scholarly journals Particle Collection in Imhoff Sedimentation Cones Enriches Both Motile Chemotactic and Particle-Attached Bacteria

2021 ◽  
Vol 12 ◽  
Author(s):  
Anneke Heins ◽  
Greta Reintjes ◽  
Rudolf I. Amann ◽  
Jens Harder
Keyword(s):  
Amplicon Sequencing ◽  
Enrichment Factors ◽  
Free Living ◽  
Particle Collection ◽  
16S Rrna Amplicon Sequencing ◽  
Heterotrophic Microorganisms ◽  
Attached Bacteria ◽  
Bacterial Aggregates ◽  
And Function ◽  
Living Bacteria

Marine heterotrophic microorganisms remineralize about half of the annual primary production, with the microbiomes on and around algae and particles having a major contribution. These microbiomes specifically include free-living chemotactic and particle-attached bacteria, which are often difficult to analyze individually, as the standard method of size-selective filtration only gives access to particle-attached bacteria. In this study, we demonstrated that particle collection in Imhoff sedimentation cones enriches microbiomes that included free-living chemotactic bacteria and were distinct from particle microbiomes obtained by filtration or centrifugation. Coastal seawater was collected during North Sea phytoplankton spring blooms, and the microbiomes were investigated using 16S rRNA amplicon sequencing and fluorescence microscopy. Enrichment factors of individual operational taxonomic units (OTUs) were calculated for comparison of fractionated communities after separation with unfractionated seawater communities. Filtration resulted in a loss of cells and yielded particle fractions including bacterial aggregates, filaments, and large cells. Centrifugation had the lowest separation capacity. Particles with a sinking rate of >2.4 m day–1 were collected in sedimentation cones as a bottom fraction and enriched in free-living chemotactic bacteria, i.e., Sulfitobacter, Pseudoalteromonas, and Vibrio. Subfractions of these bottom fractions, obtained by centrifugation, showed enrichment of either free-living or particle-attached bacteria. We identified five distinct enrichment patterns across all separation techniques: mechano-sensitive and mechano-stable free-living bacteria and three groups of particle-attached bacteria. Simultaneous enrichment of particle-attached and chemotactic free-living bacteria in Imhoff sedimentation cones is a novel experimental access to these groups providing more insights into the diversity, structure, and function of particle-associated microbiomes, including members of the phycosphere.

The Potential of Free-Living Ground Water Bacteria to Degrade Aromatic Hydrocarbons and Heterocyclic Compounds

1988 ◽  
Vol 20 (3) ◽  
pp. 109-118 ◽  
Author(s):  
E. Arvin ◽  
B. Jensen ◽  
J. Aamand ◽  
C. Jørgensen
Keyword(s):  
Ground Water ◽  
Aromatic Hydrocarbons ◽  
Biomass Concentration ◽  
Nitrogen And Phosphorus ◽  
Free Living ◽  
Soil Fractions ◽  
Fine Soil ◽  
Attached Bacteria ◽  
Considerable Degradation ◽  
Living Bacteria

This study has documented that a considerable degradation potential related to aromatic hydrocarbons and aromatic nitrogen-, sulphur- and oxygen- containing compounds is associated with the free-living ground water bacteria. All studies were performed under aerobic conditions and with surplus of nitrogen and phosphorus. After a lag period, which differs considerably between locations upstream and downstream of hydrocarbon spills, the free-living bacteria are able to degrade the hydrocarbons to concentrations less than 1 µg/l. The bacteria from one site were able to degrade naphthalene according to a zero order reaction even at 1 µg/l. Preliminary experiments indicate that the free-living bacteria may have a relatively high activity compared to the attached bacteria when compared on the basis of the same total bacteria numbers. The hypothesis is put forward that, although the attached biomass concentration in the aquifer may be much higher than the free-living biomass, the latter is still very important for the degradation capability if the attached bacteria are fixed in the fine soil fractions (silt, etc), the reason being that the flow of water, and with this the flux of substrate, is relatively small to the attached bacteria due to low hydraulic conductivity in the fine soil fractions.

Limnoithona sinensis as refuge for bacteria: protection from UV radiation and chlorine disinfection in drinking water treatment

2014 ◽  
Vol 60 (11) ◽  
pp. 745-752 ◽  
Author(s):  
Tao Lin ◽  
Bo Cai ◽  
Wei Chen
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Uv Radiation ◽  
Bacterial Population ◽  
Drinking Water Treatment ◽  
Free Living ◽  
Surrounding Water ◽  
Chlorine Disinfection ◽  
Attached Bacteria ◽  
Living Bacteria

In this study, we tested the potential of Limnoithona sinensis to provide its attached bacteria refuge against disinfection. The experimental results indicated that in water devoid of zooplankton, both UV radiation and chlorine disinfection significantly decreased the viability of free-living bacteria. In the presence of L. sinensis, however, the attached bacteria could survive and rapidly recover from disinfection. This demonstrated that L. sinensis provided protection from external damage to various aquatic bacteria that were attached to its body. The surviving bacteria remained on L. sinensis after disinfection exposure, which enabled a rapid increase in the bacterial population followed by their subsequent release into the surrounding water. Compared with UV radiation, chlorine disinfection was more effective in terms of inactivating attached bacteria. Both UV radiation and chlorine disinfection had little effect in terms of preventing the spread of undesirable bacteria, due to the incomplete inactivation of the bacteria associated with L. sinensis.

Distribution of heterotrophic bacteria in relation to the concentration of particulate organic matter in seawater

1983 ◽  
Vol 29 (5) ◽  
pp. 570-575 ◽  
Author(s):  
Kimio Fukami ◽  
Usio Simidu ◽  
Nobuo Taga
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Heterotrophic Bacteria ◽  
Viable Count ◽  
Plate Count ◽  
Free Living ◽  
Count Method ◽  
Attached Bacteria ◽  
Geographical Scale ◽  
Living Bacteria

The relationship between the number of bacteria and the concentration of particulate organic carbon (POC) in seawater was investigated. In coastal seawater in summer, the POC concentration showed better correlation to the density of bacteria obtained by the viable plate count method (viable count, V.C.) than by the total direct count method (total count, T.C.). The number of attached bacteria (A) showed significant fluctuation, both laterally on a geographical scale and vertically in the water column; on the other hand, the number of free-living bacteria (F) was relatively constant. The POC concentration had a much higher correlation with A (r = 0.8795) than with T.C. (r = 0.7339), and had a low correlation with F (r = 0.6935). Moreover, a very good correlation was observed between the density of bacteria obtained by V.C. and A (r = 0.9153). These results indicate that when the concentration of particulate organic matter (POM) increases, some free-living bacteria become attached to POM, and grow on the surface of POM. These communities of attached bacteria have the ability to make colonies on plate media and can be counted as the "viable plate count."

Bacterial community structure in cooling water and biofilm in an industrial recirculating cooling water system

2013 ◽  
Vol 68 (4) ◽  
pp. 940-947 ◽  
Author(s):  
Jinmei Wang ◽  
Min Liu ◽  
Huijie Xiao ◽  
Wei Wu ◽  
Meijuan Xie ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Water System ◽  
Cooling Water ◽  
Water Systems ◽  
Rrna Gene ◽  
Free Living ◽  
Cooling Water System ◽  
Attached Bacteria ◽  
Living Bacteria

Microbial fouling is a serious problem in open recirculating cooling water systems. The bacterial communities that cause it have not been fully understood. In this study, we analyzed the community structure of free-living bacteria and particle-attached bacteria in cooling water, and bacteria in biofilm collected from the wall of the water reservoir in an industrial recirculating cooling water system by construction of a 16S rRNA gene clone library. Based on amplified ribosomal DNA restriction analysis, clones of all three libraries were clustered into 45 operational taxonomic units (OTUs). Thirteen OTUs displaying 91–96% sequence similarity to a type strain might be novel bacterial species. Noted differences in community structure were observed among the three libraries. The relative species richness of the free-living bacteria in cooling water was much lower than that of particle-attached bacteria and bacteria in biofilm. The majority of the free-living bacterial community (99.0%) was Betaproteobacteria. The predominant bacteria in the particle-attached bacterial community were Alphaproteobacteria (20.5%), Betaproteobacteria (27.8%) and Planctomycetes (42.0%), while those in the biofilm bacterial community were Alphaproteobacteria (47.9%), Betaproteobacteria (11.7%), Acidobacteria (13.1%) and Gemmatimonadetes (11.3%). To control microbial fouling in industrial recirculating cooling water systems, additional physiological and ecological studies of these species will be essential.

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.

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.

scholarly journals Comparison of the Ocular Microbiomes of Dry Eye Patients With and Without Autoimmune Disease

2021 ◽  
Vol 11 ◽  
Author(s):  
Yun Qi ◽  
Yong Wan ◽  
Tianhui Li ◽  
Ming Zhang ◽  
Yu Song ◽  
...  
Keyword(s):  
Autoimmune Disease ◽  
Dry Eye ◽  
Area Under The Curve ◽  
Alpha Diversity ◽  
Amplicon Sequencing ◽  
Microbial Composition ◽  
16S Rrna Amplicon Sequencing ◽  
And Function ◽  
Microbiota Diversity ◽  
Inferior Fornix

PurposeThe pathogenesis of dry eye concomitant with autoimmune disease is different from that of dry eye without autoimmune disease. The aim of this study was to explore differences in the microbiota diversity and composition in dry eye with and without autoimmune disease.MethodsSwab samples from the inferior fornix of the conjunctival sac were obtained from dry eye patients without autoimmune disease (n = 49, dry eye group) and from those with autoimmune disease (n = 38, immdry eye group). Isolated bacterial DNAs from swabs were analyzed with 16S rRNA amplicon sequencing.ResultsAnalysis of the alpha diversity revealed no significant differences between subjects in the dry eye and immdry eye groups. Those in the immdry eye group had a distinct microbial composition compared with those in the dry eye group. The combination of the genera Corynebacterium and Pelomonas distinguished subjects in the immdry eye group from those in the dry eye group, with an area under the curve of 0.73 (95% CI = 0.62–0.84). For the same bacteria, the correlations between microbe abundance and the ocular surface parameters were different in the two groups. In addition, the functions of the microbial communities were altered in the two groups.ConclusionsOur study demonstrates changes in the composition and function of the ocular microbiome between subjects in the immdry eye and dry eye groups, which suggests that the potential pathogenesis is different.

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