biostudies-literatureTookmanian ENational Aeronautics and Space Administration (NASA)VW FoundationBundesministerium für Bildung und ForschungNational Aeronautics and Space AdministrationNational Science Foundation (NSF)Bundesministerium für Bildung und Forschung (BMBF)National Science Foundatione0044221https://www.ebi.ac.uk/biostudies/studies/S-EPMC9295548biostudies-literatureUnknown204(7)Rhizobia are a group of bacteria that increase soil nitrogen content through symbiosis with legume plants. The soil and symbiotic host are potentially stressful environments, and the soil will likely become even more stressful as the climate changes. Many rhizobia within the <i>Bradyrhizobium</i> clade, like Bradyrhizobium diazoefficiens, possess the genetic capacity to synthesize hopanoids, steroid-like lipids similar in structure and function to cholesterol. Hopanoids are known to protect against stresses relevant to the niche of <i>B. diazoefficiens</i>. Paradoxically, mutants unable to synthesize the extended class of hopanoids participate in symbioses with success similar to that of the wild type, despite being delayed in root nodule initiation. Here, we show that in B. diazoefficiensJournal of bacteriologyHopanoids Confer Robustness to Physicochemical Variability in the Niche of the Plant Symbiont Bradyrhizobium diazoefficiens.PMC9295548NNX16AL96G03Z22EN1293090Newman DKSaenz JTookmanian EKulkarni GJunghans LLedermann RfalseHopanoids Confer Robustness to Physicochemical Variability in the Niche of the Plant Symbiont Bradyrhizobium diazoefficiens.Rhizobia are a group of bacteria that increase soil nitrogen content through symbiosis with legume plants. The soil and symbiotic host are potentially stressful environments, and the soil will likely become even more stressful as the climate changes. Many rhizobia within the <i>Bradyrhizobium</i> clade, like Bradyrhizobium diazoefficiens, possess the genetic capacity to synthesize hopanoids, steroid-like lipids similar in structure and function to cholesterol. Hopanoids are known to protect against stresses relevant to the niche of <i>B. diazoefficiens</i>. Paradoxically, mutants unable to synthesize the extended class of hopanoids participate in symbioses with success similar to that of the wild type, despite being delayed in root nodule initiation. Here, we show that in B. diazoefficiens2022-01-01T00:00:00Z2022 Jul2026-07-14T17:17:45.73Z2026-06-21T03:12:46.865ZS-EPMC92955483565770610.1128/jb.00442-21