ALBERT

Description: Chinese coastal waters support vast fisheries and vital economies, but their productivity is threatened by increasingly frequent harmful algal blooms (HABs). Here we provide direct experimental evidence that atmospheric deposition, along with riverine input, opens new niches for bloom-forming dinoflagellates and diatoms in the East China Sea (ECS) by increasing the ratio of nitrogen to phosphorus (N:P), inducing severe P limitation, and altering trace metal micronutrient inventories. Remote sensing analysis of blooms in the region showed that dinoflagellate blooms were associated with increased aerosol optical thickness and decreased sea surface temperature, whereas diatom blooms were primarily associated with seasonally decreased temperature (e.g., during spring blooms). Bottle incubation experiments revealed that aerosol additions approximating 10 days of strong deposition increased iron availability and intensified P limitation, which together promoted dinoflagellate growth in offshore waters. Diatom growth was correlated with elevated trace metal and nutrient content from aerosols. Aerosols did not induce phytoplankton growth at a station within the Yangtze River plume where light was limiting, consistent with remote sensing observations that aerosol effects are stronger in offshore waters. Eutrophication and trace metal enrichment from Yangtze River discharge together with atmospheric deposition may underlie the transition from diatom-dominated spring blooms toward more frequent spring and summer dinoflagellate blooms that has occurred over the past three decades in the ECS.

Description: Natural products and their derivatives are mainstays of our antibiotic drugs, but they are increasingly in peril. The combination of widespread multidrug resistance in once susceptible bacterial pathogens, disenchantment with natural products as sources of new drugs, lack of success using synthetic compounds and target-based discovery methods, along with shifting economic and regulatory issues, conspire to move investment in research and development away from the antibiotics arena. The result is a growing crisis in antibiotic drug discovery that threatens modern medicine. 21st century natural product research is perfectly positioned to fill the antibiotic discovery gap and bring new drug candidates to the clinic. Innovations in genomics and techniques to explore new sources of antimicrobial chemical matter are revealing new chemistry. Increasing appreciation of the value of narrow-spectrum drugs and re-examination of once discarded chemical scaffolds coupled with synthetic biology methods to generate new compounds and improve yields offer new strategies to revitalize once moribund natural product programs. The increasing awareness that the combination of antibiotics with adjuvants, non-antibiotic compounds that overcome resistance and enhance drug activity, can rescue older chemical scaffolds, and concepts such as blocking pathogen virulence present orthogonal strategies to traditional antibiotics. In all these areas, natural products offer chemical matter, shaped by natural selection, that is privileged in this therapeutic area. Natural product research is poised to regain prominence in delivering new drugs to solve the antibiotic crisis.

Description: Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to its unique structural features and impressive physicochemical properties such as biocompatibility, biodegradability, renewability, low density, adaptable surface chemistry, optical transparency, and improved mechanical properties. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors, etc. New resources, new extraction procedures, and new treatments are currently under development to satisfy the increasing demand of manufacturing new types of cellulose nanocrystals-based materials on an industrial scale. Therefore, this review addresses the recent progress in the production methodologies of cellulose nanocrystals, covering principal cellulose resources and the main processes used for its isolation. A critical and analytical examination of the shortcomings of various approaches employed so far is made. Additionally, structural organization of cellulose and nomenclature of cellulose nanomaterials have also been discussed for beginners in this field.

Description: Chemical mediation regulates behavioral interactions between species and thus affects population structure, community organization and ecosystem function. Among marine taxa that have developed chemical mediation strategies, gastropods belong to a diverse group of molluscs found worldwide, including species with a coiled, reduced or absent shell. Most gastropods use natural products to mediate a wide range of behaviors such as defense, prey location or interactions with con- and hetero-geners. Their chemically defended diet, such as cyanobacteria, algae, sponges, bryozoans and tunicates, provides them with a considerable opportunity either as shelter from predators, or as a means to enhance their own chemical defense. In addition to improving their defenses, molluscs also use prey secondary metabolites in complex chemical communication including settlement induction, prey detection and feeding preferences. The assimilation of prey secondary metabolites further provides the opportunity for interactions with conspecifics via diet-derived chemical cues or signals. This review intends to provide an overview on the sequestration, detoxification, and biotransformation of diet-derived natural products, as well as the role of these compounds as chemical mediators in gastropod-prey interactions.

Description: Actinomycetes have been, for decades, one of the most important sources for the discovery of new antibiotics with an important number of drugs and analogs successfully introduced in the market and still used today in clinical practice. The intensive antibacterial discovery effort that generated the large number of highly potent broad-spectrum antibiotics, has seen a dramatic decline in the large pharma industry in the last two decades resulting in a lack of new classes of antibiotics with novel mechanisms of action reaching the clinic. Whereas the decline in the number of new chemical scaffolds and the rediscovery problem of old known molecules has become a hurdle for industrial natural products discovery programs, new actinomycetes compounds and leads have continued to be discovered and developed to the preclinical stages. Actinomycetes are still one of the most important sources of chemical diversity and a reservoir to mine for novel structures that is requiring the integration of diverse disciplines. These can range from novel strategies to isolate species previously not cultivated, innovative whole cell screening approaches and on-site analytical detection and dereplication tools for novel compounds, to in silico biosynthetic predictions from whole gene sequences and novel engineered heterologous expression, that have inspired the isolation of new NPs and shown their potential application in the discovery of novel antibiotics. This review will address the discovery of antibiotics from actinomycetes from two different perspectives including: (1) an update of the most important antibiotics that have only reached the clinical development in the recent years despite their early discovery, and (2) an overview of the most recent classes of antibiotics described from 2006 to 2017 in the framework of the different strategies employed to untap novel compounds previously overlooked with traditional approaches.

Description: Decades of research on human microbiota have revealed much of their taxonomic diversity and established their direct link to health and disease. However, the breadth of bioactive natural products secreted by our microbial partners remains unknown. Of particular interest are antibiotics produced by our microbiota to ward off invasive pathogens. Members of the human microbiota exclusively produce evolved small molecules with selective antimicrobial activity against human pathogens. Herein, we expand upon the current knowledge concerning antibiotics derived from human microbiota and their distribution across body sites. We analyze, using our in-house chem-bioinformatic tools and natural products database, the encoded antibiotic potential of the human microbiome. This compilation of information may create a foundation for the continued exploration of this intriguing resource of chemical diversity and expose challenges and future perspectives to accelerate the discovery rate of small molecules from the human microbiota.

Description: The review summarizes results up to 2017 on chemosensory cues occurring in both aquatic and terrestrial environments. The chemicals are grouped by their physicochemical properties to compare their potential mobility in the different media. In contrast to what is widely asserted in the literature, the report emphasizes that living organisms encounter and sense molecules of various degrees of solubility and volatility both on land and in aquatic environments. The picture that emerges from the review suggests a substantial revision of the traditional definitions of the chemical senses based on their spatial range, which is currently orienting the literature on chemosensory signaling, in favor of a new vision based on the natural products that are the actual mediators of the chemosensory perceptions. According to this perspective, natural product chemistry is a powerful tool with which to explore the evolutionary history of the chemical senses.

Description: The overwhelming majority of antibiotics in clinical use originate from Gram-positive Actinobacteria. In recent years, however, Gram-negative bacteria have become increasingly recognised as a rich yet underexplored source of novel antimicrobials, with the potential to combat the looming health threat posed by antibiotic resistance. In this article, we have compiled a comprehensive list of natural products with antimicrobial activity from Gram-negative bacteria, including information on their biosynthetic origin(s) and molecular target(s), where known. We also provide a detailed discussion of several unusual pathways for antibiotic biosynthesis in Gram-negative bacteria, serving to highlight the exceptional biocatalytic repertoire of this group of microorganisms.

Description: Metabolism of 2,3-dihydroxypropane-1-sulfonate by marine bacteria Ersin Celik Kekulé-Institut für Organische Chemie und Biochemie Rheinische Friedrich-Wilhelms-Universität Bonn 53121 Bonn Germany Michael Maczka Institut für Organische Chemie TU Braunschweig 38106 Braunschweig Germany Nils Bergen Institut für Chemie und Biologie des Meeres Universität Oldenburg 26129 Oldenburg Germany Thorsten Brinkhoff Institut für Chemie und Biologie des Meeres Universität Oldenburg 26129 Oldenburg Germany Stefan Schulz Institut für Organische Chemie TU Braunschweig 38106 Braunschweig Germany http://orcid.org/0000-0002-4810-324X Jeroen S. Dickschat Kekulé-Institut für Organische Chemie und Biochemie Rheinische Friedrich-Wilhelms-Universität Bonn 53121 Bonn Germany http://orcid.org/0000-0002-0102-0631 The uptake and conversion of the algal sulfoquinovose catabolite 2,3-dihydroxypropane-1-sulfonate by marine bacteria was studied in isotopic labelling experiments. Both enantiomers of the sulfoquinovose breakdown product 2,3-dihydroxypropane-1-sulfonate, an important sulfur metabolite produced by marine algae, were synthesised in a 34 S-labelled form and used in feeding experiments with marine bacteria. The labelling was efficiently incorporated into the sulfur-containing antibiotic tropodithietic acid and sulfur volatiles by the algal symbiont Phaeobacter inhibens , but not into sulfur volatiles released by marine bacteria associated with crustaceans. The ecological implications and the relevance of these findings for the global sulfur cycle are discussed. 2017 2919 2922 1 10.1039/rsc_crossmark_policy rsc.org true This document is Similarity Check deposited Supplementary Information Stefan Schulz (ORCID) Jeroen S. Dickschat (ORCID) The Royal Society of Chemistry has an exclusive publication licence for this journal Single-blind Received 14 February 2017; Accepted 15 March 2017; Advance Article published 22 March 2017; Version of Record published 5 April 2017 Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659 http://dx.doi.org/10.13039/501100001659 SFB TR51 10.1039/C7OB00357A 20171121163610 http://xlink.rsc.org/?DOI=C7OB00357A http://pubs.rsc.org/en/content/articlepdf/2017/OB/C7OB00357A Adv. Lipid Res. Benson 1 387 1963 10.1016/B978-1-4831-9937-5.50016-8 Z. Naturforsch., C: J. Biosci. Datz 36 856 1981 10.1515/znc-1981-9-1027 Lipids Gage 27 632 1992 10.1007/BF02536123 Biochem. Biophys. Res. Commun. Sato 470 123 2016 10.1016/j.bbrc.2016.01.006 Biochem. Soc. Trans. Harwood 7 440 1979 10.1042/bst0070440 Org. Biomol. Chem. Dickschat 13 1954 2015 10.1039/C4OB02407A Appl. Environ. Microbiol. Roy 69 6434 2003 10.1128/AEM.69.11.6434-6441.2003 Nature Denger 507 114 2014 10.1038/nature12947 Proc. Natl. Acad. Sci. U. S. A. Durham 112 453 2015 10.1073/pnas.1413137112 Nature Croft 438 90 2005 10.1038/nature04056 FEMS Microbiol. Lett. Denger 328 39 2012 10.1111/j.1574-6968.2011.02477.x Microbiology Mayer 156 1556 2010 10.1099/mic.0.037580-0 Microbiology Rein 151 737 2005 10.1099/mic.0.27548-0 Microbiology Denger 156 967 2010 10.1099/mic.0.034736-0 J. Bacteriol. Denger 191 5648 2009 10.1128/JB.00569-09 Microbiology Mikosch 145 1153 1999 10.1099/13500872-145-5-1153 Biochem. J. Denger 394 657 2006 10.1042/BJ20051311 Biochemistry White 25 5304 1986 10.1021/bi00366a047 Biochem. J. Ruff 369 275 2003 10.1042/bj20021455 Microbiology Weinitschke 153 3055 2007 10.1099/mic.0.2007/009845-0 J. Antibiot. Kintaka 37 1294 1984 10.7164/antibiotics.37.1294 ChemBioChem Dickschat 11 417 2010 10.1002/cbic.200900668 Org. Biomol. Chem. Dickschat 13 1954 2015 10.1039/C4OB02407A Nat. Chem. Seyedsayamdost 3 331 2011 10.1038/nchem.1002 Proc. Natl. Acad. Sci. U. S. A. Wilson 113 1630 2016 10.1073/pnas.1518034113 Appl. Environ. Microbiol. Geng 74 1535 2008 10.1128/AEM.02339-07 Chem. Commun. Brock 50 5487 2014 10.1039/c4cc01924e mBio Wang 7 e02118 2016 Org. Biomol. Chem. Brock 12 4318 2014 10.1039/c4ob00719k Beilstein J. Org. Chem. Brock 9 942 2013 10.3762/bjoc.9.108 Nature Reisch 473 208 2011 10.1038/nature10078 Beilstein J. Org. Chem. Rinkel 11 2493 2015 10.3762/bjoc.11.271 Tetrahedron Schulz 60 3863 2004 10.1016/j.tet.2004.03.005 Appl. Environ. Microbiol. Rao 73 7844 2007 10.1128/AEM.01543-07 Science Todd 315 666 2007 10.1126/science.1135370 Nat. Rev. Microbiol. Curson 9 849 2011 10.1038/nrmicro2653 Curr. Opin. Chem. Biol. Johnston 31 58 2016 10.1016/j.cbpa.2016.01.011 ISME J. Thole 6 2229 2012 10.1038/ismej.2012.62

Description: The first inter-calibration study of the stable silicon isotope composition of dissolved silicic acid in seawater, δ30Si(OH)4, is presented as a contribution to the international GEOTRACES program. Eleven laboratories from seven countries analyzed two seawater samples from the north Pacific subtropical gyre (Station ALOHA) collected at 300 m and at 1000 m water depth. Sampling depths were chosen to obtain samples with a relatively low (9 μmol L-1, 300 m) and a relatively high (113 μmol L-1, 1000 m) silicic acid concentration as sample preparation differs for low- and high- concentration samples. Data for the 1000m water sample were not normally distributed so the median is used to represent the central tendency for the two samples. Median δ30Si(OH)4 values of +1.66 ‰ for the low-concentration sample and +1.25 ‰ for the high-concentration sample were obtained. Agreement among laboratories is overall considered very good; however, small but statistically significant differences among the mean isotope values obtained by different laboratories were detected likely reflecting interlaboratory differences in chemical preparation including pre-concentration and purification methods together with different volumes of seawater volume analyzed, and the use of different mass spectrometers including the Neptune MC-ICP-MS (Thermo Fisher™, Germany), the Nu Plasma MC-ICP-MS (Nu Instruments™, Wrexham, UK), and the Finnigan™ (now Thermo Fisher™, Germany) MAT 252 IRMS. Future studies analyzing δ30Si(OH)4 in seawater should also analyze and report values for these same two reference waters in order to facilitate comparison of data generated among and within laboratories over time.