title: Gluconacetobacter diazotrophicus levansucrase is involved in tolerance to NaCl, sucrose and desiccation, and in biofilm formation.
abstract: Gluconacetobacter diazotrophicus is a nitrogen-fixing bacterium and endophyte of sugarcane, which expresses levansucrase, a fructosyltransferase exoenzyme with sucrose hydrolytic and levan biosynthetic activities. As a result of their physical properties, the levan can provide protection against stress caused by abiotic or biotic factors and participate in the formation of biofilms. In this study, we investigated the construction and function of a levansucrase-defective mutant of G. diazotrophicus. The lsdA mutant showed a decreased tolerance (65.5%) to 50-150 mM NaCl and a decrease of 89% in 876 mM (30%) sucrose, a reduction (99%) in tolerance to desiccation after 18 h, and a decrease (36.9-58.5%) in the ability to form cell aggregates on abiotic surfaces. Complementation of the mutant with the complete lsdA gene leads to a recovery of the ability to grow on sucrose-containing medium and to form slimy colonies, the ability to form the cell aggregates on abiotic surfaces and the tolerance to NaCl. This report demonstrates the importance of levansucrase in environmental adaptation of G. diazotrophicus under high osmotic stress and in biofilm formation.
authors.affiliation: Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Michoacán, México.
authors.forename: M Lourdes
authors.initials: ML
authors.lastname: Velázquez-Hernández
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Baizabal-Aguirre
authors.forename: Fermín
authors.initials: F
authors.lastname: Cruz-Vázquez
authors.forename: Mayra J
authors.initials: MJ
authors.lastname: Trejo-Contreras
authors.forename: Luis E
authors.initials: LE
authors.lastname: Fuentes-Ramírez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Bravo-Patiño
authors.forename: Marcos
authors.initials: M
authors.lastname: Cajero-Juárez
authors.forename: Martha P
authors.initials: MP
authors.lastname: Chávez-Moctezuma
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Valdez-Alarcón
mesh_terms: D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D003890:Desiccation; D005630:Fructans / Q000096:biosynthesis; D005816:Genetic Complementation Test; D041821:Gluconacetobacter / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D006602:Hexosyltransferases / Q000235:genetics / Q000378:metabolism*; D006982:Hypertonic Solutions / Q000494:pharmacology*; D009154:Mutation; D011092:Polyethylene Glycols / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology
chemical_list: D005630:Fructans; D006982:Hypertonic Solutions; D011092:Polyethylene Glycols; D012965:Sodium Chloride; D013395:Sucrose; C072599:levan; D006602:Hexosyltransferases; C021513:levansucrase