Study of a new strain of Fusobacterium which could inhibit L. monocytogenes in Herve cheese

A new putative species of Fusobacterium was found as a major component of the rind of a farmhouse Herve cheese and sequenced in silico. Herve cheese is a soft, washed-rind cheese made from raw cow’s milk and the only PDO cheese in Belgium. A challenge-test study has also shown that Listeria monocytohenes cannot multiply on this type of cheese.
The objective of this study is to validate the presence of this new species of Fusobacterium in different cheeses from the same operator, to study the sources of contamination and the metabolic pathways used to potentially inhibit L. monocytogenes growth.
Different cheeses were tested, after different maturation times. For each cheese/time pairing, a sample of rind and core was taken separately. The samples were studied by PCR with primers specific to the genus Fusobacterium, and to the new species studied.
The new putative species was found to be a contaminant of all the washed ripened cheeses with much higher proportions in the rind samples and not from unripened cheeses refuting probably the hypothesis that the bacterium has raw milk as a reservoir.
Isolation tests will be conducted to isolate and characterize this bacterium from cheese and it will be searched in the environment of the cheese dairy.