Comparative Genomics and Mutational Analysis Reveals a Novel XoxF-Utilizing Methylotroph in the Roseobacter Group Isolated From the Marine Environment

The Roseobacter group comprises a significant group of marine bacteria which are involved in global carbon and sulfur cycles. Some members are methylotrophs, using one-carbon compounds as a carbon and energy source. It has recently been shown that methylotrophs generally require a rare earth element when using the methanol dehydrogenase enzyme XoxF for growth on methanol. Addition of lanthanum to methanol enrichments of coastal seawater facilitated the isolation of a novel methylotroph in the Roseobacter group: Marinibacterium anthonyi strain La 6. Mutation of xoxF5 revealed the essential nature of this gene during growth on methanol and ethanol. Physiological characterization demonstrated the metabolic versatility of this strain. Genome sequencing revealed that strain La 6 has the largest genome of all Roseobacter group members sequenced to date, at 7.18 Mbp. Multilocus sequence analysis (MLSA) showed that whilst it displays the highest core gene sequence similarity with subgroup 1 of the Roseobacter group, it shares very little of its pangenome, suggesting unique genetic adaptations. This research revealed that the addition of lanthanides to isolation procedures was key to cultivating novel XoxF-utilizing methylotrophs from the marine environment, whilst genome sequencing and MLSA provided insights into their potential genetic adaptations and relationship to the wider community

Combining metagenomics with metaproteomics and stable isotope probing reveals metabolic pathways used by a naturally occurring marine methylotroph

A variety of culture-independent techniques have been developed that can be used in conjunction with culture-dependent physiological and metabolic studies of key microbial organisms, in order to better understand how the activity of natural populations influences and regulates all major biogeochemical cycles. In this study, we combined DNA-stable isotope probing with metagenomics and metaproteomics to characterize an as yet uncultivated marine methylotroph that actively incorporated carbon from 13C-labeled methanol into biomass. By metagenomic sequencing of the heavy DNA, we retrieved virtually the whole genome of this bacterium and determined its metabolic potential. Through protein-stable isotope probing, the RuMP cycle was established as the main carbon assimilation pathway, and the classical methanol dehydrogenase-encoding gene mxaF, as well as three out of four identified xoxF homologues were found to be expressed. This proof-of-concept study is the first in which theculture-independent techniques of DNA- and protein-stable isotope probing have been used to characterize the metabolism of a naturally-ocurring Methylophaga-like bacterium in the marine environment (i.e. M. thiooxydans L4) and thus provides a powerful approach to access the genome and proteome of uncultivated microbes involved in key processes in the environment

Communal metabolism by Methylococcaceae and Methylophilaceae is driving rapid aerobic methane oxidation in sediments of a shallow seep near Elba, Italy

Release of abiotic methane from marine seeps into the atmosphere is a major source of this potent greenhouse gas. Methanotrophic microorganisms in methane seeps use methane as carbon and energy source, thus significantly mitigating global methane emissions. Here we investigated microbial methane oxidation at the sediment-water interface of a shallow marine methane seep. Metagenomics and metaproteomics, combined with 13C-methane stable isotope probing, demonstrated that various members of the gammaproteobacterial family Methylococcaceae were the key players for methane oxidation, catalyzing the first reaction step to methanol. We observed a transfer of carbon to methanol-oxidizing methylotrophs of the betaproteobacterial family Methylophilaceae, suggesting an interaction between methanotrophic and methylotrophic microorganisms that allowed for rapid methane oxidation. From our microcosms, we estimated methane oxidation rates of up to 871 nmol of methane per gram sediment and day. This implies that more than 50% of methane at the seep is removed by microbial oxidation at the sediment-water interface, based on previously reported in situ methane fluxes. The organic carbon produced was further assimilated by different heterotrophic microbes, demonstrating that the methane-oxidizing community supported a complex trophic network. Our results provide valuable eco-physiological insights into this specialized microbial community performing an ecosystem function of global relevance

Morbidity of schistosomiasis mansoni in a low endemic setting in Ouro Preto, Minas Gerais, Brazil.

Introduction: Despite the advances of disease control programs, severe forms of schistosomiasis are prevalent. The prevalence of the disease in areas frequented by tourists urges for permanent prevention and control. The aim of this study was to describe the morbidity of schistosomiasis in the district of Ant?nio Pereira, Ouro Preto, Minas Gerais, Brazil. Methods: The proportion of positives was defined by Kato-Katz coproscopy and urinary POC-CCA rapid test. Hepatosplenic form was diagnosed using abdominal ultrasound. Results: Out of 180 participants,97 were examined by Kato-Katz, with 4 (4.1%) being positive. Thirtyfour (22.1%) out of 154 were positive by POC-CCA. Five (2.8%) of 177 examined by ultrasound had hepatosplenic form. One of them had undergone splenectomy. One (0.6%)participant had myeloradiculopathy. Conclusions: Severe forms of schistosomiasis are still prevalent in low endemic areas and should be thoroughly investigated

Contribution des picoeucaryotes photosynthétiques à la biomasse picoplanctonique et au carbone organique particulaire total dans l'océan ouvert

It has been known since the early eighties that picophytoplankton (50% in most of the studied area) and total phytoplankton carbon biomass (>20% in the open ocean), being indeed essential in determining the spatial variability of the former. However, this group's contribution to the diel variability in the cp-derived POC concentration was not significant (~10%). Daily rates of change (d-1) in picophytoplankton biomass, on the other hand, presented a significant positive correlation to those in cp (r = 0.7; p 50% dans la plupart de la zone d'étude) et phytoplanctonique totale (>20% dans l'océan ouvert), déterminant la variabilité spatiale de la première. De plus, la contribution de ce groupe à la variabilité journalière de la concentration de COP n'était pas significative (~10%). Les taux de changement journaliers de cp (d-1), d'une autre parte, étaient significativement corrélés à ceux de la biomasse picophytoplanctonique (r = 0.7; p < 0.001). L'utilité de cp comme proxy de la biomasse picophytoplanctonique est brièvement discutée par rapport à celle de la chlorophylle a. La biomasse des picophytoeucaryotes était beaucoup plus importante de ce qui était initialement anticipé, étant souvent plus importants que celle des Prochlorococcus dans l'océan ouvert. Les picophytoeucaryotes jouerait donc un rôle écologique et biogéochimique dominant dans les gyres subtropicaux, lesquelles occupent une vaste superficie de l'océan mondial

Contribution of photosynthetic picoeukaryotes to the picoplanktonic carbon biomass and to total particulate organic carbon in the open ocean

Le picophytoplancton (diamètre 50% dans la plupart de la zone d étude) et phytoplanctonique totale (>20% dans l océan ouvert), déterminant la variabilité spatiale de la première. De plus, la contribution de ce groupe à la variabilité journalière de la concentration de COP n était pas significative (~10%). Les taux de changement journaliers de cp (d-1), d une autre parte, étaient significativement corrélés à ceux de la biomasse picophytoplanctonique (r = 0.7; p < 0.001). L utilité de cp comme proxy de la biomasse picophytoplanctonique est brièvement discutée par rapport à celle de la chlorophylle a. La biomasse des picophytoeucaryotes était beaucoup plus importante de ce qui était initialement anticipé, étant souvent plus importants que celle des Prochlorococcus dans l océan ouvert. Les picophytoeucaryotes jouerait donc un rôle écologique et biogéochimique dominant dans les gyres subtropicaux, lesquelles occupent une vaste superficie de l océan mondial.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Sci.Terre recherche (751052114) / SudocSudocFranceF

CUANTIFICACION DEL TRANSPORTE DE AGUA COSTA-OCEANO A TRAVES DE FILAMENTOS Y REMOLINOS RICOS EN CLOROFILA a, EN LA ZONA CENTRO-SUR DE CHILE (35.5-37.5°S) CUANTIFICATION OF COAST-OCEAN WATER TRANSPORT THROUGH FILAMENTS AND EDDIES WITH HIGH CHLOROPHYLL a CONTENT, IN CENTRAL-SOUTH CHILE (35.5-37.5°S)

Se cuantificó el transporte neto de agua superficial entre la zona costera y zona oceánica a través de estructuras de mesoescala (filamentos y remolinos) identificadas a partir de imágenes satelitales diarias de clorofila a (SeaWIFS). El transporte se cuantificó en el sector comprendido entre los 35.5 y 37.5°S de la zona centro-sur de Chile, para un período de 15 días en octubre de 1998 y otro de igual duración en julio de 1999, correspondientes a los cruceros MIRC I y MIRC II. En ambos cruceros el transporte neto de agua tuvo lugar desde la zona costera hacia la zona oceánica, con 6.22 x 10(4) m³ s-1 para el período del MIRC I y de 1.64 x 10(4) m³ s-1 para el MIRC II. El sector centro-sur de Chile estudiado es un exportador neto de agua a través de filamentos y remolinos<br>The net transport of surface water, between the coastal and oceanic zone, through mesoscale structures such as filaments and eddies was quantified in central-south Chile (35.5 to 37.5°S). This transport was quantified by identifying filaments and eddies on daily chlorophyll a images (SeaWIFS) for two 15 days periods taking place in October 1998 and in July 1999. These periods correspond to the MIRC I and MIRC II cruises respectively. In both cruises the estimated superficial transport showed a net flow from the coastal to the oceanic zone, of 6.22 x 10(4) m³ s-1 and 1.64 x 10(4) m³ s-1 during MIRC I and MIRC II, respectively. The central-south part of Chile is a net exporter of water through filaments and eddie