Umeå universitets logga

Environmental bacterial biofilms play many roles in the ecosystem including cycling of nutrients and serving as food for grazing organisms. Their function is linked to their microbial and chemical composition that may be altered by several parameters including environmental stressors. This manuscript presents a well-characterized model system of four bacterial isolates from a small Swedish river: Pseudomonas sp., Sphingomonas sp., Rhizobium sp. and Pararhizobium sp. Microbiological and chemical phenotypes were investigated including cell and biofilm morphology, as well as biochemical composition in absence and presence of the drug trimethoprim. Vibrational spectroscopy, cryo-X-ray photoelectron spectroscopy and confocal optical microscopy were applied to investigate and characterize monocultures and cocultures. The chemical characterization showed variation of the energy storage substance polyhydroxyalkanoates as well as polysaccharides between isolates and drug exposures. Spatial heterogeneities were observed using Raman microspectroscopy where Sphingomonas sp. cells, formed small clusters, inside the four species consortium, an organization that appeared to protect this isolate during exposure to trimethoprim.

Developing effective fractionation methods remains challenging in biorefining. γ-Valerolactone (GVL) is a promising green solvent, yet its application in softwood biorefineries is still underexplored. In this study, GVL pretreatment for softwood biorefining was assessed at laboratory and pilot scales. The effects of temperature (170–210 °C), time (20–60 min), and GVL-to-water ratios (20:80 – 80:20 %) on the biorefining of spruce sawdust were initially investigated through lab-scale experiments using a 1-L reactor. A GVL/water solution at a 40:60 ratio, assisted by 0.4 g of sulfuric acid per 100 g of biomass, enabled the solubilization of up to 81.4 % of lignin and nearly the entire hemicellulosic fraction, while effectively preserving cellulose, which was subsequently saccharified with over 90 % conversion. Lignin was regenerated from the liquors and characterized using pyrolysis-gas chromatography/mass spectrometry, high-performance size-exclusion chromatography, Fourier-transform infrared spectroscopy, and 1H-13C heteronuclear single-quantum coherence nuclear magnetic resonance spectroscopy. The biorefinery concept was successfully scaled up and validated at pilot scale in a 50-L reactor, where enzymatic saccharification of the resulting cellulosic pulp produced hydrolysates that, upon fermentation, yielded 231.4 g of ethanol per kilogram of pulp. Lignin regenerated from the pilot-scale pretreatment liquors (118.9 g per kilogram of raw sawdust) and the lignin-rich saccharification residue (182.7 g/kg) were subjected to hydrothermal liquefaction, and the resulting biocrudes were characterized to assess their potential for biofuel formulation. The study showed the suitability of GVL for spruce biorefining to achieve high recovery of digestible cellulose, lignin and hemicelluloses fractions, that are subsequently valuable for chemicals and fuels production.

Prostate cancer treatment depends on whether the cancer exists only inside the gland or within the prostate capsule or on the outside surface of the gland. The presence on the outside surface indicates migration of the cancer to adjacent organs. This study presents a novel method for detecting prostate cancer (PCa) on the surface of excised prostate glands using Raman spectroscopy and stiffness measurements. The workflow involves assessing the location and extent of PCa via MRI before surgery, followed by 3D scanning of the excised prostate. Key positions on ten excised prostates, 211 positions with 56 deemed as cancer, are measured using Raman spectroscopy and stiffness probes. The results are mapped onto a digital representation of the prostate to aid surgical decision-making. Statistical analysis of the Raman data indicates that spectra could be divided into two components, one more related to cancer and one more related to normal tissue. A stiffness parameter was calculated from resonance measurements from the stiffness probe. The Raman components and stiffness parameters were converted to z-scores. Logistic generalized linear mixed modelling revealed that the stiffness parameter was statistically associated with cancer presence in prostate regions (p = 0.009). The scanning equipment is easy to handle and makes further larger studies possible. This method holds promise for providing real-time support during surgery, reducing the need for post-surgical therapies and minimizing patient distress.

The origin of platinum-group minerals (PGM) in the supergene environment remains debated, with contrasting models invoking (i) mechanical liberation of hypogene PGM during weathering versus (ii) in-situ neoformation of PGM. We address this debate using enigmatic Pt-Ir-Fe-Ni grains hosted in a chromitite body enclosed in limonite and provide new insights into their origin based on their morphologies, textures, structures, compositions, and mineralogical associations. The grains exhibit porous textures produced by accumulations of Pt-Ir-Fe-Ni nanoparticles arranged in aligned nanostructures within a goethite matrix. The aligned nanostructures occur in distinct bundles with three main orientations, forming previously not described stitching textures i.e. an interlacing of bundles, defining parallel and triangular patterns. The alloys are cubic, exhibit a preferential stoichiometry of (Pt, Ir)0.26Ni0.29Fe0.45 and are absent in pristine chromitites. In order to find pros and cons for their genetic history we compare our observations with globally occurring PGE alloys from magmatic, hydrothermal-related, and supergene environments. Moreover, we discuss the textural similarities with other naturally occurring materials such as martitization products and, without genetic implications, Fe–Ni meteorites showing Widmannstätten patterns. This contribution does not provide a final conclusion on how Pt-Ir-Fe-Ni alloys found in the limonite of a Ni-laterite form. Instead, we present high-resolution observations that can be used to speculate different scenarios for their possibly multi-stage genesis.

Programmed Cell Death (PCD) in eukaryotes is a regulated process occurring during development, cell differentiation and aging. Apoptosis is a particularly well studied morphotype of PCD, only observed in animal cells (metazoan). Its most definitive hallmark is the formation and release of membrane-enclosed extracellular vesicles called Apoptotic Bodies (ABs). Although apoptotic-like features have been described in plants, yeast, protozoa and phytoplankton, the production of ABs has been thought to be limited to multicellular animals. Here we report the production and release of extracellular ABs in a non-metazoan unicellular eukaryote, the cryptophyte alga Guillardia theta. Morphologies of G. theta cells during aging and pharmacologically-induced cell death confirm the presence of ABs and apoptosis in phytoplankton. G. theta ABs have similar composition to metazoan ABs, carrying DNA, proteins, lipids, carbohydrates, fragments of organelles and cytosol portions. Our results demonstrate that G. theta, a microalga that arose from secondary endosymbiosis, experiences apoptotic cell death in physiological conditions, similar to animal cells. Since secondary endosymbiosis occurred prior to the origin of multicellularity, our discovery questions the evolutionary origin of PCD.

Cuticle - a hydrophobic barrier of cutin and waxes covering the outer cell wall surface of plants - enables survival in terrestrial habitats. However, it is not understood how the hydrophobic cuticle precursors travel through the homogalacturonan-rich hydrophilic cell wall. To elucidate the role of homogalacturonan in cuticle development, we disrupted its integrity by overexpressing a pectate lyase, PtxtPL1-27, in aspen. PtxtPL1-27 had pleiotropic effects on shoot development, including the reduction of cuticle thickness and changes in cutin and wax composition, but the expression of cutin biosynthetic genes was little affected. Despite a reduction in homogalacturonan content in the leaves, labeling with the homogalacturonan-specific antibody JIM5 in the outer epidermal cell wall layer increased and displayed an altered pattern. Moreover, the ultrastructure of cell walls was changed concomitant with lipid accumulation. We propose that the disruption of homogalacturonan integrity affected the cutinsome-dependent transport and polymerization of cutin monomers in the cell wall.

In natural environments, most microorganisms reside attached to a surface growing as a biofilm, which is a universal microbial strategy for their survival. As a result, several studies have focused on the role of the biofilm matrix (made of extracellular polymeric substances (EPS)) in tolerance to antimicrobials. However, few studies have focused directly on the characterization of EPS as a response to antibiotic stress. In this study, we analyzed the impact of trimethoprim (TMP) on the production and characteristics of EPS from four natural biofilm-producing river bacterial strains. Extraction and characterization of EPS were carried out at three concentrations of TMP. EPS properties were monitored using colorimetric tests, infrared spectroscopy and sugar composition analysis. For all strains, EPS quantity and chemistry changed starting at 0.1 mM TMP. The combined results suggest that environmental bacterial strains adapt their EPS production and chemical composition in response to antibiotic exposure. Bacteria may benefit from the change in EPS chemistry since it limits the penetration of TMP into the biofilm and thus protects the cells from the action of the antibiotic. Three main mechanisms are proposed: an increase in the proportion of (i) proteins and reactive functional groups, (ii) mannose and (iii) fatty acids. This study shows that EPS represents a key factor in antibiotic tolerance of bacteria via multiple mechanisms. Thus, this study broadens the discussion concerning antibiotic-resistance as it presents additional processes that may work in tune with genetically acquired resistance to enhance bacterial tolerance to antibiotics.

Microbial exopolysaccharides (EPSs) have attracted increasing attention due to their versatile applications across diverse areas. However, large-scale production of EPSs remains challenging due to the high production costs, primarily driven by the use of synthetic carbon sources. This study demonstrates the potential of quinoa stalk hydrolysates as a sustainable alternative for EPS production using a halotolerant bacterial strain that was isolated from a hypersaline environment and termed SU4M. The bacterial isolate was identified through 16S rRNA and gyrB sequencing as a Bacillus swezeyi strain, and was then cultivated in quinoa stalk hydrolysates. The hydrolysates were produced by acid-catalyzed hydrothermal pretreatment using either sulfuric acid or phosphoric acid, followed by enzymatic saccharification. Fermentation experiments conducted in both shake flasks and bioreactors demonstrated that B. swezeyi SU4M utilized glucose from the hydrolysates efficiently, resulting in significantly higher biomass (5.1 ± 0.1 g L−1) and EPS production (1.2 ± <0.1 g L−1) compared to synthetic media (4.3 ± 0.1 g L−1 and 1.1 ± <0.1 g L−1). The kinetic analysis revealed distinct substrate consumption rates and growth patterns, with hydrolysates enhancing EPS yields under single-pulse fed-batch conditions. Advanced characterization techniques, including compositional analysis, Fourier transform infrared (FTIR) spectroscopy, 1H and 1H-13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR), high-performance size-exclusion chromatography (HPSEC), and thermogravimetric analysis (TGA), confirmed that the EPSs derived from hydrolysates were heteropolysaccharides with close structural similarities to those obtained from synthetic media. These findings underscore the potential of quinoa stalk hydrolysates as a biobased alternative to synthetic media as a substrate for EPS production.

Detection of organic biosignatures by (cryo-)Raman spectroscopy in hydromagnesite-rich samples from Lake Salda, an analogue site for the Mg-carbonate deposits in Jezero Crater.

Brown seaweeds contain a variety of saccharides which have potential industrial uses. The most abundant polysaccharide in brown seaweed is typically alginate, consisting of mannuronic (M) and guluronic acid (G). The ratio of these residues fundamentally determines the physicochemical properties of alginate. In the present study, gas chromatography/mass spectrometry (GC/MS) was used to give a detailed breakdown of the monosaccharide species in North Atlantic brown seaweeds. The anthrone method was used for determination of crystalline cellulose. The experimental data was used to calibrate multivariate prediction models for estimation of total carbohydrates, crystalline cellulose, total alginate and alginate M/G ratio directly in dried, brown seaweed using three types of infrared spectroscopy, using relative error (RE) as a measure of predictive accuracy. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) performed well for the estimation of total alginate (RE = 0.12, R² = 0.82), and attenuated total reflectance (ATR) showed good prediction of M/G ratio (RE = 0.14, R² = 0.86). Both DRIFTS, ATR and near infrared (NIR) were unable to predict crystalline cellulose and only DRIFTS performed better in determining total carbohydrates. Multivariate spectral analysis is a promising method for easy and rapid characterization of alginate and M/G ratio in seaweed.