## 1 Introduction  
The global agri-food industry generates about 1.3 billion tons of waste per year as a result of processing, among others, fruit, vegetables, dairy products, bakery products, and meat [1]. The forecasts for the generation of municipal food waste indicate an increase from 278 million in 2005 to 416 million in 2025, which is a cause of great concern [1]. The increase in the amount of environmentally hazardous waste, as well as economic and legal considerations, cause food processing companies to increasingly employ modern methods for reducing waste production and seek ways to reuse it [2]. As a result, more and more industries are trying to adapt to the circular economy model. According to the assumptions of this system, waste that is a by-product of one process can become a valuable substrate material in another process [3, 4]. Waste generated by the agri-food industry is a source of many nutrients such as proteins, polysaccharides, triacylglycerloverols, fats, and phenolic compounds [5]. One way of using by-products from the agri-food industry is to subject them to various biotransformations involving microorganisms, for example, to biosynthesis new compounds and substances with added value [2]. For example, in recent years, orange peels have been successfully used for the biosynthesis of xanthan and curdlan using _Xanthomonas campsterris_ and _Alcaligenes faecalis_, respectively [6, 7]. In turn, watermelon peels have been used as a source of nutrients for _Saccharomyces cerevisiae_ in the process of bioethanol production [8]. Lactic acid is also obtained from industrial by-products through microbial biosynthesis. Lactic acid has been successfully produced from potato peels, green pea peels, orange peels, and mango peels using _Lacticaseibacillus casei_ and _Ub. delbrueckii_[9]. Acetic acid bacteria (AAB) have been known to humans for many decades [10]. The most characteristic feature of AAB is the ability to oxidize ethanol to acetic acid; thus, it is widely used for vinegar production. This reaction is catalyzed by two enzymes: alcohol dehydrogenase (which converts ethanol into acetaldehyde) and aldehyde dehydrogenase (which oxidizes acetaldehyde into acetic acid) [11]. AAB also produce a number of other metabolites such as gluconic acid, dihydroxyacetone, acetate, or bacterial cellulose. In the industrial production of gluconic acid, _Gluconobacter_ is the most commonly used genus, as in the production of dihydroxyacetone. Acetan is mainly produced by the _Acetobacter_ and _Komagataeibacter_ genera. Bacterial cellulose is biosynthesized with the greatest efficiency mainly by the _Komagataeibacter xylinus_[12]. Bacterial cellulose ((BC) biocellulose) is an exopolymer build from glucose units linked by 1,4-\(\beta\)-glycosidic bonds. The \(\beta\)-glycosidic chains then combine into subfibrils and microfibrils forming fibers, which imparts a fibrous structure to BC [13]. Despite its similar structure to plant cellulose, biocellulose is not contaminated with lignins and hemicelluloses. Thus, its purification and further use is relatively inexpensive and environmentally friendly [14]. The unique properties of BC, such as high crystallinity, porosity, and mechanical strength, make it suitable for many applications [15]. It has gained the greatest popularity in biomedicine, where it is used, for example, as a wound dressing material or as scaffolds for tissue engineering [14; 16; 17]. In food products, it may be used as a stabilizer, emulsifier, fat replacer, or meat analogue [13; 18]. Biodegradable food packaging based on biocellulose is becoming increasingly popular [19]. In addition, biocomponents from BC can be used in the protection of the environment in water purification membranes and in cosmetics as carriers of active substances or as stabilizers of cosmetic structures [20; 21; 22]. The main limitations for the use of BC on a large scale include the high costs of the media necessary for the cultivation of microorganisms.