Bacterial strains for use as probiotics, compositions thereof, deposited strains and method to identify probiotic bacterial strains

A method comprising administering to a fish in need thereof, a probiotic active ingredient(s), wherein the probiotic active ingredient(s) is(are) a bacterial strain or combination of bacterial strains, wherein the bacterial strain or at least one bacterial strain of the combination is selected from the group consisting of:

• a Chryseobacterium massiliae strain, a Chryseobacterium massiliae strain wherein one or more virulence factor coding gene(s) and/or antibiotic resistance gene(s) is(are) deleted or inactivated, a Flavobacterium sp. strain whose genome has at least 95% or more Average Nucleotide Identity (ANI) with SEQ ID NO:
• 1 or which has at least 95% ANI with the Flavobacterium sp. strain identified by Accession Number No. I-5481 deposited at the CNCM on Jan. 24, 2020, and a Flavobacterium sp. strain whose genome has at least 95% or more Average Nucleotide Identity (ANI) with SEQ ID NO:
• 1 or which has at least 95% ANI with the Flavobacterium sp. strain identified by Accession Number No. I-5481 deposited at the CNCM on Jan. 24, 2020 wherein one or more virulence factor coding gene(s) and/or antibiotic resistance genes is(are) deleted or inactivated.

A probiotic composition or food product comprising at least one bacterial strain selected from the group consisting of:

• a Chryseobacterium massiliae strain, a Flavobacterium sp. strain with at least 95% or more Average Nucleotide Identity (ANI) value with SEQ ID NO:1 or with the Flavobacterium sp. strain identified by Accession Number No. I-5481 deposited at the CNCM on Jan. 24, 2020, and variants thereof wherein one or more virulence factor coding gene(s) and/or antibiotic resistance genes is(are) deleted or inactivated, and further acceptable carrier or delivery vehicle(s).