Tag Archives: Pseudomonas
The fatty acid composition of cell lipids in walnut bacterial pathogens
M. I. Zarudniak, L. A. Dankevych*, I. P. Tokovenko, V. P. Patyka
D. K. Zabolotny Institute of Microbiology and Virology,
*e-mail: ldankevich@ukr.net
Received: 23 April 2025; Revised: 25 September 2025;
Accepted: 28 November 2025; Available on-line: 23 December 2025
Walnut (Juglans regia) is the most economically important and widespread nut crop in Ukraine. As bacterial diseases of walnut can reduce the yield of this culture by up to 40%, the monitoring of pathogens in a given crop and their identification are extremely important. The fatty acid composition of cell lipids is used in the taxonomy of plant pathogenic bacteria. The objective of this study was to determine the fatty acid composition of cell lipids of Agrobacterium, Xanthomonas, and Pseudomonas collection strains that can actually infect walnut, and those isolated from affected walnut trees in different regions of Ukraine. Fatty acid methyl esters were obtained by two different methods of extraction, with the use of 5% acetyl chloride in methanol at 100°C for 4 h, or 1.5% sulfuric acid in methanol at 80°C for 1 hour. Fatty acid methyl esters were analyzed using gas chromatography–mass spectrometry system. According to the found similarity of the fatty acid composition, the strains isolated from the affected walnut were related to representative collection strains of A. tumefaciens, X. arboricola and P. syringae. It should be noted that during the isolation of fatty acids with the use of 1.5% solution of H2SO4 in methanol, the amount of individual saturated and unsaturated fatty acids in the studied strains decreased and almost all hydroxyl acids, identified as a key taxonomic markers, disappeared in comparison with the using of 5% solution of acetyl chloride in methanol at the hydrolysis stage.
Examining c-di-GMP and possible quorum sensing regulation in Pseudomonas fluorescens SBW25: links between intra- and inter-cellular regulation benefits community cooperative activities such as biofilm formation
O. V. Moshynets1, D. Foster2, S. A. Karakhim3, K. McLaughlin4, S. P. Rogalsky5, S. Y. Rymar1, G. P. Volynets1, A. J. Spiers4
1Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv;
e-mail: moshynets@gmail.com; galina.volinetc@gmail.com
2Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, United Kingdom;
e-mail: dona.foster@ndm.ox.ac.uk;
3Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: laserlab@biochem.kiev.ua;
4School of Science, Engineering and Technology, Abertay University, United Kingdom;
e-mail: mclaughlinkimberley@gmail.com; a.spiers@abertay.ac.uk;
5Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: sergey.rogalsky@gmail.com
Bacterial success in colonizing complex environments requires individual response to micro-scale conditions as well as community-level cooperation to produce large-scale structures such as biofilms. Connecting individual and community responses could be achieved by linking the intracellular sensory and regulatory systems mediated by bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) and other compounds of individuals with intercellular quorum sensing (QS) regulation controlling populations. There is growing evidence to suggest that biofilm formation by many pseudomonads is regulated by both intra and intercellular systems, though in the case of the model Pseudomonas fluorescens SBW25 Wrinkly Spreader in which mutations increasing c-di-GMP levels result in the production of a robust cellulose-based air-liquid interface biofilm, no evidence for the involvement of QS regulation has been reported. However, our recent review of the P. fluorescens SBW25 genome has identified a potential QS regulatory pathway and other QS–associated genes linked to c-di-GMP homeostasis, and QS signal molecules have also been identified in culture supernatants. These findings suggest a possible link between c-di-GMP and QS regulation in P. fluorescens SBW25 which might allow a more sophisticated and responsive control of cellulose production and biofilm formation when colonising the soil and plant-associated environments P. fluorescens SBW25 normally inhabits.