Characterization and Genomic Analysis of Affinirhizobium gouqiense sp. nov. Isolated from Seawater of Gouqi Island Located in the East China Sea and Reclassification of Rhizobium lemnae to the Genus Affinirhizobium as Affinirhizobium lemnae comb. nov.

A novel bacterium designated as SSA5.23T was isolated from seawater. Cells of SSA5.23T are Gram-stain-negative, short, rod-shaped, and exhibit motility via numerous peritrichous flagella. The strain could grow at temperatures ranging from 15 to 35 °C (optimum at 25 °C), in a salinity range of 0-5.0% (w/v) NaCl, and within a pH range of 6.0-9.0 (optimum at pH 7.0). The predominant cellular fatty acid of SSA5.23T was C18:1 ω7c/C18:1 ω6c, and the major respiratory quinones were Q-9 and Q-10. Diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol were identified as the primary polar lipids. The complete genome (5.47 Mb) of SSA5.23T comprises of a circular chromosome of 3.64 Mb and three plasmids, specifically sized at 59.73 kb, 227.82 kb, and 1.54 Mb, respectively. Certain genes located on the plasmids play roles in denitrification, oxidative stress resistance, and osmotic tolerance, which likely contribute to the adaptability of this strain in marine conditions. Core-proteome average amino acid identity analysis effectively identified the strain's affiliation with the genus Affinirhizobium, showing the highest value (89.9%) with Affinirhizobium pseudoryzae DSM 19479T. This classification was further supported by the phylogenetic analysis of concatenated alignment of 170 single-copy orthologous proteins. When compared to related reference strains, SSA5.23T displayed an average nucleotide identity ranging from 74.9 to 80.3% and digital DNA-DNA hybridization values ranging from 19.9 to 23.9%. Our findings confirmed that strain SSA5.23T represents a novel species of the genus Affinirhizobium, for which the name Affinirhizobium gouqiense sp. nov. (type strain SSA5.23T = LMG 32560T = MCCC 1K07165T) was suggested.

Diversity and structure of the deep-sea sponge microbiome in the equatorial Atlantic Ocean.

Sponges (phylum Porifera) harbour specific microbial communities that drive the ecology and evolution of the host. Understanding the structure and dynamics of these communities is emerging as a primary focus in marine microbial ecology research. Much of the work to date has focused on sponges from warm and shallow coastal waters, while sponges from the deep ocean remain less well studied. Here, we present a metataxonomic analysis of the microbial consortia associated with 23 individual deep-sea sponges. We identify a high abundance of archaea relative to bacteria across these communities, with certain sponge microbiomes comprising more than 90 % archaea. Specifically, the archaeal family Nitrosopumilaceae is prolific, comprising over 99 % of all archaeal reads. Our analysis revealed that sponge microbial communities reflect the host sponge phylogeny, indicating a key role for host taxonomy in defining microbiome composition. Our work confirms the contribution of both evolutionary and environmental processes to the composition of microbial communities in deep-sea sponges.

Occurrence and abundance of microplastics in surface water of Songkhla Lagoon.

Background: Microplastic (MP) pollution is now a global critical issue and has been the subject of considerable worry for multiple various types of habitats, notably in lagoons which are coastal areas connected to the ocean. MPs are of concern, particularly because floating MP in surface water can be ingested by a number of marine organisms. There are several lagoons along Southeast Asia's coastline, but Songkhla Lagoon is Thailand's only exit with a rich biodiversity. To date, there has been little research undertaken on MP in this lagoon, so there is a pressing need to learn more about the presence of MP in the lagoon's water. Methods: We investigate MPs in the surface water of Songkhla Lagoon, Thailand. Sampling took place at ten stations in the lagoon during the wet season in December 2022 and the dry season in February 2023. Samples were digested with hydrogen peroxide to remove organic matter followed by density separation using saturated sodium chloride. MPs were visually examined under a stereo microscope to describe and determine the shape, size, and color. Polymer type was identified using a micro Fourier transform infrared (FTIR) spectrometer. Moreover, the in-situ of water quality of the surface water was measured using a multi-parameter probe. A Mann-Whitney U test was performed to investigate the variations in MP levels and water quality parameters between the wet and dry seasons. Correlation analysis (Spearman rho) was used to determine the significance of correlations between MP and water quality (p < 0.05). Results: MPs were detected at all ten of the sites sampled. The most abundant MPs were small size class (<500 µm, primarily consisting of fibers). Five types of polymers were seen in surface water, including polyethylene terephthalate, rayon, polypropylene, polyester, and poly (ethylene:propylene). Rayon and polyester were the dominant polymers. Additionally, the most dominant color of MPs in the wet and dry season was black and blue, respectively. The mean contents of MPs in the wet and dry season were 0.43 ± 0.18 and 0.34 ± 0.08 items/L, respectively. The Mann-Whitney U test suggested a significant difference between water quality in the wet and dry seasons (p < 0.05). Correlation analysis (Spearman rho) indicated a negative significant difference relationship between the MPs and the values of total dissolved solid (TDS) in the wet season (r = -0.821, p = <0.05), revealing that the large amounts of MPs may possibly be dispersed within surface water bodies with low TDS concentrations. Based on the overall findings, MP pollution in the surface water of the lagoon is not found to be influenced by the seasonal context. Rivers flowing into the lagoon, especially the U-Taphao River, may be a principal pathway contributing to increased MP pollution loading in the lagoon. The results can be used as baseline data to undertake further research work relevant to sources, fates, distribution, and impacts of MPs in other coastal lagoons.

Seasonal and interannual variability of the free-living and particle-associated bacteria of a coastal microbiome.

Marine microbial communities differ genetically, metabolically, and ecologically according to their lifestyle, and they may respond differently to environmental changes. In this study, we investigated the seasonal dynamics of bacterial assemblies in the free-living (FL) and particle-associated (PA) fractions across a span of 6 years in the Blanes Bay Microbial Observatory in the Northwestern Mediterranean. Both lifestyles showed marked seasonality. The trends in alpha diversity were similar, with lower values in spring-summer than in autumn-winter. Samples from both fractions were grouped seasonally and the percentage of community variability explained by the measured environmental variables was comparable (32% in FL and 31% in PA). Canonical analyses showed that biotic interactions were determinants of bacterioplankton dynamics and that their relevance varies depending on lifestyles. Time-decay curves confirmed a high degree of predictability in both fractions. Yet, 'seasonal' Amplicon Sequence Variants (ASVs) (as defined by Lomb Scargle time series analysis) in the PA communities represented 46% of the total relative abundance while these accounted for 30% in the FL fraction. These results demonstrate that bacteria inhabiting both fractions exhibit marked seasonality, highlighting the importance of accounting for both lifestyles to fully comprehend the dynamics of marine prokaryotic communities.

Metaproteomic analysis decodes trophic interactions of microorganisms in the dark ocean.

Proteins in the open ocean represent a significant source of organic matter, and their profiles reflect the metabolic activities of marine microorganisms. Here, by analyzing metaproteomic samples collected from the Pacific, Atlantic and Southern Ocean, we reveal size-fractionated patterns of the structure and function of the marine microbiota protein pool in the water column, particularly in the dark ocean (>200 m). Zooplankton proteins contributed three times more than algal proteins to the deep-sea community metaproteome. Gammaproteobacteria exhibited high metabolic activity in the deep-sea, contributing up to 30% of bacterial proteins. Close virus-host interactions of this taxon might explain the dominance of gammaproteobacterial proteins in the dissolved fraction. A high urease expression in nitrifiers suggested links between their dark carbon fixation and zooplankton urea production. In summary, our results uncover the taxonomic contribution of the microbiota to the oceanic protein pool, revealing protein fluxes from particles to the dissolved organic matter pool.

Microdiversity in marine pelagic ammonia-oxidizing archaeal populations in a Mediterranean long-read metagenome.

The knowledge of the different population-level processes operating within a species, and the genetic variability of the individual prokaryotic genomes, is key to understanding the adaptability of microbial populations. Here, we characterized the flexible genome of ammonia-oxidizing archaeal (AOA) populations using a metagenomic recruitment approach and long-read (PacBio HiFi) metagenomic sequencing. In the lower photic zone of the western Mediterranean Sea (75 m deep), the genomes Nitrosopelagicus brevis CN25 and Nitrosopumilus catalinensis SPOT1 had the highest recruitment values among available complete AOA genomes. They were used to analyse the diversity of flexible genes (variable from strain to strain) by examining the long-reads located within the flexible genomic islands (fGIs) identified by their under-recruitment. Both AOA genomes had a large fGI involved in the glycosylation of exposed structures, highly variable, and rich in glycosyltransferases. N. brevis had two fGIs related to the transport of phosphorus and ammonium respectively. N. catalinensis had fGIs involved in phosphorus transportation and metal uptake. A fGI5 previously reported as 'unassigned function' in N. brevis could be associated with defense. These findings demonstrate that the microdiversity of marine microbe populations, including AOA, can be effectively characterized using an approach that incorporates third-generation sequencing metagenomics.

Thioclava litoralis sp. nov., a novel species of alphaproteobacterium, isolated from surface seawater.

A Gram-negative, aerobic, rod-shaped, non-motile bacterium, designated as FTW29T, was isolated from surface seawater sampled in Futian district, Shenzhen, China. Growth of strain FTW29T was observed at 15-42 ℃ (optimum, 28-30 ℃), pH 4.0-9.0 (optimum, pH 5.5-7.5) and in the presence of 0.5-10% NaCl (optimum, 3.0% NaCl). Strain FTW29T showed 95.0-96.8% 16 S rRNA gene sequence similarity to various type strains of the genera Thioclava, Sinirhodobacter, Rhodobacter, Haematobacter and Frigidibacter of the family Paracoccaceae, and its most closely related strains were Thioclava pacifica DSM 10,166T (96.8%) and Thioclava marina 11.10-0-13T (96.7%). The phylogenomic tree constructed on the bac120 gene set showed that strain FTW29T formed a clade with the genus Thioclava, with a bootstrap value of 100%. The evolutionary distance values between FTW29T and type strains of the genus Thioclava were 0.17-0.19, which are below the recommended standard (0.21-0.23) for defining a novel genus in the family Paracoccaceae. In strain FTW29T, the major fatty acids identified were summed feature 8 (C18:1ω7c) and C16:0, and the predominant respiratory quinones were ubiquinone-10 and ubiquinone-9. The composition of polar lipids in strain FTW29T included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified phospholipid, an unidentified aminolipid, two unidentified glycolipids and an unidentified lipid. The genome of strain FTW29T comprised one circle chromosome and six plasmids, with a G + C content of 61.4%. The average nucleotide identity, average amino acid identity, and digital DNA-DNA hybridization values between strain FTW29T and seven type strains of the genus Thioclava were 76.6-78.4%, 53.2-56.4% and 19.3-20.4%, respectively. Altogether, the phenotypic, phylogenetic and chemotaxonomic evidence illustrated in this study suggested that strain FTW29T represents a novel species of the genus Thioclava, with the proposed name Thioclava litoralis sp. nov. The type strain is FTW29T (= KCTC 82,841T = MCCC 1K08523T).

Diversity and dynamics of bacteria from iron-rich microbial mats and colonizers in the Mediterranean Sea (EMSO-Western Ligurian Sea Observatory): Focus on Zetaproteobacteria.

Autotrophic microaerophilic iron-oxidizing Zetaproteobacteria seem to play an important role in mineral weathering and metal corrosion in different environments. Here, we compare the bacterial and zetaproteobacterial communities of a mature iron-rich mat together with in situ incubations of different Fe-bearing materials at the EMSO-Ligure West seafloor observatory, which is located on the abyssal plain in the NW Mediterranean Sea. Our results on bacterial communities enable us to make a clear distinction between those growing on mild steel anthropic substrata and those developing on basaltic substrata. Moreover, on anthropic substrata we highlight an influence of mat age on the bacterial communities. Regarding zetaproteobacterial communities, our results point to an increase in ZetaOTUs abundance and diversification with the age of the mat. We corroborate the key role of the ZetaOTU 2 in mat construction, whatever the environment, the substrata on which they develop or the age of the mat. We also show that ZetaOTU 28 is specific to anthropogenic substrata. Finally, we demonstrate the advantage of using dPCR to precisely quantify very low abundant targets, as Zetaproteobacteria on our colonizers. Our study, also, allows to enrich our knowledge on the biogeography of Zetaproteobacteria, by adding new information on this class and their role in the Mediterranean Sea.

Genomic representativeness and chimerism in large collections of SAGs and MAGs of marine prokaryoplankton.

BACKGROUND: Single amplified genomes (SAGs) and metagenome-assembled genomes (MAGs) are the predominant sources of information about the coding potential of uncultured microbial lineages, but their strengths and limitations remain poorly understood. Here, we performed a direct comparison of two previously published collections of thousands of SAGs and MAGs obtained from the same, global environment. RESULTS: We found that SAGs were less prone to chimerism and more accurately reflected the relative abundance and the pangenome content of microbial lineages inhabiting the epipelagic of the tropical and subtropical ocean, as compared to MAGs. SAGs were also better suited to link genome information with taxa discovered through 16S rRNA amplicon analyses. Meanwhile, MAGs had the advantage of more readily recovering genomes of rare lineages. CONCLUSIONS: Our analyses revealed the relative strengths and weaknesses of the two most commonly used genome recovery approaches in environmental microbiology. These considerations, as well as the need for better tools for genome quality assessment, should be taken into account when designing studies and interpreting data that involve SAGs or MAGs. Video Abstract.

Mesobacterium hydrothermale sp. nov., isolated from shallow-sea hydrothermal systems off Kueishantao Island.

A Gram-negative, rod-shaped, non-motile, aerobic bacterium, designated as strain TK19101T, was isolated from the intermediate seawater of yellow vent in the shallow-sea hydrothermal system located near Kueishantao Island. The strain was found to grow at 10-40 °C (optimum, 35 °C), at pH 6.0-8.0 (optimum, 7.0), and in 0-5% (w/v) NaCl (optimum, 1%). Strain TK19101T was catalase-positive and oxidase-positive. The predominant fatty acids (> 10%) in strain TK19101T cells were C16:0, summed feature 8 (C18:1 ω6c and/or C18:1 ω7c), and C18:0. The predominant isoprenoid quinone of strain TK19101T was ubiquinone-10. The polar lipids of strain TK19101T comprised phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phospholipid, and unknown polar lipid. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain TK19101T belonged to the genus Mesobacterium. Strain TK19101T exhibited highest 16S rRNA gene sequence similarity value to Mesobacterium pallidum MCCC M24557T (97.48%). The estimated average nucleotide identity and digital DNA-DNA hybridization values between strain TK19101T and the closest related species Mesobacterium pallidum MCCC M24557T were 74.88% and 20.30%, respectively. The DNA G + C content was 63.49 mol%. On the basis of the analysis of 16S rRNA gene sequences, genotypic and phylogenetic data, strain TK19101T has a unique phylogenetic status and represents a novel species of genus Mesobacterium, for which the name Mesobacterium hydrothermale sp. nov. is proposed. The type strain is TK19101T (= MCCC 1K08936T = KCTC 8354T).

Microbial Health Risks of Cryptosporidium parvum and Giardia lamblia in Tropical Coastal Water in Araromi, Nigeria.

Objective: Giardia and Cryptosporidium are enteric protozoa that can cause a variety of gastrointestinal diseases, especially in vulnerable people like children, the elderly, and those with impaired immune systems. In order to ascertain the microbiological quality of the recreational water from Araromi Beach in Ilaje Local Government Area, Ondo State, Nigeria. This risk assessment is of great significance to human health protection against waterborne diseases. The aim of this study was to determine the microbial quality of recreational water from Araromi Beach in Ilaje Local Government Area, Ondo State, Nigeria. Methods: Microscopic examination of Cryptosporidium and Giardia oocysts were done. Results: Results revealed maximum occurrence of Cryptosporidium parvum (20 oocysts/100 mL) of water sample in the month of April and maximum occurrence of Giardia lamblia (300 cysts/100 mL) of water sample in the month of June. Additionally, according to Kolmogorov-Smirnov tests for normalcy Ho =0.05, Giardia lamblia and Cryptosporidium parvum were not regularly distributed in the water samples collected from the beach throughout the study period. The average likelihood of contracting Giardia lamblia and Cryptosporidium parvum infections after consuming 100 mL of beach water was 0.96 and 0.35, respectively. The risks of infection associated with Cryptosporidium parvum was lower than those associated with Giardia lamblia in water from the beach, but were both above the acceptable risk limit of 10-4. Conclusion: The results of this study indicate that Giardia and Cryptosporidium may represent serious health hazards to people who engage in aquatic activities. Adopting a comprehensive strategy that includes regular inspections, enhanced detection techniques, and the prevention of aquatic environment pollution may provide clean and safe recreational water for all, thereby safeguarding the public's health.

Bering Strait hit by unprecedented algal bloom.

The toxic organisms, which cause paralytic shellfish poisoning, are moving northward with climate change.

Marinobacter sediminicola sp. nov. and Marinobacter xiaoshiensis sp. nov., Isolated from Coastal Sediment.

Two Gram-stain-negative, facultative anaerobic, rod-shaped, motile bacterial strains, designated F26243T and F60267T were isolated from coastal sediment in Weihai, China. Strains F26243T and F60267T were grown at 4-40 °C (optimum 33 °C), pH 7.0-9.5 and pH 6.5-9.5 (optimum at pH 7.0), in the presence of 1.0-7.0% (w/v) NaCl (optimum 2.5%) and 1.0-12.0% (w/v) NaCl (optimum 2.0%), respectively. The 16S rRNA gene sequences phylogenetic analysis showed that strains F26243T and F60267T are closely related to the genus Marinobacter and exhibited the highest sequence similarities to Marinobacter salexigens HJR7T (97.7% and 98.0%, respectively), the similarity between two isolates was 96.7%. Strains F26243T and F60267T displayed genomic DNA G + C content of 53.6% and 53.8%, respectively. When compared to the M. salexigens HJR7T, the average nucleotide identity (ANI) values were 83.7% and 84.1%, and the percentage of conserved proteins (POCP) values were 79.9% and 84.6%, respectively. Ubiquinone 9 (Q-9) was the only respiratory quinone detected in both isolates. The major cellular fatty acids (> 10.0%) were summed feature 3 (comprising C16:1ω7c and/or C16:1ω6c), C16:0 and C18:1ω9c. The polar lipid profiles of strains F26243T and F60267T contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidyldimethylethanolamine, phosphatidylglycerol, aminophospholipid and one unidentified phospholipid. Based on genomic characteristics, phenotypic and chemotaxonomic, strains F26243T and F60267T represent two novel species of the genus Marinobacter, for which the names Marinobacter sediminicola sp. nov. and Marinobacter xiaoshiensis sp. nov. are proposed, the type strains are F26243T (= KCTC 92640T = MCCC 1H01345T) and F60267T (= KCTC 92638T = MCCC 1H01346T).

Streamlining large-scale oceanic biomonitoring using passive eDNA samplers integrated into vessel's continuous pump underway seawater systems.

Passive samplers are enabling the scaling of environmental DNA (eDNA) biomonitoring in our oceans, by circumventing the time-consuming process of water filtration. Designing a novel passive sampler that does not require extensive sample handling time and can be connected to ocean-going vessels without impeding normal underway activities has potential to rapidly upscale global biomonitoring efforts onboard the world's oceanic fleet. Here, we demonstrate the utility of an artificial sponge sampler connected to the continuous pump underway seawater system as a means to enable oceanic biomonitoring. We compared the performance of this passive sampling protocol with standard water filtration at six locations during a research voyage from New Zealand to Antarctica in early 2023. Eukaryote metabarcoding of the mitochondrial COI gene revealed no significant difference in phylogenetic α-diversity between sampling methods and both methods delineated a progressive reduction in number of Zero-Radius Operational Taxonomic Units (ZOTUs) with increased latitudes. While both sampling methods revealed comparable trends in geographical community compositions, distinct clusters were identified for passive samplers and water filtration at each location. Additionally, greater variability between replicates was observed for passive samplers, resulting in an increased estimated level of replication needed to recover 90 % of the biodiversity. Furthermore, traditional water filtration failed to detect three phyla observed by passive samplers and extrapolation analysis estimated passive samplers recover a larger number of ZOTUs compared to water filtration for all six locations. Our results demonstrate the potential of this passive eDNA sampler protocol and highlight areas where this emerging technology could be improved, thereby enabling large-scale offshore marine eDNA biomonitoring by leveraging the world's oceanic fleet without interfering with onboard activities.

Winogradskyella pelagia sp. nov., isolated from coastal sediment.

An orange-pigmented, Gram-stain-negative, strictly aerobic, non-flagellated and rod-shaped bacterium, designated strain DF17T, was isolated from coastal sediment collected from Jingzi Wharf, Weihai, PR China. The optimal growth conditions were determined to be at 30 °C, pH 7.5, and in 3 % (w/v) NaCl. According to phylogenetic analysis of the 16S rRNA gene sequence, strain DF17T showed the highest sequence similarity of 96.9 % to Winogradskyella aquimaris KCTC 23502T. The DNA G+C content was 35.8 mol%, and the major fatty acids were iso-C15 : 1 G, iso-C15 : 0, and iso-C17 : 0 3-OH. The major polar lipids were two aminoglycolipids, one phosphatidylethanolamine and four unidentified lipids. The predominant respiratory quinone was menaquinone-6 (MK-6). The average nucleotide identity, digital DNA-DNA hybridization, and amino acid identity values between strain DF17T and other Winogradskyella species were below the species delineation thresholds of 69.35-72.95 %, 16.9-19.6 % and 71.25-78.93 %, respectively. On the basis of its phenotypic, genetic and physiological characteristics, strain DF17T is suggested to represent a novel species of the genus Winogradskyella, for which the name Winogradskyella pelagia sp. nov. is proposed. The type strain is DF17T (MCCC 1H00456T=KCTC 82421T).

Aurantiacibacter hainanensis sp. nov. and Qipengyuania zhejiangensis sp. nov., two novel Erythrobacteraceae species isolated from tidal flat sediments.

Two Gram-stain-negative, rod-shaped, non-motile, aerobic and carotenoid-producing strains, belonging to the family Erythrobacteraceae, designated as H149T and Z2T, were isolated from tidal flat sediment samples collected in Hainan and Zhejiang, PR China, respectively. Growth of strain H149T occurred at 15-42 °C, 0-10.0 % (w/v) NaCl, and pH 6.0-8.5, with the optima at 35-37 °C, 3.0-3.5 % (w/v) NaCl and pH 7.0. Strain Z2T grew at 15-37 °C, 0-6.0 % (w/v) NaCl, and pH 6.0-9.5, with the optima at 25-30 °C, 0.5-1.0 % (w/v) NaCl and pH 6.0-6.5. Ubiquinone-10 was the sole ubiquinone in two strains. The predominant cellular fatty acids of strain H149T were C16 : 0, summed feature 3 and summed feature 8, while those of strain Z2T were C17 : 1 ω6c, summed feature 3 and summed feature 8. Strains H149T and Z2T shared diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and sphingoglycolipid as major polar lipids. The 16S rRNA gene sequence identity analysis indicated that strain H149T had the highest sequence identity of 98.4 % with Aurantiacibacter odishensis KCTC 23981T, and strain Z2T had that of 98.2 % with Qipengyuania pacifica NZ-96T. Phylogenetic trees based on 16S rRNA gene and core-genome sequences revealed that strains H149T and Z2T formed two independent clades in the genera Aurantiacibacter and Qipengyuania, respectively. Strain H149T had average nucleotide identity values of 74.0-81.3 % and in silico DNA-DNA hybridization values of 18.5-23.1 % with Aurantiacibacter type strains, while strain Z2T had values of 73.3-78.7 % and 14.5-33.3 % with Qipengyuania type strains. The genomic DNA G+C contents of strains H149T and Z2T were 64.3 and 61.8 %, respectively. Based on the genetic, genomic, phylogenetic, physiological and chemotaxonomic results, strains H149T (=KCTC 8397T=MCCC 1K08920T) and Z2T (=KCTC 8396T=MCCC 1K08946T) are concluded to represent two novel Erythrobacteraceae species for which the names Aurantiacibacter hainanensis sp. nov. and Qipengyuania zhejiangensis sp. nov. are proposed, respectively.

Application of Intracerebral Aquaporin-4 Expression in Differential Diagnosis of Drowning: an Immunohistochemical Study Related to Timing of Autopsy.

Background: The role of forensic pathologists is pivotal in definitively diagnosing drowning cases. Further differentiation becomes essential for distinguishing between freshwater drowning (FWD) and saltwater drowning (SWD). Aquaporins are small integral membrane proteins that serve as major water transport pathways in various cell types. AQP4 appears to be involved in mechanisms related to cerebral volume regulation. Our study aims to examine the expression of AQP4 in the brain as a potential marker for differentiating between FWD and SWD relating to autopsy-performing timing. Materials and Methods: A total of 23 cases were classified into three groups: FWD, SWD, and controls. All samples were classified upon autopsy-performing timing into two subgroups: within and after 72 hours of death. The samples were then processed for histological and immunohistochemical investigations. Conclusion: For autopsies performed within 72 hours of death, we found a significantly higher value of AQP4-positive astrocytes in cases of FWD compared to SWD and control groups. We also found a significantly lower AQP4 expression in SWD cases compared to the control group. For autopsies conducted after 72 hours, the immunohistochemical staining does not reveal the peripheral terminations of astrocytes, which appear blurred and only recognizable as halos. In conclusion, the data aligns with existing literature about autopsies performed within 72 hours. However, in autopsies conducted after 72 hours, uncertain and even opposed results are observed. The difference can be ascribed to the post-mortem transformative processes that take place upon the cessation of vital functions.

Enhanced nutrient supply promotes mutualistic interactions between cyanobacteria and bacteria in oligotrophic ocean.

Cyanobacteria can form complex interactions with heterotrophic microorganisms, but this relationship is susceptible to nutrient concentrations. Disentangling the cyanobacteria-bacteria interactions in relation to nutrient supply is essential to understanding their roles in geochemical cycles under global change. We hypothesize that enhanced nutrient supply in oligotrophic oceans can promote interactions among cyanobacteria and bacteria. Therefore, we investigated the planktonic bacteria and their interactions with cyanobacteria in relation to elevated nutrients caused by enhanced upwelling around a shallow and a deep seamount in the tropical western Pacific Ocean. We found obviously higher complexity of network occurred with significantly more cyanobacteria in the deep chlorophyll maximum layer of the shallow seamount when compared with that of the deep seamount. Cyanobacteria can shape bacterial interaction and community evenness in response to relatively high nutrient concentrations. The effects of the nutrients on cyanobacteria-related networks were further estimated based on the Tara Oceans data. Statistical analyses further showed a facilitative effect of nitrate concentrations on cyanobacteria-bacteria mutualistic interactions in the global oligotrophic ocean. By analysing the Tara Ocean macrogenomic data, we detected functional genes related to cyanobacteria-bacteria interactions in all samples, indicating the existence of a mutualistic relationship. Our results reveal cyanobacteria-bacteria interaction in response to nutrient elevation in oligotrophic ocean and highlight the potentially negative effects of global change on the bacterial community from the view of the bio-interaction.

Biogeography of Lentibacter algarum, description of a new strain isolated from the North Sea and emended genus and species descriptions.

A new heterotrophic, aerobic alphaproteobacterium, designated strain SH36 (=DSM 23330=LMG 25292), was obtained from a seawater sample collected in the open North Sea during a phytoplankton bloom. Analysis of the 16S rRNA gene sequence revealed affiliation of strain SH36 to the species Lentibacter algarum (family Roseobacteraceae), showing 100 and 99.9 % sequence similarity to the 16S rRNA genes of the strains L. algarum ZXM098 and ZXM100T. Digital DNA-DNA hybridization of strain SH36 with the type strain of L. algarum showed 98.0 % relatedness, confirming that strain SH36 can be classified within the same species. All three L. algarum strains were compared by physiological, morphological, chemotaxonomic, and genotypic characteristics. The strains showed only minor differences in the composition of fatty acids and polar lipids, but considerable physiological differences. Comparison of the 16S rRNA gene sequence of SH36 with sequences present in GenBank revealed that phylotypes with ≥98.65 % sequence identity to the type strain of L. algarum were found at different marine and estuarine locations of temperate and subtropic regions. Furthermore, by using a specific PCR approach L. algarum was detected throughout annual cycles at the offshore station at Helgoland Roads in the German Bight, indicating that this species is a permanent member of the microbial community in the North Sea.

Whole-Cell Biosensor for Iron Monitoring as a Potential Tool for Safeguarding Biodiversity in Polar Marine Environments.

Iron is a key micronutrient essential for various essential biological processes. As a consequence, alteration in iron concentration in seawater can deeply influence marine biodiversity. In polar marine environments, where environmental conditions are characterized by low temperatures, the role of iron becomes particularly significant. While iron limitation can negatively influence primary production and nutrient cycling, excessive iron concentrations can lead to harmful algal blooms and oxygen depletion. Furthermore, the growth of certain phytoplankton species can be increased in high-iron-content environments, resulting in altered balance in the marine food web and reduced biodiversity. Although many chemical/physical methods are established for inorganic iron quantification, the determination of the bio-available iron in seawater samples is more suitably carried out using marine microorganisms as biosensors. Despite existing challenges, whole-cell biosensors offer other advantages, such as real-time detection, cost-effectiveness, and ease of manipulation, making them promising tools for monitoring environmental iron levels in polar marine ecosystems. In this review, we discuss fundamental biosensor designs and assemblies, arranging host features, transcription factors, reporter proteins, and detection methods. The progress in the genetic manipulation of iron-responsive regulatory and reporter modules is also addressed to the optimization of the biosensor performance, focusing on the improvement of sensitivity and specificity.