Bacterial succession during biodegradation of the kelp Alaria esculenta (L.) Greville

1986 ◽  
Vol 32 (6) ◽  
pp. 505-512 ◽  
Author(s):  
Brendan T. Hollohan ◽  
Patrick E. Dabinett ◽  
John A. Gow
Keyword(s):  
Bacterial Population ◽  
Bacterial Species ◽  
Early Summer ◽  
Decay Process ◽  
Gradual Change ◽  
Northern Latitudes ◽  
Alaria Esculenta ◽  
Bacterial Succession ◽  
Detrital Food Chain ◽  
Brown Macroalga

In northern latitudes large quantities of kelp can be dislodged by ice scouring during spring and early summer. Quantities of kelp are then available to enter the detrital food chain. Bacterial succession, on decaying fronds of the brown macroalga Alaria esculenta, was investigated. There was a loss of approximately 70% of the algal mass during late spring and summer. During this time Vibrio dominated the heterotrophic bacterial population. Species of marine Pseudomonas comprised about 10–30% of the population, depending upon the occasion of isolation. By using numerical taxonomy it was shown that the strains of Vibrio formed distinct and separate clusters according to the occasion on which they were isolated. Among Pseudomonas strains a more gradual change was observed, but by the time of the final isolation, the Pseudomonas strains were different from those isolated at the beginning of the study. The results of characterization tests showed that strains from all clusters were suited to growth on substrates which are components of brown algae and that a succession of bacterial species, of more than one genus and family, occurred during the decay process.

Microflora of Meloidogyne egg masses: species composition, population density and effect on the biocontrol agent Verticillium chlamydosporium (Goddard)

Nematology ◽  
2001 ◽  
Vol 3 (8) ◽  
pp. 729-734 ◽  
Author(s):  
C.J.(Hans) Kok ◽  
Artemis Papert ◽  
C.B.(Chula) Bok-A-Bin
Keyword(s):  
Bacterial Population ◽  
Biocontrol Agent ◽  
Bacterial Species ◽  
Antagonistic Activity ◽  
Parasitic Fungus ◽  
Egg Mass ◽  
Egg Masses ◽  
Soil Suppressiveness ◽  
Verticillium Chlamydosporium

AbstractEgg masses of Meloidogyne fallax from tomato and potato growing in soil from a nematode suppressive and a nonsuppressive field sustained bacterial population densities two to three orders of magnitude higher than those of the rhizosphere soil. BIOLOG metabolic profiling identified 16 bacterial species from egg masses. Results further indicated 20 species not listed in the BIOLOG database. 122 isolates of bacteria and 19 isolates of fungi from M. fallax or M. hapla were tested for in vitro antagonism against the nematode egg parasitic fungus Verticillium chlamydosporium: 23% of the bacteria and 74% of the fungi showed antagonistic activity. Pseudomonads showed an overall stronger antagonistic activity than the other bacteria. Our conclusions are that Meloidogyne egg masses are a densely populated microbial niche and that their microflora may well be an important factor in determining the success of nematode antagonists. However, we could not find a relationship between the egg mass microflora and differences in soil suppressiveness between the sample sites.

Seasonal variations in heterotrophic bacterial populations in waters off Sydney

1964 ◽  
Vol 15 (1) ◽  
pp. 73
Author(s):  
AD Brown
Keyword(s):  
Negative Correlation ◽  
Seasonal Variations ◽  
Bacterial Population ◽  
Heterotrophic Bacteria ◽  
Bacterial Count ◽  
Early Summer ◽  
Total Bacterial Count ◽  
Bacterial Populations ◽  
Seawater Samples

Viable counts were made of heterotrophic bacteria in seawater samples taken from 0, 25, 50, 75, and 100 m at one station off Sydney over a period of 2 years. Populations, which fell largely within the range of 10-1000/ml, tended to be higher in spring and early summer than at other times. Some evidence was obtained of a negative correlation between bacterial population and chlorinity. There was no evidence of a correlation between bacterial populations and several other variables which were examined. A (presumed) species of Chromobacterium occurred intermittently at the lower depths with some suggestion of a correlation with season and total bacterial count.

scholarly journals Isolation, Characterization, and Identification of Bacterial Population from Textile and Tannery Effluents of Bangladesh

2016 ◽  
Vol 29 (2) ◽  
pp. 84-88
Author(s):  
A Hakim ◽  
S Hoque ◽  
SM Ullah
Keyword(s):  
Bacterial Population ◽  
Bacterial Species ◽  
Bacterial Count ◽  
Rrna Gene ◽  
Bacterial Isolates ◽  
Tannery Effluents ◽  
Bacterial Composition ◽  
Degrading Bacteria ◽  
Diagnostic Characteristics ◽  
Metal Treatment

Ten effluent samples from two different sites located at Hazaribagh tannery belt and Dhaka EPZ, Savar were collected. This study aimed to compare the bacterial composition isolated from tannery and textile effluents and to investigate the occurrence of metal toxicity tolerant and dye degrading bacteria and to select the potential strains for the use in bioremediation. The average bacterial count of HT and DETDE varied in between 3.35×106 and 5.45×106 cfu/mL and 4.8×106 and 7.75×106cfu/mL, respectively. A total of 12 bacterial isolates were characterized as strains of Bacillus, Staphylococcus, and Pseudomonas. A few, however, were re-cultured on other recommended media for verification of diagnostic characteristics. Maximum numbers of bacterial species were isolated from textile effluent. The results showed that a Gram-positive bacillus with a yellow pigment was considered as a major group of the population. Among them three isolates were identified based on alignments of partial sequence of 16S rRNA gene. These are also being used in different wastewater and metal treatment plants all over the world.Bangladesh J Microbiol, Volume 29, Number 2, Dec 2012, pp 84-88

Orally administered antibiotics in burn shock

1959 ◽  
Vol 197 (3) ◽  
pp. 705-710 ◽  
Author(s):  
Bernard Balikov ◽  
Ruth J. Deadrick ◽  
Russell E. Brame ◽  
Charles S. Harrison
Keyword(s):  
Beneficial Effect ◽  
Survival Time ◽  
Bacterial Population ◽  
Bacterial Species ◽  
Burn Shock ◽  
Stomach Tube ◽  
Total Elimination

Neomycin was given to rats by stomach tube prior to their being subjected to burn shock. When compared with controls, the combined results of several experiments showed an increase in the survival time of the treated rats which was significant at a P level of between 0.01 and 0.025. The beneficial effect of this neomycin prophylaxis could not readily be explained. Limited experimentation did not support the view that either a reduction in the bacterial population of the intestine or the total elimination of a particular bacterial species or genus could account for this effect. These possibilities, however, were not completely ruled out by our experiments.

scholarly journals Harnessing the Potential of Killers and Altruists within the Microbial Community: A Possible Alternative to Antibiotic Therapy?

Antibiotics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 230 ◽  
Author(s):  
Larisa N. Ikryannikova ◽  
Leonid K. Kurbatov ◽  
Surinder M. Soond ◽  
Andrey A. Zamyatnin
Keyword(s):  
Cell Death ◽  
Bacterial Communities ◽  
Bacterial Population ◽  
Bacterial Species ◽  
Microbial Populations ◽  
Ongoing Research ◽  
Life And Death ◽  
Form Part ◽  
Recent Developments ◽  
New Strategies

In the context of a post-antibiotic era, the phenomenon of microbial allolysis, which is defined as the partial killing of bacterial population induced by other cells of the same species, may take on greater significance. This phenomenon was revealed in some bacterial species such as Streptococcus pneumoniae and Bacillus subtilis, and has been suspected to occur in some other species or genera, such as enterococci. The mechanisms of this phenomenon, as well as its role in the life of microbial populations still form part of ongoing research. Herein, we describe recent developments in allolysis in the context of its practical benefits as a form of cell death that may give rise to developing new strategies for manipulating the life and death of bacterial communities. We highlight how such findings may be viewed with importance and potential within the fields of medicine, biotechnology, and pharmacology.

scholarly journals Bacterial genospecies that are not ecologically coherent: population genomics of Rhizobium leguminosarum

Open Biology ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 140133 ◽  
Author(s):  
Nitin Kumar ◽  
Ganesh Lad ◽  
Elisa Giuntini ◽  
Maria E. Kaye ◽  
Piyachat Udomwong ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Bacterial Population ◽  
Population Genomics ◽  
Bacterial Species ◽  
Core Gene ◽  
Biological Species ◽  
Ecological Groups ◽  
Genetic Isolation ◽  
Taxonomic Framework ◽  
Core Genes

Biological species may remain distinct because of genetic isolation or ecological adaptation, but these two aspects do not always coincide. To establish the nature of the species boundary within a local bacterial population, we characterized a sympatric population of the bacterium Rhizobium leguminosarum by genomic sequencing of 72 isolates. Although all strains have 16S rRNA typical of R. leguminosarum , they fall into five genospecies by the criterion of average nucleotide identity (ANI). Many genes, on plasmids as well as the chromosome, support this division: recombination of core genes has been largely within genospecies. Nevertheless, variation in ecological properties, including symbiotic host range and carbon-source utilization, cuts across these genospecies, so that none of these phenotypes is diagnostic of genospecies. This phenotypic variation is conferred by mobile genes. The genospecies meet the Mayr criteria for biological species in respect of their core genes, but do not correspond to coherent ecological groups, so periodic selection may not be effective in purging variation within them. The population structure is incompatible with traditional ‘polyphasic taxonomy′ that requires bacterial species to have both phylogenetic coherence and distinctive phenotypes. More generally, genomics has revealed that many bacterial species share adaptive modules by horizontal gene transfer, and we envisage a more consistent taxonomic framework that explicitly recognizes this. Significant phenotypes should be recognized as ‘biovars' within species that are defined by core gene phylogeny.

scholarly journals Heterogeneity among estimates of the core genome and pan-genome in different pneumococcal populations

2017 ◽  
Author(s):  
Andries J van Tonder ◽  
James E Bray ◽  
Keith A Jolley ◽  
Sigríður J Quirk ◽  
Gunnsteinn Haraldsson ◽  
...  
Keyword(s):  
Bacterial Population ◽  
Core Genome ◽  
Bacterial Species ◽  
Essential Point ◽  
Genetic Lineages ◽  
The Core ◽  
Pan Genome ◽  
Single Dataset ◽  
Genomic Regions ◽  
Core Genes

AbstractBackgroundUnderstanding the structure of a bacterial population is essential in order to understand bacterial evolution, or which genetic lineages cause disease, or the consequences of perturbations to the bacterial population. Estimating the core genome, the genes common to all or nearly all strains of a species, is an essential component of such analyses. The size and composition of the core genome varies by dataset, but our hypothesis was that variation between different collections of the same bacterial species should be minimal. To test this, the genome sequences of 3,121 pneumococci recovered from healthy individuals in Reykjavik (Iceland), Southampton (United Kingdom), Boston (USA) and Maela (Thailand) were analysed.ResultsThe analyses revealed a ‘supercore’ genome (genes shared by all 3,121 pneumococci) of only 303 genes, although 461 additional core genes were shared by pneumococci from Reykjavik, Southampton and Boston. Overall, the size and composition of the core genomes and pan-genomes among pneumococci recovered in Reykjavik, Southampton and Boston were very similar, but pneumococci from Maela were distinctly different. Inspection of the pan-genome of Maela pneumococci revealed several >25 Kb sequence regions that were homologous to genomic regions found in other bacterial species.ConclusionsSome subsets of the global pneumococcal population are highly heterogeneous and thus our hypothesis was rejected. This is an essential point of consideration before generalising the findings from a single dataset to the wider pneumococcal population.

scholarly journals Speed fluctuations of bacterial replisomes

2021 ◽  
Author(s):  
Deepak Bhat ◽  
Samuel Hauf ◽  
Charles Plessy ◽  
Yohei Yokobayashi ◽  
Simone Pigolotti
Keyword(s):  
Bacterial Population ◽  
Protein Complexes ◽  
Bacterial Species ◽  
Abundance Distribution ◽  
E Coli ◽  
Speed Error ◽  
Different Temperatures ◽  
Speed Fluctuations ◽  
Speed And Accuracy

Replisomes are multi-protein complexes that replicate genomes with remarkable speed and accuracy. Despite their importance, the dynamics of replisomes along the genome is poorly characterised, especially in vivo. In this paper, we link the replisome dynamics with the DNA abundance distribution measured in an exponentially growing bacterial population. Our approach permits to accurately infer the replisome dynamics along the genome from deep sequencing measurements. As an application, we experimentally measured the DNA abundance distribution in Escherichia coli populations growing at different temperatures. We find that the average replisome speed increases nearly five-fold between 17°C and 37°C. Further, we observe wave-like variations of the replisome speed along the genome. These variations are correlated with previously observed variations of the mutation rate along the genome. We interpret this correlation as a speed--error trade-off and discuss its possible dynamical origin. Our approach has the potential to elucidate replication dynamics in E. coli mutants and in other bacterial species.

The community structure of Lake Kinneret (Israel) microorganism populations: size distribution and succession

2000 ◽  
Vol 42 (1-2) ◽  
pp. 49-54 ◽  
Author(s):  
T. Bergstein Ben-Dan ◽  
D. Wynne ◽  
B. Shteinman ◽  
Z. Hu ◽  
Y. Kamenir
Keyword(s):  
Size Distribution ◽  
Bacterial Population ◽  
Vertical Plane ◽  
Term Effect ◽  
Lake Kinneret ◽  
Bacterial Populations ◽  
Long Term Effect ◽  
Bacterial Succession ◽  
Total P

The abundance and succession of bacterial populations, and their biovolume has been studied in the deepest station of Lake Kinneret, Israel during spring–summer. These parameters were then related to the chemical, biological and physical/hydromechanical conditions in the lake. Medium sized cells (2–3 μm) dominated the bacterial population in the spring, then in mid-summer the smaller cell fraction (1 μm) took over. Relatively low numbers of large cells (10 μm) were counted, but the biovolume of this fraction was significant, especially in mid-summer. Both the abundance and biovolume of medium sized cells were positively correlated with NH4+ and O2 concentrations, but not with NO3–, inorganic orthophosphate (Pi) and Total-P. At water temperatures above 28°C, the biovolume of medium sized cells decreased, probably due to faster grazing of zooplankton. When water circulation in the vertical plane was dominant, large cells disappeared from the water column, due to sinking to the bottom. We conclude that chemical parameters, such as NH4+ and O2 concentrations, had a long-term effect on bacterial succession and size distribution, whereas hydromechanical mechanisms, such as turbulent mixing in the horizontal or vertical planes, had a short-term effect.

Approaches and developments in studying the human microbiome network

2015 ◽  
Vol 61 (2) ◽  
pp. 90-94 ◽  
Author(s):  
Mor Nitzan ◽  
Sefi Mintzer ◽  
Hanah Margalit
Keyword(s):  
Bacterial Population ◽  
Bacterial Species ◽  
Human Microbiome ◽  
Structure And Function ◽  
Complex Relationship ◽  
Human Host ◽  
Competition And Cooperation ◽  
Health And Disease ◽  
And Function

The human microbiome is dynamic and unique to each individual, and its role is being increasingly recognized in healthy physiology and in disease, including gastrointestinal and neuropsychiatric disorders. Therefore, characterizing the human microbiome and the factors that shape its bacterial population, how they are related to host-specific attributes, and understanding the ways in which it can be manipulated and the phenotypic consequences of such manipulations are of great importance. Characterization of the microbiome so far has been mostly based on compositional studies alone, where relative abundances of different species are compared in different conditions, such as health and disease. However, inter-relationships among the bacterial species, such as competition and cooperation over metabolic resources, may be an important factor that affects the structure and function of the microbiome. Here we review the network-based approaches in answering such questions and explore the first attempts that focus on the interactions facet, complementing compositional studies, towards understanding the microbiome structure and its complex relationship with the human host.

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