Li-Li Zhang

The Diversity and Anti-Microbial Activity of Endophytic Actinomycetes Isolated from Medicinal Plants in Panxi Plateau, China

Traditional Chinese medicinal plants are sources of biologically active compounds, providing raw material for pharmaceutical, cosmetic and fragrance industries. The endophytes of medicinal plants participate in biochemical pathways and produce analogous or novel bioactive compounds. Panxi plateau in South-west Sichuan in China with its unique geographical and climatological characteristics is a habitat of a great variety of medicinal plants. In this study, 560 endophytic actinomycetes were isolated from 26 medicinal plant species in Panxi plateau. 60 isolates were selected for 16S rDNA-RFLP analysis and 14 representative strains were chosen for 16S rDNA sequencing. According to the phylogenetic analysis, seven isolates were Streptomyces sp., while the remainder belonged to genera Micromonospora, Oerskovia, Nonomuraea, Promicromonospora and Rhodococcus. Antimicrobial activity analysis combined with the results of amplifying genes coding for polyketide synthetase (PKS-I, PKS-II) and nonribosomal peptide synthetase (NRPS) showed that endophytic actinomycetes isolated from medicinal plants in Panxi plateau had broad-spectrum antimicrobial activity and potential natural product diversity, which further proved that endophytic actinomycetes are valuable reservoirs of novel bioactive compounds.

Halomonas xinjiangensis sp. nov., a halotolerant bacterium isolated from a salt lake

A novel bacterium, TRM 0175(T), belonging to the genus Halomonas, was isolated from a soil sample taken from a salt lake in Xinjiang Province, north-west China. The isolate was Gram-negative, aerobic, rod-shaped and motile by means of peritrichous flagella. It was catalase-positive and oxidase-negative. Growth occurred at NaCl concentrations of 0-20 % (optimum at 10-13 %), at 15-50 degrees C (optimum at 37 degrees C) and at pH 6.0-9.0 (optimum at pH 7.0). Metabolism was respiratory with oxygen as terminal electron acceptor. Acid was produced from D-ribose, D- and L-arabinose, D-xylose, D-galactose, D-mannose, L-rhamnose, cellobiose, maltose, trehalose and D- and L-fucose and was produced weakly from aesculin. The predominant ubiquinone was Q-9. The major fatty acids were C(18 : 1)omega7c and C(19 : 0) cyclo omega8c. The G+C content of the genomic DNA was 60.0 mol%. The affiliation of strain TRM 0175(T) with the genus Halomonas was confirmed by 16S rRNA gene sequence comparisons. The most closely related species was Halomonas anticariensis; 16S rRNA gene sequence similarity between H. anticariensis FP35(T) and strain TRM 0175(T) was 95.3 %. Phenotypically, some characteristics of TRM 0175(T) differed from those of H. anticariensis. On the basis of data from this polyphasic study, strain TRM 0175(T) represents a novel species of the genus Halomonas, for which the name Halomonas xinjiangensis sp. nov. is proposed; the type strain is TRM 0175(T) (=CCTCC AB 208329(T) =KCTC 22608(T)).

The rhizospheres of traditional medicinal plants in Panxi, China, host a diverse selection of actinobacteria with antimicrobial properties.

Actinobacteria are a prolific source of antibiotics. Since the rate of discovery of novel antibiotics is decreasing, actinobacteria from unique environments need to be explored. In particular, actinobacterial biocontrol strains from medicinal plants need to be studied as they can be a source of potent antibiotics. We combined culture-dependent and culture-independent methods in analyzing the actinobacterial diversity in the rhizosphere of seven traditional medicinal plant species from Panxi, China, and assessed the antimicrobial activity of the isolates. Each of the plant species hosted a unique set of actinobacterial strains. Out of the 64 morphologically distinct isolates, half were Streptomyces sp., eight were Micromonospora sp., and the rest were members of 18 actinobacterial genera. In particular, Ainsliaea henryi Diels. hosted a diverse selection of actinobacteria, although the 16S ribosomal RNA (rRNA) sequence identity ranges of the isolates and of the 16S rRNA gene clone library were not congruent. In the clone library, 40% of the sequences were related to uncultured actinobacteria, emphasizing the need to develop isolation methods to assess the full potential of the actinobacteria. All Streptomyces isolates showed antimicrobial activity. While the antimicrobial activities of the rare actinobacteria were limited, the growth of Escherichia coli, Verticillium dahliae, and Fusarium oxysporum were inhibited only by rare actinobacteria, and strains related to Saccharopolyspora shandongensis and Streptosporangium roseum showed broad antimicrobial activity.

Diversity of Actinobacterial community in saline sediments from Yunnan and Xinjiang, China

The diversity and community structures of actinobacteria in saline sediments collected from Yunnan and Xinjiang Provinces, China, were investigated with cultivation and 16S rRNA gene analysis. A total of 163 actinobacterial isolates were obtained, and they were affiliated with the order Actinomycetales (distributed into five suborders: Streptosporangineae, Micrococcineae, Streptomycineae, Pseudonocardineae, and Glycomycineae). A total of 748 actinobacterial 16S rRNA gene clones were examined, and they could be classified into Actinomycetales, Acidimicrobiales, and unclassified actinobacteria. The Actinomycetales sequences were distributed into nine suborders: Streptosporangineae, Glycomycineae, Micromonosporineae, Pseudonocardineae, Corynebacterineae, Frankineae, Propionibacterineae, Streptomycineae, and Micrococcineae. The unclassified actinobacteria contained three new clusters at the level of subclass or order. Our 16S rRNA gene phylogenetic data indicated that actinobacterial communities were very diverse in the investigated saline sediments (salinity 0.4–11.6%) and some actinobacterial members may be halotolerant or halophilic. The actinobacterial community structures in the saline sediments were different from those in marine and freshwater environments. Our data have implications for a better understanding of the distribution of Actinobacteria in saline environments.

Haloglycomyces albus gen. nov., sp. nov., a halophilic, filamentous actinomycete of the family Glycomycetaceae

A novel halophilic actinobacterium, designated YIM 92370(T), was isolated from a hypersaline habitat in Xinjiang Province, north-west China. The strain was aerobic, Gram-positive-staining and halophilic, with an optimum NaCl concentration for growth of 8-12 % (w/v). The whole-cell sugar pattern consisted of ribose, xylose and glucose. The predominant menaquinone was MK-9(H(4)) and the major fatty acids were iso-C(16 : 0), iso-C(17 : 0) and anteiso-C(17 : 0). The phospholipid pattern consisted of phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides, two unknown phosphoglycolipids and one unknown phospholipid. The G+C content of the genomic DNA was 60.8 mol%. Phylogenetic analysis showed that strain YIM 92370(T) can be distinguished from representatives of Glycomyces and Stackebrandtia, the two existing genera in the family Glycomycetaceae, by low 16S rRNA gene sequence similarities (<93.7 %). Strain YIM 92370(T) therefore represents a novel genus and species of the family Glycomycetaceae, for which the name Haloglycomyces albus gen. nov., sp. nov. is proposed. The type strain of Haloglycomyces albus is YIM 92370(T) (=DSM 45210(T) =KCTC 19481(T)).

Saccharopolyspora lacisalsi sp nov., a novel halophilic actinomycete isolated from a salt lake in Xinjiang, China

A novel actinomycete strain, designated TRM 40133T, was isolated from a hypersaline habitat of Tarim basin in Xinjiang Province, north-west China. Its taxonomic status was determined using a polyphasic approach. Phylogenetic analysis based on an almost-complete 16S rRNA gene sequence of the strain showed that it formed a well-seperated sub-branch within the radiation of the genus Saccharopolyspora. The highest levels of 16S rRNA gene sequence similarity was found between the strain TRM 40133T and Saccharopolyspora qijiaojingensis YIM 91168T (96.5%). The chemotaxonomic characteristics of the isolate are typical for the genus Saccharopolyspora. It contained meso-DAP as the diagnostic diamino acid. Whole cell hydrolysate contained arabinose, xylose, ribose and glucose. The diagnostic phospholipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol and two unknown phospholipids. The main menaquinone was MK-9(H6) and MK-9(H4). No mycolic acid was detected. The predominant cellular fatty acids were iso-C16:0 and anteiso-C17:0. The G+C content of the genomic DNA was 68.2xa0mol%. In addition, the strain TRM 40133T had a phenotypic profile that readily distinguished it from the recognized representatives of the genus Saccharopolyspora. The strain TRM 40133T therefore represents a novel species of the genus Saccharopolyspora, for which the name Saccharopolyspora lacisalsi sp. nov. is proposed. The type strain is TRM 40133T (=KCTC 19987Txa0=CCTCC AA 2010012T).

Actinopolyspora xinjiangensis sp. nov., a novel exteremely halophilic actinomycete isolated from a salt lake in Xinjiang, China

A novel halophilic, filamentous actinobacterium, designated TRM 40136T, was isolated from a hypersaline habitat in Xinjiang Province, north-west China. The strain is aerobic, Gram-positive, halophilic, and the optimum NaCl concentration for growth is 10–15% (w/v). The whole-cell sugar pattern consists of xylose, glucose and arabinose. The predominant menaquinone is MK-6 (51.2%) and the major fatty acids are anteiso-C15:0 (35.2%), anteiso-C17:0 (15.9%) and iso-C15:0 (13.7%). The phospholipid pattern consists of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and two unknown phospholipids. The Gxa0+xa0C content of the genomic DNA is 68.9xa0mol%. Phylogenetic analysis showed that strain TRM 40136T had 16S rRNA gene sequence similarity of 96.1% with the closest described species Actinopolyspora mortivallis, and it can be distinguished from all species in the genus Actinopolyspora by using these data of polyphasic taxonomy study. On the basis of the polyphasic evidence, the strain TRM 40136T should be designated as a novel species of the genus Actinopolyspora for which the name Actinopolyspora xinjiangensis sp.nov. is proposed. The type strain is TRM 40136T (=CCTCC AA 209080Txa0=xa0KCTC 19656T).

Glycomyces halotolerans sp. nov., a novel actinomycete isolated from a hypersaline habitat in Xinjiang, China

A novel actinomycete strain, designated TRM 40137T, was isolated from a hypersaline habitat in Xinjiang Province, north-west China, and subjected to a polyphasic taxonomic study. The strain was aerobic, Gram-positive and the optimum NaCl concentration for growth was 4–5%xa0(w/v). Phylogenetic analysis showed that strain TRM 40137T has a 16S rRNA gene sequence similarity of 95.02% with the described species Glycomycessambucus E71T and can be distinguished from all previously described representatives of the genus Glycomyces. The whole-cell sugar pattern consisted of xylose and galactose. The predominant menaquinone was MK-10(H2) and the major fatty acids were anteiso-C15:0 and anteiso-C17:0. The phospholipid pattern consists of phosphatidylglycerol, diphosphatidylglycerol, three unknown aminophospholipids and two unknown phospholipids. The G+C content of the genomic DNA was 68.8xa0mol%. A novel species Glycomyces halotolerans sp. nov. is proposed, with strain TRM 40137T (=CCTCC AA 2010013Txa0=xa0KCTC 19988T) as the type strain of G. halotolerans.

Glycomyces fuscus sp. nov. and Glycomyces albus sp. nov., actinomycetes isolated from a hypersaline habitat.

Two actinomycete strains, designated TRM 49117(T) and TRM 49136(T), were isolated from a hypersaline habitat in Xinjiang Province, north-west China and were characterized taxonomically by using a polyphasic study. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain TRM 49117(T) had 93.93% similarity with the type strain Glycomyces halotolerans TRM 40137(T) (GenBank accession no. HQ651156) and TRM 49136(T) had 94.32% similarity with G. halotolerans TRM 40137(T). The 16S rRNA gene sequence similarity between the two new isolates was 93%. The isolates contained meso-diaminopimelic acid as the diagnostic diamino acid and anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0 as major cellular fatty acids. The predominant menaquinones of the isolates were MK-9(H4) and MK-9(H6). The whole-cell sugar patterns of these strains contained xylose and ribose, and strain TRM 49136(T) also contained arabinose. The polar lipid pattern of strain TRM 49117(T) comprised phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol mannosides, phosphatidylcholine, phosphatidylinositol and three additional unknown phospholipids. The polar lipid pattern of strain TRM 49136(T) comprised phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, glycolipids and two phosphoglycolipids of unknown composition. Genotypic and phenotypic data confirmed that strains TRM 49117(T) and TRM 49136(T) represent two novel species, clearly different from related species of the genus Glycomyces, for which the names Glycomyces fuscus sp. nov. (type strain TRM 49117(T)u200a= CCTCC AA 2013003(T)u200a= NRRL B-59998(T)u200a= KACC 17682(T)) and Glycomyces albus sp. nov. (type strain TRM 49136(T)u200a= CCTCC AA 2013004(T)u200a= NRRL B-24927(T)u200a= KACC 17681(T)) are proposed.

Actinopolyspora lacussalsi sp. nov., an extremely halophilic actinomycete isolated from a salt lake.

A novel halophilic, filamentous actinobacterium, designated strain TRM 40139(T), was isolated from a hypersaline habitat in Xinjiang Province, north-west China. Its taxonomic status was determined using a polyphasic approach. Phylogenetic analysis based on the almost-complete 16S rRNA gene sequence of the strain showed that it formed a well-separated sub-branch within the radiation of the genus Actinopolyspora and the organism was related most closely to the type strains of Actinopolyspora alba (97.6 % similarity), Actinopolyspora xinjiangensis (97.6 %) and Actinopolyspora erythraea (97.1 %). However, it had relatively lower mean DNA-DNA relatedness values with the above strains (36.4, 31.3 and 26.1 %, respectively). Optimal growth occurred at 35 °C, at pH 7.0 and in the presence of 12 % (w/v) NaCl. The whole-cell sugar pattern consisted of xylose, glucose, ribose and arabinose. The major fatty acids were iso-C16 : 0 (28.0 %) and anteiso-C17 : 0 (27.6 %). The diagnostic phospholipids detected were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol and two unknown phospholipids. The predominant menaquinones were MK-9(H4) (49.8 %) and MK-10(H4) (24.2 %). The G+C content of the genomic DNA was 66.4 mol%. Strain TRM 40139(T) therefore represents a novel species of the genus Actinopolyspora, for which the name Actinopolyspora lacussalsi sp. nov. is proposed. The type strain is TRM 40139(T) (= KCTC 19657(T) = CCTCC AA 2012020(T)).