PMC

Growth of α-proteobacterium strain DS-1 in 1.7 mM 3-C12-LAS–salts–glass wool medium (●) with concomitant quantitative formation of 4-C6-SPC (inset).

Heterotrophic growth of the mixed culture utilizing commercial LADPEDS in suspended culture, including data for LADPEDS (■), SDPEC (□), the ammonium ion (○), and the sum of nitrate and nitrite formed (●). OD, optical density.

Growth of the mixed culture in 1 mM LADPEDS-salts-glass wool medium (●) and the specific activity of LADPEDS-dependent oxygen uptake during growth (▵). OD, optical density.

Primary degradation of commercial LADPEDS in a trickling filter as determined by HPLC. LADPEDS-salts medium (0.33 mM; upper chromatogram) was pumped onto the trickling filter, and the eluate in the steady state (lower chromatogram) contained largely peaks of shorter retention time. Inset, UV spectra of representative peaks of substrate (upper scan) and product (lower scan).

A representative LAS congener with its conversion to a defined SPC and a hypothetical LADPEDS congener and with its presumed metabolism to a SDPEC. Commercial LAS always shows the subterminal substitution of the 4-sulfophenyl moiety; the chain length usually ranges from C₁₀ to C₁₃ (). Commercial C₁₆ LADPEDS always shows the subterminal substitution of the diphenylether. It thus has seven positional isomers on the alkyl chain, each of which has a chiral center. Ten combinations of the alkyl, sulfonate, and ether substituents on the first ring are possible, as are three positional isomers of sulfonation on the second ring. Although substituents are nominally LADPEDS, dialkylated species and monosulfonated ethers also occur (Dowfax surfactant reaction mixture, Dow product information 1510-017A, p. 1, 1997).