scholarly journals Population Dynamics of Free-Living Bacteria Related to the Microcystin-Degrading Strain Y2 in Lake Suwa and in Microcystin Amended Enrichments

2004 ◽  
Vol 19 (2) ◽  
pp. 137-146 ◽  
Author(s):  
Tomoko Maruyama ◽  
Kenji Kato ◽  
Ho-Dong Park
Keyword(s):  
Population Dynamics ◽  
Free Living ◽  
Lake Suwa ◽  
Living Bacteria

scholarly journals Symbiosis increases population size and buffers environmental fluctuations in a physiologically-structured model parameterized for thyasirid bivalves

2021 ◽  
Author(s):  
Joany Mariño ◽  
Suzanne C Dufour ◽  
Amy Hurford
Keyword(s):  
Population Dynamics ◽  
Community Dynamics ◽  
Resource Limitation ◽  
Symbiotic Bacteria ◽  
Free Living ◽  
Additional Energy ◽  
Structured Population Model ◽  
Dynamic Energy Budget Theory ◽  
Budget Theory ◽  
Living Bacteria

Symbioses whereby one partner provisions a nutritional resource to the other may alter energy allocation towards reproduction and survival in the recipient partner, potentially impacting population dynamics. Asymbiotic thyasirid bivalves feed predominantly on free-living bacteria, which fluctuate in abundance due to seasonality-driven temperature variations. Symbiotic thyasirids are mixotrophs, gaining nutrients from free-living bacteria and symbiotic bacteria that they host on their enlarged gills. Symbiotic bacteria may function as an additional energy reserve for thyasirids, allowing the hosts to allocate more energy to reproduction. We hypothesize that, for symbiotic thyasirids, the symbionts are a nutritional source that mitigates resource limitation. Using Dynamic Energy Budget theory, we built a physiologically-structured population model assuming equal mortality rates in both species. We find that without seasonal fluctuations, symbiotic thyasirids have higher abundances than asymbiotic thyasirids since the symbionts increase reproduction. Both species have similar population sizes in fluctuating environments, suggesting different adaptations to seasonality: asymbiotic thyasirids have adapted their physiology, while symbiotic thyasirids have adapted through mixotrophy. Our results highlight the significance of linking individual energetics and life-history traits to population dynamics and are the first step towards understanding the role of symbioses in population and community dynamics.

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

Diurnal cycle of Isospora spp. oocyst shedding in Eurasian blackbirds (Turdus merula)

2004 ◽  
Vol 82 (5) ◽  
pp. 764-768 ◽  
Author(s):  
Katharina Misof
Keyword(s):  
Population Dynamics ◽  
Diurnal Cycle ◽  
Bird Species ◽  
Free Living ◽  
Turdus Merula ◽  
Coccidian Oocyst ◽  
Diurnal Fluctuations ◽  
Evolutionary Aspects ◽  
Practical Implications

Diurnal fluctuations in the appearance of parasites have been recognized for more than 60 years but have been largely ignored in studies examining the role of parasites in connection with evolutionary aspects of behaviour, ecology, and population dynamics. The disregard of diurnal fluctuations, however, can influence the reliability and interpretation of data. I examined shedding of Isospora spp. oocysts in faeces of naturally infected, free-living Eurasian blackbirds (Turdus merula L., 1758). Adult birds and nestlings shed coccidian oocysts (Isospora spp.) predominantly in the afternoon. The results are in agreement with earlier studies on coccidian oocyst shedding in other bird species. They are discussed with regard to these studies and to practical implications for future investigators in this field.

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