Macroalgal deep genomics illuminate multiple paths to aquatic, photosynthetic multicellularity.

Macroalgae are multicellular, aquatic autotrophs that play vital roles in global climate maintenance and have diverse applications in biotechnology and eco-engineering, which are directly linked to their multicellularity phenotypes. However, their genomic diversity and the evolutionary mechanisms underlying multicellularity in these organisms remain uncharacterized. In this study, we sequenced 110 macroalgal genomes from diverse climates and phyla, and identified key genomic features that distinguish them from their microalgal relatives. Genes for cell adhesion, extracellular matrix formation, cell polarity, transport, and cell differentiation distinguish macroalgae from microalgae across all three major phyla, constituting conserved and unique gene sets supporting multicellular processes. Adhesome genes show phylum- and climate-specific expansions that may facilitate niche adaptation. Collectively, our study reveals genetic determinants of convergent and divergent evolutionary trajectories that have shaped morphological diversity in macroalgae and provides genome-wide frameworks to understand photosynthetic multicellular evolution in aquatic environments.

The genome sequence of the Heterolobosean amoeboflagellate, Tetramitus jugosus CCAP 1588/3C.

We present a genome assembly from cultivated Tetramitus jugosus (Heterolobosea; Schizopyrenida; Vahlkampfiidae). The genome sequence is 26.3 megabases in span. Most of the assembly (99.3%) is scaffolded into 52 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 49.46 kilobases in length.

The genome sequence of Pycnococcus provasolii (CCAP190/2) (Guillard, 1991).

We present a genome assembly from cultured Pycnococcus provasolii (a marine green alga; Chlorophyta; None; Pseudoscourfieldiales; Pycnococcaceae). The genome sequence is 32.2 megabases in span. Most of the assembly is scaffolded into 44 chromosomal pseudomolecules (99.67%). The mitochondrial and plastid genomes have also been assembled, and the length of the mitochondrial scaffold is 24.3 kilobases and of the plastid genome has been assembled and is 80.2 kilobases in length.

Rapid Cyanobacteria Species Identification with High Sensitivity Using Native Mass Spectrometry.

Cyanobacteria have evolved over billions of years to adapt and survive in diverse climates. Environmentally, this presents a huge challenge because cyanobacteria can now rapidly form algae blooms that are detrimental to aquatic life. In addition, many cyanobacteria produce toxins, making them hazardous to animals and humans that they encounter. Rapid identification of cyanobacteria is essential to monitor and prevent toxic algae blooms. Here, we show for the first time how native mass spectrometry can quickly and precisely identify cyanobacteria from diverse aquatic environments. By monitoring phycobiliproteins, abundant protein complexes within cyanobacteria, simple, easy-to-understand mass spectral "fingerprints" were created that were unique to each species. Moreover, our method is 10-fold more sensitive than the current MALDI-TOF mass spectrometric methods, meaning that cyanobacteria can be monitored using this technology prior to bloom formation. Together, the data show great promise for the simultaneous detection and identification of co-existing cyanobacteria in situ.

Mytilus trossulus introgression and consequences for shell traits in longline cultivated mussels.

Mussels belonging to the Mytilus species complex (M. edulis, ME; M. galloprovincialis, MG; and M. trossulus, MT) often occur in sympatry, facilitating introgressive hybridization. This may be further promoted by mussel aquaculture practices, with MT introgression often resulting in commercially unfavourable traits such as low meat yield and weak shells. To investigate the relationship between genotype and shell phenotype, genetic and morphological variability was quantified across depth (1 m to 7 m) along a cultivation rope at a mussel farm on the West coast of Scotland. A single nuclear marker (Me15/16) and a novel panel of 33 MT-diagnostic single nucleotide polymorphisms were used to evaluate stock structure and the extent of MT introgression across depth. Variation in shell strength, determined as the maximum compression force for shell puncture, and shell shape using geometric morphometric analysis were evaluated in relation to cultivation depth and the genetic profiles of the mussels. Overall, ME was the dominant genotype across depth, followed by ME × MG hybrids and smaller quantities of ME × MT hybrids and pure MT individuals. In parallel, we identified multiple individuals that were either predominantly homozygous or heterozygous for MT-diagnostic alleles, likely representing pure MT and first-generation ME × MT hybrids, respectively. Both the proportion of individuals carrying MT alleles and MT allele frequency declined with depth. Furthermore, MT-introgressed individuals had significantly weaker and more elongate shells than nonintrogressed individuals. This study provides detailed insights into stock structure along a cultivation rope and suggests that practical methods to assess shell strength and shape of cultivated mussels may facilitate the rapid identification of MT, limiting the impact of this commercially damaging species.

Loss of Motility as a Non-Lethal Mechanism for Intercolony Inhibition ("Sibling Rivalry") in Marinobacter.

Bacteria from the genus Marinobacter are ubiquitous throughout the worlds' oceans as "opportunitrophs" capable of surviving a wide range of conditions, including colonization of surfaces of marine snow and algae. To prevent too many bacteria from occupying this ecological niche simultaneously, some sort of population dependent control must be operative. Here, we show that while Marinobacter do not produce or utilize an acylhomoserine lactone (AHL)-based quorum sensing system, "sibling" colonies of many species of Marinobacter exhibit a form of non-lethal chemical communication that prevents colonies from overrunning each other's niche space. Evidence suggests that this inhibition is the result of a loss in motility for cells at the colony interfaces. Although not the signal itself, we have identified a protein, glycerophosphoryl diester phosphodiesterase, that is enriched in the inhibition zone between the spreading colonies that may be part of the overall response.

Bacterial Associates Modify Growth Dynamics of the Dinoflagellate Gymnodinium catenatum.

Marine phytoplankton cells grow in close association with a complex microbial associate community known to affect the growth, behavior, and physiology of the algal host. The relative scale and importance these effects compared to other major factors governing algal cell growth remain unclear. Using algal-bacteria co-culture models based on the toxic dinoflagellate Gymnodinium catenatum, we tested the hypothesis that associate bacteria exert an independent effect on host algal cell growth. Batch co-cultures of G. catenatum were grown under identical environmental conditions with simplified bacterial communities composed of one-, two-, or three-bacterial associates. Modification of the associate community membership and complexity induced up to four-fold changes in dinoflagellate growth rate, equivalent to the effect of a 5°C change in temperature or an almost six-fold change in light intensity (20-115 moles photons PAR m-2 s-1). Almost three-fold changes in both stationary phase cell concentration and death rate were also observed. Co-culture with Roseobacter sp. DG874 reduced dinoflagellate exponential growth rate and led to a more rapid death rate compared with mixed associate community controls or co-culture with either Marinobacter sp. DG879, Alcanivorax sp. DG881. In contrast, associate bacteria concentration was positively correlated with dinoflagellate cell concentration during the exponential growth phase, indicating growth was limited by supply of dinoflagellate-derived carbon. Bacterial growth increased rapidly at the onset of declining and stationary phases due to either increasing availability of algal-derived carbon induced by nutrient stress and autolysis, or at mid-log phase in Roseobacter co-cultures potentially due to the onset of bacterial-mediated cell lysis. Co-cultures with the three bacterial associates resulted in dinoflagellate and bacterial growth dynamics very similar to more complex mixed bacterial community controls, suggesting that three-way co-cultures are sufficient to model interaction and growth dynamics of more complex communities. This study demonstrates that algal associate bacteria independently modify the growth of the host cell under non-limiting growth conditions and supports the concept that algal-bacterial interactions are an important structuring mechanism in phytoplankton communities.

MALDI-TOF Mass Spectrometry Discriminates Known Species and Marine Environmental Isolates of Pseudoalteromonas.

The genus Pseudoalteromonas constitutes an ecologically significant group of marine Gammaproteobacteria with potential biotechnological value as producers of bioactive compounds and of enzymes. Understanding their roles in the environment and bioprospecting for novel products depend on efficient ways of identifying environmental isolates. Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) biotyping has promise as a rapid and reliable method of identifying and distinguishing between different types of bacteria, but has had relatively limited application to marine bacteria and has not been applied systematically to Pseudoalteromonas. Therefore, we constructed a MALDI-TOF MS database of 31 known Pseudoalteromonas species, to which new isolates can be compared by MALDI-TOF biotyping. The ability of MALDI-TOF MS to distinguish between species was scrutinized by comparison with 16S rRNA gene sequencing. The patterns of similarity given by the two approaches were broadly but not completely consistent. In general, the resolution of MALDI-TOF MS was greater than that of 16S rRNA gene sequencing. The database was tested with 13 environmental Pseudoalteromonas isolates from UK waters. All of the test strains could be identified to genus level by MALDI-TOF MS biotyping, but most could not be definitely identified to species level. We conclude that several of these isolates, and possibly most, represent new species. Thus, further taxonomic investigation of Pseudoalteromonas is needed before MALDI-TOF MS biotyping can be used reliably for species identification. It is, however, a powerful tool for characterizing and distinguishing among environmental isolates and can make an important contribution to taxonomic studies.

Using Molecular Networking for Microbial Secondary Metabolite Bioprospecting.

The oceans represent an understudied resource for the isolation of bacteria with the potential to produce novel secondary metabolites. In particular, actinomyces are well known to produce chemically diverse metabolites with a wide range of biological activities. This study characterised spore-forming bacteria from both Scottish and Antarctic sediments to assess the influence of isolation location on secondary metabolite production. Due to the selective isolation method used, all 85 isolates belonged to the phyla Firmicutes and Actinobacteria, with the majority of isolates belonging to the genera Bacillus and Streptomyces. Based on morphology, thirty-eight isolates were chosen for chemical investigation. Molecular networking based on chemical profiles (HR-MS/MS) of fermentation extracts was used to compare complex metabolite extracts. The results revealed 40% and 42% of parent ions were produced by Antarctic and Scottish isolated bacteria, respectively, and only 8% of networked metabolites were shared between these locations, implying a high degree of biogeographic influence upon secondary metabolite production. The resulting molecular network contained over 3500 parent ions with a mass range of m/z 149-2558 illustrating the wealth of metabolites produced. Furthermore, seven fermentation extracts showed bioactivity against epithelial colon adenocarcinoma cells, demonstrating the potential for the discovery of novel bioactive compounds from these understudied locations.

The competitive dynamics of toxic Alexandrium fundyense and non-toxic Alexandrium tamarense: The role of temperature.

The dinoflagellate Alexandrium produces paralytic shellfish poisoning toxins. The genus is globally distributed, with Scottish waters being of particular interest due to the co-occurrence of different species and strains. In Scottish waters, Alexandrium was historically thought to be dominated by the highly toxic (Group I) Alexandrium fundyense. However, the morphologically indistinguishable (Group III) Alexandrium tamarense has recently also been found to co-occur, raising important questions in relation to Alexandrium biogeography. To begin to address these, we investigated Alexandrium growth, yield and toxin production in a range of temperature conditions characteristics of present and potential future conditions, using a recently developed flow cytometry method that allowed, for the first time, simultaneous enumeration of the cryptic species in co-culture. Experiments were undertaken in a range of temperatures (12, 15, 18 and 21°C) in the phosphate (P) limiting conditions that promotes A. fundyense toxicity. Cell/biomass yield was greater for A. tamarense at all temperatures, with observed growth rates varying with temperature. Growth rather and yield were different in mono- and co-culture with the outcome of these interactions also being temperature dependent. For toxic A. fundyense, GTX-3, STX and NEO were the dominant analogues, but total toxicity, toxicity per cell and the number of, and relative proportion of, toxin analogues changed in relation to the onset of P limitation and also as a function of temperature, with the highest toxin concentrations per cell being observed at 12°C. Toxin concentrations were approximately double in P limited stationary phase compared to exponential growth. Toxin concentrations were lower in the co-cultures, indicating inhibition of production in the presence of non-toxic A. tamarense. The strong performance of A. tamarense is in co-culture at odds with the historical understanding that Scottish waters were dominated by A. fundyense and indicates that changes in water temperatures, and also potentially alleopathic interactions, will influence Alexandrium populations and hence the PSP toxicity threat to humans from shellfish.

Bacterial Diversity Associated with the Coccolithophorid Algae Emiliania huxleyi and Coccolithus pelagicus f. braarudii.

Coccolithophores are unicellular calcifying marine phytoplankton that can form large and conspicuous blooms in the oceans and make significant contributions to oceanic carbon cycling and atmospheric CO2 regulation. Despite their importance, the bacterial diversity associated with these algae has not been explored for ecological or biotechnological reasons. Bacterial membership of Emiliania huxleyi and Coccolithus pelagicus f. braarudii cultures was assessed using cultivation and cultivation-independent methods. The communities were species rich compared to other phytoplankton cultures. Community analysis identified specific taxa which cooccur in all cultures (Marinobacter and Marivita). Hydrocarbon-degrading bacteria were found in all cultures. The presence of Acidobacteria, Acidimicrobidae, Schlegelella, and Thermomonas was unprecedented but were potentially explained by calcification associated with coccolith production. One strain of Acidobacteria was cultivated and is closely related to a marine Acidobacteria isolated from a sponge. From this assessment of the bacterial diversity of coccolithophores, a number of biotechnological opportunities are evident, from bioprospecting for novel taxa such as Acidobacteria to helping understand the relationship between obligate hydrocarbonoclastic bacteria occurrence with phytoplankton and to revealing bacterial taxa that have a specific association with algae and may be suitable candidates as a means to improve the efficiency of mass algal cultivation.

The effect of perhexiline on myocardial protection during coronary artery surgery: a two-centre, randomized, double-blind, placebo-controlled trial.

OBJECTIVES: Perhexiline is thought to modulate metabolism by inhibiting mitochondrial carnitine palmitoyltransferase-1, reducing fatty acid uptake and increasing carbohydrate utilization. This study assessed whether preoperative perhexiline improves markers of myocardial protection in patients undergoing coronary artery bypass graft surgery and analysed its effect on the myocardial metabolome. METHODS: In a prospective, randomized, double-blind, placebo-controlled trial, patients at two centres were randomized to receive either oral perhexiline or placebo for at least 5 days prior to surgery. The primary outcome was a low cardiac output episode in the first 6 h. All pre-specified analyses were conducted according to the intention-to-treat principle with a statistical power of 90% to detect a relative risk of 0.5 and a conventional one-sided α-value of 0.025. A subset of pre-ischaemic left ventricular biopsies was analysed using mass spectrometry-based metabolomics. RESULTS: Over a 3-year period, 286 patients were randomized, received the intervention and were included in the analysis. The incidence rate of a low cardiac output episode in the perhexiline arm was 36.7% (51/139) vs 34.7% (51/147) in the control arm [odds ratio (OR) 0.92, 95% confidence interval (CI) 0.56-1.50, P = 0.74]. Perhexiline was associated with a reduction in the cardiac index at 6 h [difference in means 0.19, 95% CI 0.07-0.31, P = 0.001] and an increase in inotropic support in the first 12 h (OR 0.55, 95% CI 0.34-0.89, P = 0.015). There were no significant differences in myocardial injury with troponin-T or electrocardiogram, reoperation, renal dysfunction or length of stay. No difference in the preischaemic left ventricular metabolism was identified between groups on metabolomics analysis. CONCLUSIONS: Preoperative perhexiline does not improve myocardial protection in patients undergoing coronary surgery and in fact reduced perioperative cardiac output, increasing the need for inotropic support. Perhexiline has no significant effect on the mass spectrometry-visible polar myocardial metabolome in vivo in humans, supporting the suggestion that it acts via a pathway that is independent of myocardial carnitine palmitoyltransferase inhibition and may explain the lack of clinical benefit observed following surgery. CLINICALTRIALSGOV ID: NCT00845364.

Continuous eclogite melting and variable refertilisation in upwelling heterogeneous mantle.

Large-scale tectonic processes introduce a range of crustal lithologies into the Earth's mantle. These lithologies have been implicated as sources of compositional heterogeneity in mantle-derived magmas. The model being explored here assumes the presence of widely dispersed fragments of residual eclogite (derived from recycled oceanic crust), stretched and stirred by convection in the mantle. Here we show with an experimental study that these residual eclogites continuously melt during upwelling of such heterogeneous mantle and we characterize the melting reactions and compositional changes in the residue minerals. The chemical exchange between these partial melts and more refractory peridotite leads to a variably metasomatised mantle. Re-melting of these metasomatised peridotite lithologies at given pressures and temperatures results in diverse melt compositions, which may contribute to the observed heterogeneity of oceanic basalt suites. We also show that heterogeneous upwelling mantle is subject to diverse local freezing, hybridization and carbonate-carbon-silicate redox reactions along a mantle adiabat.

Detection of photoactive siderophore biosynthetic genes in the marine environment.

Iron is an essential element for oceanic microbial life but its low bioavailability limits microorganisms in large areas of the oceans. To acquire this metal many marine bacteria produce organic chelates that bind and transport iron (siderophores). While it has been hypothesized that the global production of siderophores by heterotrophic bacteria and some cyanobacteria constitutes the bulk of organic ligands binding iron in the ocean because stability constants of siderophores and these organic ligands are similar, and because ligand concentrations rise sharply in response to iron fertilization events, direct evidence for this proposal is lacking. This lack is due to the difficulty in characterizing these ligands due both to their extremely low concentrations and their highly heterogeneous nature. The situation for characterizing photoactive siderophores in situ is more problematic because of their expected short lifetimes in the photic zone. An alternative approach is to make use of high sensitivity molecular technology (qPCR) to search for siderophore biosynthesis genes related to the production of photoactive siderophores. In this way one can access their "biochemical potential" and utilize this information as a proxy for the presence of these siderophores in the marine environment. Here we show, using qPCR primers designed to detect biosynthetic genes for the siderophores vibrioferrin, petrobactin and aerobactin that such genes are widespread and based on their abundance, the "biochemical potential" for photoactive siderophore production is significant. Concurrently we also briefly examine the microbial biodiversity responsible for such production as a function of depth and location across a North Atlantic transect.

Polycyclovorans algicola gen. nov., sp. nov., an aromatic-hydrocarbon-degrading marine bacterium found associated with laboratory cultures of marine phytoplankton.

A strictly aerobic, halotolerant, rod-shaped bacterium, designated strain TG408, was isolated from a laboratory culture of the marine diatom Skeletonema costatum (CCAP1077/1C) by enrichment with polycyclic aromatic hydrocarbons (PAHs) as the sole carbon source. 16S rRNA gene sequence analysis placed this organism within the order Xanthomonadales of the class Gammaproteobacteria. Its closest relatives included representatives of the Hydrocarboniphaga-Nevskia-Sinobacter clade (<92% sequence similarity) in the family Sinobacteraceae. The strain exhibited a narrow nutritional spectrum, preferring to utilize aliphatic and aromatic hydrocarbon compounds and small organic acids. Notably, it displayed versatility in degrading two- and three-ring PAHs. Moreover, catechol 2,3-dioxygenase activity was detected in lysates, indicating that this strain utilizes the meta-cleavage pathway for aromatic compound degradation. Cells produced surface blebs and contained a single polar flagellum. The predominant isoprenoid quinone of strain TG408 was Q-8, and the dominant fatty acids were C(16:0), C(16:1) ω7c, and C(18:1) ω7c. The G+C content of the isolate's DNA was 64.3 mol% ± 0.34 mol%. On the basis of distinct phenotypic and genotypic characteristics, strain TG408 represents a novel genus and species in the class Gammaproteobacteria for which the name Polycyclovorans algicola gen. nov., sp. nov., is proposed. Quantitative PCR primers targeting the 16S rRNA gene of this strain were developed and used to show that this organism is found associated with other species of marine phytoplankton. Phytoplankton may be a natural biotope in the ocean where new species of hydrocarbon-degrading bacteria await discovery and which contribute significantly to natural remediation processes.

Metal binding properties of the EPS produced by Halomonas sp. TG39 and its potential in enhancing trace element bioavailability to eukaryotic phytoplankton.

An emergent property of exopolysaccharides (EPS) produced by marine bacteria is their net negative charge, predominantly conferred by their high uronic acids content. Here, we investigated the EPS produced by an algal-associated marine bacterium, Halomonas sp. strain TG39, for its capacity to sequester trace metals and mediate their bioavailability to eukaryotic phytoplankton. Metal analysis of the purified EPS revealed that it contained high levels of K, Ca, Mg and several essential trace metals, including Zn, Cu, Fe and the metalloid Si. Desorption experiments with marine sediment showed that the EPS possessed a specific binding capacity for Ca, Si, Fe, Mn, Mg and Al. Depending on the ionic conditions, Fe was the third or fourth most highly-adsorbed metal out of 27 elements analyzed. Experiments employing Fe-limited synthetic ocean seawater showed that growth of the marine diatom Thalassiosira weissflogii (axenic strain) was enhanced when incubated in the presence of either purified EPS or EPS that had been pre-exposed to marine sediment, compared to non-EPS amended controls. This growth enhancement was attributed to the EPS binding and increasing the bioavailability of key trace metal elements, such as Fe(III). Since the bacterium used in this study was originally isolated from a marine micro-alga, this work highlights the possibility that bacterial associates of eukaryotic algae could be influencing the bioavailability of Fe(III) to phytoplankton via their production of polyanionic EPS. More widely, this work reinforces the potential importance of marine bacterial EPS in trace metal biogeochemical cycling.

Algiphilus aromaticivorans gen. nov., sp. nov., an aromatic hydrocarbon-degrading bacterium isolated from a culture of the marine dinoflagellate Lingulodinium polyedrum, and proposal of Algiphilaceae fam. nov.

A strictly aerobic, halotolerant, Gram-stain-negative, rod-shaped bacterium, designated strain DG1253(T), was isolated from a laboratory culture of the marine dinoflagellate Lingulodinium polyedrum (CCAP 1121/2). The strain was able to degrade two- and three-ring polycyclic aromatic hydrocarbons. It exhibited a narrow nutritional spectrum, preferring to utilize aliphatic and aromatic hydrocarbon compounds and small organic acids. Cells produced surface blebs and contained a single polar flagellum. The predominant isoprenoid quinone of strain DG1253(T) was Q-8. The fatty acid profile was dominated by C(18:1)ω7c. The mean DNA G+C content of strain DG1253(T) was 63.6 ± 0.25 mol%. 16S rRNA gene sequence analysis placed this organism within the order Xanthomonadales of the class Gammaproteobacteria. Its closest relatives included representatives of the Hydrocarboniphaga-Nevskia-Sinobacter clade (≤ 89.9% 16S rRNA gene sequence similarity) in the family Sinobacteraceae. On the basis of distinct phenotypic and genotypic characteristics, strain DG1253(T) is considered to represent a novel species of a new genus in the class Gammaproteobacteria, for which the name Algiphilus aromaticivorans gen. nov., sp. nov. is proposed. The type strain of the type species, Algiphilus aromaticivorans, is DG1253(T) (=ATCC BAA-2243(T)=DSM 24793(T)). In addition, a new family, Algiphilaceae fam. nov., is proposed to accommodate the genus Algiphilus.

Siderophore-mediated iron uptake in two clades of Marinobacter spp. associated with phytoplankton: the role of light.

Iron is an essential element for oceanic microbial life but its low bioavailability limits microorganisms in large areas of the oceans. To acquire this metal many marine bacteria produce organic chelates that bind and transport iron (siderophores). We have previously shown that algal-associated heterotrophic bacteria belonging to the γ-proteobacterial Marinobacter genus release the siderophore vibrioferrin (VF). The iron-VF complex was shown to be both far more photolabile than all previously examined photolabile siderophores and to generate a photoproduct incapable of re-chelating the released iron. Thus, the photo-generated iron was shown to be highly bioavailable both to the producing bacterium and its algal partner. In exchange, we proposed that algal cells produced dissolved organic matter that helped support bacterial growth and ultimately fueled the biosynthesis of VF through a light-dependent "carbon for iron mutualism". While our knowledge of the importance of light to phototrophs is vast, there are almost no studies that examine the effects of light on microbial heterotrophs. Here, we characterize iron uptake mechanisms in "algal-associated" VF-producers. Fe uptake by a VF knock-out mutant mimics the wild-type strain and demonstrates the versatility of iron uptake mechanisms in Marinobacter VF-producers. We also show that VF-producers selectively regulate a subset of their siderophore-dependent iron uptake genes in response to light exposure. The regulation of iron uptake and transport genes by light is consistent with the light driven algal-bacterial "carbon for iron mutualism" hypothesis in the marine environment.

Iron transport in the genus Marinobacter.

Marinobacter belong to the class of Gammaproteobacteria and these motile, halophilic or halotolerent bacteria are widely distributed throughout the world's oceans having been isolated from a wide variety of marine environments. They have also been identified as members of the bacterial flora associated with other marine organisms. Here, using a combination of natural products chemistry and genomic analysis, we assess the nature of the siderophores produced by this genus and their potential relationship to phylogeny and lifestyle/ecological niche of this diverse group of organisms. Our analysis shows a wide level of diversity in siderophore based iron uptake systems among this genus with three general strategies: (1) production and utilization of native siderophores in addition to utilization of a variety of exogenous ones, (2) production and utilization of native siderophores only, (3) lack of siderophore production but utilization of exogenous ones. They all share the presence of at least one siderophore-independent iron uptake ABC transport systems of the FbpABC iron metal type and lack the ability for direct transport of ferrous iron. Siderophore production and utilization can be correlated with phylogeny and thus it forms a type of chemotaxonomic marker for this genus.

Coupling of dimethylsulfide oxidation to biomass production by a marine flavobacterium.

Dimethylsulfide (DMS) is an important climatically active gas. In the sea, DMS is produced primarily by microbial metabolism of the compatible solute dimethylsulfoniopropionate. Laboratory growth of Bacteroidetes with DMS resulted in its oxidation to dimethyl sulfoxide but only in the presence of glucose. We hypothesized that electrons liberated from sulfur oxidation were used to augment biomass production.