Abstract: A composition for use in the oral cavity comprising a monophosphate represented by the following general formula (1), ##STR1## wherein R.sup.1 is a linear or branched alkyl or alkenyl group with 6 to 20 carbon atoms, and may have a substituted fluorine atom; one of X.sup.1 or X.sup.2 is a basic amino acid residual group, while the other is a hydrogen atom, an alkali metal, an ammonium, an alkyl amine, an alkanol amine, or a basic amino acid residual group; and n is an integer from 0 to 4. The composition exhibits a superior action in protecting the tooth surface, is stable, and has a pleasant taste.

Abstract: A biocide composition comprising(A) 1 to 50% by weight of a biocide, and(B) 0.005-60% by weight of a biocide activator having the specific formula is provided. The biocide effect of a biocide can be enhanced with the use of an effective amount of a biocide activator.

Abstract: The biocidal effect of a biocide can be enhanced with the use of an effective amount of the auxiliary compound having the formula (I). ##STR1## wherein at least one of R.sup.1, R.sup.2, and R.sup.3 represents a straight-chain or branched alkyl or alkenyl group having 8 to 30 carbon atoms while other(s) represent a group or a combination selected from among ##STR2## wherein n ranges from 1 to 5; R.sup.4 represents a --CH.sub.3 or --CH.sub.2 CH.sub.3 group; anda counter ion X.sup..crclbar. is an anion residue of an acid of an anionic oligomer or polymer having an average molecular weight of from 300 to 20,000.

Abstract: A bactericidal composition comprises didecyldimethyl didecyldimethylammonium chloride and an alkylene oxide adduct of a polyhydric alcohol being trivalent or more and is effective bactericidally even to feces of a cattle stall.

Abstract: A biocide is enhanced in the effect by applying an esterase to a plant stem, leaves or an insect in advance to or together with the application of the biocide. The esterase decomposes the waxy outer layers of plants and insects.