Open AccessDisruption of dTDP‐rhamnose biosynthesis modifies lipopolysaccharide core, exopolysaccharide production, and root colonization in Azospirillum brasilense
Author(s) -
Jofré Edgardo,
Lagares Antonio,
Mori Gladys
Publication year - 2004
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/s0378-1097(04)00003-5
Subject(s) - azospirillum brasilense , rhamnose , colonization , biology , microbiology and biotechnology , bacteria , bacteroides fragilis , rhizobium , microbial inoculant , polysaccharide , biochemistry , genetics
The interaction between Azospirillum brasilense and plants is not fully understood, although several bacterial surface components like exopolysaccharides (EPS), flagella, and capsular polysaccharides are required for attachment and colonization. While in other plant–bacteria associations ( Rhizobium –legume, Pseudomonas –potato), lipopolysaccharides (LPS) play a key role in the establishment of an effective association, their role in the root colonization by Azospirillum had not been determined. In this study, we isolated a Tn 5 mutant of A. brasilense Cd (EJ1) with an apparently modified LPS core structure, non‐mucoid colony morphology, increased EPS production, and affected in maize root colonization. A 3790‐bp region revealed the presence of three complete open reading frames designated rmlC , rmlB and rmlD . The beginning of a fourth open reading frame was found and designated rmlA . These genes are organized in a cluster which shows homology to the cluster involved in the synthesis of dTDP‐rhamnose in other bacteria. Additionally, the analysis of the monosaccharide composition of LPSs showed a diminution of rhamnose compared to the wild‐type strain.