Biology subjects

Streit, W.

Publications and source records attributed to Streit, W..

4 recordsLinked to original sources

bioRxiv2025

Polyethylene terephthalate (PET) primary degradation products affect c-di-GMP-, cAMP-signaling and quorum sensing (QS) in Vibrio gazogenes DSM 21264

Global plastic pollution in oceans and estuaries is increasing rapidly and its well known that bacteria colonize plastic particles of all sizes. Vibrio spp. are frequently found as part of the plastisphere. We recently showed that Vibrio gazogenes DSM 21264 harbors a promiscuous esterase designated PET6. We now provide evidence that the pet6 gene is expressed under a wide range of environmental conditions in its native host. However, in PET- and PE-grown biofilms the pet6 gene expression was not affected by the type of surface. The pet6 transcription was sufficient to allow enzyme production and release of {micro}M amounts of mono-(2-hydroxyethyl) terephthalate (MHET) and terephthalic acid (TPA) already after 24 hours of incubation on PET foil. Notably, the highest pet6 gene transcription was observed in planktonic lifestyle in the presence of bis(2-hydroxyethyl) terephthalate (BHET) one of the primary degradation products of PET. BHET was further hydrolyzed by PET6 and UlaG, a lactonase that had not been known to be involved in BHET degradation. Elevated concentrations of BHET affected the major signaling circuits involved in bacterial quorum sensing (QS), c-di-GMP and cAMP-CRP signaling. This resulted in failure to form biofilms, synthesis of the red pigment prodigiosin and altered colony morphologies. While BHET had a very wide impact, TPA interfered mainly with the bacterial QS by attenuating the expression of the CAI-I autoinducer synthase gene. These observations imply a potential role of BHET and TPA as nutritional signals in Vibrio gazogenes and that may affect its growth and survival in the plastisphere. IMPORTANCEThis study provides first evidence that Vibrio gazogenes DSM 21264 secretes an active PET hydrolase and degrades the polymer using PET6 when growing in biofilms on foils and microplastic particles. The study further provides evidence that the primary PET degradation products BHET and TPA may have a profound impact on the global QS, c-di-GMP and cAMP-CRP signaling of V. gazogenes and its capability to colonize plastic particles in the marine environment.

microbiology↗

bioRxiv2024

Partitioning biota along the Elbe River estuary: where are the community transitions?

Estuarine zonation and community assemblages are frequently correlated with salinity, although the extent or nature of this correlation varies considerably among the published studies. While a smooth transition in biological communities is often conceptualized in association with estuarine fresh, brackish, and marine conditions, many studies have shown more distinct communities and the altogether absence of a brackish community. We explore these viewpoints in light of plant observations and soil and aquatic microbial analyses from permanent plots established on the Elbe River Estuary of northern Germany. Generally, two distinct communities were observed, a polyhaline assemblage towards the mouth of the system, and another that was associated with both the fresh and brackish mesohaline regimes further upriver. This was most pronounced among plant and soil bacteria communities, while aquatic 16S assemblages reflected little distinction at all. The proportion of marine classified taxa declined from the mouth to upriver and suggests that while the transition from marine to brackish or fresh vegetation falls within the sampled area, the same transition for microbial taxa could not be observed and may be further upriver. Thus, although we were able to identify two distinct communities, the "limit" of marine taxa was only evident for vegetation. While tidal and weather-related hydrology, as well as soil properties were also influential in distinguishing the communities, much of the variance remains unexplained. Further sampling, classification, and partitioning is necessary to determine the origin and/or autochthonous habitat, if any, for the Elbe River estuarine taxa. Geographic boundsbottom left: 53.556216{degrees}N, 8.824398{degrees}E top right: 53.917760 {degrees}N, 10.155669 {degrees}E

ecology↗

bioRxiv2022

Virulence adaptation of Pseudomonas aeruginosa phospholipase mutant with altered membrane phospholipid composition

Membrane protein and phospholipid (PL) composition changes in response to environmental cues and during infections. Covalent modification and remodelling of the acyl chain length of PLs is an important bacterial adaptation mechanism. However, little is known about which bacterial pathways are regulated in response to altered PL composition. Here, we showed that P. aeruginosa phospholipase A, PlaF, which modulates membrane PL composition, is important for biofilm biogenesis, and we performed whole-cell quantitative proteomics of P. aeruginosa wild-type and {Delta}plaF biofilms to identify pathways regulated by PlaF. The results revealed profound alterations in the abundance of several two-component systems (TCSs), including accumulation of PprAB, which controls the transition to biofilm. Furthermore, a unique phosphorylation pattern of transcriptional regulators, transporters and metabolic enzymes, as well as differential production of seven proteases, in {Delta}plaF, indicate that PlaF-mediated virulence adaptation involves complex transcriptional and posttranscriptional regulation. Moreover, proteomics revealed the depletion of pyoverdine-mediated iron uptake pathway proteins in {Delta}plaF, which agrees with the decreased concentrations of extracellular pyoverdine and intracellular iron and is likely responsible for its prolonged lag growth phase, presumably due to reduced iron uptake. Conversely, the accumulation of proteins from alternative iron-uptake systems in {Delta}plaF suggests that PlaF may function as a switch between different iron-acquisition pathways. The observation that {Delta}plaF accumulates PL-acyl chain modifying and PL synthesis enzymes reveals novel insights into the role of PlaF for membrane PL homeostasis. Although the precise mechanism by which PlaF simultaneously affects multiple pathways remains to be elucidated, we suggest that PlaF-catalyses the degradation of PLs which then serve as a signal that is amplified by proteins of two-component, phosphorylation and proteolytic degradation systems to elicit the global adaptive response in P. aeruginosa.

molecular biology↗

bioRxiv2019

The global phylogenetic landscape and nosocomial spread of the multidrug-resistant opportunist Stenotrophomonas maltophilia

Recent studies portend a rising global spread and adaptation of human- or healthcare-associated pathogens. Here, we analysed an international collection of the emerging, multidrug-resistant, opportunistic pathogen Stenotrophomonas maltophilia from 22 countries to infer population structure and clonality at a global level. We show that the S. maltophilia complex is divided into 23 monophyletic lineages, most of which harboured strains of all degrees of human virulence. Lineage Sm6 comprised the highest rate of human-associated strains, linked to key virulence and resistance genes. Transmission analysis identified potential outbreak events of genetically closely related strains isolated within days or weeks in the same hospitals.\n\nOne Sentence SummaryThe S. maltophilia complex comprises genetically diverse, globally distributed lineages with evidence for intra-hospital transmission.

genomics↗