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Marine bacterioplankton perform a very important role in the cycles of carbon, nitrogen, phosphorus, and other elements in coastal waters. The impacts of environmental factors on bacterial community structure are dynamic and ongoing. This study investigated the spatiotemporal distributions of elements and their influences on bacterioplankton communities in the coastal waters around the Changli Gold Coast National Nature Reserve in northern China. The results demonstrate the significant temporal variability of phosphorus, nitrogen, and carbon in spring and summer, influenced by natural environmental factors and anthropogenic activities. In spring, increased biological activity, particularly phytoplankton growth, may elevate TOC and POC levels near the river estuaries, while in summer, microbial decomposition likely stabilized carbon concentrations. The seasonal variation in the bacterioplankton community was obvious. Bacteroidetes were enriched in spring samples and Cyanobacteriota proliferated in summer. The dominated genera in the spring, including Planktomarina, an unclassified NS5_marine_group (belonging to Flavobacteriaceae), and the OM43_clade (Methylophilaceae), showed significant positive correlation with salinity, TDP, TOC, POP, and DO levels, while Synechococcus_CC9902 (Synechococcus), PeM15_unclassified (Actinobacteria), and HIMB11 (Rhodobacteraceae), which all dominate in summer samples, are significantly positively correlated with TN, TDN, temperature, and ammonium levels. In summer in particular, the increase in human activities and river inputs greatly improves nutrient levels and promotes the propagation of photosynthetic microorganisms. These results indicate that the nutrient elements and environmental physical conditions are affected by seasonal changes and human activities, which have significant effects on the community structure of bacterioplankton. This study highlights the importance of ongoing monitoring in estuarine coastal areas, especially in protected areas like the Changli Reserve, to manage eutrophication risks and maintain ecological balance. [ABSTRACT FROM AUTHOR]

BACKGROUND Antibiotic pollution carried by reclaimed water infiltration is one of the sources of groundwater pollution, which has become a problem that cannot be ignored in the safety of urban groundwater resources. The effects of antibiotics on microbial communities and their functions in complex and fragile groundwater environments deserve attention. OBJECTIVES To explore the differences of groundwater environmental factors in different seasons and the distribution characteristics of antibiotic pollution, and to explore the influence mechanism of antibiotics on a microbial community. METHODS Based on the high-throughput sequencing method of 16S rRNA gene, the microbial community structure in urban groundwater in the infiltration area of reclaimed water in March and September was studied. Combined with field investigation and indoor analysis, the ion (K+, Na+, Ca2+, Mg2+, NH4+, F-, Cl-, SO42-, NO3-, NO2-, HCO3-, CO32-) concentration in the sample was measured, and the main antibiotic (ciprofloxacin, norfloxacin, ofloxacin, moxifloxacin, sulfapyridine, sulfacetamide) concentration was measured by ultra-high performance liquid chromatography-tandem mass spectrometry. RESULTS (1) In the study area, the concentration of antibiotics in groundwater in March was higher than that in September, mainly sulfacetamide and ciprofloxacin. In addition to seasonal factors, human activities may be another factor affecting the distribution of antibiotics. (2) The microbial community was mainly composed of Proteobacteria (81.04%), Bacteroidota (7.60%), and Firmicutes (4.21%). 3-nitrogen (NH4+, NO3-, NO2-) and antibiotics were important factors affecting the microbial community structure in the study area. Different antibiotics had different effects on the microbial community. Among them, sulfapyridine, norfloxacin, ofloxacin and moxifloxacin had the greatest impact on microorganisms, while ciprofloxacin and sulfacetamide had less impact. (3) Co-occurrence network analysis found that the two dominant functional groups had a high degree of connection with antibiotics, namely, antibiotics had a potential impact on the main microbial functional groups and their functions in the study area. CONCLUSIONS The study provides support for understanding the impact mechanism of antibiotics on a groundwater microbial community and the ecological risk.

Introduction: Alcanivorax , a typical alkane-degrading bacterium, has demonstrated the ability to utilize inorganic electron donor in some reports. However, a comprehensive analysis of its potentiality to utilize inorganic electron donor is still lacking. Methods: In this study, genomic and phylogenetic analyzes were used to explore the potential oxidative capacity of inorganic compounds in Alcanivorax. And its functions were verified through physiological experiments. Results: The sulfur oxidation-related genes sqr and tsdA are prevalent and have various evolutionary origins. Potential genes for CO oxidation were present in 39 strains, whereas genes associated with iron, hydrogen, and ammonia oxidation were either rare or absent. The physiological functions of Sqr and TsdA were confirmed in six representative strains under heterotrophic conditions. Adding thiosulfate enhanced Alcanivorax growth. However, Alcanivorax bacteria perform sulfide detoxification through Sqr rather than by gaining energy via sulfide oxidation Although no strain was confirmed to be chemoautotrophs, we discovered that the two clades, A. xenomutans and A. profundimaris , can grow under conditions with very low organic matter. Discussion: The ability to utilize inorganic compounds as a supplementary energy source and adapt to carbon oligotrophic growth may contribute to the prevalence of Alcanivorax in marine ecosystems. [ABSTRACT FROM AUTHOR]

Transport of organic matter (OM) occurs widely in the form of animal and plant detritus in global oceans, playing a crucial role in global carbon cycling. While wood- and whale-falls have been extensively studied, the in situ process of OM remineralization by microorganisms remains poorly understood particularly in pelagic regions on a global scale. Here, enrichment experiments with animal tissue or plant detritus were carried out in three deep seas for 4-12 months using the deep-sea in situ incubators. We then performed community composition analyses as well as metagenomic and metatranscriptomic analyses. The results revealed strikingly similar microbial assemblages responsible for decomposing animal and plant detritus. Genes encoding peptidases and glucoside hydrolases were highly abundant and actively transcribed in OM enrichments, which confirmed the roles of these enriched microbial assemblages in organic decomposition. Marinifilaceae , Desulfocapsaceae , Spirochaetaceae , and o- Peptostreptococcales were found to potentially contribute to nitrogen fixation. These core bacteria, acting as cosmopolitan anaerobes in decomposing fast-sinking particulate OM, may have been underestimated in terms of their role in deep-sea microbial-mediated biogeochemical cycles during conventional sampling and diversity survey., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© Crown copyright 2024.)

Mixotrophy is an important trophic strategy for bacterial survival in the ocean. However, the global relevance and identity of the major mixotrophic taxa remain largely elusive. Here, we combined phylogenetic, metagenomic, and metatranscriptomic analyses to characterize ubiquitous Arcobacteraceae based on our deep-sea in situ incubations and the global data. The phylogenomic tree of Arcobacteraceae is divided into three large clades, among which members of clades A and B are almost all from terrestrial environments, while those of clade C are widely distributed in various marine habitats in addition to some terrestrial origins. All clades harbor genes putatively involved in chitin degradation, sulfide oxidation, hydrogen oxidation, thiosulfate oxidation, denitrification, dissimilatory nitrate reduction to ammonium, microaerophilic respiration, and metal (iron/manganese) reduction. Additionally, in clade C, more unique pathways were retrieved, including thiosulfate disproportionation, ethanol fermentation, methane oxidation, fatty acid oxidation, cobalamin synthesis, and dissimilatory reductions of sulfate, perchlorate, and arsenate. Within this clade, two mixotrophic Candidatus genera represented by UBA6211 and CAIJNA01 harbor genes putatively involved in the reverse tricarboxylic acid pathway for carbon fixation. Moreover, the metatranscriptomic data in deep-sea in situ incubations indicated that the latter genus is a mixotroph that conducts carbon fixation by coupling sulfur oxidation and denitrification and metabolizing organic matter. Furthermore, global metatranscriptomic data confirmed the ubiquitous distribution and global relevance of Arcobacteraceae in the expression of those corresponding genes across all oceanic regions and depths. Overall, these results highlight the contribution of previously unrecognized Arcobacteraceae to carbon, nitrogen, and sulfur cycling in global oceans.IMPORTANCEMarine microorganisms exert a profound influence on global carbon cycling and ecological relationships. Mixotrophy, characterized by the simultaneous utilization of both autotrophic and heterotrophic nutrition, has a significant impact on the global carbon cycling. This report characterizes a group of uncultivated bacteria Arcobacteraceae that thrived on the "hot time" of bulky particulate organic matter and exhibited mixotrophic strategy during the in situ organic mineralization. Compared with clades A and B, more unique metabolic pathways were retrieved in clade C, including the reverse tricarboxylic acid pathway for carbon fixation, thiosulfate disproportionation, methane oxidation, and fatty acid oxidation. Global metatranscriptomic data from the Tara Oceans expeditions confirmed the ubiquitous distribution and extensive transcriptional activity of Arcobacteraceae with the expression of genes putatively involved in carbon fixation, methane oxidation, multiple sulfur compound oxidation, and denitrification across all oceanic regions and depths., Competing Interests: The authors declare no conflict of interest.