1,721,055 research outputs found
Cyanobacterial crust induction using two non-previously testedcyanobacterial inoculants: crusting capability and role of EPSs
No full textThe use of cyanobacteria as soil improvers and bio-conditioners (a technique often referred to as algalization) hasbeen studied for decades. Several studies proved that cyanobacteria are feasible eco-friendly candidates to triggersoil fertilization and enrichment from agricultural to arid and hyper-arid systems. This approach can be successfulto achieve stabilization and rehabilitation of degraded environments.Much of the effectiveness of algalization is due to the productivity and the characteristics of extracellularpolysaccharides (EPSs) which, among their features, embed soil particles and promote the development of a firststable organo-mineral layer (cyanobacterial crusts). In natural settings, cyanobacterial crust induction represents afirst step of a succession that may lead to the formation of mature biological soil crusts (Lan et al., 2014).The aim of this research was to investigate the crusting capabilities, and the characteristics of excreted EPSsby two newly tested non-heterocystous cyanobacterial inoculants, in microcosm experiments carried out usingoligothrophic sand collected from sand dunes in Negev Desert, Israel. The cyanobacteria tested were SchizothrixAMPL1601, originally isolated from biocrusts collected in Hobq Desert, Inner Mongolia (China) and Leptolyng-bia ohadii, originally isolated from biocrusts collected in Negev Desert, Israel.Inoculated microcosms were maintained at 30 ◦C in a growth chamber under continuous illumination and minimalwater availability. Under such stressing conditions, and for a three-months incubation time, the growth and thecolonization of the strains in the microcosms were monitored. At the same time, EPSs production and theirchemical and macromolecular characteristics were determined by applying a methodology optimized for thepurpose. Notably, EPSs were analyzed in two operationally-defined fractions, one more dispersed in the crustmatrix (loosely bound EPSs, LB-EPSs) and one more condensed and stable (tightly bound EPSs, TB-EPSs),which were deemed having different functions (Chen et al., 2014).The results demonstrated how differently (and complementarily in some ways) these two strains behave whenapplied on a poor sandy substrate, producing cyanobacterial crusts having different morphology. The outcomesof this study suggest the potential of Schizothrix AMPL1601 and Leptolyngbia ohadii as valid biotechnologicaltools for improving the properties of poor arid soils, allowing to design proper rehabilitation or restoration models.In addition, this study provided new insight on the characteristics of the cyanobacterial EPSs, secreted under aconstrained condition, compared to a non-nutrient limited and optimal one.
Chen, L., Rossi, F., Deng, S., Liu, Y., Wang, G., Adessi, A., De Philippis, R., 2014. Macromolecular andchemical features of the excreted extracellular polysaccharides in induced biological soil crusts of different ages.Soil Biology and Biochemistry 78, 1–9. doi:10.1016/j.soilbio.2014.07.004
Lan, S., Zhang, Q., Wu, L., Liu, Y., Zhang, D., Hu, C., 2014. Artificially Accelerating the Reversal of Desertifica-tion: Cyanobacterial Inoculation Facilitates the Succession of Vegetation Communities. Environmental Science &Technology 48, 307–315. doi:10.1021/es403785
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
Exocellular Polysaccharides in Microalgae and Cyanobacteria: Chemical Features, Role and Enzymes and Genes Involved in Their Biosynthesis
No full textExtracellular polysaccharides (EPSs) produced by microalgae and cyanobacteria are molecules with a great ecological significance for the producing organisms, serving in a wide array of biological processes and increasing the organism tolerance to environmental stresses. In addition, due to their distinctive chemical, rheological properties and the biological activity of some of them, these macromolecules could find application in industrial, pharmaceutical and medical fields. In this chapter, the current knowledge regarding the structure and composition of EPSs, the factors eliciting their synthesis, and the related codifying genes involved is reviewed. It is also underlined and discussed how, notwithstanding the huge number of studies available, different aspects still need to be clarified. For example, there are limited informations concerning EPS synthetic pathways, and how these processes are influenced by environmental factors. Expand the knowledge on these aspects could help elaborating biotechnological strategies to increase the yields and direct the synthesis to polymers with desired characteristics. Kywords: cyanobacteria, microalgae, extracellular polysaccharides (EPSs), EPS synthesis, EPS-encoding genes, sheath, capsular polysaccharides (CPSs), capsule, slime, EPS synthetic pathway
Ruolo della matrice polisaccaridica nelle Croste Biologiche (BSCs) dei deserti nordamericani
No full textExopolysaccharide producing Cyanobacteria in the removal of copper from industrial wastewaters
No full textCyanobacterial inoculation (cyanobacterisation): Perspectives for the development of a standardized multifunctional technology for soil fertilization and desertification reversal
No full textThe use of cyanobacteria as soil conditioners has been studied intermittently for many decades. Some of the documented direct effects of cyanobacterial inoculation are related to soil stabilization and improvement, enrichment in nutrients and increase in moisture content. While the first attempts to develop a technology were mostly aimed at improving agricultural conditions, more recently inoculation approaches have proven to be effective tools also for triggering land rehabilitation in arid and semiarid environments. This review aims to provide, for the first time, an overview of the outcomes of the application of such a technology i) to support agricultural practices in soil with poor fertility, and ii) to trigger the formation of complex microbial biolayers (biological soil crusts) on unconsolidated arid soils to counteract, and possibly reverse the spread of desertification.This review also evidences the critical points for developing a proficient technology, trying to propose a general workflow to adapt for each considered study case, according to the objectives of the treatment
The role of the exopolysaccharides in enhancing hydraulic conductivity of biological soil crusts
No full textBiological soil crusts (BSCs) are highly specialized topsoil microbial communities commonly found in arid and semiarid environments, permeated by a polymeric matrix of polysaccharides. BSCs can in principle influence edaphic properties such as texture, pore formation and water retention, which in turn determine water distribution and biological activity in dry lands. This paper investigates the influence of biotic and abiotic factors on BSC hydraulic conductivity, a parameter gauging the ease with which water can move through the pore spaces. Texture, phototroph abundance, microbial composition, and extracellular carbohydrate content were considered as potentially relevant parameters in a correlational study of BSC samples that spanned 1.5 orders of magnitude in hydraulic conductivity. A newly developed, non-destructive extraction method enabled us to directly quantify the specific role of extracellular polysaccharides on soil permeability on a variety of samples. Hydraulic conductivity showed a strongest correlation with texture (positive with sand content, negative with silt and clay). A weaker negative correlation with carbohydrate content, especially with polysaccharides having a molecular weight < 100 kDa, was also detected. In multiple regression analyses texture (silt content) was sufficient to explain most of the variation in hydraulic conductivity However, experimental removal of polymeric carbohydrates, resulted invariably in a substantial decrease in hydraulic conductivity for any given sample (between 1.7 and 3.3 fold). Our results suggest that while soil texture determines overall hydraulic conductivity in BSCs, the presence of exopolysaccharides can significantly enhance it, likely by conferring a spongy structure to a BSC thus increasing the number of waterways within it
Heavy metal sorption by three exopolysaccharide-producing cyanobacteria in multi-metal solutions
No full textExocellular polysaccharides produced by cyanobacteria contribute to their survival on the lithic surfaces of stone monuments
No full textCharacterization of the polymeric matrix of the phototrophic biofilm grown on Indian monument
Characteristics and role of the exocellular polysaccharides produced by five cyanobacteria isolated from phototrophic biofilms growing on stone monuments.
Get PDFThree coccoid and two filamentous cyanobacterial strains were isolated from phototrophic biofilms exposed to
intense solar radiation on lithic surfaces of the Parasurameswar Temple and Khandagiri caves, located in Orissa
State, India. Based on to their morphological features, the three coccoid strains were assigned to the genera
Gloeocapsosis and Gloeocapsa, while the two filamentous strains were assigned to the genera Leptolyngbya and
Plectonema. Eleven to 12 neutral and acidic sugars were detected in the slime secreted by the five strains. The
secretions showed a high affinity for bivalent metal cations, suggesting their ability to actively contribute to
weakening the mineral substrata. The secretion of protective pigments in the polysaccharide layers, namely
mycosporine amino acid-like substances (MAAs) and scytonemins, under exposure to UV radiation showed how the
acclimation response contributes to the persistence of cyanobacteria on exposed lithoid surfaces in tropical areas
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