# Cyanobacterial Potential for Restoration of Loess Surfaces through Artificially Induced Biocrusts
Biocrusts are developing successively from cyanobacteria-dominated biocrusts to biocrusts dominated by lichens and mosses [47]. However, the process of natural succession could be long-lasting [48; 49]. The study conducted by [PERSON] and [PERSON] [48] showed that the first community-building species in the biocrust were dominant even after 42 years. The full development of mature biocrusts can last even hundreds of years [50]. Assisted development of biocrusts and acceleration of their succession is considered as a potential solution for loess restoration. Many studies confirmed the role of cyanobacteria in sand stabilization through the artificial formation of biocrusts e.g., [46; 51; 52; 53; 54; 55; 56; 57; 58; 59]. Regarding loess surfaces and biocrust organisms it has been shown that using a natural moss-dominated biocrust inoculum obtained from the Loess Plateau in China, the bare loess surface was covered entirely after 10 months in the laboratory conditions [42]. In the study of [PERSON] et al. [60], the inoculation of native moss and moss-lichen crusts from the Loess Plateau resulted in the coverage of more than 65% of the bare loess surface after 10 weeks in laboratory conditions. However, the full development of moss-dominated biocrusts in field  
Figure 1: Disturbed loess surfaces present a main source of dust. Disturbed vegetation cover exposes a large surface of loess landscape which acts as a source of dust (Luochuan Xiefeng, China) (**A**) and consequently causes damage to the vegetation cover (Luochuan Xiefeng, China) (**B**). conditions was accomplished after four years [61]. On the other hand, it has been shown that the successful cultivation of cyanobacteria-dominated biocrusts under appropriate environmental conditions may require a few weeks only [46; 52]. Cyanobacteria are primary colonizers, soil stabilizers, and nitrogen fixers within biocrusts [62]. The significance of cyanobacteria in the biological soil crusts (BSCs) is reflected in their ability to survive and grow in harsh environmental conditions which is made possible by their specific traits (migration capacity, ability to survive desiccation and extreme temperatures, production of the ultraviolet (UV)-protective pigments, and production of exopolysaccharideacrylates (EPSs)) [54; 63; 64; 65]. EPSs produced by cyanobacteria form a protective layer between the cell and the environment [66]. They also bind soil particles [51] and make nutrients and water, two commonly limiting factors in drylands, available for the biocrust community [67; 68]. Cyanobacteria produce three types of EPSs: sheaths, capsules, and slimes. Capsules and slimes release polysaccharides into the cultivation medium thus forming released exopolysaccharides-rides (RPSs) [66]. Recent hypothesis on the partly biogenic origin of loess (BLOCDUST) emphasizes the role of cyanobacteria in loess formation. The model establishes the role of the EPSs in this context and discusses the necessary morphological and ecophysiological features of cyanobacteria [9; 10]. The main aim of this manuscript was to examine the potential of cyanobacteria for the restoration of the loess surfaces by initiating biocrust development. The experiments studied the cyanobacterial traits necessary for the successful and sustainable establishment of the BLCs, i.e., non-toxicity and high production of biomass and polysaccharides. Furthermore, the experiments explored the interaction of the cyanobacteria/polysaccharide with airborne particles in the formation of loess. The study also identified processes and mechanisms important for the stabilization of loess particles in their interaction with cyanobacterial colonies.