EDAPHIC CYANOBACTERIA IN Geoffroea decorticans (CHAÑAR) ISLETS AND NATURAL GRASSLANDS OFARGENTINA CENTRAL REGION

RAMOS IRAZOLA, F; MANRIQUE M; FERNANDEZ BELMONTE MC; SUELDO R; RAUBER, R.B; CENDOYA, MA

Congreso; XL Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2022

In arid and semi-arid regions, edaphic cyanobacteria presence plays an important role in ecosystems since they contribute to forming soilstructure, improve the stability of aggregates, and provide the soil with atmospheric nitrogen. The objective of this work was to identifythe cyanobacterial taxa in soils in the center and edge Geoffroea decorticans (chañar) islets and natural grasslands of the región studied.To achieve this, samples were taken at 15 sites of four establishments, located in the región called "Dune area with grasslands and islets ofGeoffroea decorticans (chañar)" in San Luis province, which were extracted from the first 5 cm of soil. Samples cultures were made inPetri dishes having Watanabe (1951) liquid medium, and were placed in FICA-UNSL Phycology Laboratory culture chamber undertemperature (20º-30ºC) and photoperiod (12 hrs light- 12 hrs darkness) controlled conditions. Cyanobacteria observation and qualitativeanalysis was carried out using an Olympus BX 50 optical microscope, in order to measure their cellular and filamentous structures Speciesfound classification was made: Non Nitrogen Fixing (NF) and Nitrogen Fixing (NF), the latter in turn, in Heterocysts (HF) and NonHeterocysts (NHF). They were taxonomically determined with specific bibliography for the Cyanobacteria group. The NF genera foundwere Oscillatoria, Phormidium, Synechocystis and Chroococcus and HF genera were Calothrix, Scytonema and Nostoc. The latter alsoappears in its NHF form. Scytonema genus was only found in one natural grassland site and also one of them on the islet edge. Sitescorresponding to natural grassland presented greater generic diversity: 9 from NF and 6 from HF. In islet center and edge sites of the islet,8 NF and 3 HF were found in both cases. Subsequently, the NF Oscillatoria subbrevis species appears in 6 natural grassland sites, in 9edge islet site and in 3 sites in the islet center. An initial NF cyanobacteria growth was observed in all sites, followed by NHF and HF,such as it occurs in other studied sites. It is concluded that arid and semi-arid environments cyanobacteria edaphic of from the studiedregion contain various genera of NF, HF and NHF. This group of microorganisms importance presence lies in the fact that all of themwould act effectively in the soil degradation recovery, therefore contributing to the productive systems sustainability.