Open AccessWhole-Genome Transcriptional Profiling of Bradyrhizobium japonicum during Chemoautotrophic Growth
Author(s) -
William L. Franck,
Woo Suk Chang,
Jing Qiu,
Masayuki Sugawara,
Michael J. Sadowsky,
Stephanie A. Smith,
Gary Stacey
Publication year - 2008
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00543-08
Subject(s) - biology , bradyrhizobium japonicum , genome , bradyrhizobium , genetics , profiling (computer programming) , computational biology , gene expression profiling , bacteria , rhizobiaceae , gene , symbiosis , gene expression , computer science , operating system
Bradyrhizobium japonicum is a facultative chemoautotroph capable of utilizing hydrogen gas as an electron donor in a respiratory chain terminated by oxygen to provide energy for cellular processes and carbon dioxide assimilation via a reductive pentose phosphate pathway. A transcriptomic analysis ofB. japonicum cultured chemoautotrophically identified 1,485 transcripts, representing 17.5% of the genome, as differentially expressed when compared to heterotrophic cultures. Genetic determinants required for hydrogen utilization and carbon fixation, including the uptake hydrogenase system and components of the Calvin-Benson-Bassham cycle, were strongly induced in chemoautotrophically cultured cells. A putative isocitrate lyase (aceA ; blr2455) was among the most strongly upregulated genes, suggesting a role for the glyoxylate cycle during chemoautotrophic growth. Addition of arabinose to chemoautotrophic cultures ofB. japonicum did not significantly alter transcript profiles. Furthermore, a subset of nitrogen fixation genes was moderately induced during chemoautotrophic growth. In order to specifically address the role of isocitrate lyase and nitrogenase in chemoautotrophic growth, we culturedaceA ,nifD , andnifH mutants under chemoautotrophic conditions. Growth of each mutant was similar to that of the wild type, indicating that the glyoxylate bypass and nitrogenase activity are not essential components of chemoautotrophy inB. japonicum .