Project description:The current study aims at the functional and kinetic characterization of protocatechuate (PCA) 4,5-dioxygenase (PcaA) from Pseudarthrobacter phenanthrenivorans Sphe3. This is the first single subunit Type II dioxygenase characterized in Actinobacteria. RT-PCR analysis demonstrated that pcaA and the adjacent putative genes implicated in the PCA meta-cleavage pathway comprise a single transcriptional unit. The recombinant PcaA is highly specific for PCA and exhibits Michaelis-Menten kinetics with Km and Vmax values of 21 ± 1.6 μM and 44.8 ± 4.0 U × mg-1, respectively, in pH 9.5 and at 20 °C. PcaA also converted gallate from a broad range of substrates tested. The enzymatic reaction products were identified and characterized, for the first time, through in situ biotransformation monitoring inside an NMR tube. The PCA reaction product demonstrated a keto-enol tautomerization, whereas the gallate reaction product was present only in the keto form. Moreover, the transcriptional levels of pcaA and pcaR (gene encoding a LysR-type regulator of the pathway) were also determined, showing an induction when cells were grown on PCA and phenanthrene. Studying key enzymes in biodegradation pathways is significant for bioremediation and for efficient biocatalysts development.
Project description:Pseudarthrobacter phenanthrenivorans strain MHSD1 is a bacterial endophyte isolated from sterilized leaves of Pellaea calomelanos, a medicinal plant capable of growing in arid environments. Here, we report the draft genome sequence and annotation of this bacterial endophyte. The draft genome sequence of P. phenanthrenivorans strain MHSD1 has 4 450 468 bp with a G + C content of 65.30%. The National Center for Biotechnology Information Prokaryotic Genome Annotation Pipeline identified a total of 4004 protein-coding genes, 56 genes coding for RNAs, and 82 pseudogenes. Biosynthesis pathways for various phytohormones such as auxin, salicylic acid, ethylene, cytokinin, jasmonic acid, abscisic acid, and gibberellins were identified. Putative genes involved in various characteristics of bacterial endophyte lifestyle such as transport, motility, adhesion, membrane proteins, secretion and delivery systems, plant cell wall modification, and detoxification were identified. Phylogenomic analysis showed P. phenanthrenivorans strain MHSD1 to be a subspecies of P. phenanthrenivorans Sphe3.
Project description:This study examines the transcriptomic response of biofilms of the PAH-degrading Sphingomonas sp. LH128 on solute stress when actively degrading and growing on the PAH compound. To address the effect of solute stress on bacterial physiology and transcriptomic response, NaCl was used as osmolyte. Both acute and chronic solute stress was invoked to assess differences in short-term and long-term responses. Transcriptomic response of phenanthrene degrading Sphingomonas sp. LH128 biofilms as a response to short-term and long-term solute (NaCl) stress was studied using genome-wide gene expression analysis. For this purpose, the strain was grown in customized continuous glass flow chambers that contain solid phenanthrene as a sole carbon source and that allow easy recovery of biofilm cells for transcriptomic and physiological analysis. A NaCl stress of 450 mM was imposed on LH128 biofilms growing on phenanthrene crystals coated on glass slides either for 4 hours (acute stress) or for 3 days (chronic stress). RNA was extracted from the biofilm and cDNA was synthesized and labeled with Cy3. Transcriptomic response in the stressed biofilms of three replicates per conditions were analyzed and compared with non-stressed
Project description:Two synthetic bacterial consortia (SC) composed by bacterial strains isolated from a natural phenanthrene-degrading consortium (CON), Sphingobium sp. AM, Klebsiella aerogenes B, Pseudomonas sp. Bc-h and T, Burkholderia sp. Bk and Inquilinus limosus Inq were grown in LMM supplemented with 200 mg/L of phenanthrene (PHN) during 72 hours in triplicate.