@article{MasotaOhlsenSchollmayeretal.2022, author = {Masota, Nelson E. and Ohlsen, Knut and Schollmayer, Curd and Meinel, Lorenz and Holzgrabe, Ulrike}, title = {Isolation and characterization of galloylglucoses effective against multidrug-resistant strains of Escherichia coli and Klebsiella pneumoniae}, series = {Molecules}, volume = {27}, journal = {Molecules}, number = {15}, issn = {1420-3049}, doi = {10.3390/molecules27155045}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286179}, year = {2022}, abstract = {The search for new antibiotics against multidrug-resistant (MDR), Gram-negative bacteria is crucial with respect to filling the antibiotics development pipeline, which is subject to a critical shortage of novel molecules. Screening of natural products is a promising approach for identifying antimicrobial compounds hosting a higher degree of novelty. Here, we report the isolation and characterization of four galloylglucoses active against different MDR strains of Escherichia coli and Klebsiella pneumoniae. A crude acetone extract was prepared from Paeonia officinalis Linnaeus leaves, and bioautography-guided isolation of active compounds from the extract was performed by liquid-liquid extraction, as well as open column, flash, and preparative chromatographic methods. Isolated active compounds were characterized and elucidated by a combination of spectroscopic and spectrometric techniques. In vitro antimicrobial susceptibility testing was carried out on E. coli and K. pneumoniae using 2 reference strains and 13 strains hosting a wide range of MDR phenotypes. Furthermore, in vivo antibacterial activities were assessed using Galleria mellonella larvae, and compounds 1,2,3,4,6-penta-O-galloyl-β-d-glucose, 3-O-digalloyl-1,2,4,6-tetra-O-galloyl-β-d-glucose, 6-O-digalloyl-1,2,3,4-tetra-O-galloyl-β-d-glucose, and 3,6-bis-O-digalloyl-1,2,4-tri-O-galloyl-β-d-glucose were isolated and characterized. They showed minimum inhibitory concentration (MIC) values in the range of 2-256 µg/mL across tested bacterial strains. These findings have added to the number of known galloylglucoses from P. officinalis and highlight their potential against MDR Gram-negative bacteria.}, language = {en} } @article{JahnSchmidtMock2014, author = {Jahn, Martin T. and Schmidt, Katrin and Mock, Thomas}, title = {A novel cost effective and high-throughput isolation and identification method for marine microalgae}, series = {Plant Methods}, volume = {10}, journal = {Plant Methods}, number = {26}, doi = {10.1186/1746-4811-10-26}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121255}, year = {2014}, abstract = {BACKROUND: Marine microalgae are of major ecologic and emerging economic importance. Biotechnological screening schemes of microalgae for specific traits and laboratory experiments to advance our knowledge on algal biology and evolution strongly benefit from culture collections reflecting a maximum of the natural inter- and intraspecific diversity. However, standard procedures for strain isolation and identification, namely DNA extraction, purification, amplification, sequencing and taxonomic identification still include considerable constraints increasing the time required to establish new cultures. RESULTS: In this study, we report a cost effective and high-throughput isolation and identification method for marine microalgae. The throughput was increased by applying strain isolation on plates and taxonomic identification by direct PCR (dPCR) of phylogenetic marker genes in combination with a novel sequencing electropherogram based screening method to assess the taxonomic diversity and identity of the isolated cultures. For validation of the effectiveness of this approach, we isolated and identified a range of unialgal cultures from natural phytoplankton communities sampled in the Arctic Ocean. These cultures include the isolate of a novel marine Chlorophyceae strain among several different diatoms. CONCLUSIONS: We provide an efficient and effective approach leading from natural phytoplankton communities to isolated and taxonomically identified algal strains in only a few weeks. Validated with sensitive Arctic phytoplankton, this approach overcomes the constraints of standard molecular characterisation and establishment of unialgal cultures."}, language = {en} }