The genus Nonomuraea is a rare actinomycete taxon with a long taxonomic history, while its generic description was recently emended. The genus is less known among the rare actinomycete genera as its taxonomic position was revised several times. It can be found in diverse ecological niches, while most of its member species were isolated from soil samples. However, new trends to discover the genus in other habitats are increasing. Generic abundance of the genus was found to be dependent on geographical changes. Novel sources together with selective and invented isolation techniques might increase a chance to explore the genus and its novel candidates. Interestingly, some of its members have been revealed as a valuable source of novel metabolites for medical and industrial purposes. Broad-range of potent bioactive compounds including antimicrobial, anticancer, and antipsychotic substances, broad-spectrum antibiotics and biocatalysts can be synthesized by the genus. In order to investigate biosynthetic pathways of the bioactive compounds and self-resistant mechanisms to these compounds, the links from genes to metabolites have yet been needed for further discovery and biotechnological development of the genus Nonomuraea.

A novel actinomycete, designated strain PT708T, was isolated from cave soil collected in Pha Tup Cave Forest Park, Nan province, Thailand. It produced compounds with antimicrobial and anticancer activities. Its chemotaxonomic properties were consistent with those of members of the genus Nonomuraea . The major menaquinone was MK-9(H4), with minor amounts of MK-9(H6), MK-9(H2), MK-10(H2) and MK-8(H4). The polar lipid profile contained phosphatidylmonomethylethanolamine, diphosphatidylglycerol, hydroxy-phosphatidylmonomethylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol mannoside and phosphatidylinositol. The major fatty acids were iso-C16 : 0, 10-methyl C17 : 0, C16 : 0 and C17 : 1ω6c. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain PT708T belonged to the genus Nonomuraea and was most closely related to Nonomuraea rhizophila YIM 67092T (98.50 % sequence similarity) and Nonomuraea rosea GW 12687T (98.30 %). The genomic DNA G+C content of strain PT708T was 73.3 mol%. Unlike the recognized members of the genus Nonomuraea , the novel strain formed single spores at the tips of aerial hyphae. Based on the phenotypic, phylogenetic and genotypic evidence, strain PT708T represents a novel species of the genus Nonomuraea , for which the name Nonomuraea monospora sp. nov. is proposed. The type strain is PT708T ( = TISTR 1910T = JCM 16114T).

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White root disease causing by Rigidoporus sp. is a severe problem that decreases latex productivity and can even cause mortality of rubber trees. With the aim to control biologically this disease, antifungal actinobacteria were isolated from rhizospheric soils of some medicinal plants cultivated in Thailand. Among all isolated actinobacteria, an isolate TM32 exhibited distinctive antagonistic activity against the fungus. Cell-free culture broth of the isolate showed median effective dose (ED50) of 2.61 ml l −1 (equal to 1.19 g l −1 of metalaxyl). The isolate was also able to solubilize phosphate and to produce chitinase (enzyme activity = 0.093 ± 0.004 U ml −1), siderophore (average clear zone, 11.75 ± 0.96 mm) and indole-3-acetic acid (54.00 ± 1.00 μg ml −1). Application of biocontrol starters produced by this isolate in nursery stage of rubber trees farming showed greater suppression of the disease than direct use of its biocontrol agents. The biocontrol starters also enhanced growth of the rubber trees by increasing their heights. This might be due to the persistent growth of the isolate by using the organic substrate remaining in soil, which could later antagonize fungal pathogens through colonization at the rhizosphere and immunization of the rubber trees. The isolate revealed phylogenetically related to Streptomyces sioyaensis supported by 99 % similarity of 16S rRNA gene sequences. We concluded that application of the biocontrol starters produced by this Streptomyces isolate would be an alternative approach for sustainable control of soil-borne fungal invasion in long-term rubber tree farming. Keywords separated by '-' Hevea brasiliensis-Soil-borne fungal pathogen-Biocontrol-Actinobacteria-Antifungal activity Foot note information 2 4 Utilization of rhizospheric Streptomyces for biological control of Rigidoporus sp. causing white root disease in rubber tree 7