High Nucleic Acid Content Bacteria Research Articles

Low and high nucleic acid content bacteria play discrepant roles in response to various carbon supply modes.

Planktonic bacteria can be grouped into 'high nucleic acid content (HNA) bacteria' and 'low nucleic acid content (LNA) bacteria.' Nutrient input modes vary in environments, causing nutrient availability heterogeneity. We incubated them with equal amounts of total glucose added in a continuous/pulsed mode. The pulse-treated LNA bacteria exhibited twice the cell abundance and four times the viability of the continuous-treated LNA, while HNA did not show an adaptation to pulsed treatment. In structural equation modelling, LNA bacteria had higher path coefficients than HNA, between growth and carbon-saving metabolic pathways, intracellular ATP and the inorganic energy storage polymer, polyphosphate, indicating their low-cost growth, and flexible energy storage and utilisation. After incubation, the pulse-treated LNA bacteria contained more proteins and polysaccharides (0.00064, 0.0012 ng cell-1 ) than the continuous-treated LNA (0.00014, 0.00014 ng cell-1 ), conferring endurance and rapid response to pulses. Compared to LNA, HNA keystone taxa had stronger correlations with the primary glucose metabolism step, glycolysis, and occupied leading positions to explain the random forest model. They are essential to introduce glucose into the element cycling of the whole community under both treatments. Our work outlines a systematic bacterial response to carbon input.

Spatiotemporal dynamics of high and low nucleic acid-content bacterial communities in Chinese coastal seawater: assembly process, co-occurrence relationship and the ecological functions.

Studies of high nucleic acid-content (HNA) and low nucleic acid-content (LNA) bacterial communities are updating our view of their distributions and taxonomic composition. However, there are still large gaps in our knowledge of the composition, assembly processes, co-occurrence relationships and ecological functions of HNA and LNA bacterial communities. Here, using 16S rRNA gene amplicon sequencing, we investigated the spatiotemporal dynamics, assembly processes, co-occurrence relationships and ecological functions of HNA and LNA bacterial communities in the samples collected in summer and winter in Chinese coastal seas. The communities of HNA and LNA bacteria had clear spatiotemporal patterns and LNA bacteria was phylogenetically less diverse than HNA bacteria in both seasons. The distribution of HNA and LNA bacteria were significantly affected by the environmental factors and a significant seasonal-consistent distance-decay patterns were found in HNA and LNA bacteria. Furthermore, a quantitative assessment of ecological processes revealed that dispersal limitation, homogeneous selection exerted important roles in the community assembly of HNA and LNA bacteria. More importantly, we observed seasonality in the co-occurrence relationships: closer inter-taxa connections of HNA bacterial communities in winter than in summer and the opposite is true in the LNA bacterial communities. Some ecological functions, such as: phototrophy, photoautotrophy, oxygenic photoautotrophy, were different between HNA and LNA bacteria. These results provide a better understanding of spatiotemporal patterns, processes, and the ecological functions of HNA and LNA bacterial communities in Chinese coastal seawater.

Translational activity is uncoupled from nucleic acid content in bacterial cells of the human gut microbiota

ABSTRACT Changes in bacterial diversity in the human gut have been associated with many conditions, despite not always reflecting changes in bacterial activity. Methods linking bacterial identity to function are needed for improved understanding of how bacterial communities adapt and respond to their environment, including the gut. Here, we optimized bioorthogonal non-canonical amino acid tagging (BONCAT) for the gut microbiota and combined it with fluorescently activated cell sorting and sequencing (FACS-Seq) to identify the translationally active members of the community. We then used this novel technique to compare with other bulk community measurements of activity and viability: relative nucleic acid content and membrane damage. The translationally active bacteria represent about half of the gut microbiota, and are not distinct from the whole community. The high nucleic acid content bacteria also represent half of the gut microbiota, but are distinct from the whole community and correlate with the damaged subset. Perturbing the community with xenobiotics previously shown to alter bacterial activity but not diversity resulted in stronger changes in the distinct physiological fractions than in the whole community. BONCAT is a suitable method to probe the translationally active members of the gut microbiota, and combined with FACS-Seq, allows for their identification. The high nucleic acid content bacteria are not necessarily the protein-producing bacteria in the community; thus, further work is needed to understand the relationship between nucleic acid content and bacterial metabolism in the human gut. Considering physiologically distinct subsets of the gut microbiota may be more informative than whole-community profiling.

Picoplankton Distribution and Activity in the Deep Waters of the Southern Adriatic Sea

Southern Adriatic (Eastern Mediterranean Sea) is a region strongly dominated by large-scale oceanographic processes and local open-ocean dense water formation. In this study, picoplankton biomass, distribution, and activity were examined during two oceanographic cruises and analyzed in relation to environmental parameters and hydrographic conditions comparing pre and post-winter phases (December 2015, April 2016). Picoplankton density with the domination of autotrophic biomasses was higher in the pre-winter phase when significant amounts of picoaoutotrophs were also found in the meso-and bathy-pelagic layers, while Synechococcus dominated the picoautotrophic group. Higher values of bacterial production and domination of High Nucleic Acid content bacteria (HNA bacteria) were found in deep waters, especially during the post-winter phase, suggesting that bacteria can have an active role in the deep-sea environment. Aerobic anoxygenic phototrophic bacteria accounted for a small proportion of total heterotrophic bacteria but contributed up to 4% of bacterial carbon content. Changes in the picoplankton community were mainly driven by nutrient availability, heterotrophic nanoflagellates abundance, and water mass movements and mixing. Our results suggest that autotrophic and heterotrophic members of the picoplankton community are an important carbon source in the food web in the deep-sea, as well as in the epipelagic layer. Besides, viral lysis may affect the activity of the picoplankton community and enrich the water column with dissolved organic carbon.

Geographic distribution pattern of low and high nucleic acid content bacteria on a river-catchment scale

Bacteria with low nucleic acid content (LNA) and high nucleic acid content (HNA) are widely distributed in aquatic environments. Most of the current understanding of these two subgroups is derived from studies in marine environments. In comparison, information on the spatial distribution of these two subgroups in freshwater environments is very limited. The present study analysed the biogeographical pattern of those two groups on a large-river scale (i.e. the Songhua River catchment, >1000km). The results showed that the concentrations of LNA and HNA bacteria were distributed over a wide range from 5.45×104 to 4.43×106cellsmL–1, and from 1.35×105 to 4.37×106cellsmL–1 respectively. The two groups have almost equal proportions in the Songhua River, with the average contribution of LNA bacteria reaching 47.0%. In comparison, the abundance of LNA bacteria in the mainstream was significantly higher than in the tributaries. The cytometric expressions (green fluorescence and side scatter) within LNA and HNA were strongly covaried, which implies that these two subgroups are intrinsically linked. Multivariate redundancy analysis indicated that both the abundance and cytometric characteristics of co-occurring LNA and HNA bacteria were regulated differently in the Songhua River. This suggests that LNA and HNA bacteria play different ecological roles in river ecosystems.

Microbial metabolism of transparent exopolymer particles during the summer months along a eutrophic estuary system.

This study explores the role of transparent exopolymer particles (TEP) as an additional carbon source for heterotrophic microbial activity in the eutrophic Qishon estuary. From the coastal station and upstream the estuary; TEP concentrations, β-glucosidase activity, bacterial production and abundance have gradually increased. TEP were often found as bio-aggregates, scaffolding algae, detritus matter and bacteria that likely formed “hotspots” for enhance microbial activity. To further demonstrate the link between TEP and heterotrophic bacterial activity, confined incubations with ambient and polysaccharide-enriched estuary water were carried out. Following polysaccharide addition, elevated (~50%) β-glucosidase activity rates were observed, leading to TEP hydrolysis. This newly formed bioavailable carbon resulted in significantly higher growth rates, with up to a 5-fold increase in heterotrophic bacterial biomass, comprising mostly high nucleic acid content bacteria. Taking together the findings from this research, we conclude that even in highly eutrophic environments heterotrophic bacteria may still be carbon limited. Further, TEP as a polysaccharide matrix can act as a metabolic surrogate, adding fresh bioavailable carbon through tight associations with bacteria in eutrophic ecosystems such as the Qishon estuary.

Flow Cytometry Total Cell Counts: A Field Study Assessing Microbiological Water Quality and Growth in Unchlorinated Drinking Water Distribution Systems

The objective of this study was to evaluate the application of flow cytometry total cell counts (TCCs) as a parameter to assess microbial growth in drinking water distribution systems and to determine the relationships between different parameters describing the biostability of treated water. A one-year sampling program was carried out in two distribution systems in The Netherlands. Results demonstrated that, in both systems, the biomass differences measured by ATP were not significant. TCC differences were also not significant in treatment plant 1, but decreased slightly in treatment plant 2. TCC values were found to be higher at temperatures above 15°C than at temperatures below 15°C. The correlation study of parameters describing biostability found no relationship among TCC, heterotrophic plate counts, and Aeromonas. Also no relationship was found between TCC and ATP. Some correlation was found between the subgroup of high nucleic acid content bacteria and ATP (R 2 = 0.63). Overall, the results demonstrated that TCC is a valuable parameter to assess the drinking water biological quality and regrowth; it can directly and sensitively quantify biomass, detect small changes, and can be used to determine the subgroup of active HNA bacteria that are related to ATP.

Effects of inorganic and organic nutrient inputs on bacterioplankton community composition along a latitudinal transect in the Atlantic Ocean

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 60:299-313 (2010) - DOI: https://doi.org/10.3354/ame01435 Effects of inorganic and organic nutrient inputs on bacterioplankton community composition along a latitudinal transect in the Atlantic Ocean Eva Teira1,*, Sandra Martínez-García1, Alejandra Calvo-Díaz2,3,4, Xosé Anxelu G. Morán2 1Departamento Ecología y Biología Animal, Facultad de Ciencias, Universidad de Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain 2Instituto Español de Oceanografía, Centro Oceanográfico de Xixón, Camín de L’Arbeyal s/n, 33212 Xixón, Spain 3Present address: Department of Biological Oceanography, Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, 1790 AB Den Burg, The Netherlands 4Present address: Department of Marine Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria *Email: teira@uvigo.es ABSTRACT: Bacterioplankton are responsible for a large fraction of respiration and dissolved organic matter (DOM) remineralisation in the ocean; therefore, changes in their taxonomic composition due to changes in nutrient inputs may have important biogeochemical implications. The impact of nutrient loading will depend on the type of input and the initial environmental conditions. We conducted a set of 5 microcosm experiments along a broad latitudinal transect in the Atlantic Ocean (26°N to 29°S) in order to assess the effects of inorganic (nitrate, ammonium, phosphate, silica) and organic (glucose, amino acids) inputs, added separately as well as jointly, on the bacterioplankton community composition at the level of major groups. We followed changes in the relative abundance of important bacterial phylogenetic (Roseobacter spp., SAR11, Gammaproteobacteria, Bacteroidetes) and cytometric (low, high and very high nucleic acid content) groups. We observed that distinct groups responded differently to nutrient additions: SAR11 and Bacteroidetes responded negatively to organic and mixed additions, while Roseobacter spp. and Gammaproteobacteria responded positively. Only the group Roseobacter spp. responded positively to inorganic additions. The abundance of very high nucleic acid content bacteria was low in the control and the inorganic treatment; however, they reached very high numbers in the organic and mixed treatments. There was a clear increasing north to south gradient in the magnitude of response of Gammaproteobacteria to organic inputs (containing carbon and nitrogen), likely related to an increasing north to south gradient in phosphate concentration. The magnitude of response of Gammaproteobacteria explained 89% of the observed variability in the magnitude of bacterial production response, which suggests a strong link between bacterial community composition and carbon cycling in the oligotrophic ocean. KEY WORDS: Nutrient enrichment · Microcosms · Bacterioplankton · Oligotrophic ocean Full text in pdf format PreviousCite this article as: Teira E, Martínez-García S, Calvo-Díaz A, Morán XAG (2010) Effects of inorganic and organic nutrient inputs on bacterioplankton community composition along a latitudinal transect in the Atlantic Ocean. Aquat Microb Ecol 60:299-313. https://doi.org/10.3354/ame01435Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 60, No. 3. Online publication date: August 03, 2010 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2010 Inter-Research.

Abundance and production of bacteria, and relationship to phytoplankton production, in a large tropical lake (Lake Tanganyika)

Summary1. Abundance and bacterial production (BP) of heterotrophic bacteria (HBact) were measured in the north and south basins of Lake Tanganyika, East Africa, during seasonal sampling series between 2002 and 2007. The major objective of the study was to assess whether BP can supplement phytoplankton particulate primary production (particulate PP) in the pelagic waters, and whether BP and particulate PP are related in this large lake. HBact were enumerated in the 0–100 m surface layer by epifluorescence microscopy and flow cytometry; BP was quantified using 3H‐thymidine incorporation, usually in three mixolimnion layers (0–40, 40–60 and 60–100 m).2. Flow cytometry allowed three subpopulations to be distinguished: low nucleic acid content bacteria (LNA), high nucleic acid content bacteria (HNA) and Synechococcus‐like picocyanobacteria (PCya). The proportion of HNA was on average 67% of total bacterial abundance, and tended to increase with depth. HBact abundance was between 1.2 × 105 and 4.8 × 106 cells mL−1, and was maximal in the 0–40 m layer (i.e. roughly, the euphotic layer). Using a single conversion factor of 15 fg C cell−1, estimated from biovolume measurements, average HBact biomass (integrated over a 100‐m water column depth) was 1.89 ± 1.05 g C m−2.3. Significant differences in BP appeared between seasons, especially in the south basin. The range of BP integrated over the 0–100 m layer was 93–735 mg C m−2 day−1, and overlapped with the range of particulate PP (150–1687 mg C m−2 day−1) measured in the same period of time at the same sites.4. Depth‐integrated BP was significantly correlated to particulate PP and chlorophyll‐a, and BP in the euphotic layer was on average 25% of PP.5. These results suggest that HBact contribute substantially to the particulate organic carbon available to consumers in Lake Tanganyika, and that BP may be sustained by phytoplankton‐derived organic carbon in the pelagic waters.