Project description:Herbaspirillum seropedicae is a Betaproteobacterium capable of colonizing epiphytically and endophytically commercial grasses, promoting plant growth. In this study, we utilized RNA-seq to compare the transcriptional profiles of planktonic and maize root-attached H. seropedicae SmR1.
Project description:Herbaspirillum seropedicae are β-proteobacteria that establish as endophytes in various plants. They are able to consume diverse carbon sources, including hexoses and pentoses like D-xylose. D-xylose catabolism pathways have been described in some microorganisms, but databases of genes involved in these routes are limited. This is of special interest in biotechnology, considering that D-xylose is the second most abundant sugar in nature. Furthermore, it is found in some potential raw materials such as lignocellulosic biomass. In this work we present a study of D-xylose catabolism pathways in H. seropedicae strain Z69, using RNA-seq analysis and the subsequent study of phenotypes determined in targeted mutants in corresponding identified genes. G5B88_22805 gene, designated xylB, encodes a NAD+- dependent D-xylose dehydrogenase. Mutant Z69∆xylB was still able to grow on D-xylose, although at a reduced rate. This is due to expression of an L-arabinose dehydrogenase encoded by G5B88_05250 gene, and was thus able to use D-xylose as substrate. According to our results, H. seropedicae Z69 uses non-phosphorylative pathways to catabolize D-xylose. The lower portion of metabolism involves co-expression of two routes: Weimberg pathway that produces α-ketoglutarate and a novel pathway recently described that produces pyruvate and glycolate. This novel pathway seems to be essential since a mutant in the last step of this pathway, Z69∆G5B88_06410, was unable to grow on D‑xylose.
Project description:Herbaspirillum seropedicae SmR1 was grown in NFbHPN medium until OD600nm of 0.6, when 5mM phenol or 2,5mM benzoic acid was added to the medium. After 30 minutes of growth, the cells were collected by centrifugation and total RNA was extracted with RiboPureBacteria. Also, a derivative strain from Herbaspirillum seropedicae SmR1 resistant to 1mM phenol (named strain RP) was grown in NFbHPN medium containing 1mM phenol until OD600nm of 0.6, then 5mM phenol was added to the medium. After 30 minutes of growth, the cells were collected by centrifugation and total RNA was extracted with RiboPureBacteria. All samples were depleted for ribossomal RNA e sequenced with Solid plataform.