PURPOSE: To obtain the present additive alleviating a smell of excrement of organisms such as dogs and cats and odor resulting from sweating, etc., by adding the additive to feeds of the organisms, also usable for removing algae of air filters, swimming pools, etc., by using specific fermenting yeast, assimilating yeast, etc.

CONSTITUTION: Any of nonpathogenic yeast of (A) yeast of the genus Candida of group II having erythritol assimilating property -, citric acid assimilating property -, maltose fermenting property + and sucrose assimilating property +, (B) yeast of the genus Candida of group VIII having galactose assimilating property +, sucrose fermenting property + and galactose fermenting property +, (C) yeast of the genus Candida of group VIII having galactose assimilating property +, vitamin demanding property -, glucose fermenting property +, sucrose assimilating property -, trehalose assimilating property - and galactose fermenting property - and (D) yeast of the genus Saccharomyces having sucrose fermenting property + and maltose fermenting property + is cultivated in a culture solution containing a carbon source, nitrogen source, etc., to give the aimed additive.