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1.
Harmful Algae ; 134: 102606, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38705611

RESUMO

Summer cyanobacterial blooms exhibit a dynamic interplay between toxic and non-toxic genotypes, significantly influencing the cyanotoxin levels within a lake. The challenge lies in accurately predicting these toxin concentrations due to the significant temporal fluctuations in the proportions of toxic and non-toxic genotypes. Typically, the toxic genotypes dominate during the early and late summer periods, while the non-toxic variants prevail in mid-summer. To dissect this phenomenon, we propose a model that accounts for the competitive interaction between toxic and non-toxic genotypes, as well as seasonal temperature variations. Our numerical simulations suggest that the optimal temperature of the toxic genotypes is lower than that of the optimal temperatures of the non-toxic counterparts. This difference of optimal temperature may potentially contribute to explain the dominance of toxic genotypes at the early and late summer periods, situation often observed in the field. Experimental data from the laboratory align qualitatively with our simulation results, enabling a better understanding of complex interplays between toxic and non-toxic cyanobacteria.


Assuntos
Cianobactérias , Estações do Ano , Temperatura , Cianobactérias/fisiologia , Proliferação Nociva de Algas , Lagos/microbiologia , Lagos/química , Modelos Biológicos
2.
Microb Ecol ; 87(1): 68, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38722447

RESUMO

It is necessary to predict the critical transition of lake ecosystems due to their abrupt, non-linear effects on social-economic systems. Given the promising application of paleolimnological archives to tracking the historical changes of lake ecosystems, it is speculated that they can also record the lake's critical transition. We studied Lake Dali-Nor in the arid region of Inner Mongolia because of the profound shrinking the lake experienced between the 1300 s and the 1600 s. We reconstructed the succession of bacterial communities from a 140-cm-long sediment core at 4-cm intervals and detected the critical transition. Our results showed that the historical trajectory of bacterial communities from the 1200 s to the 2010s was divided into two alternative states: state1 from 1200 to 1300 s and state2 from 1400 to 2010s. Furthermore, in the late 1300 s, the appearance of a tipping point and critical slowing down implied the existence of a critical transition. By using a multi-decadal time series from the sedimentary core, with general Lotka-Volterra model simulations, local stability analysis found that bacterial communities were the most unstable as they approached the critical transition, suggesting that the collapse of stability triggers the community shift from an equilibrium state to another state. Furthermore, the most unstable community harbored the strongest antagonistic and mutualistic interactions, which may imply the detrimental role of interaction strength on community stability. Collectively, our study showed that sediment DNA can be used to detect the critical transition of lake ecosystems.


Assuntos
Bactérias , DNA Bacteriano , Sedimentos Geológicos , Lagos , Lagos/microbiologia , Lagos/química , Sedimentos Geológicos/microbiologia , Bactérias/genética , Bactérias/classificação , Bactérias/isolamento & purificação , China , DNA Bacteriano/genética , Ecossistema , RNA Ribossômico 16S/genética , Microbiota
3.
Microbiome ; 12(1): 88, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38741135

RESUMO

BACKGROUND: During the bloom season, the colonial cyanobacterium Microcystis forms complex aggregates which include a diverse microbiome within an exopolymer matrix. Early research postulated a simple mutualism existing with bacteria benefitting from the rich source of fixed carbon and Microcystis receiving recycled nutrients. Researchers have since hypothesized that Microcystis aggregates represent a community of synergistic and interacting species, an interactome, each with unique metabolic capabilities that are critical to the growth, maintenance, and demise of Microcystis blooms. Research has also shown that aggregate-associated bacteria are taxonomically different from free-living bacteria in the surrounding water. Moreover, research has identified little overlap in functional potential between Microcystis and members of its microbiome, further supporting the interactome concept. However, we still lack verification of general interaction and know little about the taxa and metabolic pathways supporting nutrient and metabolite cycling within Microcystis aggregates. RESULTS: During a 7-month study of bacterial communities comparing free-living and aggregate-associated bacteria in Lake Taihu, China, we found that aerobic anoxygenic phototrophic (AAP) bacteria were significantly more abundant within Microcystis aggregates than in free-living samples, suggesting a possible functional role for AAP bacteria in overall aggregate community function. We then analyzed gene composition in 102 high-quality metagenome-assembled genomes (MAGs) of bloom-microbiome bacteria from 10 lakes spanning four continents, compared with 12 complete Microcystis genomes which revealed that microbiome bacteria and Microcystis possessed complementary biochemical pathways that could serve in C, N, S, and P cycling. Mapping published transcripts from Microcystis blooms onto a comprehensive AAP and non-AAP bacteria MAG database (226 MAGs) indicated that observed high levels of expression of genes involved in nutrient cycling pathways were in AAP bacteria. CONCLUSIONS: Our results provide strong corroboration of the hypothesized Microcystis interactome and the first evidence that AAP bacteria may play an important role in nutrient cycling within Microcystis aggregate microbiomes. Video Abstract.


Assuntos
Lagos , Microbiota , Microcystis , Microcystis/genética , Microcystis/metabolismo , Microcystis/crescimento & desenvolvimento , China , Lagos/microbiologia , Nutrientes/metabolismo , Processos Fototróficos , Aerobiose , Eutrofização , Bactérias/classificação , Bactérias/metabolismo , Bactérias/genética , Bactérias/isolamento & purificação , Nitrogênio/metabolismo , Carbono/metabolismo
4.
Sci Data ; 11(1): 456, 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38710672

RESUMO

We present metagenomes of 16 samples of water and sediment from two lakes, collected from eutrophic and non-eutrophic areas, including pooled samples enriched with phosphate and nitrate. Additionally, we assembled 167 bacterial metagenome-assembled genomes (MAGs). These MAGs were de-replicated into 83 unique genomes representing different species found in the lakes. All the MAGs exhibited >70% completeness and <10% contamination, with 79 MAGs being classified as 'nearly complete' (completeness >90%), while 54 falling within 80-90% range and 34 between 75-80% complete. The most abundant MAGs identified across all samples were Proteobacteria (n = 80), Firmicutes_A (n = 35), Firmicutes (n = 13), and Bacteriodota (n = 22). Other groups included Desulfobacteria_I (n = 2), Verrucomicrobiota (n = 4), Campylobacterota (n = 4) and Actinobacteriota (n = 6). Importantly, phylogenomic analysis identified that approximately 50.3% of the MAGs could not be classified to known species, suggesting the presence of potentially new and unknown bacteria in these lakes, warranting further in-depth investigation. This study provides valuable new dataset on the diverse and often unique microbial communities living in polluted lakes, useful in developing effective strategies to manage pollution.


Assuntos
Eutrofização , Sedimentos Geológicos , Lagos , Metagenoma , Metagenômica , Lagos/microbiologia , Sedimentos Geológicos/microbiologia , África do Sul , Bactérias/genética , Bactérias/classificação , Filogenia , Microbiologia da Água
5.
Sci Rep ; 14(1): 10012, 2024 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-38693138

RESUMO

Beta-glucosidases catalyze the hydrolysis of the glycosidic bonds of cellobiose, producing glucose, which is a rate-limiting step in cellulose biomass degradation. In industrial processes, ß-glucosidases that are tolerant to glucose and stable under harsh industrial reaction conditions are required for efficient cellulose hydrolysis. In this study, we report the molecular cloning, Escherichia coli expression, and functional characterization of a ß-glucosidase from the gene, CelGH3_f17, identified from metagenomics libraries of an Ethiopian soda lake. The CelGH3_f17 gene sequence contains a glycoside hydrolase family 3 catalytic domain (GH3). The heterologous expressed and purified enzyme exhibited optimal activity at 50 °C and pH 8.5. In addition, supplementation of 1 M salt and 300 mM glucose enhanced the ß-glucosidase activity. Most of the metal ions and organic solvents tested did not affect the ß-glucosidase activity. However, Cu2+ and Mn2+ ions, Mercaptoethanol and Triton X-100 reduce the activity of the enzyme. The studied ß-glucosidase enzyme has multiple industrially desirable properties including thermostability, and alkaline, salt, and glucose tolerance.


Assuntos
Biomassa , Lagos , beta-Glucosidase , beta-Glucosidase/genética , beta-Glucosidase/metabolismo , beta-Glucosidase/química , Lagos/microbiologia , Metagenômica/métodos , Escherichia coli/genética , Escherichia coli/metabolismo , Metagenoma , Clonagem Molecular , Estabilidade Enzimática , Hidrólise , Concentração de Íons de Hidrogênio , Celulose/metabolismo , Temperatura , Glucose/metabolismo
6.
BMC Microbiol ; 24(1): 153, 2024 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-38704527

RESUMO

BACKGROUND: Saline lakes are home to various archaea that play special and crucial roles in the global biogeochemical cycle. The Qinghai-Tibet Plateau hosts a large number of lakes with diverse salinity ranging from 0.1 to over 400 g/L, harboring complex and diverse archaea. To the best of our knowledge, the formation mechanisms and potential ecological roles of archaea in Qinghai-Tibetan Plateau saline lakes remain largely unknown. RESULTS: Using High-throughput Illumina sequencing, we uncovered the vastly distinct archaea communities between two typical saline lakes with significant salinity differences on the Qinghai Tibet Plateau (Qinghai saline lake and Chaka hypersaline lake) and suggested archaea played different important roles in methanogenesis-related and nitrate reduction-related functions of these two lakes, respectively. Rather than the individual effect of salinity, the composite effect of salinity with diverse environmental parameters (e.g., temperature, chlorophyll a, total nitrogen, and total phosphorus) dominated the explanation of the variations in archaeal community structure in different habitats. Based on the network analysis, we further found the correlations between dominant archaeal OTUs were tight but significantly different between the two habitats, implying that archaeal interactions may also largely determine the shape of archaeal communities. CONCLUSION: The present study improved our understanding of the structure and function of archaea in different saline lakes on the Qinghai-Tibet Plateau and provided a new perspective on the mechanisms underlying shaping their communities.


Assuntos
Archaea , Lagos , Salinidade , Lagos/microbiologia , Lagos/química , Archaea/genética , Archaea/classificação , Archaea/metabolismo , Tibet , Sequenciamento de Nucleotídeos em Larga Escala , Filogenia , Biodiversidade , Ecossistema , RNA Ribossômico 16S/genética , Nitrogênio/metabolismo , Nitrogênio/análise , DNA Arqueal/genética
7.
Artigo em Inglês | MEDLINE | ID: mdl-38695865

RESUMO

A novel Gram-staining-positive actinobacterium with antimicrobial activity, designated CFH 90308T, was isolated from the sediment of a salt lake in Yuncheng, Shanxi, south-western China. The isolate exhibited the highest 16S rRNA gene sequence similarities to Microbacterium yannicii G72T, Microbacterium hominis NBRC 15708T and Microbacterium xylanilyticum S3-ET (98.5, 98.4 and 98.2 %, respectively), and formed a separate clade with M. xylanilyticum S3-ET in phylogenetic trees. The strain grew at 15-40 ºC, pH 6.0-8.0 and could tolerate NaCl up to a concentration of 15 % (w/v). The whole genome of strain CFH 90308T consisted of 4.33 Mbp and the DNA G+C content was 69.6 mol%. The acyl type of the peptidoglycan was glycolyl and the whole-cell sugars were galactose and mannose. The cell-wall peptidoglycan mainly contained alanine, glycine and lysine. The menaquinones of strain CFH 90308T were MK-12, MK-13 and MK-11. Strain CFH 90308T contained anteiso-C15:0, anteiso-C17:0, iso-C16:0 and iso-C15:0 as the predominant fatty acids. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between CFH 90308T and the other species of the genus Microbacterium were found to be low (ANIb <81.3 %, dDDH <25.6 %). The secondary metabolite produced by strain CFH 90308T showed antibacterial activities against Bacillus subtilis, Pseudomonas syringae, Aeromonas hydrophila and methicillin-resistant Staphylococcus aureus. Based on genotypic, phenotypic and chemotaxonomic results, the isolate is considered to represent a novel species of the genus Microbacterium, for which the name Microbacterium salsuginis sp. nov. is proposed. The type strain is CFH 90308T (=DSM 105964T=KCTC 49052T).


Assuntos
Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano , Ácidos Graxos , Sedimentos Geológicos , Microbacterium , Filogenia , RNA Ribossômico 16S , Análise de Sequência de DNA , Vitamina K 2 , RNA Ribossômico 16S/genética , DNA Bacteriano/genética , China , Vitamina K 2/análogos & derivados , Sedimentos Geológicos/microbiologia , Peptidoglicano , Lagos/microbiologia , Hibridização de Ácido Nucleico , Cloreto de Sódio/metabolismo , Genoma Bacteriano
8.
Arch Virol ; 169(5): 117, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38739272

RESUMO

Xanthomonas phage AhaSv was isolated from lake water. Genome sequencing showed that its genome is a linear dsDNA molecule with a length of 55,576 bp and a G+C content of 63.23%. Seventy-one open reading frames (ORFs) were predicted, and no tRNAs were found in the genome. Phylogenetic analysis showed that AhaSv is closely related to members of the genus Salvovirus of the family Casjensviridae. Intergenomic similarity values between phage AhaSv and homologous phages were up to 90.6%, suggesting that phage AhaSv should be considered a member of a new species in the genus Salvovirus.


Assuntos
Bacteriófagos , Composição de Bases , Genoma Viral , Fases de Leitura Aberta , Filogenia , Xanthomonas , Xanthomonas/virologia , Xanthomonas/genética , Xanthomonas/classificação , Bacteriófagos/genética , Bacteriófagos/classificação , Bacteriófagos/isolamento & purificação , DNA Viral/genética , Análise de Sequência de DNA , Lagos/virologia , Lagos/microbiologia
9.
Methods Mol Biol ; 2788: 397-410, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38656527

RESUMO

Early monitoring of Microcystis, a cyanobacterium that produces microcystin, is paramount in order to confirm the presence of Microcystis spp. Both phenotypic and genotypic methods have been used. The phenotypic methods provide the presence of the microcystis but do not confirm its species type and toxin produced. Additionally, phenotypic methods cannot differentiate toxigenic from non-toxigenic Microcystis. Therefore, the current protocol also describes genetic methods based on PCR to detect toxigenic Microcystis spp. based on microcystin synthetase E (mcy E) gene and 16-23S RNA genes for species-specific identification, which can effectively comprehend distinct lineages and discrimination of potential complexity of microcystin populations. The presence of these microcystin toxins in blood, in most cases, indicates contamination of drinking water by cyanobacteria. The methods presented herein are used to identify microcystin toxins in drinking water and blood.


Assuntos
Cianobactérias , Lagos , Microcistinas , Lagos/microbiologia , Microcistinas/genética , Microcistinas/análise , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Fenótipo , Genótipo , Reação em Cadeia da Polimerase/métodos , Microbiologia da Água , Microcystis/genética , Microcystis/isolamento & purificação , Microcystis/classificação , Técnicas de Genotipagem/métodos
10.
Sci Total Environ ; 927: 172216, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38583614

RESUMO

Antibiotic resistance genes (ARGs) are a major threat to human and environmental health. This study investigated the occurrence and distribution of ARGs in Lake Cajititlán, a hypereutrophic subtropical lake in Mexico contaminated by anthropogenic sources (urban wastewater and runoff from crop and livestock production). ARGs (a total of 475 genes) were detected in 22 bacterial genera, with Pseudomonas (144 genes), Stenotrophomonas (88 genes), Mycobacterium (54 genes), and Rhodococcus (27 genes) displaying the highest frequencies of ARGs. Among these, Pseudomonas aeruginosa and Stenotrophomonas maltophilia showed the highest number of ARGs. The results revealed a diverse array of ARGs, including resistance to macrolides (11.55 %), aminoglycosides (8.22 %), glycopeptides (6.22 %), tetracyclines (4 %), sulfonamides (4 %), carbapenems (1.11 %), phenicols (0.88 %), fluoroquinolones (0.44 %), and lincosamides (0.22 %). The most frequently observed ARGs were associated with multidrug resistance (63.33 %), with MexF (42 genes), MexW (36 genes), smeD (31 genes), mtrA (25 genes), and KHM-1 (22 genes) being the most common. Lake Cajititlán is a recreational area for swimming, fishing, and boating, while also supporting irrigation for agriculture and potentially acting as a drinking water source for some communities. This raises concerns about the potential for exposure to antibiotic-resistant bacteria through these activities. The presence of ARGs in Lake Cajititlán poses a significant threat to both human and environmental health. Developing strategies to mitigate the risks of antibiotic resistance, including improving wastewater treatment, and promoting strategic antibiotic use and disposal, is crucial. This study represents a significant advancement in the understanding of antibiotic resistance dynamics in a hypereutrophic subtropical lake in a developing country, providing valuable insights for the scientific community and policymakers.


Assuntos
Resistência Microbiana a Medicamentos , Monitoramento Ambiental , Lagos , Lagos/microbiologia , Resistência Microbiana a Medicamentos/genética , México , Antibacterianos/farmacologia , Metagenômica , Genes Bacterianos , Farmacorresistência Bacteriana/genética , Águas Residuárias/microbiologia , Bactérias/efeitos dos fármacos , Bactérias/genética , Poluentes Químicos da Água/análise
11.
Toxins (Basel) ; 16(4)2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38668594

RESUMO

Lake Winnipeg in Manitoba, Canada is heavily impacted by harmful algal blooms that contain non-protein amino acids (NPAAs) produced by cyanobacteria: N-(2-aminoethyl)glycine (AEG), ß-aminomethyl-L-alanine (BAMA), ß-N-methylamino-L-alanine (BMAA), and 2,4-diaminobutyric acid (DAB). Our objective was to investigate the impact of microbial diversity on NPAA production by cyanobacteria using semi-purified crude cyanobacterial cultures established from field samples collected by the Lake Winnipeg Research Consortium between 2016 and 2021. NPAAs were detected and quantified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) using validated analytical methods, while Shannon and Simpson alpha diversity scores were determined from 16S rRNA metagenomic sequences. Alpha diversity in isolate cultures was significantly decreased compared to crude cyanobacterial cultures (p < 0.001), indicating successful semi-purification. BMAA and AEG concentrations were higher in crude compared to isolate cultures (p < 0.0001), and AEG concentrations were correlated to the alpha diversity in cultures (r = 0.554; p < 0.0001). BAMA concentrations were increased in isolate cultures (p < 0.05), while DAB concentrations were similar in crude and isolate cultures. These results demonstrate that microbial community complexity impacts NPAA production by cyanobacteria and related organisms.


Assuntos
Cianobactérias , Lagos , Lagos/microbiologia , Cianobactérias/metabolismo , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Manitoba , Proliferação Nociva de Algas , Aminoácidos/análise , Aminoácidos/metabolismo , Espectrometria de Massas em Tandem , Biodiversidade , Microbiota , Toxinas de Cianobactérias
12.
Sci Total Environ ; 927: 172338, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38608897

RESUMO

Algal blooms in lakes have been a challenging environmental issue globally under the dual influence of human activity and climate change. Considerable progress has been made in the study of phytoplankton dynamics in lakes; The long-term in situ evolution of dominant bloom-forming cyanobacteria in meso-eutrophic plateau lakes, however, lacks systematic research. Here, the monthly parameters from 12 sampling sites during the period of 1997-2022 were utilized to investigate the underlying mechanisms driving the superiority of bloom-forming cyanobacteria in Erhai, a representative meso-eutrophic plateau lake. The findings indicate that global warming will intensify the risk of cynaobacteria blooms, prolong Microcystis blooms in autumn to winter or even into the following year, and increase the superiority of filamentous Planktothrix and Cylindrospermum in summer and autumn. High RUETN (1.52 Biomass/TN, 0.95-3.04 times higher than other species) under N limitation (TN < 0.5 mg/L, TN/TP < 22.6) in the meso-eutrophic Lake Erhai facilitates the superiority of Dolichospermum. High RUETP (43.8 Biomass/TP, 2.1-10.2 times higher than others) in TP of 0.03-0.05 mg/L promotes the superiority of Planktothrix and Cylindrospermum. We provided a novel insight into the formation of Planktothrix and Cylindrospermum superiority in meso-eutrophic plateau lake with low TP (0.005-0.07 mg/L), which is mainly influenced by warming, high RUETP and their vertical migration characteristics. Therefore, we posit that although the obvious improvement of lake water quality is not directly proportional to the control efficacy of cyanobacterial blooms, the evolutionary shift in cyanobacteria population structure from Microcystis, which thrives under high nitrogen and phosphorus conditions, to filamentous cyanobacteria adapted to low nitrogen and phosphorus levels may serve as a significant indicator of water quality amelioration. Therefore, we suggest that the risk of filamentous cyanobacteria blooms in the meso-eutrophic plateau lake should be given attention, particularly in light of improving water quality and global warming, to ensure drinking water safety.


Assuntos
Cianobactérias , Eutrofização , Lagos , Temperatura , Lagos/microbiologia , Lagos/química , China , Monitoramento Ambiental , Nitrogênio/análise , Fitoplâncton , Mudança Climática , Estações do Ano , Fósforo/análise , Nutrientes/análise , Aquecimento Global
13.
Appl Microbiol Biotechnol ; 108(1): 309, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38661971

RESUMO

An alpha-proteobacterial strain JXJ CY 53 T was isolated from the cyanosphere of Microcystis sp. FACHB-905 (MF-905) collected from Lake Dianchi, China. JXJ CY 53 T was observed to be an aerobic, Gram-stain-negative, oval shaped, and mucus-secreting bacterium. It had C18:1ω7c and C16:0 as the major cellular fatty acids, Q-10 as the predominant ubiquinone, and sphingoglycolipid, diphosphatidylglycerol, phosphatidylcholine, and phosphatidylmethylethanolamine as the polar lipids. The G + C content of DNA was 65.85%. The bacterium had 16S rRNA gene sequence identities of 98.9% and 98.7% with Sphingomonas panni DSM 15761 T and Sphingomonas hankookensis KCTC 22579 T, respectively, while less than 97.4% identities with other members of the genus. Further taxonomic analysis indicated that JXJ CY 53 T represented a new member of Sphingomonas, and the species epithet was proposed as Sphingomonas lacusdianchii sp. nov. (type strain JXJ CY 53 T = KCTC 72813 T = CGMCC 1.17657 T). JXJ CY 53 T promoted the growth of MF-905 by providing bio-available phosphorus and nitrogen, plant hormones, vitamins, and carotenoids. It could modulate the relative abundances of nonculturable bacteria associated with MF-905 and influence the interactions of MF-905 and other bacteria isolated from the cyanobacterium, in addition to microcystin production characteristics. Meanwhile, MF-905 could provide JXJ CY 53 T dissolved organic carbon for growth, and control the growth of JXJ CY 53 T by secreting specific chemicals other than microcystins. Overall, these results suggest that the interactions between Microcystis and its attached bacteria are complex and dynamic, and may influence the growth characteristics of the cyanobacterium. This study provided new ideas to understand the interactions between Microcystis and its attached bacteria. KEY POINTS: • A novel bacterium (JXJCY 53 T) was isolated from the cyanosphere of Microcystis sp. FACHB-905 (MF-905) • JXJCY 53 T modulated the growth and microcystin production of MF-905 • MF-905 could control the attached bacteria by specific chemicals other than microcystins (MCs).


Assuntos
Composição de Bases , DNA Bacteriano , Ácidos Graxos , Filogenia , RNA Ribossômico 16S , Sphingomonas , Sphingomonas/metabolismo , Sphingomonas/genética , Sphingomonas/isolamento & purificação , Sphingomonas/classificação , RNA Ribossômico 16S/genética , China , Ácidos Graxos/metabolismo , DNA Bacteriano/genética , Fosfolipídeos/análise , Microcystis/genética , Microcystis/metabolismo , Microcystis/crescimento & desenvolvimento , Lagos/microbiologia , Análise de Sequência de DNA , Técnicas de Tipagem Bacteriana , Simbiose , Ubiquinona
14.
Environ Int ; 186: 108654, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38621322

RESUMO

Investigating the occurrence of antibiotic-resistance genes (ARGs) in sedimentary archives provides opportunities for reconstructing the distribution and dissemination of historical (i.e., non-anthropogenic origin) ARGs. Although ARGs in freshwater environments have attracted great attention, historical variations in the diversity and abundance of ARGs over centuries to millennia remain largely unknown. In this study, we investigated the vertical change patterns of bacterial communities, ARGs and mobile genetic elements (MGEs) found in sediments of Lake Chenghai spanning the past 600 years. Within resistome preserved in sediments, 177 ARGs subtypes were found with aminoglycosides and multidrug resistance being the most abundant. The ARG abundance in the upper sediment layers (equivalent to the post-antibiotic era since the 1940s) was lower than those during the pre-antibiotic era, whereas the ARG diversity was higher during the post-antibiotic era, possibly because human-induced lake eutrophication over the recent decades facilitated the spread and proliferation of drug-resistant bacteria. Statistical analysis suggested that MGEs abundance and the bacterial community structure were significantly correlated with the abundance and diversity of ARGs, suggesting that the occurrence and distribution of ARGs may be transferred between different bacteria by MGEs. Our results provide new perspectives on the natural history of ARGs in freshwater environments and are essential for understanding the temporal dynamics and dissemination of ARGs.


Assuntos
Eutrofização , Sedimentos Geológicos , Lagos , Lagos/microbiologia , Sedimentos Geológicos/microbiologia , Sedimentos Geológicos/química , Bactérias/genética , Bactérias/efeitos dos fármacos , Resistência Microbiana a Medicamentos/genética , Antibacterianos/análise , Antibacterianos/farmacologia , Genes Bacterianos , China , Farmacorresistência Bacteriana/genética
15.
J Hazard Mater ; 470: 134281, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38626680

RESUMO

Eutrophication has led to the widespread occurrence of cyanobacterial blooms. Toxic cyanobacterial blooms with high concentrations of microcystins (MCs) have been identified in the Lalla Takerkoust reservoir in Morocco. The objective of this study was to evaluate the efficiency of the Multi-Soil-Layering (MSL) ecotechnology in removing natural cyanobacterial blooms from the lake. Two MSL pilots were used in rectangular glass tanks (60 × 10 × 70 cm). They consisted of permeable layers (PLs) made of pozzolan and a soil mixture layer (SML) containing local soil, ferrous metal, charcoal and sawdust. The main difference between the two systems was the type of local soil used: sandy soil for MSL1 and clayey soil for MSL2. Both MSL pilots effectively reduced cyanobacterial cell concentrations in the treated water to very low levels (0.09 and 0.001 cells/mL). MSL1 showed a gradual improvement in MC removal from 52 % to 99 %, while MSL2 started higher at 90 % but dropped to 54% before reaching 86%. Both MSL systems significantly reduced organic matter levels (97.2 % for MSL1 and 95.8 % for MSL2). Both MSLs were shown to be effective in removing cyanobacteria, MCs, and organic matter with comparable performance.


Assuntos
Cianobactérias , Eutrofização , Lagos , Microcistinas , Solo , Lagos/microbiologia , Cianobactérias/crescimento & desenvolvimento , Microcistinas/análise , Solo/química , Purificação da Água/métodos , Recuperação e Remediação Ambiental/métodos , Marrocos
16.
Dis Aquat Organ ; 158: 27-36, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38661135

RESUMO

Streptococcus agalactiae infection is one of the major factors limiting the expansion of tilapia farming globally. In this study, we investigated the serotype distribution, virulence and antimicrobial resistance of S. agalactiae isolates from tilapia farmed in Lake Volta, Ghana. Isolates from 300 moribund fish were characterised by Gram staining, MALDI-TOF/MS and 16S rRNA sequencing. Serotype identification was based on multiplex polymerase chain reaction (PCR) amplification of the capsular polysaccharide genes. Detection of virulence genes (cfb, fbsA and cspA) and histopathology were used to infer the pathogenicity of the isolates. The susceptibility of isolates to antibiotics was tested using the Kirby-Bauer disk diffusion assay. All 32 isolates identified as S. agalactiae were of serotype Ia. This was notably different from isolates previously collected from the farms in 2017, which belonged to serotype Ib, suggesting a possible serotype replacement. The prevalence of the pathogen was related to the scale of farm operation, with large-scale farms showing higher S. agalactiae positivity. Data from histopathological analysis and PCR amplification of targeted virulence genes confirmed the virulence potential and ability of the isolates to cause systemic infection in tilapia. Except for gentamicin, the majority of the isolates were less resistant to the tested antibiotics. All isolates were fully sensitive to oxytetracycline, erythromycin, florfenicol, enrofloxacin, ampicillin and amoxicillin. This study has improved our understanding of the specific S. agalactiae serotypes circulating in Lake Volta and demonstrates the need for continuous monitoring to guide the use of antimicrobials and vaccines against streptococcal infections in Ghanaian aquaculture systems.


Assuntos
Antibacterianos , Farmacorresistência Bacteriana , Doenças dos Peixes , Sorogrupo , Infecções Estreptocócicas , Streptococcus agalactiae , Animais , Streptococcus agalactiae/efeitos dos fármacos , Streptococcus agalactiae/genética , Streptococcus agalactiae/patogenicidade , Gana/epidemiologia , Doenças dos Peixes/microbiologia , Infecções Estreptocócicas/veterinária , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/epidemiologia , Virulência , Antibacterianos/farmacologia , Lagos/microbiologia , Ciclídeos , Aquicultura
17.
Sci Total Environ ; 928: 172518, 2024 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-38631637

RESUMO

Microorganisms play important roles in the biogeochemical cycles of lake sediment. However, the integrated metabolic mechanisms governing nitrogen (N) and sulfur (S) cycling in eutrophic lakes remain poorly understood. Here, metagenomic analysis of field and bioreactor enriched sediment samples from a typical eutrophic lake were applied to elucidate the metabolic coupling of N and S cycling. Our results showed significant diverse genes involved in the pathways of dissimilatory sulfur metabolism, denitrification and dissimilatory nitrate reduction to ammonium (DNRA). The N and S associated functional genes and microbial groups generally showed significant correlation with the concentrations of NH4+, NO2- and SO42, while with relatively low effects from other environmental factors. The gene-based co-occurrence network indicated clear cooperative interactions between N and S cycling in the sediment. Additionally, our analysis identified key metabolic processes, including the coupled dissimilatory sulfur oxidation (DSO) and DNRA as well as the association of thiosulfate oxidation complex (SOX systems) with denitrification pathway. However, the enriched N removal microorganisms in the bioreactor ecosystem demonstrated an additional electron donor, incorporating both the SOX systems and DSO processes. Metagenome-assembled genomes-based ecological model indicated that carbohydrate metabolism is the key linking factor for the coupling of N and S cycling. Our findings uncover the coupling mechanisms of microbial N and S metabolism, involving both inorganic and organic respiration pathways in lake sediment. This study will enhance our understanding of coupled biogeochemical cycles in lake ecosystems.


Assuntos
Sedimentos Geológicos , Lagos , Microbiota , Nitrogênio , Enxofre , Lagos/microbiologia , Enxofre/metabolismo , Sedimentos Geológicos/microbiologia , Nitrogênio/metabolismo , Eutrofização , Ciclo do Nitrogênio , Desnitrificação
18.
Water Res ; 256: 121559, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38579508

RESUMO

Over the last six decades, northwest China has undergone a significant climatic shift from "warm-dry" to "warm-wet", profoundly impacting the structures and functions of lake ecosystem across the region. However, the influences of this climatic transition on the diversity patterns, co-occurrence network, and assembly processes of eukaryotic microbial communities in lake ecosystem, along with the underlying mechanisms, remain largely unexplored. To bridge this knowledge gap, our study focused on Lake Bosten, the largest inland freshwater body in China, conducting a comprehensive analysis. Firstly, we examined the dynamics of key water quality parameters in the lake based on long-term monitoring data (1992-2022). Subsequently, we collected 93 water samples spanning two distinctive periods: low water level (WL) and high total dissolved solids (TDS) (PerWLTDS; 2010-2011; attributed to "warm-dry" climate), and high WL and low TDS (PerTDSWL; 2021-2022; associated with "warm-wet" climate). Eukaryotic microorganisms were further investigated using 18S rRNA gene sequencing and various statistical methods. Our findings revealed that climatic warming and wetting significantly increased eukaryotic microbial α-diversity (all Wilcox. test: P<0.05), while simultaneously reducing ß-diversity (all Wilcox. test: P<0.001) and network complexity. Through the two sampling periods, assembly mechanisms of eukaryotic microorganisms were predominantly influenced by dispersal limitation (DL) and drift (DR) within stochastic processes, alongside homogeneous selection (HoS) within deterministic processes. WL played a mediating role in eukaryotic microbial DL and HoS processes in the PerTDSWL, whereas water quality and α-diversity influenced the DL process in the PerWLTDS. Collectively, these results underscore the direct and indirect impacts of "warm-wet" conditions on the eukaryotic microorganisms within Lake Bosten. This study provides valuable insights into the evolutionary dynamics of lake ecosystems under such climatic conditions and aids in predicting the ecological ramifications of global climatic changes.


Assuntos
Lagos , Lagos/microbiologia , China , Biodiversidade , Mudança Climática , Ecossistema , Eucariotos/genética , RNA Ribossômico 18S/genética
19.
Microbiol Spectr ; 12(5): e0324523, 2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38602397

RESUMO

Microorganisms are a crucial component of lake ecosystems and significant contributors to biogeochemical cycles. However, the understanding of how primary microorganism groups (e.g., bacteria and fungi) are distributed and constructed within different lake habitats is lacking. We investigated the bacterial and fungal communities of Hulun Lake using high-throughput sequencing techniques targeting 16S rRNA and Internal Transcribed Spacer 2 genes, including a range of ecological and statistical methodologies. Our findings reveal that environmental factors have high spatial and temporal variability. The composition and community structures vary significantly depending on differences in habitats. Variance partitioning analysis showed that environmental and geographical factors accounted for <20% of the community variation. Canonical correlation analysis showed that among the environmental factors, temperature, pH, and dissolved oxygen had strong control over microbial communities. However, the microbial communities (bacterial and fungal) were primarily controlled by the dispersal limitations of stochastic processes. This study offers fresh perspectives regarding the maintenance mechanism of bacterial and fungal biodiversity in lake ecosystems, especially regarding the responses of microbial communities under identical environmental stress.IMPORTANCELake ecosystems are an important part of the freshwater ecosystem. Lake microorganisms play an important role in material circulation and energy flow owing to their unique enzymatic and metabolic capacity. In this study, we observed that bacterial and fungal communities varied widely in the water and sediments of Hulun Lake. The primary factor affecting their formation was identified as dispersal limitation during stochastic processes. Environmental and geographical factors accounted for <20% of the variation in bacterial and fungal communities, with pH, temperature, and dissolved oxygen being important environmental factors. Our findings provide new insights into the responses of bacteria and fungi to the environment, shed light on the ecological processes of community building, and deepen our understanding of lake ecosystems. The results of this study provide a reference for lake management and conservation, particularly with respect to monitoring and understanding microbial communities in response to environmental changes.


Assuntos
Bactérias , Biodiversidade , Fungos , Lagos , Microbiota , Lagos/microbiologia , Fungos/genética , Fungos/classificação , Fungos/isolamento & purificação , Bactérias/genética , Bactérias/classificação , Bactérias/isolamento & purificação , Microbiota/genética , Ecossistema , RNA Ribossômico 16S/genética , Processos Estocásticos , Micobioma , Temperatura , Concentração de Íons de Hidrogênio , China
20.
Water Res ; 256: 121583, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38614031

RESUMO

The escalating antibiotic resistance threatens the long-term global health. Lake sediment is a vital hotpot in transmitting antibiotic resistance genes (ARGs); however, their vertical distribution pattern and driving mechanisms in sediment cores remain unclear. This study first utilized metagenomics to reveal how resistome is distributed from surface water to 45 cm sediments in four representative lakes, central China. Significant vertical variations in ARG profiles were observed (R2 = 0.421, p < 0.001), with significant reductions in numbers, abundance, and Shannon index from the surface water to deep sediment (all p-values < 0.05). ARGs also has interconnections within the vertical profile of the lakes: twelve ARGs persistently exist all sites and depths, and shared ARGs (e.g., vanS and mexF) were assembled by diverse hosts at varying depths. The 0-18 cm sediment had the highest mobility and health risk of ARGs, followed by the 18-45 cm sediment and water. The drivers of ARGs transformed along the profile of lakes: microbial communities and mobile genetic elements (MGEs) dominated in water, whereas environmental variables gradually become the primary through regulating microbial communities and MGEs with increasing sediment depth. Interestingly, the stochastic process governed ARG assembly, while the stochasticity diminished under the mediation of Chloroflexi, Candidatus Bathyarcaeota and oxidation-reduction potential with increasing depth. Overall, we formulated a conceptual framework to elucidate the vertical environmental adaptability of resistome in anthropogenic lakes. This study shed on the resistance risks and their environmental adaptability from sediment cores, which could reinforce the governance of public health issues.


Assuntos
Resistência Microbiana a Medicamentos , Sedimentos Geológicos , Lagos , Metagenômica , Lagos/microbiologia , Resistência Microbiana a Medicamentos/genética , Sedimentos Geológicos/microbiologia , China , Antibacterianos/farmacologia
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