AUTHOR=Sarsaiya Surendra , Jain Archana , Fan Xiaokuan , Jia Qi , Xu Quan , Shu Fuxing , Zhou Qinian , Shi Jingshan , Chen Jishuang 

TITLE=New Insights into Detection of a Dendrobine Compound From a Novel Endophytic Trichoderma longibrachiatum Strain and Its Toxicity Against Phytopathogenic Bacteria

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00337

DOI=10.3389/fmicb.2020.00337

ISSN=1664-302X

ABSTRACT=<p><italic>Dendrobium nobile</italic> is the only plant that could produce the natural bioactive dendrobine. No other source of dendrobine has been found to date except from <italic>D. nobile</italic> and via chemical synthesis. In this study, we aimed to examine the potential fungal endophyte isolated from <italic>D. nobile</italic> stem segments using the molecular method and to detect dendrobine compound through high-performance liquid chromatography (HPLC), gas chromatography–mass spectrometry (GC-MS), and liquid chromatography with tandem mass spectrometry (LC-MS/MS) and their metabolite for their antibacterial activity. The potential dendrobine producer strain was recognized as <italic>Trichoderma longibrachiatum</italic> based on molecular DNA sequencing and GenBank databases. The <italic>T. longibrachiatum</italic> MD33 produced dendrobine and other compounds in a potato dextrose medium (PDM), as confirmed by HPLC retention time peak analysis. The HPLC results revealed that <italic>T. longibrachiatum</italic> MD33 biomass showed a peak retention time of 5.28 ± 0.2 min, similar to wild <italic>D. nobile</italic> stem dendrobine (5.32 ± 0.2 min) and standard chemical reference dendrobine (5.30 ± 0.2 min), indicating the presence of dendrobine in the fungal biomass. Results of GC-MS and LC-MS analysis revealed that <italic>T. longibrachiatum</italic> MD33 produced the same molecular weight (263 in GC-MS and 264.195 in LC-MS) of dendrobine as compared with standard chemical reference dendrobine and <italic>D. nobile</italic> dendrobine. Antibacterial activity data revealed that <italic>T. longibrachiatum</italic> MD33 produced the strongest bactericidal activity against <italic>Bacillus subtilis</italic>, <italic>Bacillus mycoides</italic>, and <italic>Staphylococcus</italic> species, and the diameter of the bacterial growth inhibition zone was 12 ± 0.2, 9 ± 0.2, and 8 ± 0.2 mm, respectively. To the best of our knowledge, this was the first study to investigate <italic>T. longibrachiatum</italic> as a dendrobine producer, and the results revealed that <italic>T. longibrachiatum</italic> was directly involved in the potential production of a similar bioactive compound to <italic>D. nobile</italic> (dendrobine). In addition, the <italic>T. longibrachiatum</italic> metabolite exhibited potent antibacterial activity and can be a potential strain for medical and industrial purposes.</p>