Biology subjects

Christie-Oleza, J.

Publications and source records attributed to Christie-Oleza, J..

3 recordsLinked to original sources

bioRxiv2024

Lack of functional polyester-biodegrading potential in marine versus terrestrial environments evidenced by an innovative airbrushing technique

Biodegradable plastics, primarily aliphatic polyesters, degrade to varying extents in different environments. However, the absence of easily implementable techniques for screening microbial biodegradation potential --coupled with the limitations of non-functional omics analyses-- has restricted comparative studies across diverse polymer types and ecosystems. In this study, we optimized a novel airbrushing method that facilitates functional analyses by simplifying the preparation of polyester-coated plates for biodegradation screening. By repurposing an airbrush kit, polyester microparticles (MPs) could be evenly sprayed onto solid media, enabling rapid detection of extracellular depolymerizing activity via clearing zone halos. This technique was effective in screening both isolated microbial cultures and natural environmental samples, demonstrating its versatility. The method was successfully applied across multiple environments, ranking the biodegradability of six polyesters, from most to least biodegradable: polycaprolactone (PCL), poly[(R)-3-hydroxybutyrate] (PHB), poly(butylene succinate) (PBS), poly(ethylene succinate) (PES), poly(lactic acid) (PLA), and poly(butylene adipate-co-terephthalate) (PBAT). Most notably, it revealed a consistent 1,000-fold higher biodegradation potential in terrestrial compared to marine environments. This approach offers a valuable tool for isolating novel polyester-degrading microbes with significant biotechnological potential, paving the way for improved plastic waste management solutions. SYNOPSISScreening polyester-degrading microbes has traditionally been challenging due to the difficulty of incorporating polyesters into solid media. This study introduces an innovative airbrush spraying method that simplifies the preparation of polyester MPs on solid media plates, making the screening process significantly more efficient. Using this method, we demonstrated the differential biodegradability of aliphatic polyesters across environments. The results revealed a stark contrast in biodegrading potential, with terrestrial ecosystems exhibiting substantially higher activity compared to marine environments. Abstract graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/622231v1_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@176883eorg.highwire.dtl.DTLVardef@eab2aforg.highwire.dtl.DTLVardef@792bbdorg.highwire.dtl.DTLVardef@126ab7d_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2021

A highly active phosphate-insensitive phosphatase is widely distributed in nature

The regeneration of bioavailable phosphate from immobilised organophosphorus represents a key process in the global phosphorus cycle and is facilitated by enzymes known as phosphatases. Most bacteria possess at least one of three major phosphatases, known as PhoA, PhoX and PhoD, whose activity is optimal under alkaline conditions. The production and activity of these three phosphatase families is negatively regulated by phosphate availability and thus these enzymes play a major role in scavenging phosphorus only during times of phosphate scarcity. Here, we reveal a previously overlooked phosphate-insensitive phosphatase, PafA, prevalent in Bacteroidetes, which is highly abundant in nature and represents a major route for the remineralisation of phosphate in the environment. Using Flavobacterium johnsoniae as the model, we reveal PafA is highly active towards phosphomonoesters. Unlike other major phosphatases, PafA is fully functional in the presence of its metabolic product, phosphate, and is essential for growth on phosphorylated carbohydrates as a sole carbon source. PafA, which is constitutively produced under all growth conditions tested, rapidly remineralises phosphomonoesters producing significant quantities of bioavailable phosphate that can cross feed into neighbouring cells. pafA is both abundant and highly expressed in the global ocean and abundant in plant rhizospheres, highlighting a new and important enzyme in the global phosphorus cycle with applied implications for agriculture as well as biogeochemical cycling. We speculate PafA expands the metabolic niche of Bacteroidetes by enabling utilisation of abundant organophosphorus substrates in the presence of excess phosphate, when other microbes are rendered incapable. Significance statementPhosphorus is an essential element for all life on Earth. Global primary production, and thus the ability for oceans and soils to drawdown atmospheric carbon dioxide, is in part controlled by the availability of inorganic phosphate. Likewise, global food production is also reliant on adequate supplies of phosphorus to both plants and animals. A major fraction of the total phosphorus pool exists as organic phosphorus, which requires mineralisation to phosphate prior to incorporation into cellular biomolecules. This important process is performed by enzymes known as phosphatases. Here, we reveal that the unique bacterial phosphatase, PafA, is a key player in the global phosphorus cycle and presents a major route for the regeneration of bioavailable phosphate required for both primary and secondary production.

microbiology↗

bioRxiv2020

A novel Ca2+ signalling pathway co-ordinates environmental phosphorus sensing and nitrogen metabolism in marine diatoms

Diatoms are a diverse and globally important phytoplankton group, responsible for an estimated 20% of carbon fixation on Earth. They frequently form spatially extensive phytoplankton blooms, responding rapidly to increased availability of nutrients including phosphorus and nitrogen. Although it is well established that diatoms are common first-responders to nutrient influxes in aquatic ecosystems, little is known of the sensory mechanisms that they employ for nutrient perception. Here we show that diatoms use a novel and highly-sensitive Ca2+-dependent signalling pathway, not previously described in eukaryotes, to sense and respond to the critical macronutrient phosphorus. We demonstrate that phosphorus-Ca2+ signalling is essential for regulating diatom recovery from phosphorus limitation, by controlling rapid and substantial increases in nitrogen assimilation. Phosphorus-Ca2+ signalling thus mediates fundamental cross-talk between the vital nutrients P and N to maximise resource competition, and likely governs the success of diatoms as major bloom formers in regions of pulsed nutrient supply. Importantly, our study demonstrates that distinct mechanisms for nutrient sensing have evolved in photosynthetic eukaryotes.

microbiology↗