Ether-bond scission in the biodegradation of alcohol ethoxylate nonionic surfactants by Pseudomonas sp. strain SC25A

Abstract

Pseudomonas sp. strain SC25A, previously isolated for its ability to grow on alcohol ethoxylates (PEG dodecyl ethers) as sole source of carbon and energy, was shown to be capable of growth on the dodecyl ethers of mono-, di, tri-and octaethylene glycols. Comparative growth yields for this series of alcohol ethoxylate nonionic surfactants indicated that, whereas all of the carbon of monoethylene glycol dodecyl ether (MEGDE) was assimilable, only the alkyl chains were assimilated from the higher ethoxamers. These results are interpreted in terms of a primary biodegradation mechanism in which the scission of the dodecyl-ether bond is the first step. In the case of MEGDE this step separates the dodecyl chain from a C, fragment, both of which are readily assimilable; for the higher ethoxamers, the assimilable dodecyl chain is accompanied by an ether-containing PEG derivative which would require further rounds of ether scission before assimilation. Whole cells and cell extracts converted [1-14C]MEGDE initially and very rapidly to radiolabelled dodecanol. Disappearance of [14C]dodecanol was accompanied by production of [14C]dodecanal. [14C]D~decan~ic acid was present a t relatively low concentrations throughout the incubation periods.[14C]Dodecan-1,12-dioic acid was produced in significant quantities (up to 25% of radiolabel), and the onset of its production coincided with the peak concentration of dodecanal, the disappearance of which mirrored the appearance of the dioic acid. Under anaerobic conditions in the presence of cell extracts, dodecanol (55 O/ o of radiolabel) and dodecanal (22 %) accumulated rapidly from MEGDE, but there was little subsequent conversion to mono-or dicarboxylic acids. These results are interpreted in terms of a pathway initiated by dodecyl-ether cleavage to produce dodecanol, which is subsequently oxidized to dodecanal and dodecanoic acid. The formation of dodecan-l,12-dioic acid, probably from dodecanal, may represent a means of harbouring carbon under non-growing conditions.

Effect of ethoxylate number and alkyl chain length on the pathway and kinetics of linear alcohol ethoxylate biodegradation in activated sludge

“…The occurrence of these simultaneous and independent modes of attack has since been confirmed in a pure culture with Pseudomonas sp. strain SC25A [16] and in bench‐scale activated‐sludge systems [10]. Central fission of the test materials used in this study would yield 14 C‐PEGs, which migrate just above the origin, appearing to the far left of the parent in the chromatograms.…”

“…Mixtures are similarly identified, with x and y designating the range or average chain length and ethoxylate number. Detergent-range LAEs typically encompass C [12][13][14][15][16][17][18] alkyl chain lengths and an ethoxylate range of 1 to 22 units. In 2000, combined production of LAEs in North America and Western Europe exceeded 435,000 metric tons, with approximately 60% being used in household laundry products [1].…”

Bacteria Inside Semiconductors as Potential Sensor Elements: Biochip Progress

“…This can occur under either anaerobic or aerobic conditions [9–11]. Although many of the hundreds of surfactants present in household and industrial wastes have been shown to be biodegradable (this includes fluorinated surfactants [11]), there is little information about the type of bacteria responsible for the degradation, or the bacterial biochemistry and catabolic genetics involved; exceptions include some sulfonated surfactants [12–15] and alcohol ethoxylate surfactants [16], where the biochemistry of desulfonation and ether-bond cleavage are well established in certain strains of bacteria.…”

Effects of polyethoxylate lauryl ether (Brij 35) addition on phenanthrene biodegradation in a soil/water system

“…strain SC25A. [36] The soil-attached bacteria contained a lower proportion of specifically identifiable bacteria, and the proportions ranged from 3.43% to 6.64% (except one experiment where it reached 9.31%, data not shown). The ratio of identified species in all three phyla/subclasses of Proteobacteria among the soil-attached bacteria made up 36.82% to 62.54% of the total attached bacteria.…”