Halitosis (bad breath) is a term used to describe an unpleasant odor emanating from the mouth that could originate in the oral cavity itself or as a result of systemic factors. Halitosis is a common problem that affects most of the population worldwide and is caused mainly by the volatile sulfur compounds produced by anaerobic Gram-negative microorganisms in the oral cavity on sulfur-containing substrates in the oral cavity. On the dorsum of the tongue, the volatile sulfur compounds produced from this metabolism are hydrogen sulfide (H2S), methyl mercaptan (CH3SH3) and dimethyl sulfide (CH3-S-CH3). The concentration of these gases is used as an indicator of the severity of halitosis. Recently, the Gram positive anaerobic bacterium Solobacterium moorei (formerly known as Bulleidia moorei) has also been associated with oral malodor by volatile sulfur compounds production, particularly hydrogen sulfide in the presence of different supplements with amino acids more specifically cysteine, wich agrees with studies showing that the cysteine challenge is a in vivo and in vitro model for analyzing the production of hydrogen sulfide.