Osmotic stress induces long-term biofilm survival in Liberibacter crescens

• Published in: BMC microbiology Vol. 22; no. 1; p. 52
• Main Authors: Padgett-Pagliai, Kaylie A, Pagliai, Fernando A, da Silva, Danilo R, Gardner, Christopher L, Lorca, Graciela L, Gonzalez, Claudio F
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 11-02-2022; BioMed Central; BMC
• Subjects: Amino acids; Analysis; Bacterial diseases; Biofilm; Biofilms; Biofilms - growth & development; Biosynthesis; Candidatus Liberibacter asiaticus; Cell adhesion; Citrus; Citrus - microbiology; Citrus fruits; Citrus greening; Dimethyl sulfoxide; Diseases and pests; Fatty acids; Gene expression; Genetic aspects; Genomes; Growth; Heat stress; Heat tolerance; Liberibacter; Liberibacter - pathogenicity; Liberibacter - physiology; Liberibacter crescens; Microbial Viability; Microscopy; Nutrient availability; Osmosis; Osmotic Pressure; Osmotic stress; Pathogenicity; Pathogens; Physiological aspects; Physiological responses; Physiology; Plant bacterial diseases; Plant diseases; Plant Diseases - microbiology; Plant heat tolerance; Prevention; Ribosomal proteins; Risk factors; RNA sequencing; RNA-seq; Stress response; Sucrose; Survival; Time Factors; Transcription; Transcriptome; Tryptophan; United States; United States > US; Liberibacter crescens; RNA-seq; Transcriptome; Biofilm; Liberibacter; Heat stress; Stress response; Osmotic stress
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/s12866-022-02453-w

Citrus greening, also known as Huanglongbing (HLB), is a devastating citrus plant disease caused predominantly by Liberibacter asiaticus. While nearly all Liberibacter species remain uncultured, here we used the culturable L. crescens BT-1 as a model to examine physiological changes in response to the variable osmotic conditions and nutrient availability encountered within the citrus host. Similarly, physiological responses to changes in growth temperature and dimethyl sulfoxide concentrations were also examined, due to their use in many of the currently employed therapies to control the spread of HLB. Sublethal heat stress was found to induce the expression of genes related to tryptophan biosynthesis, while repressing the expression of ribosomal proteins. Osmotic stress induces expression of transcriptional regulators involved in expression of extracellular structures, while repressing the biosynthesis of fatty acids and aromatic amino acids. The effects of osmotic stress were further evaluated by quantifying biofilm formation of L. crescens in presence of increasing sucrose concentrations at different stages of biofilm formation, where sucrose-induced osmotic stress delayed initial cell attachment while enhancing long-term biofilm viability. Our findings revealed that exposure to osmotic stress is a significant contributing factor to the long term survival of L. crescens and, possibly, to the pathogenicity of other Liberibacter species.