Propagation method for persistent high yield of diverse Listeria phages on permissive hosts at refrigeration temperatures

The efficient production of a high concentration of bacteriophage in large volumes has been a limiting factor in the exploration of the true potential of these organisms for biotechnology, agriculture and medicine. Traditional methods focus on generating small volumes of highly concentrated samples as the end product of extensive mechanical and osmotic processing. To function at an industrial scale mandates extensive investment in infrastructure and input materials not feasible for many smaller facilities. To address this, we developed a novel, scalable, generic method for producing significantly higher titer psychrophilic phage (P < 2.0 × 10−6), 2- to 4-fold faster than traditional methods. We generate renewable high yields from single source cultures by propagating phage under refrigeration conditions in which Listeria, Yersinia and their phages grow in equilibrium. Diverse Yersinia and Listeria phages tested yielded averages of 3.49 × 108 to 3.36 × 1012 PFU/ml/day compared to averages of 1.28 × 105 to 1.30 × 1010 PFU/ml/day by traditional methods. Host growth and death kinetics made this method ineffective for extended propagation of mesophilic phages.