SummaryThe spo0A genes of Clostridium beijerinckii NCIMB 8052 and Clostridium cellulolyticum ATCC 35319 were isolated and characterized. The C-terminal DNA-binding domains of the predicted products of spo0A from these two organisms, as well as 16 other taxonomically diverse species of Bacillus and Clostridium, show extensive amino acid sequence conservation (56% identity, 65% similarity over 104 residues). A 12-amino-acid motif (SRVERAIRHAIE) that forms the putative DNA recognition helix is particularly highly conserved, suggesting a common DNA target.

No abstract

No 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.