Effects of Lysozyme and Silver Anode Treatment on Pseudomonas aeruginosa Growth and Biofilm Formation in Raw Milk

Pseudomonas aeruginosa is an important spoilage‑associated and opportunistic pathogen in raw milk, producing heat‑stable enzymes and robust biofilms that resist conventional sanitation. The limitations of existing decontamination methods necessitate novel, nonthermal, and ecofriendly strategies. This study evaluated the antibacterial and anti‑biofilm effects of lysozyme combined with the silver anode technique (SAT) against P. aeruginosa ATCC 27853 in raw milk. The minimum inhibitory concentration (MIC) of lysozyme was estimated by disk diffusion (8 g/100 mL). Raw milk samples were assigned to eight experimental groups: untreated controls, lysozyme alone, SAT alone, and their combination. Bacterial counts (log CFU/mL) and biofilm formation (crystal violet assay) were monitored over 72 h of refrigerated storage, and silver ion migration was quantified by ICP‑MS. Lysozyme alone was predominantly bacteriostatic, while SAT alone produced a bactericidal reduction (up to 1.5–2 log). The combination reduced planktonic counts by up to 2.5 log and biofilm by up to 78%. These reductions were greater than either treatment alone, although the effect was additive, not strictly synergistic. Silver migration (3.88 µg/L) gave a daily intake of 0.055 µg/kg for an adult consuming 1 L, well below EPA (5 µg/kg/day) and EFSA (50 µg/kg food) limits. The combination offers an effective, non‑thermal, eco‑friendly dairy pretreatment strategy. It can extend shelf life, reduce biofilm contamination, and minimize chemical disinfectants, aligning with green technology.