hartmannibacter hartmannibacter hartmannibacter is a gram-negative, nitrogen-fixing, strictly aerobic and motile genus of bacteria. hartmannibacter is named after the german microbiologist anton hartmann. hartmannibacter diazotrophicus has been isolated from rhizospheric soil of the plant plantago winteri. hartmannibacter scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: hyphomicrobiales family: pleomorphomonadaceae genus: hartmannibactersuarez et al. 2014 type species hartmannibacter diazotrophicus species h. diazotrophicus