ABSTRACT
<p><b>OBJECTIVE</b>To isolate and characterize endophytic fungi from seven Dendrobium species, and detect their antimicrobial activities.</p><p><b>METHOD</b>Fungal endophytes were isolated by strictly sterile sample preparation and fungal identification methods were based on their ITS ribosomal DNA (ITS rDNA gene) sequences. The agar well diffusion method was then employed to evaluate the antimicrobial activity against six pathogenic organisms and the phylogenetic tree of active isolates was constructed by the MEGA.</p><p><b>RESULT</b>Ninety-eight endophytic fungi obtained from seven Dendrobium spp., and among them twenty-four isolates, representing 11 genera and 14 species, displayed anti-microbial activities. The phylogenetic assay based on ITS-rDNA showed that 24 active isolates were sorted to 7 taxonomic orders: Hypocreales, Sordariales, Capnodiales, Eurotiales, Botryosphaeriales, Xylariales and Mucorales. The results of antimicrobial activity assay revealed that 1.02%, 10.2%, 18.4%, 1.02%, 1.02% and 10.2% of fermentation broths of 98 isolates displayed significant antimicrobial activities against E. coli, B. subtilis, S. aureus, C. albicans, C. neoformans and A. fumigatus, respectively. Four strains DL-R-3, DL-S-6, DG-R-10 and DN-S-1 displayed strong and broad antimicrobial spectrum.</p><p><b>CONCLUSION</b>Endophytic fungi associated with Dendrobium species have fungal diversity, and possess diverse antimicrobial activity.</p>
Subject(s)
Anti-Infective Agents , Metabolism , Pharmacology , Aspergillus fumigatus , Bacillus subtilis , Base Sequence , Biodiversity , Candida albicans , China , Cryptococcus neoformans , DNA, Fungal , Chemistry , DNA, Ribosomal Spacer , Chemistry , Genetics , Dendrobium , Microbiology , Physiology , Endophytes , Classification , Genetics , Physiology , Escherichia coli , Fungi , Classification , Genetics , Physiology , Microbial Sensitivity Tests , Molecular Sequence Data , Phylogeny , Plant Roots , Microbiology , Physiology , Plant Stems , Microbiology , Physiology , Sequence Alignment , Sequence Analysis, DNA , Staphylococcus aureusABSTRACT
Objective To study the correlation of polyphenol oxidase(PPO) activity and baicalin synthesis in callus of Scutellaria baicalensisi.Methods PPO Activity was determined by ultraviolet spectrophotometry and the content of baicalin was detected by HPLC.The effects of various substances(ascorbic acid,sodium chloride,benzoic acid,polyvinylpyrrolidone,and copper sulfate) on PPO activity and the content of baicalin were studied.Results There was no baicalin accumulation in the first 20 d of growth period, while PPO activity was expressed slowly during this period.From 20 d to 35 d,PPO activity increased significantly and the baicalin secondary synthesis was restrained.Conclusion The high-level expression of PPO activity do harm the baicalin secondary synthesis.These chemical substances,such as ascorbic acid, sodium chloride,and benzoic acid could inhibit the PPO activity and improve the content of baicalin;It is obvious for ascorbic acid(0.02%) to improve the content of baicalin with 17.6%(82.3 mg/g) compared with the control.However,polyvinylpyrrolidone and copper sulfate could increase the PPO activity and greatly inhibit the baicalin accumulation.
ABSTRACT
Objective To study the rule of callus culture and baicalin synthesis in Scutellaria baicalensis. Methods Callus was induced by plant cell culture technology and the content of baicalin was determind by HPLC. Results The optimal culture medium on the growth of callus and the synthesis of baicalin in S. baicalensis is: MS culture medium, 60 mmol/L (NH_4+∶NO_3-=1∶1), 0.5—1.5 mmol/L KH_2PO_4, 80 g/L sucrose, 0.3 mg/L IAA, 2 mg/L 6-BA, and 200 mg/L peptone. When it was cultured for 40 d, the total biomass reached 28.7 g/L and the content of baicalin was 167.4 mg/g, which was much higher than that of wild S. baicalensis. Conclusion The growth of S. baicalensis callus and the accumulation of baicalin are not underway simultaneously; the callus grows first and then its secondary metabolic products synthesize. It is obvious for sucrose to regulate the baicalin synthesis. When the concentration of sucrose is less than 3%, it could only promote the callus growth; when between 3% and 8%, it could greatly increase not only the callus growth but also the baicalin synthesis, when 8%, both of them arrive to the maximum content.