Targeted discovery of tetrapeptides and cyclic polyketide-peptide hybrids from a fungal antagonist of farming termites

Herein, we report the targeted isolation and characterization of four linear nonribosomally synthesized tetrapeptides (pseudoxylaramide A–D) and two cyclic nonribosomal peptide synthetase- polyketide synthase-derived natural products (xylacremolide A and B) from the termite-associated stowaway fungus Pseudoxylaria sp. X187. The fungal strain was prioritized for further metabolic analysis based on its taxonomical position and morphological and bioassay data. Metabolic data were dereplicated based on high-resolution tandem mass spectrometry data and global molecular networking analysis. The structure of all six new natural products was elucidated based on a combination of 1D and 2D NMR analysis, Marfey’s analysis and X-ray crystallography.The Deutsche Forschungsgemeinschaft (DFG)https://chemistry-europe.onlinelibrary.wiley.com/journal/14397633am2020BiochemistryGeneticsMicrobiology and Plant Patholog

Coculture of Marine Streptomyces sp. With Bacillus sp. Produces a New Piperazic Acid-Bearing Cyclic Peptide

Microbial culture conditions in the laboratory, which conventionally involve the cultivation of one strain in one culture vessel, are vastly different from natural microbial environments. Even though perfectly mimicking natural microbial interactions is virtually impossible, the cocultivation of multiple microbial strains is a reasonable strategy to induce the production of secondary metabolites, which enables the discovery of new bioactive natural products. Our coculture of marine Streptomyces and Bacillus strains isolated together from an intertidal mudflat led to discover a new metabolite, dentigerumycin E (1). Dentigerumycin E was determined to be a new cyclic hexapeptide incorporating three piperazic acids, N-OH-Thr, N-OH-Gly, β-OH-Leu, and a pyran-bearing polyketide acyl chain mainly by analysis of its NMR and MS spectroscopic data. The putative PKS-NRPS biosynthetic gene cluster for dentigerumycin E was found in the Streptomyces strain, providing clear evidence that this cyclic peptide is produced by the Streptomyces strain. The absolute configuration of dentigerumycin E was established based on the advanced Marfey's method, ROESY NMR correlations, and analysis of the amino acid sequence of the ketoreductase domain in the biosynthetic gene cluster. In biological evaluation of dentigerumycin E (1) and its chemical derivatives [2-N,16-N-deoxydenteigerumycin E (2) and dentigerumycin methyl ester (3)], only dentigerumycin E exhibited antiproliferative and antimetastatic activities against human cancer cells, indicating that N-OH and carboxylic acid functional groups are essential for the biological activity

Lobophorin Producing Endophytic Streptomyces olivaceus JB1 Associated With Maesa japonica (Thunb.) Moritzi & Zoll.

In this study, we focused on endophytes of Maesa japonica (Thunb.) Moritzi &amp;amp; Zoll. and the plant-microbe interaction at metabolite levels. We isolated seven endophytes associated with M. japonica (JB1−7), and focused on Streptomyces olivaceus JB1 because of antibacterial activities of its secondary metabolites. We confirmed lobophorin analogs production from the bacterial strain JB1 by using spectroscopic techniques such as NMR, UV, and LC/Q-TOF-MS. In the LC/MS system, thirteen reported lobophorin analogs and twelve unreported analogs were detected. Among metabolites, lobophorin A was clearly detected in the dried foliar residues of M. japonica which implies that JB1 resides in the host and accumulates its secondary metabolites likely interacting with the plant. Antimicrobial activity tests of the secondary metabolites against undesirable contaminants isolated from the external surface of M. japonica supported the host and microbe mutualistic relationship. In the meantime, lobophorin producing Streptomyces spp. were isolated from marine environments such as marine sediments, algae, corals, and sponges. As lobophorin producing Streptomyces is isolated commonly from marine environments, we conducted a saline water stress tolerance test with JB1 showing saline medium does not accelerate the growth of the bacterium.</jats:p

Fast suction-grasp-difficulty estimation for high throughput plastic-waste sorting

The selection of the grasping location is the most important task for robots that handle randomly shaped objects. In previous studies, the grasp quality was accurately evaluated, but the speed was much too low for high-throughput applications, and the focus was mainly on industrial products. In this study, a large-scale dataset for randomly deformed plastics is constructed. We propose a contact-area estimation model and difficulty function for a quantitative analysis of surface conditions. Synthetic labels were calculated using the tuned difficulty function for donut-shaped contact areas. We trained the network containing a pre-trained encoder and decoder with skip connections for grasp-difficulty map estimation. Grasp-difficulty estimations for multiple objects required at most 30.9 ms with an average error rate of 1.65 %. The algorithm had a 94.4 % grasping success rate and its computational efficiency was compared with that in previous studies. The algorithm enables the rapid sorting of continuously conveyed objects with higher throughput.

Data_Sheet_1_Lobophorin Producing Endophytic Streptomyces olivaceus JB1 Associated With Maesa japonica (Thunb.) Moritzi & Zoll..PDF

In this study, we focused on endophytes of Maesa japonica (Thunb.) Moritzi & Zoll. and the plant-microbe interaction at metabolite levels. We isolated seven endophytes associated with M. japonica (JB1−7), and focused on Streptomyces olivaceus JB1 because of antibacterial activities of its secondary metabolites. We confirmed lobophorin analogs production from the bacterial strain JB1 by using spectroscopic techniques such as NMR, UV, and LC/Q-TOF-MS. In the LC/MS system, thirteen reported lobophorin analogs and twelve unreported analogs were detected. Among metabolites, lobophorin A was clearly detected in the dried foliar residues of M. japonica which implies that JB1 resides in the host and accumulates its secondary metabolites likely interacting with the plant. Antimicrobial activity tests of the secondary metabolites against undesirable contaminants isolated from the external surface of M. japonica supported the host and microbe mutualistic relationship. In the meantime, lobophorin producing Streptomyces spp. were isolated from marine environments such as marine sediments, algae, corals, and sponges. As lobophorin producing Streptomyces is isolated commonly from marine environments, we conducted a saline water stress tolerance test with JB1 showing saline medium does not accelerate the growth of the bacterium.</p

Actinofuranone C, a new 3-furanone-bearing polyketide from a dung beetle-associated bacterium

Actinofuranone C (1), a new 3-furanone-bearing polyketide, was isolated from an actinobacterium (Amycolatopsis sp.) associated with a female of the dung beetle, Copris tripartitus Waterhouse. The structure of actinofuranone C was elucidated by the spectroscopic interpretation of NMR, mass, UV, and IR data. The discovery of actinofuranone C indicates that chemical investigation of insect-associated microorganisms would be an effective strategy to explore natural chemical diversity.N

Pentacyclic triterpenoids saponins pannosides A-E from Tripolium pannonicum

Five previously undescribed pentacyclic triterpenoid saponins, pannoside A–E (1–5), were discovered from the whole plant of seashore aster, Tripolium pannonicum, collected from the Songdo tidal flat, Incheon, Korea. The planar structures of pannosides were elucidated as pentacyclic triterpenoids bearing sugar moieties and 3-hydroxybutyrate (3-HB) based on the interpretation of the NMR, IR spectroscopic and MS data. The relative configurations of the aglycone and sugar moieties of 1–5 were determined based on careful analysis of ROESY correlations. To determine the absolute configuration of 3-hydroxybutyrate, we utilized the phenylglycine methyl ester (PGME) derivatization with LC-MS chromatographic analysis. Pannoside E (5) exhibited inhibitory activities against diverse cancer cell lines including prostate carcinoma and non-small cell lung carcinoma, with IC50 values of 0.34 and 0.89 μM, respectively. Pannosides are the first triterpenoid saponin isolated from T. pannonicum, implying that undiscovered secondary metabolites from a halophyte could be a good source of bioactive compounds.</jats:p