The burnettramic acids are a new class of antibiotics from an Australian fungus Aspergillus burnettii. The rare bolaamphiphilic scaffold consists of β-D-mannose linked to a pyrrolizidinedione unit via a 26-carbon chain. The most abundant metabolite displayed potent in vitro antifungal activity. Comparative genomics identified the hybrid PKS-NRPS bua gene cluster, which was verified by heterologous pathway reconstitution in Aspergillus nidulans.
We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log 10 increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV—CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences—is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.
A soil survey conducted in southern Queensland, Australia, identified a novel isolate belonging to the genus Aspergillus subgenus Circumdati section Circumdati, Aspergillus kumbius FRR6049. Cultivation and fractionation of secondary metabolites from A. kumbius revealed a unique chemotype comprising three new bis-indolyl benzenoids, kumbicins A–C, and a new bis-indolyl benzoquinone, kumbicin D, along with the previously reported compounds asterriquinol D dimethyl ether, petromurins C and D, aspochracin, its N-demethyl analogue JBIR-15, and neohydroxyaspergillic acid. The structures of kumbicins A–D were assigned by detailed spectroscopic analysis. Kumbicin C was found to inhibit the growth of mouse myeloma cells (IC50 0.74 μg mL–1) and the Gram-positive bacterium Bacillus subtilis (MIC 1.6 μg mL–1).
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