Transformations of chloroguaiacols, chloroveratroles, and chlorocatechols by stable consortia of anaerobic bacteria.
Metabolically stable consortia of anaerobic bacteria obtained by enrichment of sediment samples with 3,4,5-trimethoxybenzoate (TMBA), 3,4,5-trihydroxybenzoate (gallate [GA]), or 5-chlorovanillin (CV) were used to study the anaerobic transformation of a series of chloroveratroles, chloroguaiacols, and chlorocatechols used as cosubstrates. Experiments were carried out with growing cultures, and the following pathways were demonstrated for metabolism of the growth substrates: (i) TMBA produced GA, which was further degraded without the formation of aromatic intermediates; (ii) GA formed pyrogallol, which was stable to further transformation; and (iii) CV was degraded by a series of steps involving de-O-methylation, oxidation of the aldehyde group, and decarboxylation to 3-chlorocatechol before ring cleavage. Mono-de-O-methylation of the cosubstrates occurred rapidly in the order 4,5,6-trichloroguaiacol greater than 3,4,5-trichloroguaiacol approximately 3,4,5-trichloroveratrole approximately tetrachloroveratrole greater than tetrachloroguaiacol and was concomitant with degradation of the growth substrates. For the polymethoxy compounds--chloroveratroles, 1,2,3-trichloro-4,5,6-trimethoxybenzene, and 4,5,6-trichlorosyringol--de-O-methylation took place sequentially. The resulting chlorocatechols were stable to further transformation until the cultures had exhausted the growth substrates; selective dechlorination then occurred with the formation of 3,5-dichlorocatechol from 3,4,5-trichlorocatechol and of 3,4,6-trichlorocatechol from tetrachlorocatechol. 2,4,5-, 2,4,6-, and 3,4,5-trichoroanisole and 2,3,4,5-tetrachloroanisole were de-O-methylated, but the resulting chlorophenols were resistant to dechlorination. These results extend those of a previous study with spiked sediment samples and their endogenous microflora and illustrate some of the transformations of chloroguaiacols and chlorocatechols which may be expected to occur in anaerobic sediments.
Neilson
A H
AH
Swedish Environmental Research Institute, Stockholm.
Allard
A S
AS
Lindgren
C
C
Remberger
M
M
D000840:Anisoles / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D001711:Biotransformation; D002396:Catechols / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D006139:Guaiacol / Q000378:metabolism*; D007700:Kinetics; D012988:Soil Microbiology; D014871:Water Microbiology
D000840:Anisoles; D002396:Catechols; D006139:Guaiacol