scholarly journals Examining the interaction between free-living bacteria and iron in the global ocean

2021 ◽  
Author(s):  
Anh Le-Duy Pham ◽  
Olivier Aumont ◽  
Lavenia Ratnarajah ◽  
Alessandro Tagliabue
Keyword(s):  
Global Ocean ◽  
Free Living ◽  
Living Bacteria

scholarly journals Opening a next-generation black box: ecological trends for hundreds of species-like taxa uncovered within a single bacterial >99% 16S rRNA operational taxonomic unit

2021 ◽  
Author(s):  
Martin Hahn ◽  
Andrea Huemer ◽  
Alexandra Pitt ◽  
Matthias Hoetzinger
Keyword(s):  
16S Rrna ◽  
Sequence Similarity ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Taxon Richness ◽  
Large Set ◽  
Free Living ◽  
Environmental Distribution ◽  
Living Bacteria

Current knowledge on environmental distribution and taxon richness of free-living bacteria is mainly based on cultivation-independent investigations employing 16S rRNA gene sequencing methods. Yet, 16S rRNA genes are evolutionarily rather conserved, resulting in limited taxonomic and ecological resolutions provided by this marker. We used a faster evolving protein-encoding marker to reveal ecological patterns hidden within a single OTU defined by >99% 16S rRNA sequence similarity. The studied taxon, subcluster PnecC of the genus Polynucleobacter, represents a ubiquitous group of planktonic freshwater bacteria with cosmopolitan distribution, which is very frequently detected by diversity surveys of freshwater systems. Based on genome taxonomy and a large set of genome sequences, a sequence similarity threshold for delineation of species-like taxa could be established. In total, 600 species-like taxa were detected in 99 freshwater habitats scattered across three regions representing a latitudinal range of 3400 km (42°N to 71°N) and a pH gradient of 4.2 to 8.6. Besides the unexpectedly high richness, the increased taxonomic resolution revealed structuring of Polynucleobacter communities by a couple of macroecological trends, which was previously only demonstrated for phylogenetically much broader groups of bacteria. A unexpected pattern was the almost complete compositional separation of Polynucleobacter communities of Ca-rich and Ca-poor habitats, which strongly resembled the vicariance of plant species on silicate and limestone soils. The presented new cultivation-independent approach opened a window to an incredible, previously unseen diversity, and enables investigations aiming on deeper understanding of how environmental conditions shape bacterial communities and drive evolution of free-living bacteria.

scholarly journals Designer endosymbionts: Converting free-living bacteria into organelles

2020 ◽  
Vol 24 ◽  
pp. 41-50
Author(s):  
Rebecca S. Meaney ◽  
Samir Hamadache ◽  
Maximillian P.M. Soltysiak ◽  
Bogumil J. Karas
Keyword(s):  
Free Living ◽  
Living Bacteria

scholarly journals Toxin–Antitoxin Systems in Bacillus subtilis

Toxins ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 262 ◽  
Author(s):  
Sabine Brantl ◽  
Peter Müller
Keyword(s):  
Bacillus Subtilis ◽  
Physiological Role ◽  
Present Knowledge ◽  
The Other ◽  
Type I ◽  
Type Ii ◽  
Free Living ◽  
Bacterial Chromosomes ◽  
Maintenance Systems ◽  
Living Bacteria

Toxin–antitoxin (TA) systems were originally discovered as plasmid maintenance systems in a multitude of free-living bacteria, but were afterwards found to also be widespread in bacterial chromosomes. TA loci comprise two genes, one coding for a stable toxin whose overexpression kills the cell or causes growth stasis, and the other coding for an unstable antitoxin that counteracts toxin action. Of the currently known six types of TA systems, in Bacillus subtilis, so far only type I and type II TA systems were found, all encoded on the chromosome. Here, we review our present knowledge of these systems, the mechanisms of antitoxin and toxin action, and the regulation of their expression, and we discuss their evolution and possible physiological role.

scholarly journals Cell Differentiation to “Mating Bodies” Induced by an Integrating and Conjugative Element in Free-Living Bacteria

2013 ◽  
Vol 23 (3) ◽  
pp. 255-259 ◽  
Author(s):  
Friedrich Reinhard ◽  
Ryo Miyazaki ◽  
Nicolas Pradervand ◽  
Jan Roelof van der Meer
Keyword(s):  
Cell Differentiation ◽  
Free Living ◽  
Living Bacteria

scholarly journals The human pathogenic vibrios – A public health update with environmental perspectives

1989 ◽  
Vol 103 (1) ◽  
pp. 1-34 ◽  
Author(s):  
P. A. West
Keyword(s):  
Public Health ◽  
Acute Infection ◽  
Aquatic Environments ◽  
Free Living ◽  
Liver Disorders ◽  
Naturally Occurring ◽  
Pathogenic Vibrio ◽  
Ear Infections ◽  
Pathogenic Vibrios ◽  
Living Bacteria

PathogenicVibriospecies are naturally-occurring bacteria in freshwater and saline aquatic environments. Counts of free-living bacteria in water are generally less than required to induce disease. Increases in number of organisms towards an infective dose can occur as water temperatures rise seasonally followed by growth and concentration of bacteria on higher animals, such as chitinous plankton, or accumulation by shellfish and seafood. PathogenicVibriospecies must elaborate a series of virulence factors to elicit disease in humans.Activities which predispose diarrhoeal and extraintestinal infections include ingestion of seafood and shellfish and occupational or recreational exposure to natural aquatic environments, especially those above 20 °C. Travel to areas endemic for diseases due to pathogenicVibriospecies may be associated with infections. Host risk factors strongly associated with infections are lack of gastric acid and liver disorders.Involvement of pathogenicVibriospecies in cases of diarrhoea should be suspected especially if infection is associated with ingestion of seafood or shellfish, raw or undercooked, in the previous 72 h.Vibriospecies should be suspected in any acute infection associated with wounds sustained or exposed in the marine or estuarine environment. Laboratories serving coastal areas where infection due to pathogenic Vibrio species are most likely to occur should consider routine use of TCBS agar and other detection regimens for culture ofVibriospecies from faeces, blood and samples from wound and ear infections.

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