Formaldehyde is a bacterial mutagen in a range of Salmonella and Escherichia indicator strains

Abstract

Formaldehyde was examined for bacterial mutagenicity using Escherichia coli WP2(pKM101) and WP2uvrA(pKM101), and Salmonella typhimurium TA1535, TA1537, TA1538, TA98, TA100 and TA102, in the absence of any exogenous source of metabolic activation. Using pre-incubation exposure, clear mutagenicity was seen for TA98, TA100 and TA102, and both E. coli strains. In standard plate-incorporation assays, consistent mutagenicity was seen only for TA100 and WP2uvrA(pKM101). No evidence of mutagenicity was seen for TA1535, TA1537 or TA1538 using either method of exposure. These data confirm the enhanced ability of the pre-incubation method to detect the mutagenicity of formaldehyde both quantitatively, as expressed by numbers of revertant colonies, and qualitatively, in terms of the range of indicator strains reverted. The relatively greater sensitivity of the pre-incubation assay is probably due to better containment of a volatile agent and/or lack of interaction with agar during the initial period of exposure. The findings are consistent with the suggestion that formaldehyde induces lesions in bacteria which are, at least to some extent, excision-repairable, and indicate that the presence of the R-factor plasmid may be required for the expression of its mutagenicity in excision repair-deficient Salmonella.

Global Transcriptional Response of Methylorubrum extorquens to Formaldehyde Stress Expands the Role of EfgA and Is Distinct from Antibiotic Translational Inhibition

“…Formaldehyde cytotoxicity has typically been attributed to the damage it causes to DNA. In many organisms, such as Salmonella enterica and Escherichia coli, but this simple interpretation is confounded by conflicting data [52][53][54][55][56]. Inconsistent phenotypes have also been reported in formaldehyde exposure studies used to understand the tolerance of human cell lines to DNA-protein crosslinks [57][58][59][60][61].…”

Genotoxicity of formaldehyde: molecular basis of DNA damage and mutation

“…In most reports using Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, and TA1538 (Ames test), formaldehyde induced both base change and frame-shift mutations without metabolic activation, but its mutagenicity is not as strong as that of typical environmental mutagens such as 4-nitroquinoline-1-oxide and N-methyl-2-nitro-N -nitrosoguanidine (Ma and Harris, 1988;Conaway et al, 1996). Formaldehyde also shows mutagenicity in assays using Escherichia coli WP2 (Takahashi et al, 1985;O'Donovan and Mee, 1993).…”

Coping with a Halogenated One-Carbon Diet: Aerobic Dichloromethane-Mineralising Bacteria

“…However, both DCM and formaldehyde exposure may lead to single stranded DNA breaks [48]. However, Salmonella typhimurium strain TAl 00 differs from strain T A 1535 in that it is contains plasmid pMK101 carrying the mucAB genes involved in error-prone DNA excision repair [93]. Bulky DNA lesions are usually repaired by the Uvr system [104].…”

“…Bulky DNA lesions are usually repaired by the Uvr system [104]. Because formaldehyde is known to require a proficient nucleotide repair machinery to unfold its mutagenic effects [133], formaldehyde is genotoxic in strain TAIOO [93] but not in strain T A 1535 (Table 3). However, Salmonella typhimurium strain TAl 00 differs from strain T A 1535 in that it is contains plasmid pMK101 carrying the mucAB genes involved in error-prone DNA excision repair [93].…”