A yellow-pigmented, Gram-stain-negative, short-rod-shaped bacterial strain, MIMD3T, was isolated from biological soil crusts collected in Liangcheng, north-western China. Cell growth could be observed at 10–37 °C (optimum 25 °C), at pH 5–8 (optimum 6.6) and in the presence of 1 % (w/v) NaCl (optimum 0 %). The genomic DNA G+C content was 65.0 mol%. Analysis of 16S rRNA gene sequences showed that strain MIMD3T shared the highest similarity with Sphingomonas vulcanisoli KCTC 42454T (95.1 %), Sphingomonas oligophenolica JCM 12082T (94.8 %), Sphingomonas mali IFO 15500T (94.5 %), Sphingomonas . leidyi ATCC 15260T (94.4 %) and Sphingomonas formosensis CC-Nfb-2T (94.3 %). The strain had Q-10 as the predominant respiratory quinone, and sym-homospermidine as the major polyamine. The major fatty acids of the strain were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C19 : 0 cyclo ω8c, C14 : 0 2-OH and C16 : 0. The main polar lipids of strain MIMD3T were phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and sphingoglycolipid. Based on phenotypic, chemotaxonomic and phylogenetic characteristics, it is concluded that strain MIMD3T represents a novel species of the genus Sphingomonas , for which the name Sphingomonas crusticola sp. nov. is proposed. The type strain is MIMD3T (=KCTC 42801T=MCCC 1K01310T).

A pink-pigmented, Gram-stain-negative, rod-shaped, strictly aerobic bacterial strain MIMtkB3^T, was isolated from moss crusts in Hunshandake desert of China. Cells grew at 15–45 °C (optimum of 28 °C), at pH of 6.0–8.5 (optimum of 7.0) and with 0–1.0 % (w/v) NaCl (optimum of 0 %). The strain could biosynthesize the green-coloured pigment bacteriochlorophyll a (BChl a). The respiratory quinone was ubiquinone Q-10, while C_18 : 1 ω7c and C_18 : 1 2OH were the major fatty acids. Phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified aminophospholipid, one unidentified phospholipid, three unidentified glycolipid and one unidentified lipid were the major polar lipids. Strain MIMtkB3^T was most closely related to Oleisolibacter albus NAU-10^T, Niveispirillum fermenti CC-LY736^T, and Rhodocista centenaria SW of the family Rhodospirillaceae with 16S rRNA gene similarities of 93.09, 92.02 and 91.73%, respectively. The genomic DNA G+C content calculated on complete genome sequencing was 69.3 mol%. The average nucleotide identity between strain MIMtkB3^T and its closely related type strains in Rhodospirillaceae was below 77.96 % and digital DNA–DNA hybridization lower than 24.70 %. Full light utilization pathway of aerobic anoxygenic phototrophic bacteria was identified in the genome. Based on phenotypic, chemotaxonomic and phylogenetic characteristics, strain MIMtkB3^T represents a novel genus of the family Rhodospirillaceae , for which the name Aerophototrophica crusticola gen. nov., sp. nov. is proposed. The type strain is MIMtkB3^T (=KCTC 42633^T=MCCC 1K00570^T).

Biological soil crusts (BSCs) play a fundamental role in desert ecosystems by stabilizing soil, cycling nutrients, and retaining moisture. However, the assembly processes governing bacterial communities within BSCs remain largely unknown. This study aimed to reveal the spatiotemporal variations in the bacterial community diversity, co-occurrence patterns, and ecological assembly processes of BSCs and their underlying soils across different desert and seasonal conditions. We systematically analyzed the spatial differences in the bacterial diversity, co-occurrence networks, and community assembly processes of BSCs and their underlying soils using samples collected at various soil depths from different BSC types in different deserts. We discovered that BSC type and soil depth were the primary factors driving bacterial community assembly, while seasonal effects were weaker and more indirect, and mainly regulated community dynamics through changes in resource availability and environmental conditions. The underlying soils of moss- and lichen-BSCs exhibited higher bacterial diversity and richness than those of algae BSCs. In contrast, cyano-BSCs exhibited a lower diversity, but Cyanobacteria demonstrated the highest photosynthetic function. Among the different deserts, the community assembly of samples from the eastern Inner Mongolia deserts was largely influenced by environmental selection, whereas stochastic processes were more prominent in the central and western desert regions. A β-nearest taxon index (βNTI) analysis indicated that stochastic processes were dominant in surface BSC samples, while environmental selection played a stronger role in deeper layers. A co-occurrence network analysis revealed that surface BSC samples had a high degree of network connectivity, with those from moss- and lichen-BSCs being particularly high, and they also exhibited high modularity and local clustering that promoted the functional stability of the microbial communities. This study revealed the integrated effects of soil depth, BSC type, desert type, and resource availability on microbial community assembly in desert ecosystems. These findings provide a theoretical basis for the microbial management of BSCs and scientific insights to support restoration strategies in desert ecosystems.

The bacterial strain was isolated from the rhizosphere of Elymus dahuricus Turcz. in temperate semi-arid steppe, located in the northern of Inner Mongolia Autonomous Region, China. Strain PJ23^T is Gram-stain-negative, aerobic, light-pink, short rod-shaped, and does not form spores. Cell growth could be observed at 4-29 ℃ (optimum, 24 ℃), pH 6.0-8.6 (optimum, 8.0) and in the presence of 0-5 % (w/v) NaCl (optimum, 2.5 %). The major fatty acids of strain PJ23^T were Summed feature 8 (C_{18:1 ω6c} and/or C_{18:1 ω7c}) 39.42 %) and C_16:0 (9.60 %). The polar lipid profile was composed of phosphatidylcholine, two unidentified glycolipids, one unidentified aminophospholipid, and two other unidentified polar lipids. The sole respiratory quinone was ubiquinone-10. Phylogeny on full length of 16S rRNA gene sequences retrieved from the genomes showed that, the strain was closely related to Terrihabitans soli IZ6^T and Flaviflagellibacter deserti SYSU D60017^T with the sequence similarities of 96.79% and 96.15%, respectively. The G+C content was 65.23 mol% calculated on draft genome sequencing. Between the strains PJ23^T and T. soli IZ6^T, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) was 73.39 % and 15.7 %, these values are lower than the proposed and generally accepted species boundaries of dDDH and ANI. Based on phenotypic, chemotaxonomic, and phylogenetic characteristics, strain PJ23^T represents a novel species of Terrihabitans, for which the name Terrihabitans rhizophilus sp. nov. is proposed. The type strain is PJ23^T (= KCTC 92977^T=CGMCC 1.61577^T).