**4. Conclusions**

This study has explored whether probiotic bacteria able to adhere on different surfaces (i.e., packaging materials, ceramic, plastic, paper, polymers, etc.) could be used as new biotechnological solutions for industrial applications by biocontrolling the growth of pathogenic and spoilage bacteria.

The results obtained have shown the studied biofilm was able to delay the growth of some pathogenic targets; in fact, cellular pathogenic loads were always lower in presence of probiotic biofilm compared to its absence. For *E. coli* O157:H7, a significant cell load decrease (>1–2 logarithmic cycles) was recorded, whereas for *L. monocytogenes*, *St. aureus* and *S. enterica*, cell load reductions ranged from 0.5 to 1.5 logarithmic cycles.

After only 2 h, the probiotic biofilm was successfully formed on polypropylene, polyvinyl chloride, greaseproof paper, polyethylene and ceramic, with polyethylene and ceramic resultingly being the material with the highest adhesion (6.54 log CFU/cm2). When testing as a tool to control the growth of microorganisms in soft cheeses, the results highlighted the effectiveness of biofilms in slowing the growth of *L. monocytogenes* by prolonging their microbiological stability at 15 ◦C by more than 3 and 4 days.

The results obtained suggest that the developed probiotic lactic acid bacteria biofilms have a good potential to be used as biocontrol agents against pathogenic and food spoilage bacteria through exclusion mechanisms: however, the mechanisms responsible for the inhibition have to be deeply investigated.
