Industrial production of a wide range of chemicals, including dispersants, detergents, azo dyes, and wetting agents, can involve the use of one or more sulfonated naphthalenes as an intermediate. Microbial degradation of naphthalenesulfonates has been elucidated more clearly than that of naphthalenedisulfonates, and their catabolic pathways often merge with classical naphthalene metabolism after an initial desulfonation. Here, we document the desulfonations of naphthalene-1- and naphthalene-2-sulfonate by Pseudomonas strains via an initial dioxygenation, followed by spontaneous sulfite elimination ([http://www.ncbi.nlm.nih.gov/pubmed/16345814|Brilon et al., 1981]). Disulfonated naphthalenes are more resistant to biodegradation. However, Pigmentiphaga daeguensis ASL4 (formerly Moxaxella) can completely metabolize two such compounds (sulfonated at the 1,6 and 2,6 positions) ([http://www.ncbi.nlm.nih.gov/pubmed/3415238|Wittich et al., 1988]), and Pigmentiphaga sp. NDS-2 can metabolize the 2,6 compound ([http://www.ncbi.nlm.nih.gov/pubmed/16233443|Uchihashi et al., 2003]), to gentisate, a well-known intermediary metabolite.