Culturable Endophytes Diversity Isolated from Paeonia ostii and the Genetic Basis for Their Bioactivity.

Paeonia ostii is known for its excellent medicinal values as Chinese traditional plant. To date, the diversity of culturable endophytes associated with P. ostii is in its initial phase of exploration. In this study, 56 endophytic bacteria and 51 endophytic fungi were isolated from P. ostii roots in China. Subsequent characterization of 56 bacterial strains by 16S rDNA gene sequence analysis revealed that nine families and 13 different genera were represented. All the fungal strains were classed into six families and 12 genera based on ITS gene sequence. The biosynthetic potential of all the endophytes was further investigated by the detection of putative polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) genes. The PCR screens were successful in targeting thirteen bacterial PKS, five bacterial NRPS, ten fungal PKS and nine fungal NRPS gene fragments. Bioinformatic analysis of these detected endophyte gene fragments facilitated inference of the potential bioactivity of endophyte bioactive products, suggesting that the isolated endophytes are capable of producing a plethora of secondary metabolites. These results suggest that endophytes isolated from P. ostii had abundant population diversity and biosynthetic potential, which further proved that endophytes are valuable reservoirs of novel bioactive compounds.Paeonia ostii is known for its excellent medicinal values as Chinese traditional plant. To date, the diversity of culturable endophytes associated with P. ostii is in its initial phase of exploration. In this study, 56 endophytic bacteria and 51 endophytic fungi were isolated from P. ostii roots in China. Subsequent characterization of 56 bacterial strains by 16S rDNA gene sequence analysis revealed that nine families and 13 different genera were represented. All the fungal strains were classed into six families and 12 genera based on ITS gene sequence. The biosynthetic potential of all the endophytes was further investigated by the detection of putative polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) genes. The PCR screens were successful in targeting thirteen bacterial PKS, five bacterial NRPS, ten fungal PKS and nine fungal NRPS gene fragments. Bioinformatic analysis of these detected endophyte gene fragments facilitated inference of the potential bioactivity of endophyte bioactive products, suggesting that the isolated endophytes are capable of producing a plethora of secondary metabolites. These results suggest that endophytes isolated from P. ostii had abundant population diversity and biosynthetic potential, which further proved that endophytes are valuable reservoirs of novel bioactive compounds.

[Screening and phosphate-solubilizing characteristics of phosphate-solubilizing actinomycetes in rhizosphere of tree peony.] / ç‰¡ä¸¹æ ¹é™ æº¶ç£·æ”¾çº¿èŒçš„ç­›é€‰åŠå ¶æº¶ç£·ç‰¹æ€§.

A strain PSPSA1 with strong phosphate-solubilizing ability was isolated from the rhi-zosphere of tree peony. This strain was identified based on morphological characteristics, physiological and biochemical experiments, and 16S rDNA sequence analysis. Furthermore, its genetic stabi-lity and phosphate-solubilizing characteristics were investigated. Strain PSPSA1 was identified as the actinomycete Streptomyces albireticuli and showed high genetic stability. The order of phosphate solubilization capacity (PSC) in different phosphorus-source culture media was calcium phosphate (158.5 mg·L-1) > aluminum phosphate (139.9 mg·L-1) > ferric phosphate (127.7 mg·L-1) > lecithin (45.6 mg·L-1). The PSC and pH were significantly negatively correlated in inorganic phosphorus solution, but were not correlated in organic phosphorus solution. When using different carbon sources, PSC was in the order of lactose > glucose > maltose > fructose > sucrose > starch > cellulose. For different nitrogen sources, PSC was in the order of peptone > ammonium nitrate > ammonium sulfate > potassium nitrate > urea. Using glucose as a carbon source and peptone as a nitrogen source, strain PSPSA1 achieved the highest PSC of 202.6 mg·L-1. After incubated for 60 days, the available phosphorus content in soil with a single application of strain PSPSA1 increased by 68.2% compared with control, and the available phosphorus content in soil with mixed application of strain PSPSA1 and organic fertilizer increased by 76.7% compared with a single application of organic fertilizer. The results indicated that the strain PSPSA1 had a strong ability to dissolve insoluble phosphorus and its mixed application with organic fertilizer improved the phosphorus solubilization. Thus, PSPSA1 is a promising microbial resource for the production of high-efficiency biological phosphorus fertilizer.

[16S rDNA RFLP analysis of endophytic bacteria from Brassica napus].

Endophytic bacteria reside in plant hosts without causing disease symptom. In this study, 122 endophytic bacteria strains isolated from healthy oilseed rape plant were categorized preliminarily to 35 groups based on colony morphology; 16S rDNAs were amplified with universal primers of bacteria, all the strains could produce a single band about 1500bp, the PCR products were digested with restriction endoenzyme Hae III and Msp I respectively, different patterns were obtained for each enzyme, by combining all the restriction patterns for the two enzymes, the 122 strains could be grouped into 39 16S rDNA genotypes. The results indicated that endophytic bacteria from Brassica napus were genetically diversity. By comparing two methods, colony morphology only showed limited and preliminary information, and PCR-RFLP could be as a rapid and accurate tool for the diversity analysis of endophytic bacteria from Brassica napus.