their ability to produce BC and for the main phenotypic characteristics. Moreover, they were typed by applying a fingerprint analysis based on (GTG)\({}_{5}\) repetitive elements and Enterobacterial Repetitive Intragenic Consensus (ERIC) elements in order to assay the intraspecific genetic diversity.