Cyanobacteria as a Nature-Based Biotechnological Tool for Restoring Salt-Affected Soils

Abstract

Soil salinization poses an important threat to terrestrial ecosystems and is expected to increase as a consequence of climate change and anthropogenic pressures. Conventional methods such as salt-leaching or application of soil amendments, or nature-based solutions (NBSs) such as phytoremediation, have been widely adopted with contrasting results. The use of cyanobacteria for improving soil conditions has emerged as a novel biotechnological tool for ecosystem restoration due to the unique features of these organisms, e.g., ability to fix carbon and nitrogen and promote soil stabilisation. Cyanobacteria distribute over a wide range of salt concentrations and several species can adapt to fluctuating salinity conditions. Their application in agricultural saline soil remediation has been demonstrated, mostly in laboratory studies, but there is a lack of research regarding their use in natural ecosystems restoration. In this article, we provide an overview of the current knowledge on cyanobacteria in the context of ecosystem restoration. Examples of the application of cyanobacteria in alleviating salt-stress in plants and soils are presented. Furthermore, we acknowledge gaps regarding the extensive application of cyanobacteria in salt-affected soils remediation and discuss the challenges of NBSs in salt-affected soils restoration.

Cyanobacteria as a potential bioasset for restoring degraded land

“…Cyanobacteria also have a high water‐holding capacity and an increased soil biomass after their death and decomposition. An improved growth in rice, maize, and wheat is seen due to desalination of soil by cyanobacteria (Li et al, 2019; Rocha et al, 2020). Among cyanobacteria, mainly Nostoc and Anabaena species have been extensively studied as nitrogen fixers and are excellent candidates for performing bioremediation.…”

“…Though experiments on their effect on each other's activity have not been performed; yet, it seems a powerful approach for sodic land remediation based on the current evidences. The salt‐affected soils which have been remediated using biological methods show restored soil fertility and reduce our dependence on external fertilizers and promote plant growth (Rocha et al, 2020). One of the major limitations with the use of cyanobacteria for bioremediation of sodic soils remains to be the optimization and validation for broad range application, wherein the problems associated with harvesting and contamination are to be addressed.…”

“…The role of cyanobacteria in erosion-susceptible soil rebuilding has been proven through runoff inhibition, improved C and N fixation, and aggregate formation by secreting EPS (Rocha et al, 2020). Application of cyanobacterial extract, extracellular products, plant inoculation, or seed coating with living cyanobacteria has shown numerous advantageous effects such as improved seed germination, seedling growth, nutrient use efficiency, improvement in soil nutrient status, biological control of pest and diseases, and tolerance to various abiotic stresses (Chua et al, 2019;Santini et al, 2021).…”

“…The capacity to grow in appropriate amounts is a key factor in the application of native cyanobacteria for landscape-scale restoration (Rocha et al, 2020). To scale up these technologies to field conditions and evaluate their environmental-economic viability for large-scale land restoration requires improved isolation and culture techniques.…”

Peculiarities of the Edaphic Cyanobacterium Nostoc linckia Culture Response and Heavy Metal Accumulation from Copper-Containing Multimetal Systems

“…Additionally, the release of exopolysaccharides into the soil improves soil stability [ 14 ]. In recent years, it has been proposed to use cyanobacteria as a biotechnological tool for the restoration of soil ecosystems—in particular, salt-affected ones [ 15 ].…”