Actinomadura rubteroloni sp. nov. and Actinomadura macrotermitis sp. nov., isolated from the gut of the fungus growing-termite Macrotermes natalensis

Abstract

The taxonomic positions of two novel aerobic, Gram-positive actinobacteria, designated strains RB29T and RB68T, were determined using a polyphasic approach. Based on 16S rRNA gene sequence analysis, the closest phylogenetic neighbours of RB29T were identified as Actinomadura rayongensis DSM 102126T (99.2 % similarity) and Actinomadura atramentaria DSM 43919T (98.7 %), and for strain RB68T was Actinomadura hibisca DSM 44148T (98.3 %). Digital DNA–DNA hybridization (dDDH) between RB29T and its closest phylogenetic neighbours, A. rayongensis DSM 102126T and A. atramentaria DSM 43919T, resulted in similarity values of 53.2 % (50.6–55.9 %) and 26.4 % (24.1–28.9 %), respectively. Additionally, the average nucleotide identity (ANI) was 93.2 % (94.0 %) for A. rayongensis DSM 102126T and 82.3 % (78.9 %) for A. atramentaria DSM 43919T. dDDH analysis between strain RB68T and A. hibisca DSM 44148T gave a similarity value of 24.5 % (22.2–27.0 %). Both strains, RB29T and RB68T, revealed morphological characteristics and chemotaxonomic features typical for the genus Actinomadura , such as the presence of meso-diaminopimelic acid in the cell wall, galactose and glucose as major sugar components within whole-cell hydrolysates and the absence of mycolic acids. The major phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. Predominant menaquinones were MK-9(H6) and MK-9(H8) for RB29T and MK-9(H4) and MK-9(H6) for RB68T. The main fatty acids were identified as 10-methyloctadecanoic acid (10-methyl C18:0), 14-methylpentadecanoic acid (iso-C16:0), hexadecanoic acid (C16:0) and cis-9-octadecanoic acid (C18 : 1 ω9c). Here, we propose two novel species of the genus Actinomadura : Actinomadura rubteroloni sp. nov. with the type strain RB29T (=CCUG 72668T=NRRL B-65537T) and Actinomadura macrotermitis sp. nov. with the type strain RB68T (=CCUG 72669T=NRRL B-65538T).

Comparative Genomics Reveals Prophylactic and Catabolic Capabilities of Actinobacteria within the Fungus-Farming Termite Symbiosis

“…Our addition of ARTS2 resulted in the identification of an additional 50 essential genes that pass the three-marker threshold, with one of those markers being close proximity to an identified BGC. This remarkable finding speaks for the high potential to identify not only new bacterial diversity ( 64 – 66 ) but also novel natural products. Further work on both gene expression and compound production within termite colonies as well as biochemical studies to characterize the underlying gene clusters and their products is needed to further elaborate the roles of Actinobacteria within the fungus-farming termite system.…”

Polyene-Producing Streptomyces spp. From the Fungus-Growing Termite Macrotermes barneyi Exhibit High Inhibitory Activity Against the Antagonistic Fungus Xylaria

“…Based on 16S rRNA sequence analysis, seven strains were predicted to be potential novel actinomycetes ( Supplementary Table 1 ). Recently, a number of new actinomycetes have been isolated and identified from the worker gut of M. natalensis ( Benndorf et al, 2020a , b ; Schwitalla et al, 2020 ). The intestinal microflora of fungus-growing termite represents a promising resource of novel actinomycetes.…”

Actinomadura violacea sp. nov., a madurastatin A1-producing strain isolated from lichen in Thailand

“…The major menaquinones are MK-9(H 4 ), MK-9(H 6 ) and MK-9(H 8 ) [4,5]. Members of the genus have 71.8-73.7 mol% DNA G+C contents [6,7]. Actinomadura strains are mostly distributed in terrestrial soils [6,8], but many strains are found in other ecosystems such as plant tissues [9,10], marine sources [11,12] and bee hives [13], and known as a source of secondary metabolites.…”