The potential of the cyanobacterium Leptolyngbya ohadii as inoculum for stabilizing bare sandy substrates. (December 2018)

• Record Type: Journal Article
• Authors: Mugnai, Gianmarco; Rossi, Federico; Martin Noah Linus Felde, Vincent John; Colesie, Claudia; Büdel, Burkhard; Peth, Stephan; Kaplan, Aaron; De Philippis, Roberto
• Is Part Of: Soil biology and biochemistry. Volume 127(2018)
• Page Start: 318
• Page End: 328
• Publication Date: 2018-12
• Subjects: Biocrusts -- EPS -- Cyanobacteria -- Inoculation -- Soil rehabilitation -- Arid environments; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2018.08.007
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Soil inoculation with cyanobacteria to promote the formation of biocrusts is considered a potential eco-friendly method to counteract desertification spread in drylands. Research is needed to increase the number of proficient cyanobacterial strains, selected for their capability to survive in harsh conditions and to form stable biocrusts quickly. We hereby present a microcosm study to assess the capability of Leptolyngbya ohadii, native to the Negev Desert, to form biocrusts on sand collected in the same environment, during a three-month incubation period. Inoculation was carried out in sand-filled microcosms without nutrient addition and a limited water supply (equivalent to desert dew input). Parameters related to biocrusts growth and to their physico-chemical attributes were measured, and the exopolysaccharides (EPS) synthesized by the strain during biocrust formation were quantified and characterized. After 15 days of incubation, L. ohadii was able to form biocrusts with a thickness and a physical stability superior to other test strains of cyanobacteria, and typical of much older natural biocrusts. Biocrust characteristics were dependent on the synthesis of EPS, and on the capability to migrate in the sand, stabilizing sand aggregates at different locations within the microcosms. In contrast to other tested strains, L. ohadii produced compositionally complex EPS during the entire incubation period despite the lack of nutrients, producing biocrusts with an amphiphilic extracellular matrix, a character effective in conferring stability to sand aggregates, chelating nutrients and maintaining hydration. Overall, this study shows that L. ohadii is a promising inoculant that may be considered to promote the formation of biocrusts in natural desert settings. Highlights: Leptolynbya ohadii inoculation produces very thick and stable biocrusts on a sandy oligotrophic substrate. Inoculation procedure does not need any support treatment (e.g., pre-stabilization of the substrate or nutrient addition). Biocrusts formation happens with a very limited water provision. The performance as inoculant benefits from exopolysaccharide synthesis and filament gliding in the sand. Exopolysaccharide productivity and characteristics are affected by variations in water availability.