Phosphate influences ammonium dependent-RNAseq profiles Herbaspirillum seropedicae

FARIZANO, JUAN VICENTE; VILLEGAS, JOSEFINA MARÍA; PANKIEVICZ, VANIA CARLA; TADRA-SFEIR, MICHELLE; BRUSAMARELLO-SANTOS LIZIANE; RAPISARDA, VIVIANA ANDREA; SOUZA, EMANUEL MALTEMPI; GRILLO PUERTAS, MARIANA

Salta

Congreso; LV Annual SAIB y XIV PABMB Congress; 2019

SAIB

Herbaspirillum seropedicae is a nitrogen-fixing β-proteobacterium capable of colonizing commercial crops to promote plant growth. The regulation of nitrogenfixation and assimilation in this bacterium has been the object of several studies. However, how the bacterium responds to different environmental nitrogenconcentration was not yet been completely understood. It was previously described that H. seropedicae cells grown in high phosphate (Pi) medium reachedhigher cell densities than cultures grown in sufficient Pi media and maintained high polyP levels in stationary phase. In high Pi condition, genes involved inenergy production process, two component regulatory systems, amino acid transport and metabolism, chemotaxis and inorganic ion transport and metabolismwere induced. Thus, the aim of this work was to analyze if the medium Pi concentration could influence the ammonium dependent-transcriptional regulation inH. seropedicae. For RNAseq analysis, RNA was extracted from cells grown in four conditions combining low and high Pi and NH4+ concentrations (+P-N,+P+N, -P-N, and -P+N). Transcriptional analysis of +P+N vs +P-N and -P+N vs -P-N revealed a total of 996 and 1051 differentially expressed genes,respectively. Variation in NH4+ concentration showed that the most regulated metabolic pathways belong to the Translation, ribosomal structure andbiogenesis, Energy production and conversion, Inorganic ion transport and metabolism, Cell motility, Amino acid metabolism, Cell wall, and Transcriptioncategories. Pi affected NH4+-dependent differential expression of some genes related to chemotaxis, flagella, transcriptional stress regulators,polyhydroxybutyrate synthesis and N2 fixation. For instance, transcriptional stress regulators (LysR-type regulators, oxyR, risA, Hsero_2244, Hsero_2400)were up-regulated in -P+N vs -P-N, while down-regulated in +P+N vs +P-N. In summary, this study allows the identification of H. seropedicae candidate genesand pathways potentially involved with bacterial environmental adaptations.