Assessing the influence of soil abiotic and biotic factors on Nostoc commune inoculation success

Aims A possible approach to restore drylands is to recover biocrusts by inoculating cyanobacteria. Many studies have demonstrated the ability of cyanobacteria to successfully colonize soil and improve its functions. However, most studies have focused on the abiotic factors influencing the inoculation success, overlooking biotic factors. We examined the influence of the soil indigenous community on the inoculated cyanobacteria by sterilizing soils and analyzing its effects on several key soil properties. Methodology Nostoc commune was inoculated under laboratory conditions on two soil types with different levels of degradation and under two watering frequencies. All treatments were carried out in natural and sterilized soils. Results The analysis of the cyanobacterial coverage (30-50% in all inoculated soils), chlorophyll a, visible albedo, roughness, water repellency, organic carbon (OC) and exopolysaccharides (EPS) content showed that cyanobacterial inoculation succeeded, improving soil properties that varied depending on the soil type. The sterilization of soils had little effect: in less degraded soils, the results suggest a faster growth of the indigenous community reaching coverage values of 10% and an interaction with the inoculum that led to a decrease in 2 and 0.3 g Kg(-1) of OC and TB-EPS, respectively; in more degraded soils, the community reduced the cyanobacterial coverage around 11%, suggesting competitive interactions. Conclusions N. commune can be employed to restore lifeless soils. Also, the analysis of native soil community should be considered before field inoculation to plan appropriate methodologies.