Prauserella cavernicola sp. nov., isolated from cave rock

A novel actinomycete, designated strain ASG 168T, was isolated from cave rock collected from Stegodon Sea Cave in Thailand. Long chains of non-motile spores that were oval or spherical in shape with a smooth surface developed on aerial mycelia. Substrate mycelia fragmented into irregular rod-shaped elements. A polyphasic taxonomic study showed that strain ASG 168T had typical characteristics of members of the genus Prauserella . 16S rRNA gene sequence analysis indicated that strain ASG 168T shared 97.5 % similarity with Prauserella marina MS498T and 96.7 % with Prauserella coralliicola SCSIO 11529T. Average nucleotide identity values with P. coralliicola SCSIO 11529T and P. marina MS498T were 82.98 and 76.08 %, respectively. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, arabinose and galactose. The predominant menaquinone was MK-9(H4). The predominant fatty acids were iso-C16 : 0, C16 : 0 and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c). The phospholipid profile consisted of phosphatidylethanolamine, phosphatidylmethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides and two unknown phospholipids. The G+C content of the genomic DNA was 70.6 mol%. Differentiation of strain ASG 168T from closely related species was evident from digital DNA–DNA hybridization values of 29.2 and 21.3 % with P. coralliicola and P. marina , respectively. Based on comparative analysis of phenotypic, chemotaxonomic and genotypic data, the novel actinomycete strain ASG 168T (=TBRC 13679T=NBRC 114887T) is proposed to be the type strain of a novel species, Prauserella cavernicola sp. nov.

Nocardiopsis coralli sp. nov. a novel actinobacterium isolated from the coral Galaxea astreata

Strain HNM0947T, representing a novel actinobacterium, was isolated from the coral Galaxea astreata collected from the coast of Wenchang, Hainan, China. The strain was found to have morphological and chemotaxonomic characteristics consistent with the genus Nocardiopsis . The organism formed abundant fragmented substrate mycelia and aerial mycelia which differentiated into non-motile, rod-shaped spores. Whole-cell hydrolysates contained meso-diaminopimelic acid and no diagnostic sugars. The major menaquinones were MK-10(H8), MK-10(H6) and MK-10(H4). The major phospholipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were iso-C16:0, anteiso-C17:0, C18:0, C18:0 10-methyl (TBSA) and anteiso-C15:0. The G+C content was 71.3 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain HNM0947T belonged to the genus Nocardiopsis and shared highest sequence similarity to Nocardiopsis salina YIM 90010T (98.8%), Nocardiopsis xinjiangensis YIM 90004T(98.5%) and Nocardiopsis kunsanensis DSM 44524T (98.3%). The strain HNM0947T was distinguished from its closest type strain by low average nucleotide identity (90.8%) and dDDH values (60.4%) respectively. Based on genotypic, chemotaxonomic and phenotypic characteristics, it was concluded that strain HNM0947T represents a novel species of the genus Nocardiopsis whose name was proposed as Nocardiopsis coralli sp. nov. The type strain was HNM0947T (=CCTCC AA 2020015 T=KCTC 49525 T).

Kitasatospora acidiphila sp. nov., isolated from pine grove soil, exhibiting antimicrobial potential

A polyphasic study was carried out to establish the taxonomic position of an acidophilic isolate designated MMS16-CNU292T (=JCM 32302T) from pine grove soil, and provisionally assigned to the genus Kitasatospora . On the basis of 16S rRNA gene sequence similarity, the strain formed a novel evolutionary lineage within Kitasatospora and showed highest similarities to Kitasatospora azatica KCTC 9699T (98.75 %), Kitasatospora kifunensis IFO 15206T (98.74 %), Kitasatospora purpeofusca NRRL B-1817T (98.61 %) and Kitasatospora nipponensis HKI 0315T (98.42 %), respectively. Strain MMS16-CNU292T possessed MK-9(H6) and MK-9(H8) as the major menaquinones, and a major amount of meso-diaminopimelic acid in the cell-wall peptidoglycan. The whole-cell hydrolysates were rich in galactose, glucose and mannose, and the polar lipids mainly consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol and phosphatidylinositol mannosides. The major fatty acids were anteiso-C15 : 1-A, anteiso-C15 : 0, and iso-C15 : 0, and the DNA G+C content was 71.5 mol%. The strain exhibited antibacterial activity against a number of bacterial strains, and the activity was generally greater when grown in acidic conditions. The phylogenetic, chemotaxonomic and phenotypic properties enabled distinction of MMS16-CNU292T from related species, and thus the isolate should be recognized as a new species of the genus Kitasatospora , for which the name Kitasatospora acidiphila sp. nov. (type strain=MMS16-CNU292T=KCTC 49011T=JCM 32302T) is proposed.

Cellulomonas endophytica sp. nov., isolated from Gastrodia elata Blume

A Gram-stain-positive, facultatively anaerobic and non-motile strain, designated SYSUP0004T, was isolated from the tubers of Gastrodia elata Blume collected from Yunnan Province, PR China. The 16S rRNA gene sequence result showed that the strain SYSUP0004T shared low similarity (97.7 %) with the type strain of Cellulomonas marina . SYSUP0004T grew at pH 6.0–9.0 (optimum, pH 8.0), temperature 4–30 °C (optimum, 28 °C) and could tolerate NaCl up to 4 % w/v (optimum in the absence of NaCl). The cell-wall peptidoglycan type was A4β with an interpeptide bridge l-ornithine–d-glutamic acid. Cell-wall sugars were mannose, ribose, glucose, galactose and fucose. The menaquinone was MK-9(H4). The major fatty acids were anteiso-C15:0, anteiso-C15 : 1 A, C16 : 0 and anteiso-C17 : 0. The polar lipids of SYSUP0004T were diphosphatidylglycerol, unidentified phosphoglycolipid, phosphatidylinositol mannosides and unidentified glycolipid. The genomic DNA G+C content was 76.5 %. The average nucleotide identity values between SYSUP0004T and members of the genus Cellulomonas were below the cut-off level (95–96 %) recommended as the ANI criterion for interspecies identity. Thus, based on the above results strain SYSUP0004T represents a novel species of the genus Cellulomonas , for which the name Cellulomonas endophytica sp. nov. is proposed. The type strain, SYSUP0004T (=KCTC 49025T=CGMCC 1.16405T).

Saccharothrix deserti sp. nov., an actinomycete isolated from desert soil

A Gram-stain-positive, aerobic actinomycete, designated strain BMP B8144T, was isolated from desert soil, in Xinjiang province, northwest China. The isolate produced scanty aerial mycelium and fragmented substrate mycelium on most tested media. Cell-wall hydrolysates contained meso-diaminopimelic acid, galactose and mannose. The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylhydroxylethanolamine, phosphatidylinositol, and phosphatidylinositol mannosides. The major fatty acids included iso-C16 : 0, C17 : 1 ω8c and iso-C15 : 0. The predominant menaquinones were MK-9(H4) and MK-10(H4). The DNA G+C content was 70.4 mol% (genome). Based on the 16S rRNA gene sequence analysis on EzBioCloud server, strain BMP B8144T showed the closest similarities to Saccharothrix lopnurensis YIM LPA2hT (98.9 %) and ‘ Saccharothrix yanglingensis ’ Hhs.015 (98.6 %). However, it can be distinguished from the closest strains based on the low levels of DNA–DNA relatedness (59.3±1.8 and 47.9±2.3 %, respectively). A combination of morphological, chemotaxonomic and phylogenetic characteristics, strain BMP B8144T represents a novel species of the genus Saccharothrix , for which the name Saccharothrix deserti sp. nov. is proposed. The type strain is BMP B8144T (=CGMCC 4.7490T=KCTC 49001T).

The Role of Phosphatidylinositol Mannosides in the Serological Diagnosis of Mycobacterial Infections

Accurate diagnosis of mycobacterial infections, such as bovine tuberculosis and paratuberculosis, remains challenging. Available direct diagnostic tests aimed at detecting the pathogen are highly specific but lack sensitivity, depending on the stage of infection and the prevalence of infection in a population. The sensitivity of indirect diagnostic assays that measure the host immune response to infection is similarly affected by disease characteristics. The choice of antigen used to detect a host response to infection has a critical impact on test sensitivity and specificity. Many indirect tests rely on crude antigen preparations and cell-free extracts, of which the production is poorly standardized. Moreover, these preparations contain ample uncharacterized cross-reactive compounds. To enhance serological test specificity, existing assays depend on the pre-treatment of samples and a relatively high cut-off value, that in turn influences test sensitivity. Research therefore focuses on the identification of more specific, defined antigens to improve diagnostics. In the current study, we extracted phosphatidylinositol mannosides (PIMs) and investigated their potential use in antibody-based tests. Our results demonstrate that specific IgG class antibodies are generated against PIMs in cows, but this is unrelated to tuberculosis or paratuberculosis infection status, making these antigens unsuitable for diagnostic applications. In addition, we demonstrate that PIMs are widely present in crude antigen preparations and in serum pre-absorption buffer. Our results indicate that PIMs are cross-reactive compounds with immunodominant B cell epitopes that could impair serological test specificity.

Microenvironment ofMycobacterium smegmatisCulture to Induce Cholesterol Consumption Does Cell Wall Remodeling and Enables the Formation of Granuloma-Like Structures

Pathogenic species of mycobacteria are known to use the host cholesterol during lung infection as an alternative source of carbon and energy. Mycobacteria culture in minimal medium (MM) has been used as anin vitroexperimental model to study the consumption of exogenous cholesterol. Once in MM, different species of mycobacteria start to consume the cholesterol and initiate transcriptional and metabolic adaptations, upregulating the enzymes of the methylcitrate cycle (MCC) and accumulating a variety of primary metabolites that are known to be important substrates for cell wall biosynthesis. We hypothesized that stressful pressure of cultures in MM is able to induce critical adaptation for the bacteria which win the infection. To identify important modifications in the biosynthesis of the cell wall, we cultured the fast-growing and nonpathogenicMycobacterium smegmatisin MM supplemented with or without glycerol and/or cholesterol. Different from the culture in complete medium Middlebrook 7H9 broth, the bacteria when cultured in MM decreased growth and changed in the accumulation of cell wall molecules. However, the supplementation of MM with glycerol and/or cholesterol recovered the accumulation of phosphatidylinositol mannosides (PIMs) and other phospholipids but maintained growth deceleration. The biosynthesis of lipomannan (LM) and of lipoarabinomannan (LAM) was significantly modulated after culture in MM, independently of glycerol and/or cholesterol supplementation, where LM size was decreased (LM13-25KDa) and LAM increased (LAM37-100KDa), when compared these molecules after bacteria culture in complete medium (LM17-25KDaandLAM37-50KDa). These changes modified the cell surface hydrophobicity and susceptibility against H2O2. The infection of J774 macrophages withM. smegmatis,after culture in MM, induced the formation of granuloma-like structures, while supplementation with cholesterol induced the highest rate of formation of these structures. Taken together, our results identify critical changes in mycobacterial cell wall molecules after culture in MM that induces cholesterol accumulation, helping the mycobacteria to increase their capacity to form granuloma-like structures.