Exogenous Microorganisms Promote Moss Biocrust Growth by Regulating the Microbial Metabolic Pathway in Artificial Laboratory Cultivation

Abstract

Moss-dominated biocrusts (moss crusts) are a feasible approach for the ecological restoration of drylands, but difficulty obtaining inoculum severely limits the progress of large-scale field applications. Exogenous microorganisms could improve moss growth and be conducive to moss inoculum propagation. In this study, we investigated the growth-promoting effects and potential mechanisms of exogenous microorganism additives on moss crusts. We used an incubator study to examine the effects of inoculation by heterotrophic microorganisms (Streptomyces pactum, Bacillus megaterium) and autotrophic microorganisms (Chlorella vulgaris, Microcoleus vaginatus) combined with Artemisia sphaerocephala gum on the growth of Bryum argenteum, the dominant moss crusts species in sandy deserts. Amplicon sequencing (16S and 18S rRNA) and PICRUSt2 were used to illustrate the microbial community structure and potential function in the optimal treatment at different developmental stages. Our results showed that exogenous microorganisms significantly promoted moss growth and increased aboveground biomass. After 30 days of cultivation, the Streptomyces pactum (1 g kg–1 substrate) + Chlorella vulgaris (3.33 L m–2) treatment presented optimal moss coverage, height, and density of 97.14%, 28.31 mm, and 2.28 g cm–2, respectively. The best-performing treatment had a higher relative abundance of Streptophyta—involved in moss growth—than the control. The control had significantly higher soil organic carbon than the best-performing treatment on day 30. Exogenous microorganisms improved eukaryotic community diversity and richness and may enhance soil microbial functional and metabolic diversity, such as growth and reproduction, carbon fixation, and cellulose and lignin decomposition, based on functional predictions. In summary, we identified the growth-promoting mechanisms of exogenous additives, providing a valuable reference for optimizing propagation technology for moss inoculum.

Effect of crevice density on biological soil crust development on rock cut slope in mountainous regions, Sichuan, China

“…The recovery rate of BSCs is largely dependent on the environmental conditions, especially the high soil moisture, soil fertile and microorganisms activity and diversity (Belnap et al 2001(Belnap et al , 2016Belnap 2010;Karimi et al 2022;Lucieer et al 2014;Margolis et al 2022;Tian et al 2022a;Wang et al 2022a, b;Zhang et al 2002). Higher precipitation and humidity are also beneficial for the development of BSCs (Bu et al 2015b;Karger et al 2012;Langhans et al 2010;Oishi 2019;Zaady et al 2007;Zhang et al 2002;Zhang et al 2005b).…”

“…BSCs are early and fast pioneer colonizers of degraded and harsh environments, especially in strongly disturbed areas where vascular plant development is less likely to occur (Bowker 2007;Bu et al 2013). BSCs are widely considered as important ecosystem restorers (Bowker 2007;Bowker et al 2010;Karimi et al 2022;Lu et al2022a) due to the functional roles which BSCs play in natural ecosystems (Concostrina et al 2019), such as soil microorganism activity and diversity improvement (Tian et al 2022a;Wang et al 2022a, b), soil water storage (Chamizo et al 2013;Gong et al 2022;Lu et al 2022b;Belnap et al 2016), soil fertility improvement (Belnap et al 2016;Bowker 2007;Chamizo et al 2012;Deng et al 2020;Elbert et al 2009;Gao et al 2018;Giora et al 2015;Karimi et al 2022;Nyenda et al 2019;Tian et al 2022b;Wang et al 2022b;Zhang et al 2005a;Zhang et al 2022;Zubiri et al 2022), soil stability and physical structure enhancement (Gall et al 2022;Hu et al 2002;Karimi1 et al 2022;Mager and Thomas 2011), soil erosion alleviation (Chamizo et al 2013(Chamizo et al , 2019Gall et al 2022;Guo et al 2022;Kheirfam and Roohi 2022), and facilitating or inhibiting vascular plant establishment and growth…”

“…Even for extremely degraded ecosystems, BSCs can develop naturally from cyanobacterial crusts, and lichen crusts to bryophyte crusts over several years or decades (Belnap et al 2001(Belnap et al , 2016Concostrina-Zubiri et al 2019;Deng et al 2020;Xiao et al 2019a). Although BSCs can tolerate harsh environments, their growth and development are largely controlled by environmental factors such as soil water (Bu et al 2015b;Chen et al 2005;Lucieer et al 2014;Zhang et al 2005b), air humidity (Oishi 2019;Karger et al 2012), precipitation (Langhans et al 2010;Zaady et al 2007;Zhang et al 2005b), soil nutrients (Bu et al 2015b;Tian et al 2021;Zhang et al 2002), vascular plants (Peng et al 2022Zhang et al 2002) and microtopography (Ji et al 2018;Li et al 2018a;Lucieer et al 2014;Zhu 1995), soil microorganism (Karimi et al 2022;Margolis et al 2022), dusts or sediments (Peer et al 2022;Reynolds et al 2001), as well as human activities and inoculation (Chaudhary et al 2020;Chen et al 2009;Deng et al 2020;Karimi et al 2022;Tian et al 2022a). Microtopography, as an important environmental factor, also affects BSCs type (Chen et al 2005), distribution (Ji et al 2018;Zhang et al2002;Zhang et al 2005b;…”