Biological Soil Crust Bacterial Communities Vary Along Climatic and Shrub Cover Gradients Within a Sagebrush Steppe Ecosystem

Abstract

Numerous studies have examined bacterial communities in biological soil crusts (BSCs) associated with warm arid to semiarid ecosystems. Few, however, have examined bacterial communities in BSCs associated with cold steppe ecosystems, which often span a wide range of climate conditions and are sensitive to trends predicted by relevant climate models. Here, we utilized Illumina sequencing to examine BSC bacterial communities with respect to climatic gradients (elevation), land management practices (grazing vs. non-grazing), and shrub/intershrub patches in a cold sagebrush steppe ecosystem in southwestern Idaho, United States. Particular attention was paid to shifts in bacterial community structure and composition. BSC bacterial communities, including keystone N-fixing taxa, shifted dramatically with both elevation and shrub-canopy microclimates within elevational zones. BSC cover and BSC cyanobacteria abundance were much higher at lower elevation (warmer and drier) sites and in intershrub areas. Shrub-understory BSCs were significantly associated with several non-cyanobacteria diazotrophic genera, including Mesorhizobium and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium. High elevation (wetter and colder) sites had distinct, highly diverse, but low-cover BSC communities that were significantly indicated by non-cyanobacterial diazotrophic taxa including families in the order Rhizobiales and the family Frankiaceae. Abiotic soil characteristics, especially pH and ammonium, varied with both elevation and shrub/intershrub level, and were strongly associated with BSC community composition. Functional inference using the PICRUSt pipeline identified shifts in putative N-fixing taxa with respect to both the elevational gradient and the presence/absence of shrub canopy cover. These results add to current understanding of biocrust microbial ecology in cold steppe, serving as a baseline for future mechanistic research.

Analysis of Internal and External Microorganism Community of Wild Cicada Flowers and Identification of the Predominant Cordyceps cicadae Fungus

“…These genera occupied more than 29 and 50% in the coremia and sclerotia, respectively, and less than 1% in soil. Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium , belonging to non-cyanobacteria diazotrophic genera that are known to be associated with plant roots ( You et al, 2021 ), was the dominant genus in the sclerotia and coremia, which might support the previous speculation that cicada flower may exchange carbon and nitrogen elements in soil via endophytic bacteria to affect the content of carbon and nitrogen compounds in cicada flower ( Zeng et al, 2021 ). A previous study found that four strains of Enterobacteriaceae isolated from wild cicada flower can inhibit C. cicadae on PDA medium and increase the yield of fungal metabolites of C. cicadae ( Qu et al, 2019 ), and Enterobacteriaceae may play an important role in host fitness by resisting pathogenic microbes ( Hu et al, 2020 ), so we speculated that Enterobacteriaceae might have an inhibitory effect on C. cicadae and may help C. cicadae to resist other pathogens.…”

Sugarcane–Peanut Intercropping System Enhances Bacteria Abundance, Diversity, and Sugarcane Parameters in Rhizospheric and Bulk Soils

“…Contrary to our finding, Dang et al (2020) reported that Myxococcales diminished significantly under proso millet and mung bean intercropping systems. It has been reported that Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium is a rhizobia N-fixer ( You et al, 2021 ), and Bradyrhizobium is one of the genera of N-fixing bacteria in leguminous crops capable of forming symbiotic nodules, whereas Sphingomonas is widely regarded as the best environmentally friendly approach for phosphorus nutrition mobilization for plants ( Zhang et al, 2018 ). Consistently, Lindström and Mousavi (2019) identified and described these bacteria as nitrogen-fixing bacteria of legumes.…”

Source and acquisition of rhizosphere microbes in Antarctic vascular plants

“…Some of these bacterial genera have been described as essential parts of the rhizosphere microbiome in woody plants and grasses in other environments globally. For example, the genera Dyadobacter (diazotrophic bacteria), Mucilaginibacter, Asticcacaulis , and Neorhizobium (diazotrophic bacteria) are considered plant growth-promoting bacteria (PGPB) and are part of the core microbiome of diverse plants and cultivars across the globe ( Costa et al, 2006 ; Madhaiyan et al, 2010 ; Wei et al, 2017 ; Yeoh et al, 2017 ; Ishizawa et al, 2018 ; Xu et al, 2018 ; Liu et al, 2019 ; You et al, 2021 ). Strains of Devosia have been isolated from the rhizosphere of Cq and display a high tolerance to salt, where in vitro experiments have demonstrated that this bacteria can improve the osmotic and physiological performance of the Antarctic vascular plants ( Gallardo-Cerda et al, 2018 ).…”