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| Titel |
Optimizing N-Fixing cyanobacteria culture to restore arid degraded soils |
| VerfasserIn |
Beatriz Roncero-Ramos, Raúl Román, Cintia Gómez, Sonia Chamizo, Emilio Rodriguez-Caballero, Yolanda Cantón |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138057
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| Publikation (Nr.) |
 EGU/EGU2017-965.pdf |
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| Zusammenfassung |
| Cyanobacteria present several metabolic activities and mechanisms of adaptation which
enable them to colonize different habitats, in almost all biome and continents, especially
under extreme environmental conditions, as on the surface of the most arid soils and under
the highest temperatures. In drylands, they are usually found among plants, cohabiting with
organisms such as algae, lichens, mosses, bacteria and fungi, and in association with soil
surface particles, forming communities known as biocrusts. Because they can survive under
water stress and are considered ecosystem engineers, facilitating the establishment of other
organisms, they can play a key role in the development of a successful restoration
approach to recover the functionality of soils in arid and semiarid regions. In addition
cyanobacteria can be cultured “ex-situ” obtaining high quantities of biomass to be
used as soil inoculum at large scale. For these reasons, the inoculation of degrades
soils with cyanobacteria can be considered an alternative to traditional restoration.
This approach is expected to promote: the stabilization of the soil surface and the
decrease of water and wind erosion; the increase of soil fertility by fixing N and C; and
the succession of more developed organisms as mosses or vascular and annual
plants.
The objectives were: to evaluate the potential of a soil native cyanobacteria strain to be
artificially cultured and the optimization of the process, and to analyze the effects of the
inoculation of the biomass on soil under laboratory conditions. Cyanobacteria were isolated
from biocrusts sampled on a limestone quarry located at the southeastern edge of the Sierra
de Gádor massif (Spain). It was genetically and morphological identified as belonging to the
nitrogen-fixing genera Nostoc. Essays were accomplished in bubble columns reactors (0.25
L), using different culture media: BG11+N, BG110, and two media made with fertilizers.
Illumination simulated a circadian cycle with a maximum irradiance of 1035 μE m−2s−1.
Absorbance, chlorophyll fluorescence and dry weight were measured daily. The
produced biomass was inoculated (6 g m−2) on Petri dishes with 80g of sterilized soil
coming from the limestone quarry. Soils were watered below field capacity twice
a week during three months, under constant illumination of 70 μE m−2s−1 and
25oC.
The growth rate and biomass productivity obtained for each culture media verified that
this strain can be successfully cultured under laboratory conditions. The best results were
obtained with BG11+N, nevertheless results from media made with fertilizers were very
similar, key to develop a low-cost culture strategy. The culture process has been optimized
simulating a continuous mode, in order to produce biomass on a large scale, obtaining an
optimal productivity of 0.41 g L−1 d−1, with a dilution rate of 20% and a concentration of
2.06 g L−1.
Soils inoculated with cyanobacteria biomass obtained from laboratory culture showed an
increase in biocrust cover and soil organic carbon content with time. Thus our results
demonstrate that inoculation with native cyanobacteria cultured “ex- situ” represent
a very promising and “low-cost” tool for the restoration of arid degraded soils. |
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