Deciphering the pathogenic risks of microplastics as emerging particulate organic matter in aquatic ecosystem.

Microplastics are accumulating rapidly in aquatic ecosystems, providing habitats for pathogens and vectors for antibiotic resistance genes (ARGs), potentially increasing pathogenic risks. However, few studies have considered microplastics as particulate organic matter (POM) to elucidate their pathogenic risks and underlying mechanisms. Here, we performed microcosm experiments with microplastics and natural POM (leaves, algae, soil), thoroughly investigating their distinct effects on the community compositions, functional profiles, opportunistic pathogens, and ARGs in Particle-Associated (PA) and Free-Living (FL) bacterial communities. We found that both microplastics and leaves have comparable impacts on microbial community structures and functions, enriching opportunistic pathogens and ARGs, which may pose potential environmental risks. These effects are likely driven by their influences on water properties, including dissolved organic carbon, nitrate, DO, and pH. However, microplastics uniquely promoted pathogens as keystone species and further amplified their capacity as hosts for ARGs, potentially posing a higher pathogenic risk than natural POM. Our research also emphasized the importance of considering both PA and FL bacteria when assessing microplastic impacts, as they exhibited different responses. Overall, our study elucidates the role and underlying mechanism of microplastics as an emerging POM in intensifying pathogenic risks of aquatic ecosystems in comparison with conventional natural POM.

Cereibacter flavus sp. nov., a novel member of the family Rhodobacteraceae isolated from seawater of the South China Sea and reclassification of Rhodobacter alkalitolerans as Cereibacter alkalitolerans comb. nov.

A Gram-stain-negative, aerobic, motile, ovoid-shaped and yellow-coloured strain, designated SYSU M79828T, was isolated from seawater collected from the South China Sea. Growth of this strain was observed at 4-37 °C (optimum, 28 °C), pH 6.0-8.0 (optimum, pH 7.0) and with 0-6% NaCl (optimum, 3.0 %, w/v). The respiratory quinone was found to be Q-10. Major fatty acid constituents were C18 : 1 ω7c/C18 : 1 ω6c, C18 : 1 ω7c11-methyl and C18 : 0 (>5 % of total). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, phosphoglycolipid, two unidentified phospholipid, one unidentified lipid and an unidentified glycolipid. The genomic DNA G+C content was 64.5 mol%. Phylogenetic analyses based on 16S rRNA gene sequences and core genes indicated that strain SYSU M79828T belonged to the genus Cereibacter and had the highest sequences similarity to 'Rhodobacter xinxiangensis' TJ48T (98.41 %). Based on 16S rRNA gene phylogeny, physiological and chemotaxonomic characterizations, we consider that strain SYSU M79828T represents a novel species of the genus Cereibacter, for which the name Cereibacter flavus sp. nov. is proposed. The type strain is SYSU M79828T (=GDMCC 1.3803T=KCTC 92893T). In addition, according to the results of phylogenetic analysis and similar taxonomic characteristics, we propose that Rhodobacter alkalitolerans should be reclassified as Cereibacter alkalitolerans comb. nov.

Alsobacter ponti sp. nov., a novel denitrification and sulfate reduction bacterium isolated from Pearl River sediment.

A Gram-staining negative, aerobic, motile, and short rods strain, designated SYSU M60028T, was isolated from a Pearl River sediment sample in Guangzhou, Guangdong, China. The isolate could be able to grow at pH 6.0-8.0 (optimum, pH 7.0), 25-37 °C (optimum, 28 °C) and in the presence of 0-2% (w/v) NaCl (optimum, 0% NaCl). The cellular polar lipids of this strain were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, one unidentified aminolipid and three unidentified lipids. The respiratory quinone of SYSU M60028T was found to be Q-10. The major fatty acids (> 5% of total) were summed feature 8, C16:0, and C18:1 ω7c 11-methy1. The genomic DNA G + C content was 69.9%. Phylogenetic analyses based on 16S rRNA gene sequences and core genes indicated that strain SYSU M60028T belonged to the genus Alsobacter and had the highest sequences similarities to Alsobacter metallidurans SK200a-9T (96.87%) and Alsobacter soli SH9T (96.87%). Based on the phenotypic, genotypic, and phylogenetic data, strain SYSU M0028T should be considered to represent a novel species of the genus Alsobacter, for which the name Alsobacter ponti sp. nov. is proposed. The type strain is SYSU M60028T (= CGMCC 1.19341T = KCTC 92046T).

Nanostructures in Chinese herbal medicines (CHMs) for potential therapy.

With its long clinical history, traditional Chinese medicine (TCM) has gained acceptance for its specific efficacy and safety in the treatment of multiple diseases. Nano-sized materials study of Chinese herbal medicines (CHMs) leads to an increased understanding of assessing TCM therapies, which may be a promising way to illustrate the material basis of CHMs through their processing and extraction. In this review, we provide an overview of the nanostructures of natural and engineered CHMs, including extracted CHMs, polymer nanoparticles, liposomes, micelles, and nanofibers. Subsequently, the applications of these CHM-derived nanostructures to particular diseases are summarized and discussed. Additionally, we discuss the advantages of these nanostructures for studying the therapeutic efficacy of CHMs. Finally, the key challenges and opportunities for the development of these nanostructures are outlined.

Ectobacillus ponti sp. nov., a novel bacterium isolated from Pearl River Estuary.

A Gram-staining-positive, aerobic, motile, and rod-shaped strain, designated SYSU M60031T, was isolated from a Pearl River Estuary sediment sample, Guangzhou, Guangdong, China. The isolate could grow at pH 5.0-8.0 (optimum, pH 7.0), 25-37 °C (optimum, 28 °C) and in the presence of 0-1 % (w/v) NaCl (optimum, 0 %). The predominant respiratory menaquinone of SYSU M60031T was MK-7. The cellular polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid, and one unidentified aminolipid. The major fatty acids (>10 % of total) were iso-C14 : 0, iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0, and C16 : 0. The genomic DNA G+C content was 51.2 %. Phylogenetic analyses based on 16S rRNA gene sequences and core genes indicated that strain SYSU M60031T belonged to the genus Ectobacillus and showed the highest sequence similarity to Ectobacillus funiculus NAF001T (96.16%), followed by Ectobacillus antri SYSU K30001T (95.08 %). Based on the phenotypic, genotypic, and phylogenetic data, strain SYSU M60031T should be considered to represent a novel species of the genus Ectobacillus, for which the name Ectobacillus ponti sp. nov. is proposed. The type strain of the proposed novel isolate is SYSU M60031T (=CGMCC 1.19243T =NBRC 115614T).

Viral community-wide auxiliary metabolic genes differ by lifestyles, habitats, and hosts.

BACKGROUND: Viral-encoded auxiliary metabolic genes (AMGs) are important toolkits for modulating their hosts' metabolisms and the microbial-driven biogeochemical cycles. Although the functions of AMGs have been extensively reported in numerous environments, we still know little about the drivers that shape the viral community-wide AMG compositions in natural ecosystems. Exploring the drivers of viral community-wide AMG compositions is critical for a deeper understanding of the complex interplays among viruses, hosts, and the environments. RESULTS: Here, we investigated the impact of viral lifestyles (i.e., lytic and lysogenic), habitats (i.e., water, particle, and sediment), and prokaryotic hosts on viral AMG profiles by utilizing metagenomic and metatranscriptomic techniques. We found that viral lifestyles were the most important drivers, followed by habitats and host identities. Specifically, irrespective of what habitats viruses came from, lytic viruses exhibited greater AMG diversity and tended to encode AMGs for chaperone biosynthesis, signaling proteins, and lipid metabolism, which could boost progeny reproduction, whereas temperate viruses were apt to encode AMGs for host survivability. Moreover, the lytic and temperate viral communities tended to mediate the microbial-driven biogeochemical cycles, especially nitrogen metabolism, in different manners via AMGs. When focusing on each lifestyle, we further found clear dissimilarity in AMG compositions between water and sediment, as well the divergent AMGs encoded by viruses infecting different host orders. CONCLUSIONS: Overall, our study provides a first systematic characterization of the drivers of viral community-wide AMG compositions and further expands our knowledge of the distinct interactions of lytic and temperate viruses with their prokaryotic hosts from an AMG perspective, which is critical for understanding virus-host-environment interactions in natural conditions. Video Abstract.

Habitat-dependent prokaryotic microbial community, potential keystone species, and network complexity in a subtropical estuary.

Microbes (e.g., bacteria and archaea) are indispensable components for the key biological processes of estuarine ecosystems and three main habitats (sediment, particle, and water) are harboring diverse estuarine microbes. However, we still know little about how the microbial community structures, potential keystone species, and network properties change among these three habitats in estuarine ecosystems. In this study, we collected size-fractioned water and sediment samples from the Pearl River Estuary to reveal their microbial diversity, community structures, network properties, and potential keystone taxa. We found that the sediment microbial community was remarkably more diverse than particle-attached (PA) and free-living (FL) communities, whereas its ecological network was less complex in terms of node distance and connectivity. TOC was determined as the main driver of sediment community, while the PA and FL communities were predominantly shaped by NO2-, non-ionic ammonia (NH) and pH. Among the bulk water, there were no significant differences between PA and FL communities in diversity, community structure, and network complexity. However, the PA community was more susceptible to metal elements, suggesting their higher level of involvement in physiological metabolism. Potential keystone taxa among community networks were taxonomically divergent in three habitats. Specifically, Synechococcales (Cyanobacteria) and Actinomarinales (Actinobacteria) exclusively served as the module-hubs in FL network, while members from phylum Proteobacteria and Bacteroidetes were the module-hubs and connectors in PA network. Potential keystone taxa in sediment network were more diverse and covered 9 phyla, including the only archaeal lineage Bathyarchaeia (Crenarchaeota). Overall, our study provided more detailed information about estuarine microbial communities in three habitats, especially the potential keystone species, which provided new perspectives on evaluating further effects of anthropogenic disturbances on estuarine microbes and facilitated the environment monitoring based on microbial community.