Devosia aquimaris sp. nov., isolated from seawater of the Changjiang River estuary of China

A gram-stain-negative, aerobic, rod-shaped bacterium strain CJK-A8-3T was isolated from a polyamine-enriched seawater sample collected from the Changjiang River estuary of China. The colonies were white and circular. Strain CJK-A8-3T grew optimally at 35 °C, pH 7.0 and 1.5% NaCl. Its polar lipids contained phosphatidylglycerol, phosphatidic acid, unidentified glycolipids, and a combination of phospholipids and glycolipids. The respiratory quinone was ubiquinone-10, and its main fatty acids were C16:0, 11-methyl C18:1ω7c and Summed Feature 8 (including C18:1ω7c/C18:1ω6c). The phylogenetic tree based on 16S rRNA genes placed strain CJK-A8-3T in a new linage within the genus Devosia. 16S rRNA gene sequence of strain CJK-A8-3T showed identities of 98.50% with Devosia beringensis S02T, 98.15% with D. oryziradicis, and 98.01% with D. submarina JCM 18935T. The genome size of strain CJK-A8-3T was 3.81 Mb with the DNA G + C content 63.9%, higher than those of the reference strains (60.4-63.8%). The genome contained genes functional in the metabolism of terrigenous aromatic compounds, alkylphosphonate and organic nitrogen, potentially beneficial for nutrient acquirement and environmental remediation. It also harbored genes functional in antibiotics resistance and balance of osmotic pressure, enhancing their adaptation to estuarine environments. Both genomic investigation and experimental verification showed that strain CJK-A8-3T could be versatile and efficient to use diverse organic nitrogen compounds as carbon and nitrogen sources. Based on phenotypic, chemotaxonomic, phylogenetic and genomic characteristics, strain CJK-A8-3T was identified as a novel Devosia species, named as Devosia aquimaris sp. nov. The type strain is CJK-A8-3T (= MCCC 1K06953T = KCTC 92162T).

Copper Nanoparticles Confined in a Silica Nanochannel Film for the Electrochemical Detection of Nitrate Ions in Water Samples

The nitrate ion (NO3-) is a typical pollutant in environmental samples, posing a threat to the aquatic ecosystem and human health. Therefore, rapid and accurate detection of NO3- is crucial for both the aquatic sciences and government regulations. Here we report the fabrication of an amino-functionalized, vertically ordered mesoporous silica film (NH2-VMSF) confining localized copper nanoparticles (CuNPs) for the electrochemical detection of NO3-. NH2-VMSF-carrying amino groups possess an ordered perpendicular nanochannel structure and ultrasmall nanopores, enabling the confined growth of CuNPs through the electrodeposition method. The resulting CuNPs/NH2-VMSF-modified indium tin oxide (ITO) electrode (CuNPs/NH2-VMSF/ITO) combines the electrocatalytic reduction ability of CuNPs and the electrostatic attraction capacity of NH2-VMSF towards NO3-. Thus, it is a rapid and sensitive electrochemical method for the determination of NO3- with a wide linear detection range of 5.0-1000 μM and a low detection limit of 2.3 μM. Direct electrochemical detection of NO3- in water samples (tap water, lake water, seawater, and rainwater) with acceptable recoveries ranging from 97.8% to 109% was performed, demonstrating that the proposed CuNPs/NH2-VMSF/ITO sensor has excellent reproducibility, regeneration, and anti-interference abilities.

Metagenomic Features Characterized with Microbial Iron Oxidoreduction and Mineral Interaction in Southwest Indian Ridge

The Southwest Indian Ridge (SWIR) is one of the typical representatives of deep-sea ultraslow-spreading ridges, and has increasingly become a hot spot of studying subsurface geological activities and deep-sea mining management. However, the understanding of microbial activities is still limited on active hydrothermal vent chimneys in SWIR. In this study, samples from an active black smoker and a diffuse vent located in the Longqi hydrothermal region were collected for deep metagenomic sequencing, which yielded approximately 290 GB clean data and 295 mid-to-high-quality metagenome-assembled genomes (MAGs). Sulfur oxidation conducted by a variety of Gammaproteobacteria, Alphaproteobacteria, and Campylobacterota was presumed to be the major energy source for chemosynthesis in Longqi hydrothermal vents. Diverse iron-related microorganisms were recovered, including iron-oxidizing Zetaproteobacteria, iron-reducing Deferrisoma, and magnetotactic bacterium. Twenty-two bacterial MAGs from 12 uncultured phyla harbored iron oxidase Cyc2 homologs and enzymes for organic carbon degradation, indicated novel chemolithoheterotrophic iron-oxidizing bacteria that affected iron biogeochemistry in hydrothermal vents. Meanwhile, potential interactions between microbial communities and chimney minerals were emphasized as enriched metabolic potential of siderophore transportation, and extracellular electron transfer functioned by multi-heme proteins was discovered. Composition of chimney minerals probably affected microbial iron metabolic potential, as pyrrhotite might provide more available iron for microbial communities. Collectively, this study provides novel insights into microbial activities and potential mineral-microorganism interactions in hydrothermal vents. IMPORTANCE Microbial activities and interactions with minerals and venting fluid in active hydrothermal vents remain unclear in the ultraslow-spreading SWIR (Southwest Indian Ridge). Understanding about how minerals influence microbial metabolism is currently limited given the obstacles in cultivating microorganisms with sulfur or iron oxidoreduction functions. Here, comprehensive descriptions on microbial composition and metabolic profile on 2 hydrothermal vents in SWIR were obtained based on cultivation-free metagenome sequencing. In particular, autotrophic sulfur oxidation supported by minerals was presumed, emphasizing the role of chimney minerals in supporting chemosynthesis. Presence of novel heterotrophic iron-oxidizing bacteria was also indicated, suggesting overlooked biogeochemical pathways directed by microorganisms that connected sulfide mineral dissolution and organic carbon degradation in hydrothermal vents. Our findings offer novel insights into microbial function and biotic interactions on minerals in ultraslow-spreading ridges.