Summary
Pristine marine environments are highly oligotrophic ecosystems populated by well‐established specialized microbial communities. Nevertheless, during oil spills, low‐abundant ...hydrocarbonoclastic bacteria bloom and rapidly prevail over the marine microbiota. The genus Alcanivorax is one of the most abundant and well‐studied organisms for oil degradation. While highly successful under polluted conditions due to its specialized oil‐degrading metabolism, it is unknown how they persist in these environments during pristine conditions. Here, we show that part of the Alcanivorax genus, as well as oils, has an enormous potential for biodegrading aliphatic polyesters thanks to a unique and abundantly secreted alpha/beta hydrolase. The heterologous overexpression of this esterase proved a remarkable ability to hydrolyse both natural and synthetic polyesters. Our findings contribute to (i) better understand the ecology of Alcanivorax in its natural environment, where natural polyesters such as polyhydroxyalkanoates (PHA) are produced by a large fraction of the community and, hence, an accessible source of carbon and energy used by the organism in order to persist, (ii) highlight the potential of Alcanivorax to clear marine environments from polyester materials of anthropogenic origin as well as oils, and (iii) the discovery of a new versatile esterase with a high biotechnological potential.
Summary
The Burkholderia cepacia complex is a group of Burkholderia species that are opportunistic pathogens causing high mortality rates in patients with cystic fibrosis. An environmental stress ...often encountered by these soil‐dwelling and pathogenic bacteria is phosphorus limitation, an essential element for cellular processes. Here, we describe cellular and extracellular proteins differentially regulated between phosphate‐deplete (0 mM, no added phosphate) and phosphate‐replete (1 mM) growth conditions using a comparative proteomics (LC–MS/MS) approach. We observed a total of 128 and 65 unique proteins were downregulated and upregulated respectively, in the B. cenocepacia proteome. Of those downregulated proteins, many have functions in amino acid transport/metabolism. We have identified 24 upregulated proteins that are directly/indirectly involved in inorganic phosphate or organic phosphorus acquisition. Also, proteins involved in virulence and antimicrobial resistance were differentially regulated, suggesting B. cenocepacia experiences a dramatic shift in metabolism under these stress conditions. Overall, this study provides a baseline for further research into the biology of Burkholderia in response to phosphorus stress.
The regeneration of bioavailable phosphate from immobilized organophosphorus represents a key process in the global phosphorus cycle and is facilitated by enzymes known as phosphatases. Most bacteria ...possess at least one of three phosphatases with broad substrate specificity, known as PhoA, PhoX, and PhoD, whose activity is optimal under alkaline conditions. The production and activity of these phosphatases is repressed by phosphate availability. Therefore, they are only fully functional when bacteria experience phosphorus-limiting growth conditions. Here, we reveal a previously overlooked phosphate-insensitive phosphatase, PafA, prevalent in
, which is highly abundant in nature and represents a major route for the regeneration of environmental phosphate. Using the enzyme from
, we show that PafA is highly active toward phosphomonoesters, is fully functional in the presence of excess phosphate, and is essential for growth on phosphorylated carbohydrates as a sole carbon source. These distinct properties of PafA may expand the metabolic niche of
by enabling the utilization of abundant organophosphorus substrates as C and P sources, providing a competitive advantage when inhabiting zones of high microbial activity and nutrient demand. PafA, which is constitutively synthesized by soil and marine flavobacteria, rapidly remineralizes phosphomonoesters releasing bioavailable phosphate that can be acquired by neighboring cells. The
gene is highly diverse in plant rhizospheres and is abundant in the global ocean, where it is expressed independently of phosphate availability. PafA therefore represents an important enzyme in the context of global biogeochemical cycling and has potential applications in sustainable agriculture.
KGd(WO sub(4)) sub(2) has been studied by high-pressure Raman spectroscopy at room temperature up to 32.2 GPa. Evidences of two pressure-driven phase transitions have been detected. The low-pressure ...monoclinic phase undergoes a phase transition at 7.2(+ or-0.9) GPa. The second transition is found at 14.2(+ or-1.6) GPa. Both transitions are reversible. No evidence of pressure-induced amorphization is found up to 32 GPa. The pressure dependence of the Raman active modes of the low-and high-pressure phases is reported. A Raman mode is detected to exhibit a weak softening in the low-pressure phase. Three Raman modes are also observed to have a similar behavior in the second high-pressure phase. The reported results are discussed comparing with the studies available in related tungstates. Emphasis is placed on the physical implications of the results.
We report a new method for the determination of photothermal conversion efficiency of photothermal agents, based on the use of an integrating sphere. We validated this method by comparing the ...photothermal conversion efficiency of Au nanorods calculated by this method and by the more conventional time constant method. Then, we applied this method to determine the photothermal conversion efficiency of graphene and graphene oxide nanosheets dispersions in dimethylformamide and water, respectively, finding out that they are excellent photothermal agents with photothermal conversion efficiencies among the highest reported up to now. We also analyzed the influence of the concentration of the materials, and the wavelength and power of irradiation in the temperature increase that can be achieved with them, finding out that they can be used, for instance, in cancer treatment through hyperthermia procedures with reduced costs when compared to other photothermal agents.
We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er3+ (1 mol %) and Yb3+ (20 mol %) and determined their thermal sensing properties through the fluorescence ...intensity ratio (FIR) technique. We also analyzed how a silica coating, in a core–shell structure, affects the temperature sensing properties of this material. Spectra were recorded in the range of biological temperatures (298–343 K). The absolute sensitivity for temperature determination calculated for the core–shell nanoparticles is double the one calculated for bare nanoparticles, achieving a thermal resolution of 0.4 K. Moreover, silica-coated nanoparticles show good dispersibility in different solvents, such as water, DMSO, and methanol. Also, they show good luminescence stability without interactions with solvent molecules. Furthermore, we also observed that the silica coating shell prevents progressive heating of the nanoparticles during prolonged excitation periods with the 980 nm laser, preventing effects on their thermometric applications.
Dimethylsulfoniopropionate (DMSP) is a ubiquitous organosulfur compound in marine environments with important functions in both microorganisms and global biogeochemical carbon and sulfur cycling. The ...SAR11 clade and marine Roseobacter group (MRG) represent two major groups of heterotrophic bacteria in Earth's surface oceans, which can accumulate DMSP to high millimolar intracellular concentrations. However, few studies have investigated how SAR11 and MRG bacteria import DMSP. Here, through comparative genomics analyses, genetic manipulations, and biochemical analyses, we identified an ABC (ATP-binding cassette)-type DMSP-specific transporter, DmpXWV, in Ruegeria pomeroyi DSS-3, a model strain of the MRG. Mutagenesis suggested that DmpXWV is a key transporter responsible for DMSP uptake in strain DSS-3. DmpX, the substrate binding protein of DmpXWV, had high specificity and binding affinity towards DMSP. Furthermore, the DmpX DMSP-binding mechanism was elucidated from structural analysis. DmpX proteins are prevalent in the numerous cosmopolitan marine bacteria outside the SAR11 clade and the MRG, and dmpX transcription was consistently high across Earth's entire global ocean. Therefore, DmpXWV likely enables pelagic marine bacteria to efficiently import DMSP from seawater. This study offers a new understanding of DMSP transport into marine bacteria and provides novel insights into the environmental adaption of marine bacteria.
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