Argentinean Lactococcus lactis bacteriophages: genetic characterization and adsorption studies

Area of Science:

• Microbiology
• Virology
• Food Science

Background:

• Lactococcus lactis is crucial in dairy fermentation.
• Bacteriophages pose a significant threat to L. lactis cultures in cheese production.
• Understanding phage diversity is vital for dairy industry stability.

Purpose of the Study:

• To characterize four virulent Lactococcus lactis phages isolated from Argentinean cheese plants.
• To determine phage host range, genome type, and optimal growth conditions.
• To classify these phages based on existing taxonomic groups.

Main Methods:

• Electron microscopy for phage morphology.
• Host range determination across various L. lactis strains.
• DNA restriction profiling and multiplex PCR for species classification.
• Investigating the impact of Ca(2+), pH, temperature, and cell state on phage adsorption and lysis.

Main Results:

• Four virulent L. lactis phages (CHD, QF9, QF12, QP4) were isolated and characterized.
• Phage QP4 belongs to the P335 species; phages CHD, QF9, and QF12 belong to the 936 group.
• Ca(2+) is essential for lysis by QF9 but not adsorption for any phage.
• Optimal adsorption occurs between pH 5-8 and 0-40°C, with QF12 showing reduced adsorption at pH 8 and 0°C.

Conclusions:

• Argentinean L. lactis phages share common characteristics with those found internationally.
• These phages belong to the predominant P335 and 936 groups.
• This study provides the first characterization of L. lactis bacteriophages in Argentina.