Sattahipmycin, a Hexacyclic Xanthone Produced by a Marine-Derived Streptomyces.

Sattahipmycin was isolated from the mycelium of marine-derived Streptomyces sp. GKU 257-1 by following the antibiofilm activity against E. coli NBRC 3972 throughout the purification steps. The structure of sattahipmycin was determined to be a new polycyclic xanthone related to xantholipin but lacking a dioxymethylene and a chlorinated carbon. This compound showed activity toward Gram-positive bacteria and Plasmodium falciparum, antibiofilm formation of Escherichia coli, and cytotoxicity to human cancer cell lines. Using genome sequence data, a biosynthetic pathway leading to sattahipmycin has been proposed involving an uncharacterized type II polyketide synthase biosynthetic gene cluster.

Detection of Penicillin G Produced by Penicillium chrysogenum with Raman Microspectroscopy and Multivariate Curve Resolution-Alternating Least-Squares Methods.

Raman microspectroscopy is a minimally invasive technique that can identify molecules without labeling. In this study, we demonstrate the detection of penicillin G inside Penicillium chrysogenum KF425 fungal cells. Raman spectra acquired from the fungal cells had highly overlapped spectroscopic signatures and hence were analyzed with multivariate curve resolution by alternating least-squares (MCR-ALS) to extract the spectra of individual molecular constituents. In addition to detecting spatial distribution of multiple constituents such as proteins and lipids inside the fungal body, we could also observe the subcellular localization of penicillin G. This methodology has the potential to be employed in screening the production of bioactive compounds by microorganisms.

Sarpeptins A and B, Lipopeptides Produced by Streptomyces sp. KO-7888 Overexpressing a Specific SARP Regulator.

Whole genome analysis of Streptomyces sp. KO-7888 has revealed various pathway-specific transcriptional regulatory genes associated with silent biosynthetic gene clusters. A Streptomyces antibiotic regulatory protein gene, speR, located adjacent to a novel nonribosomal peptide synthetase (NRPS) gene cluster, was overexpressed in the wild-type strain. The resulting recombinant strain of Streptomyces sp. KO-7888 produced two new lipopeptides, sarpeptins A and B. Their structures were elucidated by high-resolution electrospray ionization mass spectrometry, NMR analysis, and the advanced Marfey's method. The distinct modular sections of the corresponding NRPS biosynthetic gene cluster were characterized, and the assembly line for production of the lipopeptide chain was proposed.

Total Synthesis and Determination of the Absolute Configuration of Naturally Occurring Mangromicin A, with Potent Antitrypanosomal Activity.

An enantioselective total synthesis of (+)-mangromicin A has been accomplished. The tetrahydrofuran ring of mangromicin A, possessing a tetrasubstituted carbon center, was constructed by Mukaiyama-type vinylogous alkylation via a cyclic oxocarbenium intermediate derived from a γ-hydroxy ketone with ideal stereoselectivity, and the 4-hydroxydihydropyrone scaffold was generated via Dieckmann cyclization at a late stage of the total synthesis. The reliable asymmetric synthesis of (+)-mangromicin A has revealed the absolute configuration of naturally occurring mangromicin A.

Proposal of Sphaerimonospora cavernae gen. nov., sp. nov. and transfer of Microbispora mesophila (Zhang et al., 1998) to Sphaerimonospora mesophila comb. nov. and Microbispora thailandensis (Duangmal et al., 2012) to Sphaerimonospora thailandensis comb. nov.

The actinomycete strain N74T, isolated from cave soil, was studied using a polyphasic taxonomic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain N74T formed a stable, distinct lineage cluster together with Microbispora thailandensis NN276T (99.3% similarity) and Microbispora mesophila JCM 3151T (97.5%). Strain N74T was observed to produce single spherical spores on aerial mycelium as reported for M. mesophila JCM 3151T and M. thailandensis NN276T but different from other known species of the genus Microbispora, which are characterized by pairs of spores on aerial hyphae. Multilocus sequence analyses based on concatenated partial gyrB, rpoB, atpD, recA and 16S rRNA gene sequences showed a clear distinction of strain N74T, M. mesophila JCM 3151T and M. thailandensis NN276T from other members of the genus Microbispora, although the chemotaxonomic characteristics of strain N74T were similar to the genus Microbispora; the cell wall contained meso-diaminopimelic acid and the whole-cell hydrolysate contained madurose as the diagnostic sugar. The major menaquinone was MK-9(H4). The fatty acid profile contained iso-C16:0. On the basis of morphological, chemotaxonomic and phylogenetic evidence, strain N74T is assigned to a novel species of a new genus, for which the name Sphaerimonospora cavernae gen. nov., sp. nov. is proposed. The type strain of Sphaerimonospora cavernae is N74T (=BCC 77604T=NBRC 111481T). It is also proposed that M. mesophila and M. thailandensis be transferred to this genus as Sphaerimonospora mesophila comb. nov. (type strain JCM 3151T=NBRC 14179T=DSM 43048T) and Sphaerimonospora thailandensis comb. nov. (type strain NN276T=BCC 41490T=NBRC 107569T), respectively.