Detection of residual microbial biomarkers in bacterial cellulose using laser-induced fluorescence spectroscopy.

Bacterial cellulose (BC) is a promising biomaterial for medical and biotechnological applications. However, microbial contaminants and their metabolic residues remain a critical limitation for its clinical use. Many of the BC purity tests are labor-intensive and time-consuming. This study investigates the feasibility of using laser-induced fluorescence (LIF) spectroscopy for monitoring microbial contamination in BC. BC samples were obtained from a Medusomyces gisevii consortium and subjected to various purification protocols (alkaline, detergent and oxidative treatments). LIF spectra were recorded across 220-290 nm excitation wavelengths and analyzed chemometrically. For better interpretation of the results, the same samples were examined by laser scanning confocal microscopy (LSM). The results reveal that both native and treated BC samples exhibit fluorescence features associated with tryptophan and tyrosine, indicative of microbial residues. Treatment with NaOH effectively reduced tryptophan-associated signals, while hydrogen peroxide diminished tyrosine-related fluorescence. None of the purification strategies completely eliminated these signals. A good correlation between the LIF and the more labor-consuming LSM data was observed. LIF showed the capability of rapid and reliable differentiation between treatment variants and provided spectral fingerprints linked to residual contamination. Future work may focus on standardizing LIF-based diagnostic protocols and integrating them into biotechnological workflows for contamination monitoring.