Dataset Information

EPS Glycoconjugate Profiles Shift as Adaptive Response in Anaerobic Microbial Granulation at High Salinity.

ABSTRACT: Anaerobic granulation at elevated salinities has been discussed in several analytical and engineering based studies. They report either enhanced or decreased efficiencies in relation to different Na+ levels. To evaluate this discrepancy, we focused on the microbial and structural dynamics of granules formed in two upflow anaerobic sludge blanket (UASB) reactors treating synthetic wastewater at low (5 g/L Na+) and high (20 g/L Na+) salinity conditions. Granules were successfully formed in both conditions, but at high salinity, the start-up inoculum quickly formed larger granules having a thicker gel layer in comparison to granules developed at low salinity. Granules retained high concentrations of sodium without any negative effect on biomass activity and structure. 16S rRNA gene analysis and Fluorescence in Situ Hybridization (FISH) identified the acetotrophic Methanosaeta harundinacea as the dominant microorganism at both salinities. Fluorescence lectin bar coding (FLBC) screening highlighted a significant shift in the glycoconjugate pattern between granules grown at 5 and 20 g/L of Na+, and the presence of different extracellular domains. The excretion of a Mannose-rich cloud-like glycoconjugate matrix, which seems to form a protective layer for some methanogenic cells clusters, was found to be the main distinctive feature of the microbial community grown at high salinity conditions.

SUBMITTER: Gagliano MC

PROVIDER: S-EPMC6036115 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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EPS Glycoconjugate Profiles Shift as Adaptive Response in Anaerobic Microbial Granulation at High Salinity.

Gagliano Maria C MC Neu Thomas R TR Kuhlicke Ute U Sudmalis Dainis D Temmink Hardy H Plugge Caroline M CM

Frontiers in microbiology 20180702

Anaerobic granulation at elevated salinities has been discussed in several analytical and engineering based studies. They report either enhanced or decreased efficiencies in relation to different Na+ levels. To evaluate this discrepancy, we focused on the microbial and structural dynamics of granules formed in two upflow anaerobic sludge blanket (UASB) reactors treating synthetic wastewater at low (5 g/L Na+) and high (20 g/L Na+) salinity conditions. Granules we ...[more]

PMID: 30013532

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Project description:In the recent years anaerobic sludge granulation at elevated salinities in upflow anaerobic sludge blanket (UASB) reactors has been investigated in few engineering based studies, never addressing the microbial community structural role in driving aggregation and keeping granules stability. In this study, the combination of different techniques was applied in order to follow the microbial community members and their structural dynamics in granules formed at low (5 g/L Na+) and high (20 g/L Na+) salinity conditions. Experiments were carried out in four UASB reactors fed with synthetic wastewater, using two experimental set-ups. By applying 16S rRNA gene analysis, the comparison of granules grown at low and high salinity showed that acetotrophic Methanosaeta harundinacea was the dominant methanogen at both salinities, while the dominant bacteria changed. At 5 g/L Na+, cocci chains of Streptoccoccus were developing, while at 20 g/L Na+ members of the family Defluviitaleaceae formed long filaments. By means of Fluorescence in Situ Hybridization (FISH) and Scanning Electron Microscopy (SEM), it was shown that aggregation of Methanosaeta in compact clusters and the formation of filaments of Streptoccoccus and Defluviitaleaceae during the digestion time were the main drivers for the granulation at low and high salinity. Interestingly, when the complex protein substrate (tryptone) in the synthetic wastewater was substituted with single amino acids (proline, leucine and glutamic acid), granules at high salinity (20 g/L Na+) were not formed. This corresponded to a decrease of Methanosaeta relative abundance and a lack of compact clustering, together with disappearance of Defluviitaleaceae and consequent absence of bacterial filaments within the dispersed biomass. In these conditions, a biofilm was growing on the glass wall of the reactor instead, highlighting that a complex protein substrate such as tryptone can contribute to granules formation at elevated salinity.

Project description:BackgroundBacterial communities are responsible for biological nutrient removal and flocculation in engineered systems such as activated floccular sludge. Predators such as bacteriophage and protozoa exert significant predation pressure and cause bacterial mortality within these communities. However, the roles of bacteriophage and protozoan predation in impacting granulation process remain limited. Recent studies hypothesised that protozoa, particularly sessile ciliates, could have an important role in granulation as these ciliates were often observed in high abundance on surfaces of granules. Bacteriophages were hypothesized to contribute to granular stability through bacteriophage-mediated extracellular DNA release by lysing bacterial cells. This current study investigated the bacteriophage and protozoan communities throughout the granulation process. In addition, the importance of protozoan predation during granulation was also determined through chemical killing of protozoa in the floccular sludge.ResultsFour independent bioreactors seeded with activated floccular sludge were operated for aerobic granulation for 11 weeks. Changes in the phage, protozoa and bacterial communities were characterized throughout the granulation process. The filamentous phage, Inoviridae, increased in abundance at the initiation phase of granulation. However, the abundance shifted towards lytic phages during the maturation phase. In contrast, the abundance and diversity of protozoa decreased initially, possibly due to the reduction in settling time and subsequent washout. Upon the formation of granules, ciliated protozoa from the class Oligohymenophorea were the dominant group of protozoa based on metacommunity analysis. These protozoa had a strong, positive-correlation with the initial formation of compact aggregates prior to granule development. Furthermore, chemical inhibition of these ciliates in the floccular sludge delayed the initiation of granule formation. Analysis of the bacterial communities in the thiram treated sludge demonstrated that the recovery of 'Candidatus Accumulibacter' was positively correlated with the formation of compact aggregates and granules.ConclusionPredation by bacteriophage and protozoa were positively correlated with the formation of aerobic granules. Increases in Inoviridae abundance suggested that filamentous phages may promote the structural formation of granules. Initiation of granules formation was delayed due to an absence of protozoa after chemical treatment. The presence of 'Candidatus Accumulibacter' was necessary for the formation of granules in the absence of protozoa.

Project description:Cell proliferation is achieved by numerous enzyme reactions. Temperature governs the activity of each enzyme, which overall determines the optimal growth temperature. Synthesizing useful chemicals and fuels utilizes only part of the metabolic pathways, especially the central metabolic pathways such as glycolysis and TCA cycle to metabolize glucose. However, the optimal temperature for the activity of the central metabolic pathways is inconclusive whether it is correlated with the optimal temperature for cell proliferation. Here, we found that Corynebacterium glutamicum wild type increased the metabolic activity to consume glucose under anaerobic (oxygen deprived) conditions at 42.5ºC, in which the cell hardly grows under aerobic conditions. Glucose consumption rate was increased by 24% at 42.5ºC compared to that at the optimal growth temperature of 30.0ºC. Transcriptional analysis showed that gapX gene encoding glycelaldehydre-3-phosphate dehydrogenase, glucokinase gene, and a gene involved in glucose uptake were upregulated at 42.5ºC. Production of fermentative lactate was increased by 69% than that at 30.0ºC, whereas succinate production was decreased by 13%. In addition to several glycolytic enzymes, the activity of pyruvate kinase was increased with increasing the temperature, whereas the activity of phosphoenolpyruvate carboxylase in anapleotic pathway leading to succinate synthesis was decreased. However, a metabolically engineered succinate over-producing strain, in which lactate production was shut off and pyruvate carboxylase encoding gene in another anapleotic pathway was overexpressed, produced 34% higher succinate at 42.5ºC than that at 30.0ºC with increased glucose consumption. This study provides the evidence that the optimal reaction temperature for production of fermentative products can be set beyond upper limit of growth temperature in C. glutamicum, and hence it could be applicable for producing various chemicals and fuels in C. glutamicum under anaerobic conditions and non-growing cell reactions in other microorganisms.

Project description:BackgroundVaccine clinical studies typically provide time-resolved data on adaptive response read-outs in response to the administration of that particular vaccine to a cohort of individuals. However, modeling such data is challenged by the properties of these time-resolved profiles such as non-linearity, scarcity of measurement points, scheduling of the vaccine at multiple time points. Linear Mixed Models (LMM) are often used for the analysis of longitudinal data but their use in these time-resolved immunological data is not common yet. Apart from the modeling challenges mentioned earlier, selection of the optimal model by using information-criterion-based measures is far from being straight-forward. The aim of this study is to provide guidelines for the application and selection of LMMs that deal with the challenging characteristics of the typical data sets in the field of vaccine clinical studies.MethodsWe used antibody measurements in response to Hepatitis-B vaccine with five different adjuvant formulations for demonstration purposes. We built piecewise-linear, piecewise-quadratic and cubic models with transformations of the axes with pre-selected or optimized knot locations where time is a numerical variable. We also investigated models where time is categorical and random effects are shared intercepts between different measurement points. We compared all models by using Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), Deviance Information Criterion (DIC), variations of conditional AIC and by visual inspection of the model fit in the light of prior biological information.ResultsThere are various ways of dealing with the challenges of the data which have their own advantages and disadvantages. We explain these in detail here. Traditional information-criteria-based measures work well for the coarse selection of the model structure and complexity, however are not efficient at fine tuning of the complexity level of the random effects.ConclusionsWe show that common statistical measures for optimal model complexity are not sufficient. Rather, explicitly accounting for model purpose and biological interpretation is needed to arrive at relevant models.Trial registrationClinical trial registration number for this study: NCT00805389, date of registration: December 9, 2008 (pro-active registration).

Dataset Information

EPS Glycoconjugate Profiles Shift as Adaptive Response in Anaerobic Microbial Granulation at High Salinity.

Publications

EPS Glycoconjugate Profiles Shift as Adaptive Response in Anaerobic Microbial Granulation at High Salinity.

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