Geofilum rubicundum gen. nov., sp. nov., isolated from deep subseafloor sediment

Appropriate characterization of reservoir properties and investigation of their effect on microbial enhanced oil recovery through simulated laboratory studies

Appropriate characterization of reservoir properties and investigation of the effect of these properties on microbial metabolism and oil recovery under simulated reservoir conditions can aid in development of a sustainable microbial enhanced oil recovery (MEOR) process. Our present study has unveiled the promising potential of the hyperthermophilic archaeon, identified as Thermococcus petroboostus sp. nov. 101C5, to positively influence the microenvironment within simulated oil reservoirs, by producing significant amounts of metabolites, such as biosurfactants, biopolymers, biomass, acids, solvents, gases. These MEOR desired metabolites were found to cause a series of desirable changes in the physicochemical properties of crude oil and reservoir rocks, thereby enhancing oil recovery. Furthermore, our study demonstrated that the microbial activity of 101C5 led to the mobilization of crude oil, consequently resulting in enhanced production rates and increased efficiency in simulated sand pack trials. 101C5 exhibited considerable potential as a versatile microorganism for MEOR applications across diverse reservoir conditions, mediating significant light as well as heavy oil recovery from Berea/carbonaceous nature of rock bearing intergranular/vugular/fracture porosity at extreme reservoir conditions characterized by high temperature (80-101 °C) and high pressure (700-1300 psi). Core flood study, which truly mimicked the reservoir conditions demonstrated 29.5% incremental oil recovery by 101C5 action from Berea sandstone at 900 psi and 96 °C, underscoring the potential of strain 101C5 for application in the depleted high temperature oil wells.

Xiashengella succiniciproducens gen. nov., sp. nov., a succinate-producing bacterium isolated from an anaerobic digestion tank in the family Marinilabiliaceae of the order Bacteroidales

A strictly anaerobic, motile bacterium, designated as strain Ai-910T, was isolated from the sludge of an anaerobic digestion tank in China. Cells were Gram-stain-negative rods. Optimal growth was observed at 38 °C (growth range 25-42 °C), pH 8.5 (growth range 5.5-10.5), and under a NaCl concentration of 0.06% (w/v) (range 0-2.0%). Major cellular fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The respiratory quinone was MK-7. Using xylose as the growth substrate, succinate was produced as the fermentation product. Phylogenetic analysis based on the 16 S rRNA gene sequences indicated that strain Ai-910T formed a distinct phylogenetic lineage that reflects a new genus in the family Marinilabiliaceae, sharing high similarities to Alkaliflexus imshenetskii Z-7010T (92.78%), Alkalitalea saponilacus SC/BZ-SP2T (92.51%), and Geofilum rubicundum JAM-BA0501T (92.36%). Genomic similarity (average nucleotide identity and digital DNA-DNA hybridization) values between strain Ai-910T and its phylogenetic neighbors were below 65.27 and 16.90%, respectively, indicating that strain Ai-910T represented a novel species. The average amino acid identity between strain Ai-910T and other related members of the family Marinilabiliaceae were below 69.41%, supporting that strain Ai-910T was a member of a new genus within the family Marinilabiliaceae. Phylogenetic, genomic, and phenotypic analysis revealed that strain Ai-910T was distinguished from other phylogenetic relatives within the family Marinilabiliaceae. The genome size was 3.10 Mbp, and the DNA G + C content of the isolate was 42.8 mol%. Collectively, differences of the phenotypic and phylogenetic features of strain Ai-910T from its close relatives suggest that strain Ai-910T represented a novel species in a new genus of the family Marinilabiliaceae, for which the name Xiashengella succiniciproducens gen. nov., sp. nov. was proposed. The type strain of Xiashengella succiniciproducens is Ai-910T (= CGMCC 1.17893T = KCTC 25,304T).

Quantitative assessment of exposure to fecal contamination in urban environment across nine cities in low-income and lower-middle-income countries and a city in the United States

BACKGROUND

During 2014 to 2019, the SaniPath Exposure Assessment Tool, a standardized set of methods to evaluate risk of exposure to fecal contamination in the urban environment through multiple exposure pathways, was deployed in 45 neighborhoods in ten cities, including Accra and Kumasi, Ghana; Vellore, India; Maputo, Mozambique; Siem Reap, Cambodia; Atlanta, United States; Dhaka, Bangladesh; Lusaka, Zambia; Kampala, Uganda; Dakar, Senegal.

OBJECTIVE

Assess and compare risk of exposure to fecal contamination via multiple pathways in ten cities.

METHODS

In total, 4053 environmental samples, 4586 household surveys, 128 community surveys, and 124 school surveys were collected. E. coli concentrations were measured in environmental samples as an indicator of fecal contamination magnitude. Bayesian methods were used to estimate the distributions of fecal contamination concentration and contact frequency. Exposure to fecal contamination was estimated by the Monte Carlo method. The contamination levels of ten environmental compartments, frequency of contact with those compartments for adults and children, and estimated exposure to fecal contamination through any of the surveyed environmental pathways were compared across cities and neighborhoods.

RESULTS

Distribution of fecal contamination in the environment and human contact behavior varied by city. Universally, food pathways were the most common dominant route of exposure to fecal contamination across cities in low-income and lower-middle-income countries. Risks of fecal exposure via water pathways, such as open drains, flood water, and municipal drinking water, were site-specific and often limited to smaller geographic areas (i.e., neighborhoods) instead of larger areas (i.e., cities).

CONCLUSIONS

Knowledge of the relative contribution to fecal exposure from multiple pathways, and the environmental contamination level and frequency of contact for those "dominant pathways" could provide guidance for Water, Sanitation, and Hygiene (WASH) programming and investments and enable local governments and municipalities to improve intervention strategies to reduce the risk of exposure to fecal contamination.

Use of Microorganisms in the Recovery of Oil From Recalcitrant Oil Reservoirs: Current State of Knowledge, Technological Advances and Future Perspectives

The depletion of oil resources, increasing global energy demand, the current low, yet unpredictable, price of oil, and increasing maturity of major oil fields has driven the need for the development of oil recovery technologies that are less costly and, where possible, environmentally compatible. Using current technologies, between 20 and 40% of the original oil in a reservoir can be extracted by conventional production operations (e.g., vertical drilling), with secondary recovery methods yielding a further 15-25%. Hence, up to 55% of the original oil can remain unrecovered in a reservoir. Enhanced oil recovery (EOR) is a tertiary recovery process that involves application of different thermal, chemical, and microbial processes to recover an additional 7-15% of the original oil in place (OOIP) at an economically feasible production rate from poor-performing and depleted oil wells. EOR can significantly impact oil production, as increase in the recovery rate of oil by even a small margin could bring significant revenues without developing unconventional resources. Microbial enhanced oil recovery (MEOR) is an attractive, alternative oil recovery approach, which is claimed to potentially recover up to 50% of residual oil. The in situ production of biological surface-active compounds (e.g., biosurfactants) during the MEOR process does not require vast energy inputs and are not affected by global crude oil prices. Compared to other EOR methods, MEOR can be an economically and more environmentally friendly alternative. In this review, the current state of knowledge of MEOR, with insights from discussions with the industry and other stakeholders, is presented and in addition to the future outlook for this technology.

Analysis of 1,000 Type-Strain Genomes Improves Taxonomic Classification of Bacteroidetes

Although considerable progress has been made in recent years regarding the classification of bacteria assigned to the phylum Bacteroidetes, there remains a need to further clarify taxonomic relationships within a diverse assemblage that includes organisms of clinical, piscicultural, and ecological importance. Bacteroidetes classification has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees and a limited number of phenotypic features. Here, draft genome sequences of a greatly enlarged collection of genomes of more than 1,000 Bacteroidetes and outgroup type strains were used to infer phylogenetic trees from genome-scale data using the principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families and genera, including taxa proposed long ago such as Bacteroides, Cytophaga, and Flavobacterium but also quite recent taxa, as well as a few species were shown to be in need of revision. According proposals are made for the recognition of new orders, families and genera, as well as the transfer of a variety of species to other genera. In addition, emended descriptions are given for many species mainly involving information on DNA G+C content and (approximate) genome size, both of which can be considered valuable taxonomic markers. We detected many incongruities when comparing the results of the present study with existing classifications, which appear to be caused by insufficiently resolved 16S rRNA gene trees or incomplete taxon sampling. The few significant incongruities found between 16S rRNA gene and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences and the impediment in using ordinary bootstrapping in phylogenomic studies, particularly when combined with too narrow gene selections. While a significant degree of phylogenetic conservation was detected in all phenotypic characters investigated, the overall fit to the tree varied considerably, which is one of the probable causes of misclassifications in the past, much like the use of plesiomorphic character states as diagnostic features.

Carboxylicivirga sediminis sp. nov., isolated from coastal sediment

A yellow-pigmented bacterial strain (JR1^T) isolated from a sediment sample was subjected to a taxonomic study, based on phenotypic, genetic and physiological characterization. Here, we describe the cultivation and characteristics of strain JR1^T, a novel member of the genus Carboxylicivirga in the family Marinilabiliaceae. Cells of strain JR1^T were rod-shaped, Gram-stain-negative, non-motile and facultatively anaerobic. The temperature range for growth was 15-42 °C (optimum, 33 °C) and the pH range for growth was pH 6.0-8.5 (optimum, pH 7.0-7.5). Growth occurred in the presence of 0.0-10.0 % (w/v) NaCl (optimum 2.0-3.0 %). 16S rRNA gene sequence analysis produced results with 97.4 % similarity to Carboxylicivirga taeanensisMEBiC 08903^T, 96.8 % similarity to Carboxylicivirga mesophilaMEBiC 07026^T, 94.9 % similarity to Carboxylicivirga linearis FB218^T and 94.6 % similarity to Carboxylicivirga flava Q15^T. The DNA G+C content was 42.3 mol% and the major fatty acids were iso-C15 : 0, C15 : 0, anteiso-C15 : 0, C17 : 1ω6c and iso-C17 : 0-3OH. The major polar lipids detected were phosphatidylethanolamine and two unidentified lipids; the major respiratory quinone detected was MK-7. The results of the phenotypical, phylogenetic and biochemical analyses between the study strain and some related type strains indicated that this strain represent a novel species of the genus Carboxylicivirga within the family Marinilabiliaceae, for which the name Carboxylicivirga sediminis sp. nov. is proposed. The type strain is JR1^T (=MCCC 1K03323^T=KCTC 52869^T).

Biofilm formation and granule properties in anaerobic digestion at high salinity

For the anaerobic biological treatment of saline wastewater, Anaerobic Digestion (AD) is currently a possibility, even though elevated salt concentrations can be a major obstacle. Anaerobic consortia and especially methanogenic archaea are very sensitive to fluctuations in salinity. When working with Upflow Sludge Blanket Reactor (UASB) technology, in which the microorganisms are aggregated and retained in the system as a granular biofilm, high sodium concentration negatively affects aggregation and consequently process performances. In this research, we analysed the structure of the biofilm and granules formed during the anaerobic treatment of high salinity (at 10 and 20 g/L of sodium) synthetic wastewater at lab scale. The acclimated inoculum was able to accomplish high rates of organics removal at all the salinity levels tested. 16S rRNA gene clonal analysis and Fluorescence In Situ Hybridization (FISH) analyses identified the acetoclastic Methanosaeta harundinacea as the key player involved acetate degradation and microbial attachment/granulation. When additional calcium (1 g/L) was added to overcome the negative effect of sodium on microbial aggregation, during the biofilm formation process microbial attachment and acetate degradation decreased. The same result was observed on granules formation: while calcium had a positive effect on granules strength when added to UASB reactors, Methanosaeta filaments were not present and the degradation of the partially acidified substrate was negatively influenced. This research demonstrated the possibility to get granulation at high salinity, bringing to the forefront the importance of a selection towards Methanosaeta cells growing in filamentous form to obtain strong and healthy granules.

Labilibacter aurantiacus gen. nov., sp. nov., isolated from sea squirt (Styela clava) and reclassification of Saccharicrinis marinus as Labilibacter marinus comb. nov

A Gram-stain-negative, facultatively anaerobic, orange-pigmented bacterium, designated HQYD1T, was isolated from a sea squirt (Styelaclava) and characterized using a polyphasic approach. Morphologically, strain HQYD1T exhibited rods with gliding motility. This novel isolate grew optimally at 28 °C in the presence of 2-3 % (w/v) NaCl. The 16S rRNA gene sequence was most similar to [Saccharicrinis] marinus Y11T (96.3 %), followed by Saccharicinis fermentans DSM 9555T (93.8 %). The dominant fatty acids of strain HQYD1T were identified as C16 : 0, C18 : 0 and iso-C15 : 0. Major polar lipids included an unidentified lipid and a phospholipid. The major respiratory quinone was found to be MK-7, and the genomic DNA G+C content was determined to be 35.1 mol%. Based on evidence from this taxonomic study, a novel genus, Labilibacter gen. nov., is proposed in the family Marinilabiliaceae with type species Labilibacter aurantiacus sp. nov. The type strain of the type species is HQYD1T (=MCCC 1K02304T=KCTC 42583T). As [Saccharicrinis] marinus Y11T clustered phylogenetically with strain HQYD1T, we also propose [Saccharicrinis] marinus Y11T be reclassified as Labilibacter marinus comb. nov. (type strain Y11T=CICC 10837T=KCTC 42400T).

Carboxylicivirga flava sp. nov., isolated from marine surface sediment

A novel bacterial strain, designated Q15T, was isolated from sediments obtained from the Bohai Sea in China and subjected to a polyphasic taxonomic study. Cells of strain Q15T were Gram-stain-negative, strictly aerobic rods that produced circular, flat, orange colonies. Phylogenetic analysis based on 16S rRNA gene sequences revealed that Q15T was affiliated with the genus Carboxylicivirga in the family Marinilabiliaceae of the phylum Bacteroidetes. Strain Q15T differed genotypically from the type strains of the three recognized species of this genus (Carboxylicivirga taeanensis MEBiC 08903T, Carboxylicivirga mesophila MEBiC 07026T and Carboxylicivirga linearis FB218T) and shared 94.0-95.2 % 16S rRNA gene sequence similarity with them. The DNA G+C content of strain Q15T was 44.7 mol%. The predominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and iso-C17 : 0 3-OH, and menaquinone MK-7 was the main respiratory quinone. Polar lipids contained phosphatidylethanolamine, an unidentified aminolipid, an unidentified phospholipid and other unknown lipids. Based on the data from the current polyphasic analysis, a novel species, Carboxylicivirga flava sp. nov., is hereby proposed with Q15T (=CICC 23923T=KCTC 42707T) as the type strain.

Description of Ancylomarina subtilis gen. nov., sp. nov., isolated from coastal sediment, proposal of Marinilabiliales ord. nov. and transfer of Marinilabiliaceae, Prolixibacteraceae and Marinifilaceae to the order Marinilabiliales

A Gram-stain-negative, facultatively anaerobic, moderately halophilic, filamentous, non-motile bacterium, designated FA102T, was isolated from marine sediment from the coast of Weihai, PR China. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain FA102T formed a distinct evolutionary lineage within the family Marinifilaceae and its closest relative was Marinifilum fragile JCM 15579T (93.2 % sequence similarity). The DNA G+C content of the novel strain was 36.5 mol%. The predominant cellular fatty acids and respiratory quinone were iso-C15 : 0 and iso-C15 : 0 3-OH, and MK-7, respectively. On the basis of the phylogenetic, phenotypic and physiological data, strain FA102T represents a novel genus and species, for which the name Ancylomarina subtilis gen. nov., sp. nov. is proposed. The type strain of Ancylomarina subtilis is FA102T (=KCTC 42257T=DSM 28825T=CICC 10902T). Furthermore, a new order named Marinilabiliales is proposed to accommodate three families previously classified in the order Bacteroidales. Marinilabiliales ord. nov. encompasses the families Marinilabiliaceae, Prolixibacteraceae and Marinifilaceae.

Variance and potential niche separation of microbial communities in subseafloor sediments off Shimokita Peninsula, Japan

Subseafloor pelagic sediments with high concentrations of organic matter form habitats for diverse microorganisms. Here, we determined depth profiles of genes for SSU rRNA, mcrA, dsrA and amoA from just beneath the seafloor to 363.3 m below the seafloor (mbsf) using core samples obtained from the forearc basin off the Shimokita Peninsula. The molecular profiles were combined with data on lithostratigraphy, depositional age, sedimentation rate and pore-water chemistry. The SSU rRNA gene tag structure and diversity changed at around the sulfate-methane transition zone (SMTZ), whereas the profiles varied further with depth below the SMTZ, probably in connection with the variation in pore-water chemistry. The depth profiles of diversity and abundance of dsrA, a key gene for sulfate reduction, suggested the possible niche separations of sulfate-reducing populations, even below the SMTZ. The diversity and abundance patterns of mcrA, a key gene for methanogenesis/anaerobic methanotrophy, suggested a stratified distribution and separation of anaerobic methanotrophy and hydrogenotrophic or methylotrophic methanogensis below the SMTZ. This study provides novel insights into the relationships between the composition and function of microbial communities and the chemical environment in the nutrient-rich continental margin subseafloor sediments, which may result in niche separation and variability in subseafloor microbial populations.

The Characterization of Novel Tissue Microbiota Using an Optimized 16S Metagenomic Sequencing Pipeline

Background

Substantial progress in high-throughput metagenomic sequencing methodologies has enabled the characterisation of bacteria from various origins (for example gut and skin). However, the recently-discovered bacterial microbiota present within animal internal tissues has remained unexplored due to technical difficulties associated with these challenging samples.

Results

We have optimized a specific 16S rDNA-targeted metagenomics sequencing (16S metabarcoding) pipeline based on the Illumina MiSeq technology for the analysis of bacterial DNA in human and animal tissues. This was successfully achieved in various mouse tissues despite the high abundance of eukaryotic DNA and PCR inhibitors in these samples. We extensively tested this pipeline on mock communities, negative controls, positive controls and tissues and demonstrated the presence of novel tissue specific bacterial DNA profiles in a variety of organs (including brain, muscle, adipose tissue, liver and heart).

Conclusion

The high throughput and excellent reproducibility of the method ensured exhaustive and precise coverage of the 16S rDNA bacterial variants present in mouse tissues. This optimized 16S metagenomic sequencing pipeline will allow the scientific community to catalogue the bacterial DNA profiles of different tissues and will provide a database to analyse host/bacterial interactions in relation to homeostasis and disease.

Temperature and pressure adaptation of a sulfate reducer from the deep subsurface

Microbial life in deep marine subsurface faces increasing temperatures and hydrostatic pressure with depth. In this study, we have examined growth characteristics and temperature-related adaptation of the Desulfovibrio indonesiensis strain P23 to the in situ pressure of 30 MPa. The strain originates from the deep subsurface of the eastern flank of the Juan de Fuca Ridge (IODP Site U1301). The organism was isolated at 20°C and atmospheric pressure from ~61°C-warm sediments approximately 5 m above the sediment-basement interface. In comparison to standard laboratory conditions (20°C and 0.1 MPa), faster growth was recorded when incubated at in situ pressure and high temperature (45°C), while cell filamentation was induced by further compression. The maximum growth temperature shifted from 48°C at atmospheric pressure to 50°C under high-pressure conditions. Complementary cellular lipid analyses revealed a two-step response of membrane viscosity to increasing temperature with an exchange of unsaturated by saturated fatty acids and subsequent change from branched to unbranched alkyl moieties. While temperature had a stronger effect on the degree of fatty acid saturation and restructuring of main phospholipids, pressure mainly affected branching and length of side chains. The simultaneous decrease of temperature and pressure to ambient laboratory conditions allowed the cultivation of our moderately thermophilic strain. This may in turn be one key to a successful isolation of microorganisms from the deep subsurface adapted to high temperature and pressure.

Saccharicrinis marinus sp. nov., isolated from marine sediment

A novel bacterial strain, designated Y11T, was isolated from marine sediment at Weihai in China. Comparative analysis of 16S rRNA gene sequences demonstrated that the novel isolate showed highest similarity to Saccharicrinis fermentans DSM 9555T (94.0 %) and Saccharicrinis carchari SS12T (92.7 %). Strain Y11T was a Gram-stain-negative, rod-shaped, non-endospore-forming, yellow-pigmented bacterium and was able to hydrolyse agar weakly. It was catalase-negative, oxidase-positive, facultatively anaerobic and motile by gliding. Optimal growth occurred at 28–30 °C, at pH 7.0–7.5 and in the presence of 2–3 % (w/v) NaCl. The DNA G+C content was 34.4 mol%. The strain contained MK-7 as the prevalent menaquinone. The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and C15 : 1ω6c. The predominant polar lipids were phosphatidylethanolamine and two unknown lipids. Data from the present polyphasic taxonomic study clearly place the strain as representing a novel species within the genus Saccharicrinis, for which the name Saccharicrinis marinus sp. nov. is proposed. The type strain is Y11T ( = CICC10837T = KCTC42400T).

Carboxylicivirga linearis sp. nov., isolated from a sea cucumber culture pond

A yellow-pigmented, Gram-stain-negative and facultatively anaerobic bacterium, designated FB218T, was isolated from a sediment sample collected from a sea cucumber culture pond in Rongcheng, China (36° 54′ 36″ N 122° 14′ 34″ E). Cells of strain FB218T were slender, gliding, catalase-positive and oxidase-negative. Optimal growth occurred at 30 °C, pH 6.5–7.0 and in medium containing 2–3 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain FB218T belonged to the genus Carboxylicivirga, family Marinilabiliaceae. The predominant fatty acids were iso-C15 : 0 and anteiso-C15 : 0. MK-7 was the main respiratory quinone. The major polar lipids of strain FB218T were two unidentified lipids and a phospholipid. The genomic DNA G+C content was 40.0 mol%. Based on the distinct phylogenetic position and the combination of physiological and phenotypic characteristics, strain FB218T represents a novel species of the genus Carboxylicivirga, for which the name Carboxylicivirga linearis sp. nov. is proposed. The type strain is FB218T ( = KCTC 42254T = MCCC 1H00106T). An emended description of the genus Carboxylicivirga is also provided.

Distribution and evolution of nitrogen fixation genes in the phylum Bacteroidetes

Diazotrophs had not previously been identified among bacterial species in the phylum Bacteroidetes until the rapid expansion of bacterial genome sequences, which revealed the presence of nitrogen fixation (nif) genes in this phylum. We herein determined the draft genome sequences of Bacteroides graminisolvens JCM 15093(T) and Geofilum rubicundum JCM 15548(T). In addition to these and previously reported 'Candidatus Azobacteroides pseudotrichonymphae' and Paludibacter propionicigenes, an extensive survey of the genome sequences of diverse Bacteroidetes members revealed the presence of a set of nif genes (nifHDKENB) in strains of Dysgonomonas gadei, Dysgonomonas capnocytophagoides, Saccharicrinis fermentans, and Alkaliflexus imshenetskii. These eight species belonged to and were distributed sporadically within the order Bacteroidales. Acetylene reduction activity was detected in the five species examined, strongly suggesting their diazotrophic nature. Phylogenetic analyses showed monophyletic clustering of the six Nif protein sequences in the eight Bacteroidales species, implying that nitrogen fixation is ancestral to Bacteroidales and has been retained in these species, but lost in many other lineages. The identification of nif genes in Bacteroidales facilitates the prediction of the organismal origins of related sequences directly obtained from various environments.

Description of Mariniphaga anaerophila gen. nov., sp. nov., a facultatively aerobic marine bacterium isolated from tidal flat sediment, reclassification of the Draconibacteriaceae as a later heterotypic synonym of the Prolixibacteraceae and description of the family Marinifilaceae fam. nov

A mesophilic, chemoheterotrophic bacterium, strain Fu11-5(T), was isolated from tidal-flat sediment from Tokyo Bay, Chiba, Japan. Cells of strain Fu11-5(T) were facultatively aerobic, Gram-negative, non-sporulating, non-motile and rod-shaped (1.9-6.9 µm long). Strain Fu11-5(T) grew optimally at 35-37 °C and pH 6.5-7.0 and with 1-2% (w/v) NaCl. Oxygen and l-cysteine were used as an alternative electron acceptor and donor, respectively. Strain Fu11-5(T) also grew fermentatively on some pentoses, hexoses and disaccharides and soluble starch. Succinic acid was the major end product from d-glucose. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain Fu11-5(T) was affiliated with the order Bacteroidales, and its nearest neighbours were members of the genera Meniscus, Prolixibacter, Sunxiuqinia, Mangrovibacterium and Draconibacterium, with 87-91% sequence similarity. Cell morphology, optimum growth temperature and utilization of sugars of strain Fu11-5(T) distinguished the strain from phylogenetically related bacteria. On the basis of its phenotypic features and phylogenetic position, a novel genus and species are proposed to accommodate strain Fu11-5(T), with the name Mariniphaga anaerophila gen. nov., sp. nov. The type strain of Mariniphaga anaerophila is strain Fu11-5(T) ( =JCM 18693(T) =NBRC 109408(T) =DSM 26910(T)). We also propose to combine the family Draconibacteriaceae into the family Prolixibacteraceae as a later heterotypic synonym and to place the distinct sublineage of the genus Marinifilum in the family Marinifilaceae fam. nov.

Carboxylicivirga gen. nov. in the family Marinilabiliaceae with two novel species, Carboxylicivirga mesophila sp. nov. and Carboxylicivirga taeanensis sp. nov., and reclassification of Cytophaga fermentans as Saccharicrinis fermentans gen. nov., comb. nov

Two facultatively anaerobic mesophilic bacteria, strains MEBiC 07026T and MEBiC 08903T, were isolated from two different tidal flat sediments and both strains showed approximately 92.2 % 16S rRNA gene sequence similarity with [Cytophaga] fermentans DSM 9555T. 16S rRNA gene sequence similarity between the two new isolates was 97.5 % but levels of DNA–DNA relatedness between the two were 31.3–31.8 %. Phylogenetic analysis revealed that the two isolates and [Cytophaga] fermentans DSM 9555T were affiliated with the family Marinilabiliaceae in the class Bacteroidia . The dominant fatty acids of strains MEBiC 07026T, MEBiC 08903T and [Cytophaga] fermentans DSM 9555T were branched-type or hydroxylated C15 : 0, but [Cytophaga] fermentans DSM 9555T contained a higher proportion of anteiso-branched fatty acids. The two new isolates contained a markedly higher proportion of monounsaturated fatty acids than other members of the family Marinilabiliaceae . The major respiratory quinone of the strains was MK-7. Strains MEBiC07026T and MEBiC08903T utilized a wide range of carboxylic acids whereas [Cytophaga] fermentans DSM 9555T utilized carbohydrates rather than carboxylic acids. The DNA G+C content of the novel strains was about 44 mol% but that of [Cytophaga] fermentans DSM 9555T revealed from the genome sequence was 37.6 mol%. Based on evidence from this polyphasic taxonomic study, a novel genus, Carboxylicivirga gen. nov., is proposed in the family Marinilabiliaceae with two novel species, Carboxylicivirga mesophila sp. nov. with type strain MEBiC 07026T ( = KCCM 42978T = JCM 18290T) and Carboxylicivirga taeanensis sp. nov. with type strain MEBiC 08903T ( = KCCM 43024T = JCM 19490T). Additionally, [Cytophaga] fermentans DSM 9555T ( = ATCC 19072T) is reclassified as Saccharicrinis fermentans gen. nov., comb. nov.

Thermophagus xiamenensis gen. nov., sp. nov., a moderately thermophilic and strictly anaerobic bacterium isolated from hot spring sediment

A moderately thermophilic and strictly anaerobic bacterium, designated HS1T, was isolated from offshore hot spring sediment in Xiamen, China. Cells were Gram-negative, catalase-positive, oxidase-negative, slender and flexible rods without flagella. The strain could grow at 35–55 °C (optimum at 50 °C) and in 1–8 % NaCl (w/v; optimum 2–4 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain HS1T was affiliated with the family Marinilabiliaceae and shared a distant relationship with the previously described genera. The isolate was most closely related to Anaerophaga thermohalophila Fru22T with 16S rRNA gene sequence similarity of 92.4 %, followed by the other members of the family Marinilabiliaceae with 88.7–91.1 % similarity. The dominant cellular fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The predominant quinone was MK-7. The major polar lipids were phosphatidylethanolamine (PE) and an unknown polar lipid. The genomic DNA G+C content was 38.7 mol%. Besides the phylogenetically distant relationship, strain HS1T was obviously distinguished from the most closely related genera in several phenotypic properties including colony colour and pigment production, optimal temperature, optimal NaCl, relation to O2, bicarbonate/carbonate requirement, catalase activity, nitrate reduction, fermentation products and cellular fatty acid profile. Based on the phenotypic and phylogenetic data, strain HS1T represents a novel species of a new genus, for which the name Thermophagus xiamenensis gen. nov., sp. nov. is proposed. The type strain of the type species is HS1T ( = DSM 19012T = CGMCCC 1.5071T).

Natronoflexus pectinivorans gen. nov. sp. nov., an obligately anaerobic and alkaliphilic fermentative member of Bacteroidetes from soda lakes

Anaerobic enrichment with pectin at pH 10 and moderate salinity inoculated with sediments from soda lakes of the Kulunda Steppe (Altai, Russia) resulted in the isolation of a novel member of the Bacteroidetes, strain AP1(T). The cells are long, flexible, Gram-negative rods forming pink carotenoids. The isolate is an obligate anaerobe, fermenting various carbohydrates to acetate and succinate. It can hydrolyze and utilize pectin, xylan, starch, laminarin and pullulan as growth substrates. Growth is possible in a pH range from 8 to 10.5, with an optimum at pH 9.5, and at a salinity range from 0.1 to 2 M Na(+). Phylogenetic analysis based on 16S rRNA sequences placed the isolate into the phylum Bacteroidetes as a separate lineage within the family Marinilabilaceae. On the basis of distinct phenotype and phylogeny, the soda lake isolate AP1(T) is proposed to be assigned in a new genus and species Natronoflexus pectinivorans (=DSM24179(T) = UNIQEM U807(T)).