1,354,287 research outputs found
Exploring Metal Interactions with Released Polysaccharides from Cyanothece sp. CE4: A Chemical and Spectroscopic Study on Biosorption Mechanism
No full textThis study investigates the potential of released polysaccharides (RPS) from the halophilic cyanobacterium Cyanothece sp. CE4 as biosorbents for heavy metals, specifically copper (Cu), nickel (Ni), and zinc (Zn). By combining ICP-OES, SEM-EDX, FT-IR spectroscopy, and XAS techniques, this work provides a comprehensive chemical and spectroscopic analysis of the biosorption mechanisms driving metal removal. The results revealed a strong binding affinity for Cu, followed by Ni and Zn, with RPS functional groups playing a key role in metal coordination. The RPS efficiently removed metals from both monometallic and multimetallic solutions, emphasizing their adaptability in competitive environments. XAS analysis highlighted unique metal-specific coordination patterns. Ni preferentially binds to oxygen donors and Zn to chlorine, and Cu exhibits non-selective binding. Remarkably, the extracted RPS achieved a maximum Cu removal capacity of 67 mg per gram of RPS dry weight, surpassing previously reported biosorption capacities. This study not only advances the understanding of biosorption mechanisms by cyanobacterial RPS but also emphasizes their dual role in environmental remediation and circular resource management. The insights provided here establish a foundation for the development of sustainable, cyanobacteria-based solutions for heavy-metal recovery and environmental sustainability
Generalized Merkle Tree Representation for Actuarial Applications
No full textThe Merkle Tree (MT) was introduced by Merkle (1987) in his PhD thesis and studied in depth in further papers – Merkle (1987-1991). The MT is a tree where the values associated with each node are one-way functions of the values
of the born-nodes and therefore strictly path-dependent.
The MT finds wide applications within cryptography – Merkle(1987-1991) –and particularly in authentication protocols and transmission – Indrajit (2003),
Merkle (1982), Perrig (2002) – in coding and decoding of digital images – Deng(2003).
The present paper aims at proposing a study, finalized to financial (optin pricing) and insurance (determination of premium) applications, of a discrete Bayes-process as described through the Merkle Tree with K states and N stages.
We hereby suggested three algorithms – two of them are generalized, as already described in Addessi (2002), and aim at calculating the average current
value of a random performance, whose discreet variable below may take up K
separate determinations at the most (stages of the system).
Such algorithms are based on the use of vectors and matrices: according to the
first algorithm, a vector having KN components, where N stands for the number of the stages, is associated with each time unit (stage of the system); according
to the second one, the node values are calculated through the matrices and at a
fixed stage, based on all the nodes that have been generated; according to the third one, a recursive function is proposed, based on the use of fractal and attimes diagonal matrices.
The algorithms we propose are applicable to a discreet stochastic path dependent process: in particular, a simple application within the actuarial field is proposed
Macromolecular and chemical features of the excreted extracellular polysaccharides in induced biological soil crusts of different ages
No full textThe development of biological soil crusts (BSCs) is widely recognized as beneficial to soil fertility due to their contribution to the stabilization of soils and to the increase in their carbon and moisture content. An important role in these processes is played by the extracellular polysaccharidic (EPS) matrix embedding microbial cells and soil particles in BSCs. The present study was aimed at investigating the molecular and chemical features of the EPSs and the degradation processes of the polysaccharidic matrix (i.e. dehydrogenase and sucrase activities) in induced biological soil crusts (IBSCs) of different ages displayed within an investigation area in Hobq Desert (Dalatequi County, Inner Mongolia, China). Two operationally-defined EPS fractions, the colloidal (C-EPS) and the EDTA extractable (tightly bound, TB-EPS) fractions, were analyzed. In BSCs, C-EPSs are loosely bound to cells and sediments while TB-EPSs are tightly bound to the crustal biotic and abiotic constituents of the crusts. In this study, the C-EPS and TB-EPS fractions extracted from the IBSCs of different age (4-, 6- and 8-years old IBSCs) were found present in comparable amounts but showed marked differences in terms of their molecular size distribution and monosaccharidic composition. C-EPS showed to be mostly constituted by sugar fractions with molecular weight (MW) distributed in the range 2000-76 kDa and in the range 64-0.34 kDa. Conversely, the TB-EPSs showed to be prominently constituted by one fraction having a MW in the range 2000-76 kDa. While the chemical and macromolecular characteristics of TB-EPSs did not show significant changes with the age of the crusts, the older IBSCs showed a lower content of low MW C-EPSs, as well a higher number of different types of monosaccharides constituting the C-EPS. Moving from these results, it can be hypothesized that C-EPSs, which are dispersed in the soil and thus more accessible, have been rather easily degraded by the heterotrophic microorganisms dwelling in mature IBSCs and reduced to low MW carbohydrates that are easily metabolized by chemoheterotrophs. This hypothesis is supported by the higher activity observed in older IBSCs of the two enzymes associated with sugar degradation in the soil, dehydrogenases and sucrases, that is consistent with an increased release of low MW carbohydrates in the crusts
Produzione di idrogeno con batteri fotosintetici da effluente di impianto di biometanazione di residui dell’agroindustria
No full textHydrogen is a clean fuel. Its combustion produces just water and energy. The opportunity of obtaining renewable energy from vegetable residues largely available makes
microbiological processes an interesting perspective. Aim of this research activity was to evaluate the possibility of inserting the photofermentative hydrogen producing process after or in between the acidogenic and/or methanogenic stages. The whole process was conducted starting from selected vegetable residues deriving from department stores. The study showed how the characteristics of the vegetable substrate chosen had an influence on the whole process; a high conversion yield of the substrate to energy was obtained when producing hydrogen by photofermentation using the effluent of the acidogenic stage as a substrate.
Furthermore, light intensity showed to be very important for obtaining better production rates. Indeed, the only possible applicative solutions for proposing photobiological hydronen production as an economically and energetically sustainable process are the use of both wastes as substrates and sunlight as the light source
Hydrogen production under salt stress conditions by a freshwater Rhodopseudomonas palustris strain
No full textHydrogen represents a possible alternative energy carrier to face the growing request for energy and the shortage of fossil fuels. Photofermentation for the production of H2 constitutes a promising way for integrating the production of energy with waste treatments. Many wastes are characterized by high salinity, and polluted seawater can as well be considered as a substrate. Moreover, the application of seawater for bacterial culturing is considered cost-effective. The aims of this study were to assess the capability of the metabolically versatile freshwater Rhodopseudomonas palustris 42OL of producing hydrogen on salt-containing substrates and to investigate its salt stress response strategy, never described before. R. palustris 42OL was able to produce hydrogen in media containing up to 3 % added salt concentration and to grow in media containing up to 4.5 % salinity without the addition of exogenous osmoprotectants. While the hydrogen production performances in absence of sea salts were higher than in their presence, there was no significant difference in performances between 1 and 2 % of added sea salts. Nitrogenase expression levels indicated that the enzyme was not directly inhibited during salt stress, but a regulation of its expression may have occurred in response to salt concentration increase. During cell growth and hydrogen production in the presence of salts, trehalose was accumulated as a compatible solute; it protected the enzymatic functionality against salt stress, thus allowing hydrogen production. The possibility of producing hydrogen on salt-containing substrates widens the range of wastes that can be efficiently used in production processes
Introducing capnophilic lactic fermentation in a combined dark-photo fermentation process: a route to unparalleled H2 yields
No full textTwo-stage process based on photofermentation of dark fermentation effluents is widely recognized as the most effective method for biological production of hydrogen from organic substrates. Recently, it was described an alternative mechanism, named capnophilic lactic fermentation, for sugar fermentation by the hyperthermophilic bacterium Thermotoga neapolitana in CO2-rich atmosphere. Here, we report the first application of this novel process to two-stage biological production of hydrogen. The microbial system based on T. neapolitana DSM 4359T and Rhodopseudomonas palustris 42OL gave 9.4 mol of hydrogen per mole of glucose consumed during the anaerobic process, which is the best production yield so far reported for conventional two-stage batch cultivations. The improvement of hydrogen yield correlates with the increase in lactic production during capnophilic lactic fermentation and takes also advantage of the introduction of original conditions for culturing both microorganisms in minimal media based on diluted sea water. The use of CO2 during the first step of the combined process establishes a novel strategy for biohydrogen technology. Moreover, this study opens the way to cost reduction and use of salt-rich waste as feedstock
The induction of biological soil crusts: an environmental biotechnology based on the exploitation of phototrophic microorganisms
No full textThe lecture was focused on the recent results obtained by applying the biotechnology based on large scale cyanobacterial inoculation and BSC induction, and stresses how the potential of cyanobacterial inoculation can be translated in a flexible technology applicable in different contexts such as the stabilization and fertilization of aeolian sandy lands in arid and semiarid environment
Biological Soil Crusts: A microenvironment affected by the microbial-secreted exopolysaccharidic matrix
No full textExtended abstract allegat
The degradative capabilities of new Amycolatopsis isolates on polylactic acid
No full textPolylactic 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 Amycolatopsis. 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
Biological soil crusts: from ecology to biotechnology
No full textWhile the beneficial effects of algalization to improve agricultural fields are well known, a limited number of inoculation studies
have been so far carried out in prohibitive constrained ecosystems, where soil is unconsolidated, with very limited nutrient levels and high
abiotic stress levels. Recent results show that some cyanobacterial strains such as the non-heterocystous exopolysaccharide-producer
Microcoleus vaginatus, are able to grow in such conditions developing quickly into biological soil crusts, kicking off beneficial microbiological
processes potentially able to shift the state of the environment. This paper reviews the state of the art of this technology, pointing
out the existing gaps to fulfill in order to address different issues, including land rehabilitation and desertification counteractio
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