Biology subjects

Schlüter, R.

Publications and source records attributed to Schlüter, R..

3 recordsLinked to original sources

bioRxiv2024

Transformation of the drug ibuprofen by Priestia megaterium: Reversible glycosylation and generation of hydroxylated metabolites

As one of the most-consumed drugs worldwide, ibuprofen (IBU) reaches the environment in considerable amounts as environmental pollutant, necessitating studies of its further biotransformation as potential removal mechanism. Therefore, we screened bacteria with known capabilities to degrade aromatic environmental pollutants, belonging to the genera Bacillus, Priestia (formerly also Bacillus) Paenibacillus, Mycobacterium, and Cupriavidus, for their ability to transform ibuprofen. We identified five transformation products, namely 2-hydroxyibuprofen, carboxyibuprofen, ibuprofen pyranoside, 2-hydroxyibuprofen pyranoside, and 4-carboxy--methylbenzene-acetic acid. Based on our screening results, we focused on ibuprofen biotransformation by Priestia megaterium SBUG 518 with regard to structure of transformation products and bacterial physiology. Biotransformation reactions by P. megaterium involved (A) the hydroxylation of the isobutyl side chain at two positions, and (B) conjugate formation via esterification with a sugar molecule of the carboxylic group of ibuprofen and an ibuprofen hydroxylation product. Glycosylation seems to be a detoxification process, since the ibuprofen conjugate (ibuprofen pyranoside) was considerably less toxic than the parent compound to P. megaterium SBUG 518. Based on proteome profile changes and inhibition assays, cytochrome P450 systems are likely crucial for ibuprofen transformation in P. megaterium SBUG 518. The toxic effect of ibuprofen appears to be caused by interference of the drug with different physiological pathways, including especially sporulation, as well as amino acid and fatty acid metabolism. ImportanceIbuprofen is a highly consumed drug, and, as it reaches the environment in high quantities, also an environmental pollutant. It is therefore of great interest how microorganisms transform this drug and react to it. Here, we screened several bacteria for their ability to transform ibuprofen. Priestia megaterium SBUG 518 emerged as highly capable and was therefore studied in greater detail. We show that P. megaterium transforms ibuprofen via two main pathways, hydrolyzation and reversible conjugation. These pathways bear resemblance to those in humans. Ibuprofen likely impacts the physiology of P. megaterium on several levels, including spore formation. Taken together, P. megaterium SBUG 518 is well suited as a model organism to study bacterial ibuprofen metabolism.

microbiology↗

bioRxiv2024

In-host evolution of classic to convergent Klebsiella pneumoniae sequence type 147 isolates and impact of associated capsular changes on different morphotypes

Klebsiella pneumoniae, an important opportunistic pathogen, has long been categorized into two distinct pathotypes: the often multidrug-resistant classic (cKp) and the highly virulent hypervirulent (hvKp). However, a recent global trend has witnessed the emergence of convergent strains, seamlessly combining antimicrobial resistance with hypervirulence. Our study delved into a series of K. pneumoniae isolates sourced from the same patient, all belonging to the international, high-risk clonal lineage of sequence type 147. As reported in a previous study, these isolates exhibited diverse morphotypes on blood agar, ranging from small white to normal-sized white, grey, or grey and dry (g/d) colonies. Through an interplay of omics and phenotypic experiments, we unraveled the intricate mechanisms governing these distinct colony morphologies and their implications on bacterial virulence and resilience. While the earlier isolates demonstrated modest levels of resistance and virulence, their later counterparts showed significantly heightened levels, attributed to the acquisition of additional plasmids. Bioinformatics analysis unveiled a chromosomal insertion of a hybrid plasmid in one isolate, marking an unprecedented in-host microevolution from the classic to the convergent pathotype. All morphotypes exhibited positive insertion sequences around or within the K loci, with the grey or g/d phenotypes arising from impaired K loci. Despite lower serum resistance, these morphotypes demonstrated superior adhesion to human epithelial cells. Interestingly, while capsule-deficient strains are conventionally associated with decreased virulence, our isolates displayed high mortality rates in the Galleria mellonella infection model. In conclusion, our findings not only provide unprecedented insights into in-host microevolution within a patient, transitioning from the classic to the convergent pathotype, but also contribute significantly to the understanding of the diverse morphotypes exhibited by K. pneumoniae.

microbiology↗

bioRxiv2024

Temperatures above 37°C increase virulence of a convergent Klebsiella pneumoniae sequence type 307 strain

Hypermucoviscosity in Klebsiella pneumoniae is often related to the overexpression of capsular polysaccharides, regulated by complex biosynthetic mechanisms in response to external cues. However, little is known about the processes involved in hypermucoviscosity in convergent K. pneumoniae, which combine extensive drug resistance with high bacterial virulence, under pathophysiological conditions. This study aimed to fill this gap by investigating the temperature dependence of hypermucoviscosity and overall virulence in a convergent K. pneumoniae strain isolated during a clonal outbreak belonging to the high-risk sequence type (ST)307. Hypermucoviscosity, biofilm formation, and mortality rates in Galleria mellonella larvae were examined at different temperatures (room temperature, 28{degrees}C, 37{degrees}C, 40{degrees}C and 42{degrees}C) and with various phenotypic experiments including electron microscopy. The underlying mechanisms of the phenotypic changes were explored via qPCR analysis to evaluate plasmid copy numbers, and transcriptomics. Our results indicate a temperature-dependent "switch" above 37{degrees}C to a hypermucoviscous phenotype, correlating with increased biofilm formation capacity and in vivo mortality, which might be due to a bacterial response to pathophysiological conditions, i.e., fever. In addition, we detected upregulation of a hybrid plasmid encoding both carbapenemase and the mucoid regulator rmpA genes. Surprisingly, rmpA did not exhibit temperature-dependent differential gene expression, suggesting other drivers. Apparent co-regulation of hypermucoviscosity and fimbrial expression was also identified. This study not only revealed the impact that increased temperatures above 37{degrees}C have on hypermucoviscosity and virulence in a convergent K. pneumoniae strain but contributes to the understanding of previously unrecognized dimension of K. pneumoniaes behavior, emphasizing its adaptability to changing environments. Abstract importanceUnderstanding the temperature-dependent dynamics of hypermucoviscosity in Klebsiella pneumoniae is crucial for unraveling the intricacies of its hypervirulence. This study investigates a convergent K. pneumoniae strain, ST307, revealing a temperature-dependent switch to hypermucoviscosity above 37 {degrees}C. The findings showcase a correlation between increased temperature, hypermucoviscosity, enhanced attachment, and heightened in vivo mortality. Notably, a hybrid plasmid encoding carbapenemase and mucoid regulator genes was upregulated at elevated temperatures. The study sheds light on previously unexplored aspects of K. pneumoniae behavior, emphasizing its adaptability in response to changing environments. The identified temperature-associated regulatory mechanisms offer insights into the pathogens response to fever, contributing to our broader understanding of bacterial adaptation. This research contributes to addressing the global challenge of hypervirulent, drug-resistant K. pneumoniae strains, providing valuable implications for future treatment strategies.

microbiology↗