Cyanobacteria are widespread phototrophic microorganisms that represent a promising biotechnological tool to satisfy current sustainability and circularity requirements. They are potential ...bio-factories of a wide range of compounds that can be exploited in several fields including bioremediation and nanotechnology sectors. This article aims to illustrate the most recent trends in the use of cyanobacteria for the bioremoval (i.e., cyanoremediation) of heavy metals and metal recovery and reuse. Heavy metal biosorption by cyanobacteria can be combined with the consecutive valorization of the obtained metal-organic materials to get added-value compounds, including metal nanoparticles, opening the field of phyconanotechnology. It is thus possible that the use of combined approaches could increase the environmental and economic feasibility of cyanobacteria-based processes, promoting the transition toward a circular economy.
Land degradation in drylands is a drawback of the combined action of climate change and human activities. New techniques have been developed to induce artificial biocrusts formation as a tool for ...restoration of degraded drylands, and among them soils inoculation with cyanobacteria adapted to environmental stress. Improvement of soil properties by cyanobacteria inoculation is largely related to their ability to synthesize exopolysaccharides (EPS). However, cyanobacterial EPS features amount, molecular weight (MW), composition can change from one species to another or when grown in different conditions. We investigated the differences in growth and polysaccharidic matrix features among three common biocrust-forming cyanobacteria (
Nostoc commune, Scytonema javanicum
, and
Phormidium ambiguum
), when grown in liquid media and on sandy soil microcosms under optimal nutrient and water, in controlled laboratory conditions. We extracted and analyzed the released EPS (RPS) and sheath for the liquid cultures, and the more soluble or loosely-bound (LB) and the more condensed or tightly-bound (TB) soil EPS fractions for the sandy soil microcosms. In liquid culture,
P. ambiguum
showed the greatest growth and EPS release. In contrast, on the sandy soil,
S. javanicum
showed the highest growth and highest LB-EPS content.
N. commune
showed no relevant growth after its inoculation of the sandy soil. A difference was observed in terms of MW distribution, showing that the higher MW of the polymers produced by
P. ambiguum
and
S. javanicum
compared to the polymers produced by
N. commune
, could have had a positive effect on growth for the first two organisms when inoculated on the sandy soil. We also observed how both RPS and sheath fractions reflected in the composition of the soil TB-EPS fraction, indicating the role in soil stabilization of both the released and the cell attached EPS. Our results indicate that the features of the polysaccharidic matrix produced by different cyanobacteria can influence their growth success in soil. These results are of great relevance when selecting suitable candidates for large-scale cyanobacteria applications in soil restoration.
The Euganean Thermal District, situated in North-East Italy, is one of Europe's largest and oldest thermal centres. The topical application of its therapeutic thermal muds is recognised by the ...Italian Health System as a beneficial treatment for patients suffering from arthro-rheumatic diseases. Polysaccharides produced by the mud microbiota have been recently identified as anti-inflammatory bioactive molecules. In this paper we analysed the efficacy of Microbial-Polysaccharides (M-PS) derived from mature muds obtained at different maturation temperatures, both within and outside the codified traditional mud maturation range. M-PSs were extracted from six mature muds produced by five spas of the Euganean Thermal District and investigated for their chemical properties, monosaccharide composition and in vivo anti-inflammatory potential, using the zebrafish model organism. Additionally, mature muds were characterized for their microbiota composition using Next-Generation Sequencing. The results showed that all M-PSs exhibit similar anti-inflammatory potential, referable to their comparable chemical composition. This consistency was observed despite changes in cyanobacteria populations, suggesting a possible role of the entire microbial community in shaping the properties of these biomolecules. These findings highlight the importance of scientific research in untangling the origins of the therapeutic efficacy of Euganean Thermal muds in the treatment of chronic inflammatory conditions.
A novel method was developed for virus-like particle (VLP) extraction and characterization from biological soil crust (BSC) after microbial community reactivation. The method consisted of a single ...cell analysis by flow cytometry to monitor viable cells in BSC reactivated under controlled hydration, temperature, and light/dark exposure. Then, VLPs were extracted from reactivated BSCs, followed by viral DNA extraction and shotgun metagenomic analysis. The hydrated BSC under light/dark conditions showed the highest number of viable cells, and this condition was optimal for VLPs isolation. Taxonomic composition showed that families of the order of
Caudovirales
(
Podoviridae, Myoviridae
and
Syphoviridiae
) were the most abundant double strand DNA phages while
Microviridiae
were the most abundant single strand DNA phages. The isolated VLPs also carried sequences of relevant bacterial inhabiting soil. The functional categories of “phages, prophages, transposable elements, plasmids” and “clustering-base subsystem” were abundant (38 and 12%, respectively). All these data suggest viral predation as a key factor in shaping and maintaining bacterial diversity in the BSCs.
•Biomass rich in non-structural carbohydrates was more suitable for combined system.•Wheat bran showed the highest H2/CH4 potential and energy recovery.•Olive pomace and giant reed were unsuitable ...for combined H2/CH4 production.
Aim of this study was to evaluate the suitability of ensiled giant reed, ensiled maize, ensiled olive pomace, wheat bran for combined systems (CS: dark fermentation+anaerobic digestion (AD)) producing hydrogen-rich biogas (biohythane), tested in batch under basic operational conditions (mesophilic temperatures, no pH control). Substrates were also analyzed under a single stage AD batch test, in order to investigate the effects of DF on estimated energy recovery (ER) in combined systems. In CS, maize and wheat bran exhibited the highest hydrogen potential (13.8 and 18.9NLkgVS−1) and wheat bran the highest methane potential (243.5NLkgVS−1). In one-stage AD, giant reed, maize and wheat bran showed the highest methane production (239.5, 267.3 and 260.0NLkgVS−1). Butyrate/acetate ratio properly described the dark fermentation, correlating with hydrogen production (r=0.92). Wheat bran proved to be a promising residue for CS in terms of hydrogen/methane potential and ER.
Cyanobacteria can cope with various environmental stressors, due to the excretion of exopolysaccharides (EPS). However, little is known about how the composition of these polymers may change ...according to water availability. This work aimed at characterizing the EPS of
(Oscillatoriales; Oscillatoriaceae) and
(Pseudanabaenales; Leptolyngbyaceae), when grown as biocrusts and biofilms, subject to water deprivation. The following EPS fractions were quantified and characterized: soluble (loosely bound, LB) and condensed (tightly bound, TB) for biocrusts, released (RPS), and sheathed in
and glycocalyx (G-EPS) in
for biofilms. For both cyanobacteria upon water deprivation, glucose was the main monosaccharide present and the amount of TB-EPS resulted was significantly higher, confirming its importance in these soil-based formations. Different profiles of monosaccharides composing the EPSs were observed, as for example the higher concentration of deoxysugars observed in biocrusts compared to biofilms, demonstrating the plasticity of the cells to modify EPS composition as a response to different stresses. For both cyanobacteria, both in biofilms and biocrusts, water deprivation induced the production of simpler carbohydrates, with an increased dominance index of the composing monosaccharides. The results obtained are useful in understanding how these very relevant cyanobacterial species are sensitively modifying the EPS secreted when subject to water deprivation and could lead to consider them as suitable inoculants in degraded soils.
The Euganean Thermal District (Italy) represents the oldest and largest thermal center in Europe, and its therapeutic mud is considered a unique product whose beneficial effects have been documented ...since Ancient Roman times. Mud properties depend on the heat and electrolytes of the thermal water, as well as on the bioactive molecules produced by its biotic component, mainly represented by cyanobacteria. The investigation of the healing effects of compounds produced by the Euganean cyanobacteria represents an important goal for scientific validation of Euganean mud therapies and for the discovering of new health beneficial biomolecules. In this work, we evaluated the therapeutic potential of exopolysaccharides (EPS) produced by
sp. ETS05, the most abundant cyanobacterium of the Euganean mud. Specifically,
EPS resulted in exerting anti-inflammatory and pro-resolution activities in chemical and injury-induced zebrafish inflammation models as demonstrated using specific transgenic zebrafish lines and morphometric and expression analyses. Moreover, in vivo and in vitro tests showed no toxicity at all for the EPS concentrations tested. The results suggest that these EPS, with their combined anti-inflammatory and pro-resolution activities, could be one of the most important therapeutic molecules present in the Euganean mud and confirm the potential of these treatments for chronic inflammatory disease recovery.
Cancer is a leading cause of death worldwide with a huge societal and economic impact. Clinically effective and less expensive anticancer agents derived from natural sources can help to overcome ...limitations and negative side effects of chemotherapy and radiotherapy. Previously, we showed that the extracellular carbohydrate polymer of a
Δ
overproducing mutant displayed a strong antitumor activity towards several human tumor cell lines, by inducing high levels of apoptosis through p53 and caspase-3 activation. Here, the Δ
polymer was manipulated to obtain variants that were tested in a human melanoma (Mewo) cell line. Our results demonstrated that high molecular mass fractions were important for the polymer bioactivity, and that the reduction of the peptide content generated a variant with enhanced
antitumor activity. This variant, and the original Δ
polymer, were further tested
using the chick chorioallantoic membrane (CAM) assay. Both polymers significantly decreased xenografted CAM tumor growth and affected tumor morphology, by promoting less compact tumors, validating their antitumor potential
. This work contributes with strategies for the design and testing tailored cyanobacterial extracellular polymers and further strengths the relevance of evaluating this type of polymers for biotechnological/biomedical applications.
Polylactic acid (PLA), a bioplastic synthesized from lactic acid, has a broad range of applications owing to its excellent proprieties such as a high melting point, good mechanical strength, ...transparency, and ease of fabrication. However, the safe disposal of PLA is an emerging environmental problem: it resists microbial attack in environmental conditions, and the frequency of PLA-degrading microorganisms in soil is very low. To date, a limited number of PLA-degrading bacteria have been isolated, and most are actinomycetes. In this work, a method for the selection of rare actinomycetes with extracellular proteolytic activity was established, and the technique was used to isolate four mesophilic actinomycetes with the ability to degrade emulsified PLA in agar plates. All four strains-designated SO1.1, SO1.2, SNC, and SST-belong to the genus
. The PLA-degrading capability of the four strains was investigated by testing their ability to assimilate lactic acid, fragment PLA polymers, and deteriorate PLA films. The strain SNC was the best PLA degrader-it was able to assimilate lactic acid, constitutively cleave PLA, and form a thick and widespread biofilm on PLA film. The activity of this strain extensively eroded the polymer, leading to a weight loss of 36% in one month in mesophilic conditions.
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