Abstract
Three Gram-stain-positive, aerobic, motile actinobacterial strains designated as CPCC 205119T, CPCC 205215, and CPCC 205251 were isolated from different biological soil crust samples collected from Tengger Desert, China. The 16S rRNA gene sequence comparison of these three strains showed they had almost identical 16S rRNA genes, which were closely related to members of the family Geodermatophilaceae, with the highest similarities of 96.3–97.3% to the species of Modestobacter. In the phylogenetic tree based on 16S rRNA gene sequences, these isolates clustered into a subclade next to the branch containing the species of Modestobacter lapidis and Modestobacter multiseptatus, within the lineage of the genus Modestobacter. The comparative genomic characteristics (values of ANI, dDDH, AAI, and POCP) and the phenotypic properties (morphological, physiological, and chemotaxonomic characteristics) of these isolates readily supported to affiliate them to the genus Modestobacter as a single separate species. For which, we proposed that the isolates CPCC 205119T, CPCC 205215, and CPCC 205251 represent a novel species of the genus Modestobacter as Modestobacter deserti sp. nov. CPCC 205119T (=I12A-02624=NBRC 113528T=KCTC 49201T) is the type strain. The genome of strain CPCC 205119T consisted of one chromosome (4,843,235bp) containing 4,424 coding genes, 48 tRNA genes, five rRNA genes, three other ncRNA genes, and 101 pseudogenes, with G+C content of 74.7%. The whole-genome sequences analysis indicated that this species contained alkaline phosphatase genes (phoA/phoD), phosphate transport-related genes (phoU, phnC, phnD, phnE, phoB, phoH, phoP, phoR, pitH, ppk, pstA, pstB, pstC, and pstS), trehalose-phosphate synthase gene (otsA), trehalose 6-phosphate phosphatase gene (otsB) and other encoding genes for the properties that help the microorganisms to adapt to harsh environmental conditions prevalent in deserts. Strains of this species could solubilize tricalcium phosphate [Ca3(PO4)2] and phytin, assimilate pyrophosphate, thiophosphate, dithiophosphate, phosphoenol pyruvate, 2-deoxy-d-glucose-6-phosphate, and cysteamine-S-phosphate.
Highlights
Water scarcity, violent temperature fluctuation, strong ultraviolet radiation, and low-substrate supply are the key abiotic stress factors for life in desert environments
Strains designated as CPCC 205119T and CPCC 205215 were isolated from moss-dominated soil crust samples IMB12100 and IMB12108, respectively, and strain CPCC 205251 was acquired from cyanobacteria-dominated soil crust sample CCL12125, collected from Shapotou National Desert EcologicalReserve” (NDER) in Tengger Desert, China
BLAST search results showed that they exhibited the highest similarities with the validly described species of the genus Modestobacter, i.e., M. lapidis DSM 100206T (97.3%), M. multiseptatus DSM 44406T (97.3%), and other type strains of the genus Modestobacter (
Summary
Violent temperature fluctuation, strong ultraviolet radiation, and low-substrate supply are the key abiotic stress factors for life in desert environments. In the northwest of China is the first Chinese NDER This NDER acts as a model for studying the development of biological soil crusts. Found that the members of the family Geodermatophilaceae (Normand, 2006) were ubiquitous in different types of crusts in Shapotou NDER. Among the validly described species of the family Geodermatophilaceae, most validly described type strains, especially the Modestobacter (a major genus in the family Geodermatophilaceae) members were isolated from harsh environments, including desert soils (Busarakam et al., 2016; Golińska et al, 2020), sandstone (Trujillo et al, 2015), stone surfaces (Normand et al, 2012; Montero-Calasanz et al., 2019), as well as the newly recognized species Modestobacter excelsi from a high altitude Atacama Desert soil (Golinska et al, 2020). The genome study of Modestobacter revealed that the multiple copies of genes, such as coxSML (carbon monoxide dehydrogenase related genes), katA (catalase coding gene), and uvrACD (UvrABC system protein coding genes; Chouaia et al, 2012; Gtari et al, 2012; Sghaier et al, 2016)
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