Green waste, especially of municipal origin, is currently used as a material only to a limited extent. However, the large material flows could also be used in a more economical way if they were integrated into biorefinery concepts. Besides the production of basic and fine chemicals, green waste could also be used as source of industrial relevant enzymes. Here, the purification and characterization of peroxidases from common lawn grass species Lolium perenne and Festuca arundinacea are reported. The purified peroxidase fractions as well as crude extracts were investigated for the removal of common wastewater pollutants such as phenol, m-cresol, and 2,4-dichlorophenol by oxidative polymerization. The grass-derived peroxidases showed the highest affinity towards 2,4-dichlorophenol, followed by m-cresol and phenol. A crude extract of real lawn grass was able to remove over 95 % of 0.5 mM 2,4-dichlorophenol within 20 min.

In chemical process engineering, process intensification (PI) has proven itself as a method that resulted very often in processes with an at least doubled process performance. In recent years, the PI techniques have found more and more applications in biotechnology. Exemplary continuous processes, single-use reactors, electrobiotechnology and hybrid techniques are discussed here.

Unspecific peroxygenases have recently gained significant interest due to their ability to catalyse the hydroxylation of non-activated C−H bonds using only hydrogen peroxide as a co-substrate. However, the development of preparative processes has so far mostly concentrated on benzylic hydroxylations using liquid substrates. Herein, we demonstrate the application of a peroxygenase for the hydroxylation of the inert, gaseous substrate butane to 2-butanol in a bubble column reactor. The influence of hydrogen peroxide feed rate and enzyme loading on product formation, overoxidation to butanone and catalytic efficiency is investigated at 200 mL scale. The process is scaled up to 2 L and coupled with continuous extraction. This setup allowed the production of 115 mmol 2-butanol and 70 mmol butanone with an overall total turnover number (TTN) of over 15.000, thereby demonstrating the applicability of peroxygenases for preparative hydroxylation of such inert, gaseous substrates at mild reaction conditions.

Various enzymes utilize hydrogen peroxide as an oxidant. Such “peroxizymes” are potentially very attractive catalysts for a broad range of oxidation reactions. Most peroxizymes, however, are inactivated by an excess of H₂O₂. The electrochemical reduction of oxygen can be used as an in situ generation method for hydrogen peroxide to drive the peroxizymes at high operational stabilities. Using conventional electrode materials, however, also necessitates significant overpotentials, thereby reducing the energy efficiency of these systems. This study concerns a method to coat a gas-diffusion electrode with oxidized carbon nanotubes (oCNTs), thereby greatly reducing the overpotential needed to perform an electroenzymatic halogenation reaction. In comparison to the unmodified electrode, with the oCNTs-modified electrode the overpotential can be reduced by approximately 100 mV at comparable product formation rates.