Biology subjects

Tomas-Martinez, S.

Publications and source records attributed to Tomas-Martinez, S..

4 recordsLinked to original sources

bioRxiv2022

Enrichment and application of bacterial sialic acids containing polymers from the extracellular polymeric substances of Candidatus Accumulibacter

Pseudaminic and legionaminic acids are a subgroup of nonulosonic acids (NulOs) unique to bacterial species. There is a lack of advances in the study of these NulOs due to their complex synthesis and production. Recently, it was seen that "Candidatus Accumulibacter" can produce Pse or Leg analogues as part of its extracellular polymeric substances (EPS). In order to employ a "Ca. Accumulibacter" enrichment as production platform for bacterial sialic acids, it is necessary to determine which fractions of the EPS of "Ca. Accumulibacter" contain NulOs and how to enrich and/or isolate them. We extracted the EPS from granules enriched with "Ca. Accumulibcater" and used size-exclusion chromatography to separate them into different molecular weight fractions. This separation resulted in two high molecular weight (> 5,500 kDa) fractions dominated by polysaccharides, with a NulO content up to 4 times higher than the extracted EPS. This suggests that NulOs in "Ca. Accumulibacter" are likely located in high molecular weight polysaccharides. Additionally, it was seen that the extracted EPS and the NulO-rich fractions can bind and neutralize histones. This suggest that they can serve as source for sepsis treatment drugs, although further purification needs to be evaluated. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/508216v1_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@1f59ff7org.highwire.dtl.DTLVardef@d933fcorg.highwire.dtl.DTLVardef@1e3ff78org.highwire.dtl.DTLVardef@1994948_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LINulOs in "Ca. Accumulibacter" are likely located in high molecular weight polysaccharides. C_LIO_LISize exclusion chromatography allows to obtain high molecular weight polysaccharide-rich fractions enriched with NulOs. C_LIO_LIEPS and the NulOs-rich fractions can serve as source for sepsis treatment drugs. C_LI

microbiology↗

bioRxiv2022

Turnover of the extracellular polymeric matrix in an EBPR microbial community

Polyphosphate accumulating organisms (PAOs) are responsible for enhanced biological phosphate removal (EBPR) from wastewater, where they grow embedded in a matrix of extracellular polymeric substances (EPS). EPS comprise a mixture of biopolymers like polysaccharides or (glyco)proteins. Despite previous studies, little is known about the dynamics of EPS in mixed cultures, and their production by PAOs and potential consumption by flanking microbes. EPS are biodegradable and have been suggested to be a substrate for other organisms in the community. Studying EPS turnover can help elucidate their biosynthesis and biodegradation cycles. We analyzed the turnover of proteins and polysaccharides in the EPS of an enrichment culture of PAOs relative to the turnover of internal proteins. An anaerobic-aerobic sequencing batch reactor (SBR) simulating EBPR conditions was operated to enrich for PAOs. After achieving a stable culture, carbon source was switched to uniformly 13C-labelled acetate. Samples were collected at the end of each aerobic phase. EPS were extracted by alkaline treatment. 13C enrichment in proteins and sugars (after hydrolysis of polysaccharides) in the extracted EPS were measured by mass spectrometry. The average turnover rate of sugars and proteins (0.167 and 0.192 d-1 respectively) was higher than the expected value based on the solid removal rate (0.132 d-1), and no significant difference was observed between intracellular and secreted proteins. This indicates that EPS from the PAO enriched community is not selectively degraded by flanking populations under stable EBPR process conditions. Instead, we observed general decay of biomass, which corresponds to a value of 0.048 d-1. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/503576v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@925680org.highwire.dtl.DTLVardef@16d15ccorg.highwire.dtl.DTLVardef@b23a26org.highwire.dtl.DTLVardef@107d2b1_HPS_FORMAT_FIGEXP M_FIG C_FIG Key points- Proteins showed a higher turnover rate than carbohydrates. - Turnover of EPS was similar to the turnover of intracellular proteins. - EPS is not preferentially consumed by flanking populations.

microbiology↗

bioRxiv2020

Production of nonulosonic acids in the extracellular polymeric substances of Candidatus Accumulibacter phosphatis

Nonulosonic acids (NulOs) are a family of acidic carbohydrates with a nine-carbon backbone, which include different related structures, such as sialic acids. They have mainly been studied for their relevance in animal cells and pathogenic bacteria. Recently, sialic acids have been discovered as important compound in the extracellular matrix of virtually all microbial life and in "Candidatus Accumulibacter phosphatis", a well-studied polyphosphate-accumulating organism, in particular. Here, bioaggregates highly enriched with these bacteria (approx. 95% based on proteomic data) were used to study the production of NulOs in an enrichment of this microorganism. Fluorescence lectin-binding analysis, enzymatic quantification, and mass spectrometry were used to analyze the different NulOs present, showing a wide distribution and variety of these carbohydrates, such as sialic acids and bacterial NulOs, in the bioaggregates. Phylogenetic analysis confirmed the potential of "Ca. Accumulibacter" to produce different types of NulOs. Proteomic analysis showed the ability of "Ca. Accumulibacter" to reutilize and reincorporate these carbohydrates. This investigation points out the importance of diverse NulOs in non-pathogenic bacteria, which are normally overlooked. Sialic acids and other NulOs should be further investigated for their role in the ecology of "Ca. Accumulibacter" in particular, and biofilms in general. Key PointsO_LI"Ca. Accumulibacter" has the potential to produce a range of nonulosonic acids. C_LIO_LIMass spectrometry and lectin binding can reveal the presence and location of nonulosonic acids. C_LIO_LIRole of nonulosonic acid in non-pathogenic bacteria needs to be studied in detail. C_LI

microbiology↗

bioRxiv2019

The environment selects: Modeling energy allocation in microbial communities under dynamic environments

What will be the best metabolic strategy in a competitive environment where oxygen is periodically unavailable? A few decades ago, an accidental, man-made cyclic anaerobic/aerobic environment selected for Polyphosphate Accumulating Organisms (PAOs) and this strategy is now widely used to allow for Enhanced Biological Phosphorus Removal (EBPR) of wastewater. But could it have been predicted? Here, a dynamic resource allocation modeling formalism was used to analyze the impact of selection pressures on metabolic function. With the same meta-network but modified selective pressures, different successful strategies can be predicted: Polyphosphate-AOs, Glycogen-AOs, Polyhydroxyalkanoate-AOs, and regular aerobic heterotrophs. The results demonstrate how storage metabolism allows for different trade-offs between growth yield, robustness, and competitiveness, and highlight how each metabolic function is an important determining factor for a selective advantage in a given environment. This can be seen as an example of when \"Unity in biochemistry\" by A.Kluyver meets \"Everything is everywhere, but the environment selects\" by B.Becking and how microbial ecosystems may be described by the energy allocation phenotype instead of a detailed description of each organism.

systems biology↗