420 research outputs found
The use of exopolysaccharide-producing cyanobacteria as biosorbents to remove copper from industrial wastewaters
No full textThe accumulation of heavy metals in water bodies represent a widespread cause of pollution, and poses the need
to develop novel technologies to remove metals at the source, abating the costs of the commonly used chemical
and physio-chemical methods. The use of cyanobacteria as biosorbents has been acknowledged as a promising
alternative, due to their charged polysaccharidic envelopes which have affinity for metal ions. Nonetheless, the
reseach must move towards: i) assessing the effectiveness of the process towards complex wastewater solutions
which contain chemical species that can interfere with the sorption process, also considering the characteristics
of the used strains, and ii) developing novel devices that support biomass growth and use, in order to achieve
a scaling up of the process. We compared the specific removal of three cyanobacteria, Cyanothece 16 Som 2,
Cyanothece ET5 and Cyanospira capsulata, towards Cu2+ contained, with various other metals, in two industrial
effluents (one at pH 1.26 and one at pH 10.26). The strains were selected due to their previously assayed affinity
toward Cu2+ in pure solutions (De Philippis et al. 2011). Acid or basic pretreatments (respectively for the acid
and the basic effluent) were performed in the tentative to increase the specific removal. Metal concentration in
solution, before and after the contact with the biomasses, was determined by atomic absorption spectrometry.
Specific removals resulted different to those obtained towards pure metal solutions, likely due to the presence of
other competing ions. Cyanothece 16 Som 2 showed the highest Cu2+ specific removal towards both the effluents.
The pretreatment was effective only in the case of the basic effluent. Results proved the capacity of Cyanothece 16
Som 2 to act as a selective Cu2+ sorbent even in the presence of complex solutions. A novel prototype device is
being projected in order to support the growth and the immobilization of the cyanobacterial biomass for its use in
industrial field.
De Philippis et al. 2011. Applied Microbiology and Biotechnology 92, 697-708
Role of Cyanobacterial Exopolysaccharides in Phototrophic Biofilms and in Complex Microbial Mats
No full textExopolysaccharides (EPSs) are an important class of biopolymers with great ecological importance. In natural environments, they are a common feature of microbial biofilms, where they play key protective and structural roles. As the primary colonizers of constrained environments, such as desert soils and lithic and exposed substrates, cyanobacteria are the first contributors to the synthesis of the EPSs constituting the extracellular polymeric matrix that favors the formation of microbial associations with varying levels of complexity called biofilms. Cyanobacterial colonization represents the first step for the formation of biofilms with different levels of complexity. In all of the possible systems in which cyanobacteria are involved, the synthesis of EPSs contributes a structurally-stable and hydrated microenvironment, as well as chemical/physical protection against biotic and abiotic stress factors. Notwithstanding the important roles of cyanobacterial EPSs, many aspects related to their roles and the relative elicited biotic and abiotic factors have still to be clarified. The aim of this survey is to outline the state-of-the-art of the importance of the cyanobacterial EPS excretion, both for the producing cells and for the microbial associations in which cyanobacteria are a key component
The use of exopolysaccharide - producing cyanobacteria as biosorbents to remove copper from industrial waste - waters
No full textThe accumulation of heavy metals in water bodies represent a widespread cause of pollution, and poses the need to develop novel technologies to remove metals at the source, abating the costs of the commonly used chemical and physio-chemical methods. The use of cyanobacteria as biosorbents has been acknowledged as a promising alternative, due to their charged polysaccharidic envelopes which have affinity for metal ions. Nonetheless, the reseach must move towards: i) assessing the effectiveness of the process towards complex wastewater solutions which contain chemical species that can interfere with the sorption process, also considering the characteristics of the used strains, and ii) developing novel devices that support biomass growth and use, in order to achieve a scaling up of the process. We compared the specific removal of three cyanobacteria, Cyanothece 16 Som 2, Cyanothece ET5 and Cyanospira capsulata, towards Cu2+ contained, with various other metals, in two industrial effluents (one at pH 1.26 and one at pH 10.26). The strains were selected due to their previously assayed affinity toward Cu2+ in pure solutions (De Philippis et al. 2011). Acid or basic pretreatments (respectively for the acid and the basic effluent) were performed in the tentative to increase the specific removal. Metal concentration in solution, before and after the contact with the biomasses, was determined by atomic absorption spectrometry. Specific removals resulted different to those obtained towards pure metal solutions, likely due to the presence of other competing ions. Cyanothece 16 Som 2 showed the highest Cu2+ specific removal towards both the effluents. The pretreatment was effective only in the case of the basic effluent. Results proved the capacity of Cyanothece 16 Som 2 to act as a selective Cu2+ sorbent even in the presence of complex solutions. A novel prototype device is being projected in order to support the growth and the immobilization of the cyanobacterial biomass for its use in industrial fiel
Hydrogen Production and Possible Impact on Global Energy Demand: Open Problems and Perspectives
No full textThe main goal of this Chapter is to take the reader to the unconventional concept that if
hydrogen is used as an energy carrier, there are consistent benefi ts to be expected, depending
on how hydrogen is generated. As it will be illustrated, the technical problems lying ahead of
the creation of an apparent “Hydrogen Based Society” are of technical nature although we
are all confi dent that they can be solved within a reasonable period of time
Drought-tolerant cyanobacteria and mosses as biotechnological tools to attain land degradation neutrality
No full textThe induction of biocrusts through inoculation-based techniques has gained increasing scientific attention in the last 2 decades due to its potential to address issues related to soil degradation and desertification. The technology has shown the most rapid advances in the use of biocrust organisms, particularly cyanobacteria and mosses, as inoculants and biocrust initiators. Cyanobacteria and mosses are poikilohydric organisms - i.e., desiccation-tolerant organisms capable of reactivating their metabolism upon rehydration - that can settle on bare soils in abiotically stressing habitats, provided that selected species are used and an appropriate and customized protocol is applied. The success of inoculation of cyanobacteria and mosses depends on the inoculant's physiology, but also on the ability of the practitioner to identify and control, with appropriate technical approaches in each case study, those environmental factors that most influence the inoculant settlement and its ability to develop biocrusts.This review illustrates the current knowledge and results of biocrust induction biotechnologies that use cyanobacteria or mosses as inoculants. At the same time, this review's purpose is to highlight the current technological gaps that hinder an efficient application of the technology in the field
Microbial secreted exopolysaccharides of induced biological soil crusts in Inner Mongolian desert soils: chemical characteristics and role in affecting water-soil relations
No full textRole of polysaccharides produced by cyanobacteria in affecting the structure and the hydrological properties of the soi
Complex role of the polymeric matrix in biological soil crusts
No full textExtracellular polymeric matrix (EPM) is a complex component of the organo-mineral assemblages created by biological soil crusts (BSCs). Mainly of polysaccharidic origin, embeds soil and sediments and provides key benefits to the crust community. Services provided include: sediment cohesion and resistance to erosion, moisture provision, protection from external harmful factors, as well as a possible natural plant fertilizing effect. EPM is the product of BSC microbial community, and it is constituted by exopolysaccharides (EPS) associated to other substances, organized in a three-dimensional structure having different gelification grades, and degrees of condensation. This review aims at focusing scientific attention, for the first time, on the characteristics and the roles of three operationally defined EPM fractions, one water soluble, one more adherent to cell and sediment, and one firmly attached to microbial cells. The latest results obtained by analyzing EPM of natural and induced (i.e, the result of cyanobacteria inoculation) BSCs are outlined, and the optimized extraction methodology is described in details.
The review underlines the complexity of investigating the characteristics and the role of microbial EPS, and its supra-structure (EPM), in natural conditions (as opposed to unialgal culture in laboratory conditions), where the matrix is subjected to continuous microbial rearrangement due to biosynthetic, self- and cross-feeding processes, and to microbial activity affected by environmental parameters.Background Extracellular polymeric matrix (EPM) is a complex component of the organo-mineral assemblages created by biological soil crusts (BSCs). Mainly of polysaccharidic origin, it embeds soil and sediments and provides key benefits to the crust community. Services provided include: sediment cohesion and resistance to erosion, moisture provision, protection from external harmful factors, as well as support to plant establishment and growth. EPM is the product of BSC microbial community, and it is constituted by exopolysaccharides (EPS) associated to other substances, organized in a three-dimensional structure having different levels of gelation, and degrees of condensation.Scope This review aims at focusing scientific attention, for the first time, on the characteristics and the roles of three operationally defined EPM fractions, one water soluble, one more adherent to cells and sediments, and one firmly attached to microbial cells. The latest results obtained by analyzing EPM of natural and induced (i.e, the result of cyanobacteria inoculation) BSCs are outlined, and the optimized extraction methodology is described in details.Conclusions The review underlines the complexity of investigating the characteristics and the role of microbial EPS, and its supra-structure (EPM), in natural conditions (as opposed to cultures in laboratory conditions), where the matrix is subjected to continuous microbial rearrangement due to biosynthetic, self- and cross-feeding processes, and where microbial activity affected by environmental parameters
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
Cyanobacterial biocrust induction: A comprehensive review on a soil rehabilitation-effective biotechnology
No full textThe use of cyanobacteria as soil inoculants is a very promising biotechnological approach that is receiving increasing scientific attention for its potential for soil degradation control. Inoculation of selected cyanobacterial strains has shown the ability to significantly improve the physicochemical properties of degrading soils in different environmental settings and on soils with different textures. First, inoculation of cyanobacteria promotes sediment stability against wind and water erosive action. Second, successful establishment of cyanobacteria in the target soil can lead to the development of self-sustaining microbial communities known as biocrusts, which are recognized as ecosystem engineers in drylands. Due to their important natural ecological role, the artificial onset of biocrusts contributes to the improvement of ecosystem status. Advances in cyanobacteria inoculation studies both at laboratory and field scale demonstrated that the technology can represent a valuable tool for rehabilitating even hyper-arid soils subjected to severe abiotic conditions.This review provides an overview of the state of the art of cyanobacteria inoculation, highlighting the most recent published results on the use of cyanobacteria to address soil rehabilitation. At the same time, it examines the remaining knowledge gaps that currently limit the potential of the technology and its applicability in different environmental settings. We found that three main aspects require further investigation: the need to standardize and optimize inoculation protocols in order to maximize the percentage of success in soil rehabilitation, the need to clearly define benchmarks to validly assess inoculation effects and ease the comparison between different studies, and the need to better understand and control the influence of environmental factors on inoculation success/failure. The improvement of these aspects of the technology are fundamental for its optimization and its applicability on a wide scale
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