Project description:A bacterial strain identified as Cupriavidus basilensis uses aromatic compounds as carbon and energy sources and has a high capability to transform the structurally related and hormonally active substance bisphenol A (BPA). Biphenyl-grown and phenol-grown cells converted BPA to five products within 24 h of incubation representing four different transformation pathways: (a) ring hydroxylation, (b) ring fission, (c) transamination and acetylation, and (d) dimerization. Products of the ring fission pathway were non-toxic and all five products exhibited a significantly reduced estrogenic activity compared to BPA. Cell cultivation in nutrient broth resulted in lower product quantities and dimerization was not proved. Thus the question arose whether enzymes of the biphenyl or phenol degradation pathway are involved in the transformation of BPA. Proteomic analyses revealed the constitutive expression of biphenyl degrading enzymes and indicated that the 2,3 dihydroxybiphenyl-1,2-dioxygenase might catalyse the meta-cleavage of the aromatic ring of BPA while enzymes of other pathways seemed to be involved in ring hydroxylation.
Project description:The degradation of aromatic compounds comprises an important step in the removal of pollutants and re-utilization of plastics and other non-biological polymers. Here we set out to study Pseudomonas sp. strain phDV1, a gram-negative bacterium that was selected for its ability to degrade aromatic compounds. In order to understand how the aromatic compounds and their degradation products are reintroduced in the metabolism of the bacteria and the systematic/metabolic response of the bacterium to the new carbon source, the proteome of this strain was analysed in the presence of succinate, phenol and o-, m-, p-cresol as sole carbon source. We then applied label-free quantitative proteomics to monitor overall proteome remodeling during metabolic adaptation to different carbon sources. As a reference proteome, we grew the bacteria in succinate and then compared the respective proteomes of bacteria grown on phenol and different cresols. In total, we identified 2295 proteins; 1908 proteins were used for quantification between different growth conditions. We found that 70, 100, 150 and 155 proteins were significantly differentially expressed in cells were grown in phenol, o-, m- and p-cresol-containing medium, respectively. The carbon source affected the synthesis of enzymes related to aromatic compound degradation, and in particular, the enzyme involved in the meta-pathway of monocyclic aromatic compounds degradation. In addition, proteins involved in the production of polyhydroxyalkanoate (PHA), an attractive biomaterial, showed higher expression levels in the presence of monocyclic aromatic compounds.Our results provide for the first time comprehensive information on the proteome response of this strain to monocyclic aromatic compounds.
2020-10-22 | PXD021237 | Pride
Project description:Isolation of Carcinogenic Polycyclic Aromatic Hydrocarbons degrading bacteria from Earthworm Gut
Project description:White-rot fungi (WRF) are the most effective lignin-degrading organisms in nature, making them essential to Earth’s carbon cycle. Lignin is a highly methoxylated, heterogeneous biopolymer derived from plants. However, the pathways WRF use to metabolize methoxylated aromatic compounds as carbon sources remain unidentified. Here, we employ a systems biology approach to elucidate the intracellular catabolism of vanillate – a monomethoxylated aromatic compound – in two white-rot fungi (WRF), Gelatoporia subvermispora and Trametes versicolor. We identified and biochemically validated a four-enzyme pathway that converts vanillate into β-ketoadipate – a metabolite that enters central carbon metabolism. This pathway deviates from typical bacterial pathways, where vanillate is initially demethylated and ring-cleaved by intradiol dioxygenases; instead, oxidative decarboxylation occurs prior to ring cleavage by extradiol dioxygenases. Thus, we conducted an in-depth investigation of ring cleavage and further downstream catabolism by the identified fungal enzymes using biochemical and structural approaches. This revealed non-canonical enzymes, including a highly substrate-specific extradiol dioxygenase and a metal-free, promiscuous reductase, the latter capable of acting on catabolic intermediates derived from both methoxylated and non-methoxylated aromatic compounds. This work emphasizes the potential of WRF and their enzymes to advance lignin valorization and enhance our understanding of their role during wood decay.
Project description:Bacterial degradation of the ubiquitous and persistent steroids is important for their removal from the environment, particularly for the endocrine disrupting steroid sex hormones. While aerobic bacteria use oxygenases to attack non-activated C-H/C-C bonds of the isoprenoid side chain or the steran skeleton of steroids, initial studies of steroid degradation in anaerobic bacteria suggested that water-dependent enzymes are involved in C-H hydroxylation and ring cleavage reactions. In anaerobic steroid catabolism, the hydrolytic enzymes involved in the cleavage of the steran ring system of the common intermediate androst-1,4-diene-3-one have remained unknown. Here, we have enriched a hydrolase from the cholesterol/nitrate grown Sterolibacterium denitrificans and from Escherichia coli after heterologous expression of its gene. It specifically cleaves the cyclic 1,3-diketone degradation intermediate of ring A, androsta-1,4,17-trione, to 1,17-dioxo-2,3-seco-androstan-3-oate (DSAO), a hallmark reaction of anaerobic steroid degradation. The highly conserved ring A hydrolase was identified in all known and many previously unknown steroid-degrading Proteobacteria. Using the enriched enzyme, we enzymatically produced the CoA ester of DSAO from the chemically synthesized androst-1-ene-3-one precursor, allowing the identification of subsequent metabolites involved in ring A degradation. The results obtained suggest the involvement of an additional hydrolase, an aldolase, and a -oxidation-like cascade for complete ring A degradation during which acetate and acetyl-CoA are released to form the three-ring 5,10-seco-1,2,3,4-tetranorandrosta-5,17-dione. The results identified a key enzyme of anaerobic steroid degradation that may serve as functional marker for monitoring steroid contaminant degradation at anoxic environmental sites.
Project description:Bacterial aromatic degradation may cause oxidative stress. The long-chain flavodoxin FldX1 of Paraburkholderia xenovorans LB400 counteracts reactive oxygen species (ROS). The aim of this study was to evaluate the protective role of FldX1 in P. xenovorans LB400 during the degradation of 4-hydroxyphenylacetate (4-HPA) and 3-hydroxyphenylacetate (3-HPA). Functionality of FldX1 was assessed by P. xenovorans p2-fldX1 that overexpresses FldX1. The effects of FldX1 on P. xenovorans were studied measuring growth on hydroxyphenylacetates, degradation of 4-HPA and 3-HPA, and ROS formation. The effects of hydroxyphenylacetates on the proteome (LC–MS/MS) and gene expression (qRT-PCR) were quantified. Bioaugmentation with strain p2-fldX1 of 4-HPA-polluted soil was assessed, measuring aromatic degradation (HPLC), 4-HPA-degrading bacteria, and plasmid stability.
Project description:The opportunistic pathogen Streptococcus gallolyticus is one of the few intestinal bacteria that has been consistently linked to colorectal cancer (CRC). This study aimed to identify S. gallolyticus-induced pathways that could on the long-term add to CRC progression. Transcription profiling of S. gallolyticus-exposed CRC-cells revealed the persistent induction of enzymes involved in biotransformation pathways. Specifically, a diffusible factor of S. gallolyticus (SGF-X) interacts with the aryl hydrocarbon receptor thereby inducing CYP1 enzymes that catalyze the bioactivation of polycyclic aromatic hydrocarbons (PAHs) into toxic intermediates. Importantly, priming CRC-cells with SGF-X containing medium increased the DNA damaging effect of the PAH 3-methylcholanthrene, which was not observed for other intestinal bacteria. In conclusion, this study shows for the first time that bacteria can modulate the biotransformation capacity of CRC-cells that offers a novel theory for a contributing role of S. gallolyticus in the etiology of sporadic CRC. Key words : Colorectal cancer cells, Streptococcus bovis, streptococcus gallolyticus, host-pathogen interactions, Cytochrome P4501A1, DNA-damage, polycyclic aromatic hydrocarbons