Hexadecyltrimethylammonium (hta) chloride is a quaternary ammonium salt that is widely used in consumer products. This synthetic organic chemical is an active ingredient for hair conditioner, anti-static agents, detergent sanitizer, and performs as a disinfection agent. It is present in wastewaters and usually biodegraded and adsorbed in wasterwater treatment plants, but small amounts will enter natural ecosystems. Pseudomonas sp. B1 metabolizes hexadecyltrimethylammonium chloride with NAD(P)H and oxygen to yield hexadecanal and trimethylamine. Hexadecanal can be converted directly into hexadecanoyl-CoA by hexadecanal dehydrogenase, or can be oxidized to hexadecanoate before conversion into hexadecanoyl-CoA ([http://www.ncbi.nlm.nih.gov/pubmed/1444422|van Ginkel et al., 1992]). Both routes lead into common intermediary metabolism. The other initial product, trimethylamine, is degraded by Pseudomonas 3A2, Pseudomonas aminovorans, and Hyphomicrobium vulgare. It can also degrade in two branches: it may go through subsequent demethylations to liberate formaldehyde ([http://www.ncbi.nlm.nih.gov/pubmed/15760891|Shi et al., 2005]) or be oxidized to trimethylamine N-oxide before demethylation ([http://www.ncbi.nlm.nih.gov/pubmed/4404764|Large et al., 1972]).