Assessing the Impact of Polyamide Nanofibrous Material Areal Weight on Lacticaseibacillus rhamnosus Biofilm Formation and Resistance to Storage Conditions and Contamination.

Probiotic biofilms are considered the fourth most advanced generation of probiotics. To maximize the benefits of probiotic biofilms, suitable carriers ensuring bacterial viability during storage are being sought. The use of nanofibrous platforms is beginning to appear as one of the most promising approaches. We investigated the influence of three polyamide (PA) nanofibrous materials with different areal weights (5, 11, 27 g/m2) and the resulting morphological properties on the biofilm formation of Lacticaseibacillus rhamnosus ATCC 9595 and its tolerance to various conditions. PA promoted biofilm formation more than the reference material, polystyrene. PA's areal weight influenced the biofilm biomass amount, phenotype, and structure; PAs with a high areal weight promoted biofilm formation. Further, we examined the tolerance of matured biofilms on the PAs to various external conditions: (i) storage temperature (-20, 4, 21 °C), environment (aqueous/dry), and time (0-35 days), (ii) pH (2, 4, 6, 7, 8 and 10), and (iii) bacterial contamination by Staphylococcus aureus and Escherichia coli. Generally, PAs increased biofilm resistance, and the areal weight of the PA played a crucial role in it. The PA with the highest areal weight (27 g/m2) provided the highest long-term stability and tolerance of the biofilm and thus was confirmed to be the most suitable tested nanomaterial. The overall results suggest that the presented PAs could be suitable carriers of probiotic biofilm, enabling large-scale production. We also highlight the need for further research on the influence of nanomaterials' morphology on microbial interactions, possibly enabling target modification for a particular use.