PubMed · 3941630
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G P Young. 1986-01-06. Testing for Clostridium difficile.. https://doi.org/10.5694/j.1326-5377.1986.tb113647.x
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Using treated municipal wastewater for crop irrigation is a key strategy to combat drought-induced water scarcity. However, current wastewater reclamation standards systematically underestimate risks from spore-forming pathogens. As highlighted in a recent minireview by A. Mrozinski, C. Le Maréchal, and E. Topp in Applied and Environmental Microbiology (92:e00173-26, 2026, https://doi.org/10.1128/aem.00173-26), Clostridioides difficile and Clostridium perfringens survive conventional disinfection, persist indefinitely in agricultural soils, and harbor critical antibiotic resistance genes. To safeguard the food supply and protect public health, regulatory frameworks must shift from relying solely on standard vegetative bacterial indicators and include monitoring resilient, spore-forming pathogens.
The chemical and molecular mechanism of toxicity of nitrite towards food-spoilage bacteria such as Clostridium botulinum or Clostridium sporogenes is not well understood. In order to discover the active species and explore its chemistry, a number of compounds related to nitrite were synthesized. Their bacteriocidal effects on C. sporogenes were investigated in Oxoid nutrient broth No. 2 growth medium at pH 7.0. Inhibition of cell growth, expressed as the concentration which causes 50% cell inhibition, was observed with nitrite at 10 mM, whereas [Fe4S3(NO)7]-(the anion of Roussin's black salt) and (Fe2(SCH2CH2OH)2(NO)4] (a water-soluble Roussin's red salt ester) were found to be effective at 0.001 mM and 0.005 mM, respectively, confirming previous reports that iron-sulphur-nitrosyl complexes are much more toxic to these organisms than nitrite itself. The nitroprusside anion, [Fe(CN)5NO]2- was found to be toxic at 0.030 mM and the corresponding chromium species, [Cr(CN)5NO]3-, at 0.1 mM. Therefore, on the basis of the number of NO groups present, the nitrosylcyano complexes are comparable in activity with the iron-sulphur-nitrosyl compounds. These results show that neither iron nor sulphur are essential for the bacteriostatic effect of the Roussin's type compounds. The property that all these compounds have in common is that they contain NO+. It is proposed that this is the active species responsible for the preservative effect of nitrite, and that a relationship may exist between the N-O stretching frequency, a measure of the NO+ character, and the toxicity of these NO(+)-containing complexes.
A new crystal form of the hexameric NAD(+)-linked glutamate dehydrogenase (GDH) from Clostridium symbiosum has been grown using the hanging drop method of vapour diffusion. The crystals are obtained either by using high concentrations of the amino acid substrate of the enzyme, glutamate, as the precipitant or by co-crystallization from ammonium sulphate in the presence of either p-chloromercuribenzene sulphonate or potassium tetracyanoplatinate. The crystals diffract well and X-ray photographs have established that they are in the space group R32. Considerations of the values of Vm indicate that the asymmetric unit of the R32 crystals contains a single subunit. Packing considerations based on the structure of the native enzyme determined from a different crystal form suggest that the molecule must undergo a significant conformational change in order to be accommodated in the new cell. Such a conformational rearrangement may represent an important step in the catalytic cycle.