MDN-0171, a new medermycin analogue from <i>Streptomyces albolongus</i> CA-186053

<p>A new medermycin derivative, MDN-0171 (<b>1</b>), and two known structurally related compounds, medermycin (<b>2</b>) and antibiotic G15-F (<b>3</b>) were isolated from the acetone extract of culture broths of the marine-derived <i>Streptomyces albolongus</i> strain CA-186053. Their structures were determined using a combination of spectroscopic techniques, including 1D and 2D NMR and electrospray-time of flight mass spectrometry (ESI-TOF MS). Compounds <b>2</b> and <b>3</b> accounted for the antimicrobial activity (against methicillin-resistant <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>) previously detected in the crude extract of this actinomycete.</p

Taxonomic affiliation of the bioactive bacteria isolated from <i>E. discophorus</i>.

<p>Taxonomic affiliation of the bioactive bacteria isolated from <i>E. discophorus</i>.</p

Results of bioactivity by genera and screening method (<i>Janus</i> and Duetz systems) obtained against <i>Bacillus subtilis</i>, <i>Staphylococcus aureus</i> MRSA, <i>Aliivibrio fisheri</i> and <i>Vibrio harveyi.</i>

<p>Results of bioactivity by genera and screening method (<i>Janus</i> and Duetz systems) obtained against <i>Bacillus subtilis</i>, <i>Staphylococcus aureus</i> MRSA, <i>Aliivibrio fisheri</i> and <i>Vibrio harveyi.</i></p

Assessing the effects of adsorptive polymeric resin additions on fungal secondary metabolite chemical diversity

<div><p>Adsorptive polymeric resins have been occasionally described to enhance the production of specific secondary metabolites (SMs) of interest. Methods that induce the expression of new chemical entities in fungal fermentations may lead to the discovery of new bioactive molecules and should be addressed as possible tools for the creation of new microbial chemical libraries for drug lead discovery. Herein, we apply both biological activity and chemical evaluations to assess the use of adsorptive resins as tools for the differential expression of SMs in fungal strain sets. Data automation approaches were applied to ultra high performance liquid chromatography analysis of extracts to evaluate the general influence in generating new chemical entities or in changing the production of specific SMs by fungi grown in the presence of resins and different base media.</p></div

Isolation, Structure Elucidation, and Antibacterial Activity of Methiosetin, a Tetramic Acid from a Tropical Sooty Mold (<i>Capnodium</i> sp.)

Drug-resistant bacteria continue to make many existing antibiotic classes ineffective. In order to avoid a future epidemic from drug-resistant bacterial infections, new antibiotics with new modes of action are needed. In an antibiotic screening program for new drug leads with new modes of action using antisense <i>Staphylococcus aureus</i> Fitness Test screening, we discovered a new tetramic acid, methiosetin, from a tropical sooty mold, <i>Capnodium</i> sp. The fungus also produced epicorazine A, a known antibiotic. The structure and relative configuration of methiosetin was elucidated by 2D NMR and ESIMS techniques. Methiosetin and epicorazine A showed weak to modest antibacterial activity against <i>S. aureus</i> and <i>Haemophilus influenzae</i>. The isolation, structure elucidation, and antibacterial activity of both compounds are described

Branimycins B and C, Antibiotics Produced by the Abyssal Actinobacterium <i>Pseudonocardia carboxydivorans</i> M‑227

Two new antibiotics, branimycins B (<b>2</b>) and C (<b>3</b>), were produced by fermentation of the abyssal actinobacterium <i>Pseudonocardia carboxydivorans</i> M-227, isolated from deep seawater of the Avilés submarine Canyon. Their structures were elucidated by HRMS and NMR analyses. These compounds exhibit antibacterial activities against a panel of Gram-positive bacteria, including <i>Corynebacterium urealyticum</i>, <i>Clostridium perfringens</i>, and <i>Micrococcus luteus</i>, and against the Gram-negative bacterium <i>Neisseria meningitidis.</i> Additionally, branimycin B displayed moderate antibacterial activity against other Gram-negative bacteria such as <i>Bacteroides fragilis</i>, <i>Haemophilus influenzae</i>, and <i>Escherichia coli</i>, and branimycin C against the Gram-positive <i>Enterococcus faecalis</i> and methicillin-sensitive and methicillin-resistant <i>Staphylococcus aureus.</i