Plant pathogenic bacteria cause major crop losses globally, necessitating precise identification tools for effective management. Fatty acid profiling, particularly via fatty acid methyl ester (FAME) analysis, has long served as a valuable method for distinguishing closely related taxa based on membrane lipid signatures. Characteristic patterns, such as unsaturated fatty acids in Pseudomonas syringae and branched-chain fatty acids in Clavibacter michiganensis, offer stable biochemical markers. Recent advances in phospholipidomics using LC–MS/MS now enable structural resolution of intact phospholipids, including isomeric phosphatidylethanolamines, improving taxonomic precision and physiological insight. These developments mark a shift from bulk FAME profiling toward lipidomics-driven bacterial classification, revealing lipid adaptations to environmental and host-derived stresses. This review explores the diagnostic and ecological relevance of bacterial fatty acid profiles in light of emerging lipidomic technologies

Fatty acid profiling, Plant pathogenic bacteria, FAME, Lipidomics, LC–MS/MS, Bacterial taxonomy

Fatty acid profiles are diverse and often genus-specific. Fatty acid (FA) composition is increasingly used as a chemotaxonomic tool to distinguish bacterial genera and species (Kaneda, 1991; Sasser, 2001; Kozlova et al., 2011). The types and proportions of saturated, unsaturated, branched, hydroxylated, and cyclopropane fatty acids vary significantly across genera. These differences reflect evolutionary adaptations to niche environments, membrane requirements, and biosynthetic capabilities unique to each genus. The types and proportions of saturated, unsaturated, branched-chain, hydroxylated, and cyclopropane fatty acids vary significantly across bacterial genera. These variations reflect: •Evolutionary adaptations to ecological niches (Sohlenkamp & Geiger, 2016), •Differences in membrane functionality and structural demands (Zhang & Rock, 2008), and •Genetically determined biosynthetic capabilities, such as the presence or absence of specific desaturases, methyltransferases, or hydroxylases (Kaneda, 1991; Grogan & Cronan, 1984). For instance: •Xanthomonas species exhibit a high proportion of branched-chain and hydroxy FAs, •Pseudomonas are rich in unsaturated and cyclopropane FAs, •Clavibacter and Streptomyces are dominated by iso-/anteiso-BCFAs, characteristic of Gram-positive bacteria (Kozlova et al., 2011). These genus-specific fatty acid fingerprints are widely employed in FAME (Fatty Acid Methyl Ester) analysis, enabling rapid identification and differentiation of phytopathogenic bacteria based on their membrane lipid signatures (Sasser, 2001; Zhang & Rock, 2008). Fatty acid (FA) profiling in plant pathogenic bacteria offers valuable insights into their taxonomy, physiology, adaptability, and pathogenicity. Species-specific differences in FA composition—such as the dominance of iso- and anteiso-branched fatty acids in Gram-positive pathogens and the prevalence of straight-chain saturated and monounsaturated fatty acids in Gram-negatives—highlight the taxonomic and structural diversity among these organisms (Wiedmaier-Czerny et al., 2021). The advent of advanced lipidomic techniques like LC–MS/MS has further refined our understanding by resolving complex isomeric structures of membrane phospholipids, allowing more precise characterization of microbial membrane architecture (Rudt et al., 2024). Environmental conditions, including temperature, pH, nutrient composition, and growth stage, markedly influence FA composition. These adaptations affect membrane fluidity, stress resilience, and antibiotic resistance—traits critical for bacterial survival and virulence (Segura et al., 2022). Additionally, certain fatty acid derivatives, such as oxylipins, act as signaling molecules that regulate host–pathogen interactions and cross-kingdom communication, playing an emerging role in the modulation of plant immunity and microbial pathogenicity (Beccaccioli et al., 2022). In summary, fatty acid profiles serve not only as biochemical fingerprints for identification and classification but also as dynamic biomarkers reflecting the ecological adaptability and virulence potential of plant pathogenic bacteria. Future research integrating lipidomics, genomics, and metabolomics will enhance our understanding of bacterial pathogenesis and may open new avenues for developing targeted disease management strategies

Rini Sonowal, Ingle Amol Sakharam, Kavita Pujari and E. Premabati Devi (2025). Fatty Acid Profiles in Plant Pathogenic Bacteria. International Journal on Emerging Technologies, 16(2): 73–82