Numerical classification of thermophilic streptomycetes showed three major, five minor and two single-member clusters [10]. Analysis of the 16S rRNA genes and morphological and chemical properties indicate their classification within the genus Streptomyces [11, 12]. Most thermophilic Streptomyces species have growth temperature ranges from 28 to 55°C and

so are only moderately thermophilic [11, 12]. However, some thermophilic Streptomyces species can grow up to 68°C [13]; the optimum growth temperature of S. thermoautotrophicus is 65°C and no growth is observed below 40°C, so it is a truly thermophilic strain [14]. Growth of thermophilic Streptomyces strains is rapid at high temperature BAY 1895344 order [15]; for example, S. thermoviolaceus has a doubling time of 1 h at 50°C [16]. Thermophilic Streptomyces species buy Erastin produce thermostable enzymes and antibiotics [15], such as xylanase [17], alpha-amylase [18], granaticin [16] and anthramycin [19]. Since thermophilic Streptomyces strains lack a genetic manipulation system, mesophilic strains (e.g. S. lividans) have been employed for expression of some genes or antibiotic

biosynthetic gene clusters from thermophilic Streptomyces species [[20–22]]. We MLN0128 order report here the development of a gene cloning system in a fast-growing (about twice the rate of S. coelicolor) and moderately thermophilic (growing at both 30°C and 50°C) Streptomyces strain, and successful heterologous expression of antibiotic biosynthetic gene clusters from both thermophilic and mesophilic Streptomyces species. Results and Discussion Isolation and identification of thermophilic Progesterone Streptomyces strains from various soil samples To isolate thermophilic Streptomyces

strains, various soil samples from China were collected (see Methods). As summarized in Table 1, 22, 11 and eight strains were isolated from samples of garden soil, weed compost and swine manure, respectively. Thermophilic Streptomyces species have been isolated from composts, soil and sewage [23], as well as lakes and hot-springs [13]. Our results reinforce the idea of a widespread occurrence of these organisms. Table 1 Strains used in this study Strains Genotype or description Source or reference Streptomyces         S. coelicolor M145 SCP1- SCP2- [6]     S. lividans 1326 SLP2 SLP3 [6]     S. lividans ZX7 pro-2 str-6 rec-46 dnd SLP2- SLP3- [37]     S.