The effect of fifteen biocides on formaldehyde-resistant strains ofPseudomonas aeruginosa

Summary Evaluation of formaldehyde and fifteen biocides in formaldehyde sensitive (S) and resistant (R) strains ofPseudomonas aeruginosa revealed a pattern of response that allowed a comparison of the mode of action of these biocides. The response of these strains to the various biocides, as well as the induction of transient resistance or cross-resistance in the (S) strain, allowed a grouping of biocides based on this pattern of response. Group 1 biocides acted in a manner indistinguishable from formaldehyde for both the (S) and (R) strains. Group 2 biocides were not effective against either the (S) or (R) strains at concentrations calculated to release equimolar concentrations of formaldehyde. However, treatment of the (S) strain with formaldehyde or Group 2 biocides resulted in the development of cross-resistance. Group 3 biocides were equally effective against the (S) and (R) strain, but the (S) strain survivors of treatment with Group 3 biocides were resistant to formaldehyde. Group 4 biocides (controls) had no presumed connection to formaldehyde mode of action. These four groupings, based on pattern of response, also resulted in groupings of biocides based on chemical structure.     

Effects of myxothiazol and 5-undecyl-6-hydroxy-4,7-dioxobenzothiazole on the respiratory pathways of the phytopathogenic fluorescent bacteria Pseudomonas cichorii and Pseudomonas aptata

Myxothiazol inhibited the electron transport in the cytochrome b/c segment of membrane particles from Pseudomonas cichorii. A residual NADH-oxidation due to the presence of an alternative pathway via cytochrome o (Em,7=+250 mV) was sensitive to the quinone analog 5-undecyl-6-hydroxy-4,7-dioxobenzothiazole (UHDBT). This latter inhibitor was equally effective in blocking the linear respiratory chain of Pseudomonas aptata, a strain deficient in cytochromes of c type and Rieske iron-sulphur centre. The analysis of the oxido-reduction kinetic patterns of cytochromes indicated that, among the b type haems present in P. aptata, only cyt. o could be reduced by ubiquinol-1 in a reaction insensitive to both antimycin A and myxothiazol but inhibited by UHDBT. This latter finding has been correlated to the fact that P. aptata exhibits a defective b/c complex. In membranes from P. cichorii, in which the absorption maximum of dithionite reduced cytochrome(s) b shifted by 2–3 nm in the presence of antimycin A and/or myxothiazol, the electron flow through the b/c oxidoreductase complex has tentatively been arranged in a proton motive Q-cycle like mechanism.Non standard abbreviations UHDBT 5-undecyl-6-hydroxy-4,7-dioxobenzothiazole - cyt. cytochrom - Em, 7 mid-point potential at pH 7.0 - b/c complex ubiquinol-cyt. c oxidoreductase     

A versatile bacterial enzyme: l-methionine γ-lyase

The properties and application of l-methionine γ-lyase [methioninase, l-methionine methanethiol-lyase (deaminating), EC 4.4.1.11], a pyridoxal 5′-phosphate enzyme, purified from Pseudomonas putida and Aeromonas sp. are presented. The enzyme has multicatalytic functions: it catalyses α,γ-elimination and γ-replacement reactions of l-methionine and its analogues (e.g. ethionine, homocysteine, O-acetylhomoserine and selenomethionine), α,β-elimination and β-replacement reactions of l-cysteine and its analogues (e.g. S-methylcysteine, O-acetylserine and Se-methylselenocysteine), deamination and γ-addition of vinylglycine, and deuterium labelling at the α and β positions of l-methionine and other straight-chain l-amino acids. These reactions are applicable to the synthesis of various optically active sulphur and selenium amino acids, preparation of deuterium or tritium labelled l-amino acids, and determination of sulphur amino acids. In addition, the enzyme shows potent anti-neoplastic activity.     

青枯假单胞杆菌噬菌体ZP-2和ZP-3的生物学性状

噬菌体可作为检测和区分植物病原细菌的一种手段。有关青枯假单胞杆菌(Pseudomo-n~(as solanacearum) 噬菌体的研究工作报道不多,姜瘟菌株上的噬菌体则还未见报道。本文所报道的关于分离自土壤的青枯假单胞杆菌姜瘟菌株(ZO-12)的噬菌体ZP-2和ZP-3生物学性状的研究结果,可为这些噬菌体的利用提供参考依据。     

Biotransformations Of Fluoroaromatic Compounds: Accumulation Of Hydroxylated Products From 3-Fluorophthalic Acid Using Mutant Strains Of Pseudomonas Testosteroni

Biotransformations of 3-fluorophthalic acid have been investigated using blocked mutants of Pseudomonas testosteroni that are defective in the metabolism of phthalic acid (benzene-1,2-dicar-boxyfic acid). Mutant strains were grown with L-glutamic acid in the presence of 3-fluorophthalic acid as inducer of phthalic acid catabolic enzymes. Products that accumulated in the medium were isolated, purified and identified as the fluoroanalogues of those produced from phthalic acid by the same strains. The previously undescribed fluorochemicals cis-3-fluoro-4,5-dihydro-4,5-dihydroxyphthalic acid (VI) and 3-fluoro-4,5-dihydroxyphthalic acid (VII) have been obtained by biotransformation of 3-fluorophthalic acid, and 3-fluoro-5-hydroxyphthalic acid (X) from (VI) by freeze drying. In addition, samples of 2-fluoro-3,4-dihydroxybenzoic acid (2-fluoroprotocatechuic acid, VIII) and 3-fluoro-4,Sdi-hydroxybenzoic acid (5-fluoroprotocatechuic acid, IX) were obtained with a mutant deficient in the ring-fission enzyme, showing that the fluorine substituent in their precursor substrate (VII) is not recognized by the decarboxylase of the pathway, which shows no preference for which carboxyl group is removed. These studies of 3-fluorophthalic acid catabolism demonstrate the opportunities available for the production of novel fluorochemicals in reasonable yields by microbial transformations.     

Effect of oxygen limitation on the formation of the electron transport system of the phytopathogenic fluorescent bacteriumPseudomonas cichorii

The composition of the membrane-bound electron transport system of the phytopathogenic bacteriumPseudomonas cichorii underwent modification in response to oxygen supply. Growth adaptation to low oxygen concentrations was characterized by repression of cytochromes involved in ubiquinol-cyt.c oxidoreductase and cyt.c oxidase activities. By contrast, cyto.o, i.e., the alternative cyanide-insensitive oxidase ofP. cichorii, was unaffected by low oxygen tension. Noa-type cytochromes could be detected at any stage of growth.     

Accumulation of fructose 1,6-bisphosphate in mutant cells of mucoid Pseudomonas aeruginosa as an evidence of phosphofructokinase activity

Phosphoglucose isomerase negative mutant of mucoid Pseudomonas aeruginosa accumulated relatively higher concentration of fructose 1,6-bisphosphate (Fru-1,6-P₂) when mannitol induced cells were incubated with this sugar alcohol. Also the toluene-treated cells of fructose 1,6-bisphosphate aldolase negative mutant of this organism produced Fru-1,6-P₂ from fructose 6-phosphate in presence of ATP, but not from 6-phosphogluconate. The results together suggested the presence of an ATP-dependent fructose 6-phosphate kinase (EC 2.7.1.11) in mucoid P. aeruginosa.Abbreviations ALD Fru-1,6-P₂ aldolse - DHAP dihydroxyacetone phosphate - F6P fructose 6-phosphate - G6P glucose 6-phosphate - Gly3P glyceraldehyde 3-phosphate - KDPG 2-keto 3-deoxy 6-phosphogluconate - PFK fructose 6-phosphate kinase - PGI phosphoglucose isomerase - 6PG 6-phosphogluconate     

Three-dimensional structure of a regular surface layer from Pseudomonas acidovorans

The regular surface layer of Pseudomonas acidovorans was investigated by computer processing of a series of tilted view electron micrographs, and a reconstruction of the three-dimensional structure was obtained. The pattern is tetragonal and consists of massive identical subunits, block-like in face-view, which interlock loosely in a simple cobblestone pattern. The square unit cell has a lattice constant of 11 nm. The surface layer pattern of P. acidovorans appears to be more dependent on the underlying membrane for maintaining its integrity than those so far studied in other bacteria.     

CO2 is the first species formed upon CO oxidation by CO dehydrogenase from Pseudomonas carboxydovorans

The active species of CO₂, i.e. CO₂ or HCO ₃ ^- , formed in the CO dehydrogenase reaction was determined using the pure enzyme from the carboxydotrophic bacterium Pseudomonas carboxydovorans. Employing an assay system similar to that used to test for carbonic anhydrase, data were obtained which are quite compatible with those expected if CO₂ is the first species formed. In addition, carbonic anhydrase activity was not detected in P. carboxydovorans.