Carbonic anhydrase is an important enzyme that can play a significant role in the processes of lowering carbon dioxide concentration in the atmosphere. The aim of the work was to investigate the extracellular carbonic anhydrase (CA) production by the bacteria Pseudomonas fragi. In the research, we focused on the evaluation of the phase of bacterial growth correlated with carbonic anhydrase production and on the evaluation of induction of CA production by calcium carbonate concentration in the nutrient medium. Presented data indicated that calcium carbonate can serve as the only carbon source for Pseudomonas fragi, inducing carbonic anhydrase secretion to culture broth. The enzyme was produced mainly in the adaptation growth phase reaching the maximal activity at the end of this phase or at the beginning of the growth phase. The maximal enzyme activity detected in all batches was at a similar level. The enzyme activity was constant but lower in the exponential phase growth. Therefore, the enzyme production is not growth-dependent, but it is correlated with bacteria adaptation to cultivation conditions.

The possibility of producing chitosan by enzymatic deacetylation of chitin has been the subject of numerous investigations over the last twenty years, but to date no satisfactory method has been developed. In this paper the influence of chitin chain conformation and chitin particle crystallinity on the enzymatic deacetylation of chitin is investigated to determine the relative importance of these two factors on the process. It is shown that the high crystallinity of chitin is the main obstacle to converting chitin to chitosan by enzymatic deacetylation.

Despite its unique properties (biocompatibility and nontoxicity), chitin itself has limited application. Chitin is completely insoluble in most organic or inorganic solvents what can be beneficial when chitin is investigated as a support for chromatography or enzyme immobilization. These applications require the particles to have an extensive outer surface with a large number of reactive ligands. The increase in specific surface area of chitin particles can be performed by dissolution in ionic liquid and precipitation with water. To increase the number of reactive ligands (amine groups), deacetylation of the surface of chitin particles is necessary. The deacetylation process can be carried out by an enzymatic process with the enzyme, chitin deacetylase. In our investigation, 21 ionic liquids were used for chitin particle structure modification followed by enzymatic deacetylation. Results proved positive effect of modifications with ionic liquid on enzymatic deacetylation of the chitin surface with chitin deacetylase. For 12 samples the deacetylation gave an increase in number of active ligands in comparison to natural chitin. The best results were observed for [Bmim][Br], [Emim][Cl] and [MPpip][Ac]. That could be correlated with an increase in outer surface area by increasing porosity of particles or by structural changes in chitin particles.

Chitin deacetylase is the only known enzyme which is able to deacetylate N-acetyl-D-glucosamine units in chitin or chitosan chains. As chitin can hardly be dissolved in organic/inorganic solvents, new solvents are still searched. Ionic liquids are promising for that application and for homophase enzymatic deacetylation. The aim of the work was to investigate the influence of selected ionic liquids on activity of chitin deacetylase.

It has been shown that [Amim] ionic liquids increase the activity of chitin deacetylase. The highest activity was observed for [Amim][Cl]. Ionic liquids with shorter (ethyl (C2)) and longer side chain (buthyl (C4)) only insignificantly influenced the activity of the enzyme. All tested ionic liquids with [Br] anion increased the activity of chitin deacetylase while the [Emim] and [Bmim] cation in combination with [Cl] anion inhibited the activity of the enzyme.