Termite-engineered microbial communities of termite nest structures: a new dimension to the extended phenotype

Termites are a prototypical example of the 'extended phenotype' given their ability to shape their environments by constructing complex nesting structures and cultivating fungus gardens. Such engineered structures provide termites with stable, protected habitats, and nutritious food sources, respectively. Recent studies have suggested that these termite-engineered structures harbour Actinobacteria-dominated microbial communities. In this review, we describe the composition, activities, and consequences of microbial communities associated with termite mounds, other nests, and fungus gardens. Culture-dependent and culture-independent studies indicate that these structures each harbour specialized microbial communities distinct from those in termite guts and surrounding soils. Termites select microbial communities in these structures through various means: opportunistic recruitment from surrounding soils; controlling physicochemical properties of nesting structures; excreting hydrogen, methane, and other gases as bacterial energy sources; and pretreating lignocellulose to facilitate fungal cultivation in gardens. These engineered communities potentially benefit termites by producing antimicrobial compounds, facilitating lignocellulose digestion, and enhancing energetic efficiency of the termite 'metaorganism'. Moreover, mound-associated communities have been shown to be globally significant in controlling emissions of methane and enhancing agricultural fertility. Altogether, these considerations suggest that the microbiomes selected by some animals extend much beyond their bodies, providing a new dimension to the 'extended phenotype'.

Pseudonocardia terrae sp. nov., an actinobacterium isolated from rice rhizosphere soil in Thailand

A novel actinomycete, designated strain RS11V-5T, was isolated from rhizosphere soil of Oryza sativa L. collected from Roi Et Province, Thailand, and its taxonomic position was evaluated. Cells of strain RS11V-5T were Gram-stain-positive, aerobic, and non-motile. Whole-cell hydrolysates contained meso-diaminopimelic acid, arabinose, galactose, glucose and ribose. MK-8(H4) was detected as the predominant menaquinone of this strain. The polar lipids were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, hydroxy-phosphatidylmethylethanolamine, hydroxy-phosphatidylethanolamine, an unidentified phospholipid, an unidentified aminolipid and an unidentified glycolipid. The major fatty acids were iso-C16 : 0, C16 : 0 and C16 : 1 ω7c/C16 : 1 ω6c. Phylogenetic analyses based on the 16S rRNA gene sequences showed that strain RS11V-5T belonged to the genus Pseudonocardia and had high 16S rRNA sequence similarity of 99.3 % to Pseudonocardia kujensis KCTC 29062T and less than 98.4 % to other members of the genus Pseudonocardia . The DNA G+C content of the strain RS11V-5T was 73.3 mol%. Strain RS11V-5T showed 46.5 % digital DNA–DNA hybridization, 92.2 % orthologous average nucleotide identity (OrthoANI), 90.2 % ANI based on blast and 92.7 % ANI based on MUMmer to P. kujensis KCTC 29062T. Based its phenotypic, genotypic, phylogenetic and chemotaxonomic characteristics, strain RS11V-5T represents a novel species of the genus Pseudonocardia , for which the name Pseudonocardia terrae sp. nov. is proposed. The type strain is RS11V-5T (=TBRC 15286T=NBRC 115296T).

Genus Pseudonocardia: What we know about its biological properties, abilities and current application in biotechnology

The genus Pseudonocardia belongs to a group of Actinomycetes, and is a member of the family Pseudonocardiacea. The members of this genus are aerobic, Gram-positive, non-motile bacteria that are commonly found in soil, plant and environment. Although this genus has a low clinical significance; however, it has an important role in biotechnology due to the production of secondary metabolites, some of which have anti-bacterial, anti-fungal and anti-tumour effects. The use of phenotypic tests, such as gelatinase activity, starch hydrolysis, catalase and oxidase tests, as well as molecular methods, such as polymerase chain reaction, are necessary for Pseudonocardia identification at the genus and species levels.

Pseudonocardia broussonetiae sp. nov., an endophytic actinomycete isolated from the roots of Broussonetia papyrifera

A novel endophytic actinomycete, designated strain Gen 01^T, was isolated from the roots of Broussonetia papyrifera and characterized by using a polyphasic approach. The predominant cellular fatty acids were iso-C_16 : 0, summed feature 3, iso H-C_16 : 1, C_16 : 0 and iso-C_14 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol mannosides, phospholipids of unknown structure containing glucosamine inositol, phosphatidylinositol and unidentified phospholipids. The major menaquinone was MK-8 (H₄). The DNA G+C content of the genome sequence, consisting of 7 177 725 bp, was 74.5 mol%. Phylogenetic analysis of the full-length 16S rRNA gene sequences showed that strain Gen 01^T belongs to the genus Pseudonocardia with the highest sequence similarity to Pseudonocardia petroleophila CGMCC 4.1532^T (98.9 %) and lower than 98.7 % similarity to other species of the genus Pseudonocardia with validly published names. The average nucleotide identity and digital DNA-DNAhybridization values between strain Gen 01^T and P. petroleophila CGMCC 4.1532^T were 84.6 and 30.9 %, respectively. Furthermore, the morphological, physiological and biochemical characteristics were sufficient to categorize strain Gen 01^T as being distinct from P. petroleophila CGMCC 4.1532^T. Consequently, based on phenotypic and genotypic characteristics, strain Gen 01^T represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia broussonetiae sp. nov. is proposed. The type strain is Gen 01^T (=CICC 24820^T=JCM 33840^T).

Pseudonocardia tritici sp. nov., a novel actinomycete isolated from rhizosphere soil of wheat (Triticum aestivum L.)

An aerobic, non-motile, Gram-stain positive actinomycete, designated strain NEAU-YY211^T, was isolated from the rhizosphere soil of wheat (Triticum aestivum L.) collected from Zhumadian, Henan Province, mid-eastern China, and characterised taxonomically using a polyphasic approach. Comparative analysis of the 16S rRNA gene sequence indicated that strain NEAU-YY211^T belongs to the genus Pseudonocardia, showing high similarities with respect to Pseudonocardia ammonioxydans H9^T (99.1%) and Pseudonocardia antitumoralis SCSIO 01299^T (99.0%), respectively. The cell wall was found to contain meso-diaminopimelic acid and the whole cell sugars were identified as arabinose and galactose. The predominant menaquinone of strain NEAU-YY211^T was identified as MK-8(H₄) and the major fatty acids were identified as iso-C_16:0, C_17:1ω8c and iso-C_16:1. The phospholipid profile was found to consist of diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol and an unidentified phospholipid. The G+C content of the genomic DNA was determined to be 72.6 mol%. Levels of DNA-DNA relatedness with P. ammonioxydans JCM 12462^T and P. antitumoralis DSM 45322^T were 54.5 ± 3.5% and 49.8 ± 2.5% (mean ± SD), respectively. Based on phylogenetic analysis, phenotypic and genotypic data, it is concluded that the isolate can be distinguished from closely related type strains and thus represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia tritici sp. nov. is proposed. The type strain is NEAU-YY211^T (= DSM 106068^T = CGMCC 4.7474^T).

Pseudonocardia mangrovi sp. nov., isolated from soil

A novel Gram-stain-positive, aerobic actinomycete, designated strain SMC 195^T, was isolated from soil collected from a mangrove forest in Thailand. The strain produced extensively branched substrate and aerial mycelia. The substrate mycelium was fragmented into rod-shaped elements, and spore chains consisting of smooth and rod-shaped spores were formed on the aerial mycelium. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that SMC 195^T represented a member of the genus Pseudonocardia, and the most closely phylogenetically related species were Pseudonocardia yuanmonensisJCM 18055^T (99.2 % 16S rRNA gene sequence similarity), Pseudonocardia halophobicaNRRL B-16514^T (98.9 %) and Pseudonocardia kujensisNRRL B-24890^T (98.7 %). However, the DNA-DNA relatedness values between SMC 195^Tand the closest phylogenetically related species were significantly below 70 %. The G+C content of the genomic DNA was 74±0.8 mol%. The cell wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars consisted of arabinose, galactose, glucose, rhamnose and ribose. The menaquinone was MK-8(H4) only. The major cellular fatty acid was the branched fatty acid iso-C16 : 0 (33.6 %). The polar lipids detected were phosphatidylethanolamine, phosphatidylmethylethanolamine, hydroxyphosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol and unidentified glycolipids. On the basis of the results from phenotypic, chemotaxonomic and genotypic studies, it is concluded that SMC 195^T represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia mangrovi sp. nov. is proposed. The type strain is SMC 195^T (=TBRC 7778^T=NBRC 113150^T).