scholarly journals Diversity of Bacterial Communities in Contrasting Aquatic Environments: Lake Timsah, Egypt

2011 ◽  
Vol 4 ◽  
pp. MBI.S6948 ◽  
Author(s):  
Magdy Bahgat
Keyword(s):  
Bacterial Communities ◽  
Bacterial Species ◽  
Bacterial Community Composition ◽  
Suez Canal ◽  
Aquatic Environments ◽  
The West ◽  
Free Living ◽  
Abundant Genus ◽  
Living Bacteria ◽  
Water Depths

Effect of pollution on diversity of attached and free-living bacteria in two contrasting stations, namely, Suez Canal and outlet of West Lagoon to Lake Timsah was investigated. Bacillus was the most abundant genus especially in West Lagoon station where higher organic agricultural and municipal loads was discharged. Bacterial species richness differed among water depths and was higher in subsurface samples. In Suez Canal more Gram negative populations were isolated. The possible influences of pollution in the West Lagoon station on the bacterial community composition were discussed.

scholarly journals Dynamics of Free-Living and Attached Bacterial Assemblages in Skeletonema sp. Diatom Cultures at Elevated Temperatures

2021 ◽  
Vol 8 ◽  
Author(s):  
Zichao Deng ◽  
Shouchang Chen ◽  
Ping Zhang ◽  
Xu Zhang ◽  
Jonathan M. Adams ◽  
...  
Keyword(s):  
Community Structure ◽  
Elevated Temperature ◽  
Bacterial Communities ◽  
Elevated Temperatures ◽  
Bacterial Species ◽  
Positive Interactions ◽  
Growth Stages ◽  
Free Living ◽  
Attached Bacteria ◽  
Living Bacteria

In the context of global warming, changes in phytoplankton-associated bacterial communities have the potential to change biogeochemical cycling and food webs in marine ecosystems. Skeletonema is a cosmopolitan diatom genus in coastal waters worldwide. Here, we grew a Skeletonema strain with its native bacterial assemblage at different temperatures and examined cell concentrations of Skeletonema sp. and free-living bacteria, dissolved organic carbon (DOC) concentrations of cultures, and the community structure of both free-living and attached bacteria at different culture stages. The results showed that elevated temperature increased the specific growth rates of both Skeletonema and free-living bacteria. Different growth stages had a more pronounced effect on community structure compared with temperatures and different physical states of bacteria. The effects of temperature on the structure of the free-living bacterial community were more pronounced compared with diatom-attached bacteria. Carbon metabolism genes and those for some specific amino acid pathways were found to be positively correlated with elevated temperature, which may have profound implications on the oceanic carbon cycle and the marine microbial loop. Network analysis revealed evidence of enhanced cooperation with an increase in positive interactions among different bacteria at elevated temperature. This may help the whole community to overcome the stress of elevated temperature. We speculate that different bacterial species may build more integrated networks with a modified functional profile of the whole community to cope with elevated temperature. This study contributes to an improved understanding of the response of diatom-associated bacterial communities to elevated temperature.

Symbiotic bacteria of helminths: what role may they play in ecosystems under anthropogenic stress?

2016 ◽  
Vol 90 (6) ◽  
pp. 647-657 ◽  
Author(s):  
N.J. Morley
Keyword(s):  
Climate Change ◽  
Environmental Stress ◽  
Bacterial Communities ◽  
Bacterial Species ◽  
Symbiotic Bacteria ◽  
Anthropogenic Pressure ◽  
Anthropogenic Stress ◽  
Similar Function ◽  
Free Living ◽  
Terrestrial Habitats

AbstractSymbiotic bacteria are a common feature of many animals, particularly invertebrates, from both aquatic and terrestrial habitats. These bacteria have increasingly been recognized as performing an important role in maintaining invertebrate health. Both ecto- and endoparasitic helminths have also been found to harbour a range of bacterial species which provide a similar function. The part symbiotic bacteria play in sustaining homeostasis of free-living invertebrates exposed to anthropogenic pressure (climate change, pollution), and the consequences to invertebrate populations when their symbionts succumb to poor environmental conditions, are increasingly important areas of research. Helminths are also susceptible to environmental stress and their symbiotic bacteria may be a key aspect of their responses to deteriorating conditions. This article summarizes the ecophysiological relationship helminths have with symbiotic bacteria and the role they play in maintaining a healthy parasite and the relevance of specific changes that occur in free-living invertebrate–bacteria interactions under anthropogenic pressure to helminths and their bacterial communities. It also discusses the importance of understanding the mechanistic sensitivity of helminth–bacteria relationships to environmental stress for comprehending the responses of parasites to challenging conditions.

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.

scholarly journals Soil Water Contents Control the Responses of Dissolved Nitrogen Pools and Bacterial Communities to Freeze-Thaw in Temperate Soils

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Nan Jiang ◽  
Yinghua Juan ◽  
Lulu Tian ◽  
Xiaodong Chen ◽  
Wentao Sun ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Soil Water ◽  
Community Composition ◽  
Bacterial Communities ◽  
N Mineralization ◽  
Bacterial Species ◽  
Bacterial Community Composition ◽  
N Immobilization ◽  
Freeze Thaw ◽  
Dissolved Nitrogen

Background. Freeze-thaw influences soil-dissolved nitrogen (N) pools due to variations in bacterial communities in temperate regions. The availability of soil water is important to soil biogeochemical cycles under frozen conditions. However, it is unclear how soil water content (SWC) mediates the effects of freeze-thaw on soil-dissolved N pools and bacterial communities. Method. In this study, freeze-thaw microcosms were incubated at three levels of SWC, including 10% (air-dried soils), 15% (natural SWC), and 30% (wet soils). In addition to measuring soil-dissolved N pools, variations in bacterial communities were examined using high-throughput sequencing. Results and Conclusions. Total dissolved N (TDN), NO3--N, NH4+-N, microbial biomass N (MBN), and net N mineralization rate (NNMR) were significantly influenced by SWC, freeze-thaw, and their interaction (NH4+-N excluded). N immobilization was inhibited under both low and high SWC, which was accompanied by varied bacterial community composition. However, only higher SWC substantially modified the freeze-thaw effects on the soil-dissolved N pools, characterized by a decrease in N mineralization (especially for the content of NO3--N and NNMR) and an increase in N immobilization (MBN). These scenarios could be significantly correlated to variations in bacterial community composition based on redundancy analysis, especially by species belonging to Bacteroidetes, Nitrospirae, Alphaproteobacteria, Gemmatimonadetes, and Verrucomicrobia (Spearman’s correlations). In conclusion, bacterial species passed through biotic (bacterial species) and abiotic filters (soil N pools) in response to freeze-thaw under varied SWC.

scholarly journals Impacts of Extreme Weather Events on Bacterial Community Composition of a Temperate Humic Lake

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2757
Author(s):  
Alexa Hoke ◽  
Jason Woodhouse ◽  
Luca Zoccarato ◽  
Valerie McCarthy ◽  
Elvira de Eyto ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Bacterial Communities ◽  
Bacterial Community Composition ◽  
Critical Role ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Free Living ◽  
Drought Period ◽  
Weather Events

Extreme weather events are projected to increase in frequency and intensity as climate change continues. Heterotrophic bacteria play a critical role in lake ecosystems, yet little research has been done to determine how they are affected by such extremes. The purpose of this study was to use high-throughput sequencing to explore the bacterial community composition of a humic oligotrophic lake on the North Atlantic Irish coast and to assess the impacts on composition dynamics related to extreme weather events. Samples for sequencing were collected from Lough Feeagh on a fortnightly basis from April to November 2018. Filtration was used to separate free-living and particle-associated bacterial communities and amplicon sequencing was performed for the 16S rRNA V4 region. Two named storms, six high discharge events, and one drought period occurred during the sampling period. These events had variable, context-dependent effects on bacterial communities in Lough Feeagh. The particle-associated community was found to be more likely to respond to physical changes, such as mixing, while the free-living population responded to changes in nutrient and carbon concentrations. Generally, however, the high stability of the bacterial community observed in Lough Feeagh suggests that the bacterial community is relatively resilient to extreme weather events.

scholarly journals Groundwater bacterial communities evolve over time, exhibiting oscillating similarity patterns in response to recharge

2021 ◽  
Author(s):  
Lijuan Yan ◽  
Syrie Hermans ◽  
Kai Uwe Totsche ◽  
Robert Lehmann ◽  
Martina Herrmann ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Bacterial Communities ◽  
Bacterial Community Composition ◽  
High Temporal Resolution ◽  
Aquatic Environments ◽  
Rrna Gene ◽  
Sequencing Data ◽  
Environmental Selection ◽  
The Impact ◽  
Over Time

Time series analyses are a crucial tool for uncovering the patterns and processes shaping microbial communities and their functions, especially in aquatic ecosystems. Subsurface aquatic environments are perceived to be more stable than oceans and lakes, due to the lack of sunlight, the absence of photosysnthetically-driven primary production, low temperature variations, and oligotrophic conditions. However, periodic groundwater recharge should affect the structure and succession of groundwater microbiomes. To disentangle the long-term temporal changes in groundwater bacterial communities of shallow fractured bedrock community, and identify the drivers of the observed patterns, we analysed bacterial 16S rRNA gene sequencing data for samples collected monthly from three groundwater wells over a six-year period (n=230) along a hillslope recharge area. We show that the bacterial communities in the groundwater of limestone-mudstone alternations were not stable over time and showed oscillating dissimilarity patterns which corresponded to periods of groundwater recharge; the impact of recharge events on the groundwater microbiome was linked to the recharge strength and local environmental selection strength. Sampling period was able to explain up to 29.5% of the variability in bacterial community composition. We observed an increase in dissimilarity over time (generalized additive model P < 0.001) indicating that the successive recharge events result in communities that are increasingly more dissimilar to the initial reference time point. The majority of groundwater bacteria originated from the recharge-related sources (mean = 66.5%, SD = 15.1%) and specific bacterial taxa were identified as being either enriched or repressed during recharge events. Overall, similar to surface aquatic environments, groundwater microbiomes vary through time, though we revealed groundwater recharges as unique driving factors for these patterns. The high temporal resolution employed here highlights the complex dynamics of bacterial communities in groundwater and demonstrated that successive shocks disturb the bacterial communities, leading to decreased similarity to the initial state over time.

scholarly journals Similarity of salivary microbiome in parents and adult children

2019 ◽  
Author(s):  
Kati Sundström ◽  
Pashupati P Mishra ◽  
Mikko J Pyysalo ◽  
Terho Lehtimäki ◽  
Pekka J Karhunen ◽  
...  
Keyword(s):  
Adult Children ◽  
Bacterial Communities ◽  
Bacterial Species ◽  
Amplicon Sequencing ◽  
Human Saliva ◽  
Oral Microbiome ◽  
Rrna Gene ◽  
Genus Level ◽  
Abundant Genus ◽  
Dna Profiles

Background: Human saliva contains approximately 700 bacterial species but the relatedness of salivary bacteria from parents to adult children is not investigated in humans. The objectives were to investigate the entirety of salivary bacterial DNA profiles and whether and how families share these profiles and also compare these communities between adult parent-off-spring pairs using 16S rRNA gene amplicon sequencing. Results: The most abundant phyla in two separate families were Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria and Actinobacteria. Family ties explained 13 % of the variance between individuals’ bacterial communities (R2=0.13; P=0.001). Mothers shared more OTUs with their adult children compared to fathers, but this linkage seemed to be weaker in the family with older adult children. We identified 29 differentially abundant genus level OTUs (FDR < 0.05) between the families, which accounted for 31 % of the total identified genus level OTUs Conclusions: Our results indicate that adult family members share bacterial communities and adult children were more similar to mothers than fathers. Our results suggest implicitly that a similarity in oral microbiome between parent-child pairs is present, but may change over time.

scholarly journals Complexity of Bacterial Communities in a River-Floodplain System (Danube, Austria)

2005 ◽  
Vol 71 (2) ◽  
pp. 609-620 ◽  
Author(s):  
Katharina Besemer ◽  
Markus M. Moeseneder ◽  
Jesus M. Arrieta ◽  
Gerhard J. Herndl ◽  
Peter Peduzzi
Keyword(s):  
Organic Matter ◽  
Bacterial Community ◽  
Bacterial Communities ◽  
Temporal Dynamics ◽  
Bacterial Community Composition ◽  
Inorganic Nutrients ◽  
Danube River ◽  
Polymorphism Analysis ◽  
Free Living ◽  
River Floodplain

ABSTRACT Natural floodplains play an essential role in the processing and decomposition of organic matter and in the self-purification ability of rivers, largely due to the activity of bacteria. Knowledge about the composition of bacterial communities and its impact on organic-matter cycling is crucial for the understanding of ecological processes in river-floodplain systems. Particle-associated and free-living bacterial assemblages from the Danube River and various floodplain pools with different hydrological characteristics were investigated using terminal restriction fragment length polymorphism analysis. The particle-associated bacterial community exhibited a higher number of operational taxonomic units (OTUs) and was more heterogeneous in time and space than the free-living community. The temporal dynamics of the community structure were generally higher in isolated floodplain pools. The community structures of the river and the various floodplain pools, as well as those of the particle-associated and free-living bacteria, differed significantly. The compositional dynamics of the planktonic bacterial communities were related to changes in the algal biomass, temperature, and concentrations of organic and inorganic nutrients. The OTU richness of the free-living community was correlated with the concentration and origin of organic matter and the concentration of inorganic nutrients, while no correlation with the OTU richness of the particle-associated assemblage was found. Our results demonstrate the importance of the river-floodplain interactions and the influence of damming and regulation on the bacterial-community composition.

scholarly journals Acanthamoeba castellanii Promotes the Survival of Vibrio parahaemolyticus

2008 ◽  
Vol 74 (23) ◽  
pp. 7183-7188 ◽  
Author(s):  
Michelle A. Laskowski-Arce ◽  
Kim Orth
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Acanthamoeba Castellanii ◽  
Survival Advantage ◽  
Aquatic Environments ◽  
Pathogenic Species ◽  
Free Living ◽  
Food Borne ◽  
And Function ◽  
Living Bacteria

ABSTRACT Vibrio parahaemolyticus is a food-borne pathogen that naturally inhabits both marine and estuarine environments. Free-living protozoa exist in similar aquatic environments and function to control bacterial numbers by grazing on free-living bacteria. Protozoa also play an important role in the survival and spread of some pathogenic species of bacteria. We investigated the interaction between the protozoan Acanthamoeba castellanii and the bacterium Vibrio parahaemolyticus. We found that Acanthamoeba castellanii does not prey on Vibrio parahaemolyticus but instead secretes a factor that promotes the survival of Vibrio parahaemolyticus in coculture. These studies suggest that protozoa may provide a survival advantage to an extracellular pathogen in the environment.

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