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Nine new chromone analogs ( 1 - 9 ) were isolated from the soil actinomycete Microbispora sp. TBRC6027. The chemical structures were determined based upon NMR spectroscopic methods. These compounds were evaluated in vitro by using P19-derived neurons for neuroprotective activity against oxidative stress induced by serum deprivation and showed % viability of neurons at the concentration of 1 ng/mL varied from 43.51% to 52.99% without significant neurotoxicity for P19-derived neurons at the same concentration. Moreover, all tested compounds were inactive for antibacterial activity against both Gram-positive and Gram-negative bacteria and for cytotoxicity against MCF-7 (human breast cancer) and Vero cells at maximum tested concentration 50 μg/mL. However, compounds 4 , 6 , and 7 displayed weak cytotoxicity against NCI-H187 (human small-cell lung cancer) cells with IC 50 in a range of 87.99-91.57 μM.

Three undescribed abyssomicin derivatives, including microbimisin, abyssomicins Z1, and Z2, were isolated from the soil actinomycete Microbispora rhizosphaerae sp. nov. TBRC6028. Chemical structures were determined by NMR spectroscopic data ( 1 H, 13 C, COSY, HSQC, HMBC, and NOESY spectra) and the absolute configurations were verified by single-crystal X-ray diffraction analyses together with the ECD spectral data. Microbimisin and abyssomicin Z1 exhibited weak antibacterial activity against Bacillus cereus with MIC values of 25.0 and 50.0 μg/mL without cytotoxicity against MCF-7 and Vero cells at the concentration of 50 μg/mL., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

An endophytic actinobacterium, designated strain KE2-3 T , was isolated from surface-sterilised rhizome of Kaempferia elegans. The polyphasic approach was used for evaluating the taxonomic position of this strain. The taxonomic affiliation of this strain at genus level could be confirmed by its chemotaxonomic characteristic, i.e. the presence of ll-diaminopimelic acid in the cell peptidoglycan, MK-9(H4) as the major menaquinone, iso-C16 : 0, anteiso-C15 : 0, iso-C14 : 0 and iso-C15 : 0 as the predominant fatty acids in cells, and the presence of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside in its membranes. Based on 16S rRNA gene sequence analysis, strain KE2-3 T was identified as a member of the genus Jiangella and showed the highest similarities to Jiangella muralis DSM 45357 T (99.3 %) followed by Jiangella albaDSM 45237 T (99.2 %), Jiangella alkaliphilia DSM 45079 T (99.0 %), Jiangella gansuensisDSM 44835 T (98.8 %) and Jiangella mangrovi3SM4-07 T (98.6 %). However, the draft genome sequence of strain KE2-3 T exhibited low average nucleotide identity values to the reference strains (85.5-90.2 %), which were well below the 95-96 % species circumscription threshold. The DNA G+C content of genomic DNA was 72.3 mol%. With the differences of physiological, biochemical and genotypic data, strain KE2-3 T could be discriminated from its closest neighbour. Thus, strain KE2-3 T should be recognised as a novel species of genus Jiangella, for which the name Jiangellaendophytica sp. nov. is proposed. The type strain is KE2-3 T (=BCC 66359 T =NBRC 110004 T ).

A novel actinomycete strain PS42-9 T , which formed short chains of spores borne on the tip of long sporophores arising from the substrate mycelium, was isolated from soil in Phu-Sang National Park, Phayao province, Thailand. The isolate contained meso-diaminopimelic acid in the cell-wall peptidoglycan. The whole-cell sugars of strain PS42-9 T were glucose, madurose, mannose, rhamnose and ribose. The characteristic phospholipids were phosphatidylethanolamine, phosphatidylmethylethanolamine, hydroxyphosphatidylethanolamine and ninhydrin-positive glycophospholipids. The major menaquinone was MK-10(H4). The main cellular fatty acids were C17 : 1ω8c and C17 : 0. The G+C content of the genomic DNA was 71.5 mol%. Phylogenetic analysis using 16S rRNA gene sequences revealed that strain PS42-9 T should be classified in the genus Herbidospora and was closely related to Herbidospora sakaeratensis DMKUA 205 T (99.10 %) and Herbidospora yilanensis NBRC 106371 T (98.61 %). The result of DNA-DNA hybridization and some physiological and biochemical properties indicated that strain PS42-9 T could be readily distinguished from its closest phylogenetic relatives. On the basis of these phenotypic and genotypic data, this strain represents a novel species, for which the name Herbidospora soli sp. nov. is proposed. The type strain is PS42-9 T (=BCC 46909 T =NBRC 108780 T ).