Bacterial compositions for treating and preventing halitosis

A nutritional supplement comprising a bacterial mixture and a carrier, the bacterial mixture comprising:

• (i) a first bacterial strain comprising a genome having at least 99.5% average nucleotide identity (ANI) to the genome of SEQ ID NO:
• 18, and which reduces abundance of one or more volatile sulfur compounds (VSCs);
• (ii) a second bacterial strain comprising a genome having at least 99.5% ANI to the genome of SEQ ID NO:
• 19, and which enhances the reduction in abundance of one or more VSCs by the first bacterial strain;
• and
• (iii) a third bacterial strain comprising a genome having at least 99.5% ANI to the genome of SEQ ID NO:
• 20, and which reduces pH of an oral microenvironment of a subject to a value less than 7.5, wherein each of the bacterial strains is lyophilized and in powder form,
• wherein the nutritional supplement has a water content of 5% or less.