scholarly journals Coastal Bacterial Community Response to Glacier Melting in the Western Antarctic Peninsula

2021 ◽  
Vol 9 (1) ◽  
pp. 88
Author(s):  
María Estrella Alcamán-Arias ◽  
Sebastián Fuentes-Alburquenque ◽  
Pablo Vergara-Barros ◽  
Jerónimo Cifuentes-Anticevic ◽  
Josefa Verdugo ◽  
...  
Keyword(s):  
Microbial Community ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Antarctic Peninsula ◽  
Gene Sequencing ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Western Antarctic Peninsula ◽  
Dilution Experiments ◽  
Rrna Gene Sequencing

Current warming in the Western Antarctic Peninsula (WAP) has multiple effects on the marine ecosystem, modifying the trophic web and the nutrient regime. In this study, the effect of decreased surface salinity on the marine microbial community as a consequence of freshening from nearby glaciers was investigated in Chile Bay, Greenwich Island, WAP. In the summer of 2016, samples were collected from glacier ice and transects along the bay for 16S rRNA gene sequencing, while in situ dilution experiments were conducted and analyzed using 16S rRNA gene sequencing and metatranscriptomic analysis. The results reveal that certain common seawater genera, such as Polaribacter, Pseudoalteromonas and HTCC2207, responded positively to decreased salinity in both the bay transect and experiments. The relative abundance of these bacteria slightly decreased, but their functional activity was maintained and increased the over time in the dilution experiments. However, while ice bacteria, such as Flavobacterium and Polaromonas, tolerated the increased salinity after mixing with seawater, their gene expression decreased considerably. We suggest that these bacterial taxa could be defined as sentinels of freshening events in the Antarctic coastal system. Furthermore, these results suggest that a significant portion of the microbial community is resilient and can adapt to disturbances, such as freshening due to the warming effect of climate change in Antarctica.

scholarly journals Arsenic mobilization in a high arsenic groundwater revealed by metagenomic and Geochip analyses

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Zhou Jiang ◽  
Ping Li ◽  
Yanhong Wang ◽  
Han Liu ◽  
Dazhun Wei ◽  
...  
Keyword(s):  
Microbial Community ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Gene Sequencing ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Arsenic Mobilization ◽  
Rrna Gene Sequencing ◽  
High Arsenic ◽  
High Arsenic Groundwater

Abstract Microbial metabolisms of arsenic, iron, sulfur, nitrogen and organic matter play important roles in arsenic mobilization in aquifer. In this study, microbial community composition and functional potentials in a high arsenic groundwater were investigated using integrated techniques of RNA- and DNA-based 16S rRNA gene sequencing, metagenomic sequencing and functional gene arrays. 16S rRNA gene sequencing showed the sample was dominated by members of Proteobacteria (62.3–75.2%), such as genera of Simplicispira (5.7–6.7%), Pseudomonas (3.3–5.7%), Ferribacterium (1.6–4.4%), Solimonas (1.8–3.2%), Geobacter (0.8–2.2%) and Sediminibacterium (0.6–2.4%). Functional potential analyses indicated that organics degradation, assimilatory sulfate reduction, As-resistant pathway, iron reduction, ammonification, nitrogen fixation, denitrification and dissimilatory nitrate reduction to ammonia were prevalent. The composition and function of microbial community and reconstructed genome bins suggest that high level of arsenite in the groundwater may be attributed to arsenate release from iron oxides reductive dissolution by the iron-reducing bacteria, and subsequent arsenate reduction by ammonia-producing bacteria featuring ars operon. This study highlights the relationship between biogeochemical cycling of arsenic and nitrogen in groundwater, which potentially occur in other aquifers with high levels of ammonia and arsenic.

scholarly journals Seasonal Sampling of a Microbial Community in the Sediment of Geoje-Hansan Bay, Republic of Korea

2021 ◽  
Vol 10 (31) ◽  
Author(s):  
Seongsik Park ◽  
Hee-Eun Woo ◽  
Jong-Oh Kim ◽  
In-Cheol Lee ◽  
Seokjin Yoon ◽  
...  
Keyword(s):  
Microbial Community ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Marine Pollution ◽  
Gene Sequencing ◽  
16S Rrna Gene Sequencing ◽  
Republic Of Korea ◽  
Rrna Gene ◽  
Oyster Farms ◽  
Rrna Gene Sequencing

Several oyster farms are concentrated in Geoje-Hansan Bay, Republic of Korea, and there is concern about marine pollution. Hence, we monitored the sediment at this site for a year using 16S rRNA gene sequencing. The predominant phyla were Proteobacteria (69.9 to 79.1%) and Bacteroidetes (8.2 to 10.6%) in all seasons.

scholarly journals Controlling for contaminants in low biomass 16S rRNA gene sequencing experiments

2018 ◽  
Author(s):  
Lisa Karstens ◽  
Mark Asquith ◽  
Sean Davin ◽  
Damien Fair ◽  
W. Thomas Gregory ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Biomass ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Gene Sequencing ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Bacterial Dna ◽  
Computational Approaches ◽  
Rrna Gene Sequencing

AbstractBackgroundMicrobial communities are commonly studied using culture-independent methods such as 16S rRNA gene sequencing. However, one challenge in accurately characterizing microbial communities is exogenous bacterial DNA contamination. This is particularly problematic for sites of low microbial biomass such as the urinary tract, placenta, and lower airway. Computational approaches have been proposed as a post-processing step to identify and remove potential contaminants, but their performance has not been independently evaluated.To identify the impact of decreasing microbial biomass on polymicrobial 16S rRNA gene sequencing experiments, we used a serial dilution of a mock microbial community. We evaluated two computational approaches to identify and remove contaminants: 1) identifying sequences that have an inverse correlation with DNA concentration implemented in Decontam and 2) predicting the proportion of experimental sample arising from defined contaminant sources implemented in SourceTracker.ResultsAs expected, the proportion of contaminant bacterial DNA increased with decreasing starting microbial biomass, with 79.12% of the most dilute sample arising from contaminant sequences. Inclusion of contaminant sequences in analyses leads to overinflated diversity estimates (up to 12 times greater than the expected values) and distorts microbiome composition. SourceTracker successfully removed over 98% of contaminants when the experimental environments are well defined. However, SourceTracker performed poorly when the experimental environment is unknown, failing to remove the majority of contaminants. Decontam successfully removed 74-91% of contaminants regardless of prior knowledge of the experimental environment.ConclusionsOur study indicates that computational methods can reduce the amount of contaminants in 16S rRNA gene sequencing experiments. The appropriate computational approach for removing contaminant sequences from an experiment depends on the prior knowledge about the microbial environment under investigation and can be evaluated with a dilution series of a mock microbial community.

scholarly journals High-throughput 16S rRNA gene sequencing reveals gut microbial changes in 6-hydroxydopamine-induced Parkinson’s disease mice

2019 ◽  
Author(s):  
Jin Gyu Choi ◽  
Eugene Huh ◽  
Namkwon Kim ◽  
Dong-Hyun Kim ◽  
Myung Sook Oh
Keyword(s):  
Microbial Community ◽  
16S Rrna ◽  
Gut Microbiota ◽  
16S Rrna Gene ◽  
Gene Sequencing ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Rrna Gene Sequencing ◽  
6 Hydroxydopamine ◽  
Gut Microbial Community

AbstractRecently, there has been a rapid increase in studies on the relationship between brain diseases and gut microbiota, and clinical evidence on gut microbial changes in Parkinson’s disease (PD) has accumulated. 6-hydroxydopamine (6-OHDA) is a widely used neurotoxin that leads to PD pathogenesis, but whether the alterations of gut microbial community in 6-OHDA-treated mice has not been investigated. Here we performed the 16S rRNA gene sequencing to analyze changes in gut microbial community of mice. We found that there were no significant changes in species richness and its diversity in the 6-OHDA-lesioned mice. The relative abundance ofLactobacillus gasseriandL. reuteriprobiotic species in feces of 6-OHDA-lesioned mice was significantly decreased compared with those of sham-operated mice, while the commensal bacteriumBacteroides acidifaciensin 6-OHDA-treated mice was remarkably higher than sham-operated mice. These results provides a baseline for understanding the microbial communities of 6-OHDA-induced PD model to investigate the role of gut microbiota in the pathogenesis of PD.

Screening and Molecular Characterization of Cellulase Producing Actinobacteria from Litchi Orchard

2019 ◽  
Vol 13 (1) ◽  
pp. 90-101
Author(s):  
Sanju Kumari ◽  
Utkarshini Sharma ◽  
Rohit Krishna ◽  
Kanak Sinha ◽  
Santosh Kumar
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Molecular Characterization ◽  
Biochemical Characterization ◽  
Evolutionary Relationship ◽  
Gene Sequencing ◽  
Cellulase Activity ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Rrna Gene Sequencing

Background: Cellulolysis is of considerable economic importance in laundry detergents, textile and pulp and paper industries and in fermentation of biomass into biofuels. Objective: The aim was to screen cellulase producing actinobacteria from the fruit orchard because of its requirement in several chemical reactions. Methods: Strains of actinobacteria were isolated on Sabouraud’s agar medium. Similarities in cultural and biochemical characterization by growing the strains on ISP medium and dissimilarities among them perpetuated to recognise nine groups of actinobacteria. Cellulase activity was measured by the diameter of clear zone around colonies on CMC agar and the amount of reducing sugar liberated from carboxymethyl cellulose in the supernatant of the CMC broth. Further, 16S rRNA gene sequencing and molecular characterization were placed before NCBI for obtaining recognition with accession numbers. Results: Prominent clear zones on spraying Congo Red were found around the cultures of strains of three groups SK703, SK706, SK708 on CMC agar plates. The enzyme assay for carboxymethylcellulase displayed extra cellulase activity in broth: 0.14, 0.82 and 0.66 µmol mL-1 min-1, respectively at optimum conditions of 35°C, pH 7.3 and 96 h of incubation. However, the specific cellulase activities per 1 mg of protein did not differ that way. It was 1.55, 1.71 and 1.83 μmol mL-1 min-1. The growing mycelia possessed short compact chains of 10-20 conidia on aerial branches. These morphological and biochemical characteristics, followed by their verification by Bergey’s Manual, categorically allowed the strains to be placed under actinobacteria. Further, 16S rRNA gene sequencing, molecular characterization and their evolutionary relationship through phylogenetics also confirmed the putative cellulase producing isolates of SK706 and SK708 subgroups to be the strains of Streptomyces. These strains on getting NCBI recognition were christened as Streptomyces glaucescens strain SK91L (KF527284) and Streptomyces rochei strain SK78L (KF515951), respectively. Conclusion: Conclusive evidence on the basis of different parameters established the presence of cellulase producing actinobacteria in the litchi orchard which can convert cellulose into fermentable sugar.

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