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Cyanobacteria for restoration of degraded soils

Periodic Reporting for period 1 - Cyano4REST (Cyanobacteria for restoration of degraded soils)

Reporting period: 2016-11-01 to 2018-10-31

Dryland regions are particularly vulnerable to land degradation processes caused by anthropogenic activities and impacts of climate change. Soil degradation reduces the capability of soils to provide basic ecological services (water filtering and storage, substrate for living organisms, carbon and nitrogen cycling etc.) and to sequester CO2 and other greenhouse gases involved in global warming. To mitigate on-going degradation processes in drylands, large scale and low-cost sustainable restoration strategies are required.
Inoculation of soils with key organisms forming biocrusts such as cyanobacteria is presented a sustainable tool to promote biocrust formation and mitigate soil degradation in drylands. Artificial induction of biocrusts has been reported to improve soil stabilization and increase soil water retention and fertility in degraded arid areas, and previous experiences have shown good results for stabilization of desert sand dunes in China. Many of the functions that biocrusts play in dryland environments are related to their ability to secrete large amounts of exopolysaccharides (EPS), having an important effect in the improvement of water relations, soil structure and stability, and soil fertility.
The aim of Cyano4REST was getting a better understanding of the relationships between the characteristics of the polysaccharidic matrix produced by different cyanobacteria and their role in affecting chemical soil properties on different soil types. The final goal of Cyano4REST is to develop an innovative methodology for recovering degraded soils by using environmentally-friendly EPS-producing cyanobacteria.
To give answer to this general objective, four specific objectives were addressed:
-Objective 1. Identification of common cyanobacteria species present in biocrusts from semiarid regions.
-Objective 2. Chemical and macromolecular characterization of the EPS secreted by different cyanobacteria species in liquid culture and their effect on biocrust development, soil polysaccharidic matrix characteristics and soil properties change.
-Objective 3. Effect of cyanobacteria inoculation on soil properties related to soil stability and fertility in different textured soils, under laboratory conditions.
-Objective 4. Analysis of the influence of cyanobacteria inoculation on biocrust development and physico-chemical properties in arid soils under field conditions.
Objectives of Cyano4REST were achieved by development of the following Work packages:
● WP1. Isolation and identification of cyanobacteria species (Objective 1). Twenty-five strains were successfully isolated from biocrusts from three semiarid sites in SE Spain, cultured and characterized.
● WP2. Characterization of cyanobacterial EPSs in liquid culture and soil microcosms (objective 2). Culture of non-heterocystous (Phormidium ambiguum) and heterocystous species (Nostoc commune, Scytonema javanicum) was realized under various conditions. Results showed that cyanobacteria growth and EPS composition significantly varies depending on growth conditions. These factors should be taken into account for selection of suitable cyanobacteria species as inoculants for restoration of degraded arid soils.
● WP3. Influence of inoculated cyanobacteria on soil properties in different textured soils (objective 3). Two widely spread arid soil cyanobacteria, one N-fixing (Scytonema javanicuum) and one non N-fixing cyanobacteria (Phormidium ambiguum), were inoculated in four soil types with different physico-chemical soil properties and particle size distribution. The results found showed that the effect of cyanobacteria inoculation on soil properties greatly depends on the inoculated species and soil type and that the improvement in properties related to soil fertility and stability is more remarkable in soils having a lower quality of their physico-chemical properties.
● WP4. Influence of inoculated cyanobacteria on soil properties under field conditions (objective 4). A field experiment was conducted in a semiarid area of SE Spain consisting of the inoculation of a mixture of three heterocystous cyanobacteria on a bare degraded soil. Crust samples were collected after six months and characterization of the crust polysaccharidic matrix was done in order to examine the influence of cyanobacteria inoculation on EPS characteristics under natural conditions in the different treatments. Monitoring of the induced biocrust will continue during the next months in order to explore the effect of cyanobacteria inoculation in soil properties change in the long term and select the best inoculation strategy for up-scale of this technology in the next future.
● WP5. Scientific training. This has been achieved by learning of different techniques related to isolation and culture of cyanobacteria in the laboratory and chemical and macromolecular characteristics of cyanobacterial EPS.
● WP6. Complementary training. This has been achieved through co-supervision of three Bachelor Thesis at UNIFI and obtaining the C1 certificate in Italian language.
● WP7. Scientific dissemination has included ten presentations at six international congresses and four open-access articles in peer-reviewed journals. Dissemination to general public has been conducted through the European Researcher’s Night, the publication of a divulgation article in a local newsletter, and communication of the research conducted and its main findings to High School and University students and to private companies.
● WP8. Project management. This has been performed through realization of weekly meetings, continuous reporting of the project at the European participation portal, and preparation of the final technical report
Findings of the project demonstrated that soil inoculation with EPS-forming cyanobacteria leads to improvement in soil stability and fertility in different soil types. As a result, the sustainable biotechnological technique proposed here could provide positive results, not only for restoration of degraded dryland soils, but for a number of different applications. Therefore, results from Cyano4REST will allow advancing in the achievement of one of the Commission’s political priorities, i.e. “Building a low-carbon, climate resilient future”, and advancing in societal challenges for the H2020 including “Food security, sustainable agriculture and forestry” and “Climate action, environment, resource efficiency and raw materials”. At the same time, the results obtained will facilitate the transfer of knowledge to the private sector giving the possibility to use the proposed technology for solving environmental problems that are of high concern for the society.
Awarding of Cyano4REST greatly improved fellow’s skills through acquisition of new scientific knowledge and skills applicable during her future research career, of new collaborations, and of complementary skills. Advance in the researcher’s career definitely will contribute to an important objective for the European society which is to strengthen, quantitatively and qualitatively, the human potential in research and technology and to promote the careers and formation of high-quality researchers, building an European knowledge-based economy and society. This will provide them with the ability to assist society in facing and managing the environmental problems that dryland regions are likely to face with climate change and growing human populations.
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