An alpha-proteobacterium converts linear alkylbenzenesulfonate surfactantsinto sulfophenylcarboxylates and linear alkyldiphenyletherdisulfonate surfactants into sulfodiphenylethercarboxylates

The surfactant linear alleylbenzenesulfonate (LAS; 0.5 mM) or linear monoal kyldiphenyletherdisulfonate (LADPEDS; 0.5 mM) in salts medium was easily de graded in laboratory trickling filters, whereas carbon-limited, aerobic enr ichment cultures in suspended culture with the same inocula did not grow. W e took portions of the trickling filters which degraded LADPEDS, shook the organisms from the solid support (polyester), and found that growth in susp ended culture in LADPEDS-salts medium occurred only in the presence of some solid support (polyester fleece or glass wool), though little biomass was immobilized on the support. The end products in suspended culture were iden tical with those from the trickling filters, There was low plating efficien cy of LADPEDS-grown cultures on complex medium, and no picked colony or mix ture of colonies grew in LADPEDS-salts-glass wool medium. However, selectiv e plates containing LADPEDS-salts medium solidified with agarose yielded LA DPEDS-dependent, pinpoint colonies which could be picked singly and subcult ured in selective liquid medium. Isolate DS-1 was a bacterium which showed 93% sequence homology (16S ribosomal DNA) to its nearest phylogenetic neigh bor, an alpha-proteobacterium. Strain DS-1 grew heterotrophically in LADPED S-salts-glass wool medium and converted the set of aryl-substituted alkanes to the corresponding aryl-substituted carboxylic acids of shorter chain le ngth, Similarly, strain DS-1 grew heterotrophically with commercial LAS, co nverting it to a set of sulfaphenylcarboxylates. Growth with a single isome r of LAS [3-(4sulfophenyl)dodecane] was concomitant with excretion of 4-(4- sulfophenyl)hexanoate, which was identified by matrix-assisted laser desorp tion ionization mass spectrometry, The growth yield (6.4 g of protein/mol o f C) indicated mass balance, which, with the specific growth rate (0.05 h(- 1)), indicated a specific utilization rate of LAS of 2.2 mkat/kg of protein .