Biocatalysis attracts attention as the interdisciplinary research of the single-enzyme one-stage processes of highly selective conversion of initial reagents-substrates into valuable products in demand on the market. Biocatalytic technologies, which possess all the important features of enzymatic catalysis, such as chemo-, regio- and stereospecificity, are energy saving and environmentally friendly green alternative processes that are quite competitive in comparison with conventional chemical production, including organic synthesis (Hou, 2005; Tao and Kazlauskas, 2011; Reetz, 2013; Sheldon and Woodley, 2018). In recent decades, a direction called “enzyme engineering” or “biocatalyst engineering”, which studies the modulation of the functional properties of enzymes immobilized on supports with various chemical nature, has been intensively developed (Cunha et al., 2014, Santos et al., 2015; Tacias-Pascacio et al., 2017; Lokha et al., 2020; Guimarães et al., 2022; Kovalenko et al., 2022). According to the authors opinions (Mateo et al., 2007, Boudranta et al., 2020), this direction is fully compatible with other chemical and/or biological approaches to improving the functional properties of enzymes, and the success of such “engineering” work is determined by the presence of numerous immobilization protocols. Undoubtedly, targeted control and purposeful modulation of the properties of immobilized enzymes, particularly their activity, substrate specificity and stability, form an interesting and promising area of heterogeneous biocatalysis.

Enzyme immobilization has been developed since the 1960s, and many modern large-scale industrial biocatalytic processes are implemented in a heterogeneous mode using active and highly stable biocatalysts (BCs) placed in specially designed reactors of various types, most often continuous fixed-bed and periodic stirred tank reactors, less often vortex and even less often fluidized bed reactors. It should be especially emphasized that the biocatalysts in granular form (rather than in fine powder) is more preferable for use in industrial reactors than its fine powder, since the problem of its separation from the reaction medium is easily solved and hydrodynamic resistance in the catalyst bed is reduced. Authors of a tutorial review (Bolivar et al., 2022) entitled “Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization” came to the conclusion, that “enzyme immobilization, far from being a mature discipline, remains as a subject of high interest and where intense research is still necessary to take full advantage of the possibilities”. The authors also described how to overcome all challenges of incorrectly designed immobilization protocols. They expressed confidence that the latest developments in materials science, bioprocess engineering and protein science would open up new opportunities for the future. It should be noted that although there are hundreds of immobilization protocols, the design of new protocols, which may allow improving the properties of BCs, is still an exciting goal.

Lipases (triacylglycerol acyl hydrolases, EC 3.1.1.3) have long attracted the attention of chemists due to their unique ability to carry out the synthesis, particularly of various esters, in a non-aqueous medium of nonpolar organic solvents (Adlercreutz, 2013, Stergiou et al., 2013). It seems interesting that the immobilization on hydrophobic supports led to hyperactivation of the lipase, i.e., the specific activity of immobilized lipases was many times greater than the activity of the soluble enzyme in the hydrolysis of triglycerides which is the direct lipase reaction in an aqueous medium (Manoel et al., 2015, Lokha et al., 2020, Souza et al., 2021, Guimarães et al., 2023). This effect was explained by a change in the configuration of the active center of immobilized lipase: upon interaction with the hydrophobic surface, the lid of the active center opened (Fernández-Lorente et al., 2008; Tacias-Pascacio et al., 2016; Rodrigues et al., 2019). The observed hyperactivation of lipase in the ester synthesis (the reverse reaction in a non-aqueous medium) was attributed to the formation of a favorable aqueous microenvironment inside the heterogeneous biocatalysts due to the accumulation of the produced water in the immediate vicinity of immobilized lipase (Kovalenko et al., 2019, Kovalenko et al., 2021b).

The biocatalysts prepared by adsorptive immobilization of the lipase produced by the authors' recombinant strain of Komagataella phaffii (Pichia pastoris) (denoted as rPichia/lip) on granulated supports – macroporous carbon (MWCNTs-based) aеrоgel and mesoporous silica – were comprehensively studied in the reactions of low-temperature esterification of saturated monocarboxylic (fatty) C4-C18 acids with primary aliphatic C2-C16 alcohols (Kovalenko et al., 2018, Kovalenko et al., 2021b, Kovalenko et al., 2022).

In this research, we investigated the influence of the monotonically varying balance of hydrophobic-hydrophilic properties of adsorbents, which depended on the binary composition of the developed carbon-silica materials (CCSMs), on the catalytic properties of the prepared BCs. This balance was regulated by the process of decorating multi-walled carbon nanotubes (MWCNTs) with silica micelles, the concentration of which was different in the impregnation solutions. Thus, the mass ratio of such individual components as hydrophobic carbon nanotubes and hydrophilic silica monotonically varied over a wide range. Additionally, finely dispersed MWCNTs were aggregated into CCSM granules. The catalytic properties of BCs, particularly the enzymatic activity, substrate conversion and specificity, operational stability, as well as tolerance to some organic solvents were studied in the esterification of fatty C4, C7, C18 acids with aliphatic C2, C4, C16 alcohols in hexane under ambient conditions (20 ± 2°C, 1 bar, 30–50% humidity).