scholarly journals Phylogenetic characterisation of bacterial assemblages and the role of sulphur-cycle bacteria in an Arenicola marina bioturbated mesocosm

2011 ◽  
Vol 439 ◽  
pp. 19-30 ◽  
Author(s):  
EJ Ashforth ◽  
PJW Olive ◽  
AC Ward
Keyword(s):  
Arenicola Marina ◽  
Sulphur Cycle ◽  
Bacterial Assemblages

Polystyrene influences bacterial assemblages in Arenicola marina-populated aquatic environments in vitro

2016 ◽  
Vol 219 ◽  
pp. 219-227 ◽  
Author(s):  
Katharina Kesy ◽  
Sonja Oberbeckmann ◽  
Felix Müller ◽  
Matthias Labrenz
Keyword(s):  
Aquatic Environments ◽  
Arenicola Marina ◽  
Bacterial Assemblages

scholarly journals Effects of Organic Acids on the Chemotaxis Profiles and Biocontrol Traits of Antagonistic Bacterial Endophytes Against Root-Rot Disease in Panax Notoginseng

2021 ◽  
Author(s):  
Li Ma ◽  
Wu-Qin Wang ◽  
Rui Shi ◽  
Xue-Mei Zhang ◽  
Xin Li ◽  
...  
Keyword(s):  
Fumaric Acid ◽  
Hierarchical Cluster ◽  
Panax Notoginseng ◽  
Ecological Interactions ◽  
Plant Soil ◽  
Rrna Sequencing ◽  
Response Profiles ◽  
Rot Disease ◽  
Bacterial Assemblages

Abstract Understanding the role of chemotaxis in ecological interactions between plants and microbes in the rhizosphere is necessary to optimize biocontrol strategies targeting plant soil-borne diseases. Therefore, we examined and profiled the antagonistic endophytic bacteria (AEB) population with chemotaxis potential in the medicinal plant Panax notoginseng using a cheA gene-based approach coupled with 16S rRNA sequencing. Phylogenetic analysis of the chemotactic AEB (CAEB) community in P. notoginseng enabled the identification of 56 CAEB strains affiliated with 30 species of Actinobacteria, Firmicutes, and Proteobacteria; Actinobacteria, especially Bacillus, were predominant. We then systematically quantified the chemotactic response profiles of CAEB toward five organic acid (OA) attractants: citric acid (CA), fumaric acid (FA), malic acid (MA), oxalic acid (OX), and succinic acid (SA). Further hierarchical cluster analysis revealed that the chemotaxis of CAEB to the same attractant exhibited different patterns among not only genera but also species and even strains of the same species. Following chemotaxis and hierarchical analysis, we selected the strongest chemoattractant, fumaric acid (FA), as the target for evaluating the effects of OAs on the representative CAEB strain Bacillus amyloliquefaciens subsp. plantarum YP1. Application of FA significantly stimulated the chemotaxis ability and growth of YP1, and increased the transcript levels of cheA and biocontrol-related genes in YP1. This is the first study to characterise the diversity of chemotaxis profiles toward OAs in natural bacterial assemblages of P. notoginseng and to highlight how FA promotes the biocontrol-related traits of P. notoginseng-associated CAEB.

Influence of zinc on bacterial populations and their proteolytic enzyme activities in freshwater environments: a cross-site comparison

2016 ◽  
Vol 62 (4) ◽  
pp. 320-328 ◽  
Author(s):  
Lauren Rasmussen ◽  
Ola A. Olapade
Keyword(s):  
Enzyme Activities ◽  
Proteolytic Enzyme ◽  
Hydrolytic Enzyme ◽  
Aquatic Environments ◽  
Time Intervals ◽  
Bacterial Populations ◽  
Bacterial Assemblages ◽  
Role Of Zn ◽  
Freshwater Environments

Temporal responses of indigenous bacterial populations and proteolytic enzyme (i.e., aminopeptidase) activities in the bacterioplankton assemblages from 3 separate freshwater environments were examined after exposure to various zinc (Zn) concentrations under controlled microcosm conditions. Zn concentrations (ranging from 0 to 10 μmol/L) were added to water samples collected from the Kalamazoo River, Rice Creek, and Huron River and examined for bacterial abundance and aminopeptidase activities at various time intervals over a 48 h incubation period in the dark. The results showed that the Zn concentrations did not significantly influence total bacterial counts directly; however, aminopeptidase activities varied significantly to increasing zinc treatments over time. Also, analysis of variance and linear regression analyses revealed significant positive relationships between bacterial numbers and their hydrolytic enzyme activities, suggesting that both probably co-vary with increasing Zn concentrations in aquatic systems. The results from this study serve as additional evidence of the ecological role of Zn as an extracellular peptidase cofactor on the dynamics of bacterial assemblages in aquatic environments.

The tropospheric sulphur cycle and the role of volcanic SO2

2003 ◽  
Vol 213 (1) ◽  
pp. 295-305 ◽  
Author(s):  
D. S. Stevenson ◽  
C. E. Johnson ◽  
W. J. Collins ◽  
R. G. Derwent
Keyword(s):  
Sulphur Cycle
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