## 3 Occurrence and Function of Lacases  
Lacases are commonly synthesized by living organisms, including bacteria, plants, insects and fungi, and are involved in various biological processes that are different depending on the organism producing them [22; 27; 31]. Producers of prokaryotic lacase can include Gram-positive and Gram-negative bacteria living in different environments, among which are representatives of _Streptomyces_: _S. lavendulae, S. cyaneus, Ralstonia solanacearum_, _Sinorhizobium meliloti_, _Bacillus subtilis_, _Marinomonas mediterranea_ and _Escherichia coli_. Currently, the best characterized is lacase CotA synthesized by _B. subtilis_[32; 33; 34]. Intracellular lacases are responsible for neutralizing toxic by-products released in biochemical reactions. Under natural conditions, bacterial lacases are also involved in pigmentation, morphogenesis, toxin oxidation and protection from UV light and the cross-linking of envelope proteins in bacterial spores, among others [18; 35; 36; 37; 38; 39; 40]. Most of the available literature data on lacase-synthesizing fungi concerns species belonging to the phylum _Basidiomycota_ and _Ascomycota_[21; 40]. One of the main functions of fungal lacases is the breakdown of lignocellulosic, which affects the carbon cycle in the biosphere. Fungal lacases also have more specialized functions, e.g., participation in the synthesis of pigment that protects fungal spores from factors such as high temperatures or UV radiation or the synthesis of antibacterial compounds [41; 42]. Phytopathogenic fungi have been shown to produce lacase to inactivate plant defense mechanisms. In the case of _Cryptococcus neoformans_, lacase is considered a virulence factor. Immunocompromised individuals, such as those with AIDS or patients taking high levels of corticosteroids, are particularly vulnerable. The enzyme is thought to convert host catecholamines into melanin, which promotes protection of the pathogen and allows it to cause more damage to the host [43; 44]. All plant lacases have one common function, which is to participate in a multienzymatic system involved in the synthesis of lignin in wood cells responsible for maintaining the structure and rigidity of the cell wall. It is found in the xylem, where it is involved in the initial phase of lignin biosynthesis by oxidizing monolignols [45; 46]. This enzyme is also involved in the repair mechanism of damaged plant tissues. Above this, its participation can also be seen in plant defense processes, iron accumulation and the polymerization of phenolic compounds [21; 47]. In the plant family _Anacardiac_, it is found in resin ducts, indicating a defensive function of the enzyme against herbivores, predators and microorganisms. In the common radish (_Arabidopsis thaliana_), on the other hand, the aforementioned enzyme is involved in the polymerization of flavonoids needed for seed coating and in the production of brown polymers with a putative protective function. In green algae present in both aquatic and terrestrial environments, the main role is the detoxification of phenolic compounds and participation in the synthesis of cell walls and UV-absorbing compounds, as well as in nutrient acquisition [21; 48]. Insects are the best-known lacase producers in the animal world. The presence of this enzyme has been found in insects of the order _Hymenoptera_, _Diptera_, _Lepidoptera_ and _Coleoptera_[2; 49; 50; 51]. The main role of lacase produced by insects is its involvement in epidermal synthesis, wound healing, morphogenesis and immune system development [2; 21; 52; 53]. In insects, lacase, located in the intestinal cells, plays a defensive role against toxic lignin derivatives entering the host organism as a result of its consumption of plant products. In these organisms, the aforementioned enzyme is also involved in epidermal hardening in larval forms, pupae and adults, as in _Drosophilia virilis_[3].