≤10^9 phage per ml of whey: ≤10^5 phage per m^3 in the air
||Chibani-Chennoufi S, Bruttin A, Dillmann ML, Brüssow H. Phage-host interaction: an ecological perspective. J Bacteriol. 2004 Jun186(12):3677-86 DOI: 10.1128/JB.186.12.3677-3686.2004 p.3678 left column 4th paragraphPubMed ID15175280
|| Neve, H., U. Kemper, A. Geis, and K. J. Heller. 1994. Monitoring and characterization of lactococcal bacteriophage in a dairy plant. Kiel. Milchwirtsch. Forschungsber. 46: 167-178
||P.3678 left column 4th paragraph: "Phages are also present in the food we eat. Many food products from our daily life are the result of fermentation processes by lactic acid bacteria. Cheese factories using Lactococcus lactis can be contaminated with high levels of phages: one study reported up to 10^9 phage per ml of whey and up to 10^5 phage per m^3 in the air (primary source)."