Bioprospecting Of Actinomycetes As Pharmaceutical Resource Collected In Jiuliancheng Nur And Polyphasic Taxonomy On Novel Actinomycetes From Special Habitats

Antibiotic effectiveness is diminished by antibiotic use. Keeping it available requires both conservation and innovation. Conservation encompasses making the best use of current antibiotic effectiveness by reducing demand through effective measures. Innovation includes improving the efficacy of current drugs and replenishing effectiveness by developing new drugs. In sharp contrast to the widespread of bacterial drug resistance, the development of new antibiotics is relatively slow. Microorganisms are the important source of antibiotics, and actinomycetes are the main antibiotics production organisms. In addition to innovation of screening approach, Pharmaceutical microbial resources is one of the bottleneck issues restricting the development of new antibiotics. Bioprospecting of actinomycetes as pharmaceutical resource from special habitats is becomeing one current research focus.Based on the above research background, a salt lake, Jiuliancheng Nur, is subjected to exploiting of pharmaceutical actinomycetes and 3 novel actinomycetes isolated from special habitats were subjected to polyphsic taxonomic study, the mainly research work are as follows.1. Culturable actinomycetes was isolated from soil samples collected in the dried Jiuliancheng Nur. Representative actinomycete isolates were subjected to flask fermentation and crude extraction of metabolites were obtained. Antibacterial and antifungal assay were performed for the crude extraction of metabolites. Meanwhile, representative actinomycete isolates were further screened for PKS Ⅰ, PKS Ⅱ and NRPS antibiotics biosynthetic genes. A total of 251 actinobacterial strains, isolated from 11 soil samples, belonged to 31 genera affiliated with 15 families in 10 orders, and Streptomyces and Nocardiopsis were dominant genera. Out of 96 representative fermented strains,56 exhibited positive activity in antibacterial or antifungal assay, and the level of total positive rate was relatively high. Several actinomycete isolates showing antibacterial activities to gram-negative organisms with drug resistance were obtained. Out of 96 isolates,84 isolates carried at least one antibiotic biosynthetic gene, the level of positive rate was high.2. Strain J11Y309T isolated from Jiuliancheng Nur shared the highest 16S rRNA gene sequence similarities with Salininema proteolyticum Miq-4T (95.80%), Paraglycomyces xinjiangensis TRM 49201T (95.77%) and Haloglycomyces albus YIM 92370T (94.84%). Phylogenetic analysis based on the 16S rRNA gene sequences revealed that P. xinjiangensis TRM 49201T is highly related to S. proteolyticum Miq-4T, sharing 99.5% 16S rRNA gene sequence similarity. Phylogenetic trees showed that it could not be clearly assigned to any known genus within the family Glycomycetaceae and formed a distinct phylogenetic line in the clade with the members of the genera Salininema, Paraglycomyces, and Haloglycomyces. Combined the polyphasic taxonomic data, strain J11Y309T represents a novel species of a new genus in the family Glycomycetaceae, for which the name Salilacibacter albus gen. nov., sp. nov. is proposed. Meanwhile, P. xinjiangensis Luo et al.2015 was reclassified as a later heterotypic synonym of S. roteolyticum Nikou et al. 2015 with emended descriptions of the genus Salininema and Salininema proteolyticum.3. Strain J12GA03T isolated from Jiuliancheng Nur shared the highest 16S rRNA gene sequence similarities with Amycolicicoccus subflavus DQS3-9A1T (98.18%) and Hoyosella altamirensis OFN S31T (97.75%). Amycolicicoccus subflavus DQS3-9A1T was highly related to Hoyosella altamirensis OFN S31T, sharing 99.77% 16S rRNA gene sequence similarity. Phylogenetic trees showed that strain J12GA03T firmly formed a distinct monophyletic branch in the subclade with A. subflavus DQS3-9A1T and H. altamirensis OFN S31T, and the subclade was most nearest to the cluster of Mycobacterium species. Combined the polyphasic taxonomic data, strain J12GA03T represents a novel species of the genus of Hoyosella, for which the name Hoyosella rhizosphera sp. nov. is proposed, and Amycolicicoccus subflavus Wang et al.2010 was reclassified as a later heterotypic synonym of Hoyosella altamirensis Jurado et al.2009 with emended descriptions of the genus Hoyosella. Meanwhile, the genus Hoyosella is proposed as a member of the family Mycobacteriaceae.4. Strain S6R2A4-9T was isolated from a karst cave, Shenxian Cave. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain S6R2A4-9T resided in the cluster of genus Tenggerimyces within the family Nocardioidaceae and shared the highest 16S rRNA gene sequence similarity (98.98%) with Tenggerimyces mesophilus I12A-02601T. Level of DNA-DNA relatedness between strain S6R2A4-9T and T. mesophilus I12A-02601T was 27.6±3.0%. Combined the polyphasic taxonomic evidences, strain S6R2A4-9T represents a novel species of the genus of Tenggerimyces, for which the name Tenggerimyces flavus sp. nov. is proposed.