Luffa cylindrica-based immobilization: Effects on metabolic activity and paracetamol degradation by Pseudomonas moorei KB4

Pseudomonas moorei KB4 belongs to the paracetamol-degrading strains. This strain was immobilized on a biodegradable carrier – a cellulose sponge from Luffa cylindrica. The study aimed to determine the impact of the immobilization process on the metabolic activity of the strain, including the biodegradation process of paracetamol. The research that was conducted showed significant differences in the level of transcription of selected genes, as well as in the metabolic profile and the composition of total fatty acids. However, the immobilization process did not significantly affect the degradation of paracetamol. This indicates a lack of limitation in the availability of the substrate, which is not very toxic to the tested strain. However, immobilization causes greater strain resistance to the appearance of the toxic 4-aminophenol. After immobilization, it is possible to decompose higher concentrations of paracetamol, which, under normal conditions, leads to the accumulation of 4-aminophenol, inhibiting the free strain's growth. Differences in the degradation of this drug by free and immobilized cells, depending on the number of doses, were observed. After analyzing the enzymes and intermediates of the paracetamol degradation pathway, differences were shown between the metabolism of this compound by the free and immobilized strain. It was shown that, 3-methyl-3-vinyl-cyclohexanon was a characteristic intermediate identified only during paracetamol degradation by the free strain of KB4. Moreover, no deaminase and hydroquinone 1,2-dioxygenase were active in the system with immobilized KB4. The resulting hydroquinone ring was probably not cleaved in the immobilized system. Hence, decomposition probably proceeds by catechol cleavage.