Atsuko Katsuta

Rare carotenoids, (3R)-saproxanthin and (3R,2′S)-myxol, isolated from novel marine bacteria (Flavobacteriaceae) and their antioxidative activities

We isolated three orange or yellow pigment-producing marine bacteria, strains 04OKA-13-27 (MBIC08261), 04OKA-17-12 (MBIC08260), and YM6-073 (MBIC06409), off the coast of Okinawa Prefecture in Japan. These strains were classified as novel species of the family Flavobacteriaceae based on their 16S rRNA gene sequence. They were cultured, and the major carotenoids produced were purified by chromatographic methods. Their structures were determined by spectral data to be (3R)-saproxanthin (strain 04OKA-13-27), (3R,2′S)-myxol (strain YM6-073), and (3R,3′R)-zeaxanthin (strains YM6-073 and 04OKA-17-12). Saproxanthin and myxol, which are monocyclic carotenoids rarely found in nature, demonstrated significant antioxidative activities against lipid peroxidation in the rat brain homogenate model and a neuro-protective effect from l-glutamate toxicity.

Endozoicomonas numazuensis sp. nov., a gammaproteobacterium isolated from marine sponges, and emended description of the genus Endozoicomonas Kurahashi and Yokota 2007.

Two non-motile, rod-shaped gammaproteobacteria were isolated from marine sponges collected from the coast of Japan at Numazu. The isolates were oxidase- and catalase-positive facultative anaerobes that fermented carbohydrates. They required sodium ions for growth and were slightly halophilic, growing in the presence of 1.0-5.0 % (w/v) NaCl (optimum of 2.0 % NaCl). Under aerobic conditions, the major isoprenoid quinones were ubiquinone-9 and menaquinone-9 and the minor quinones were ubiquinone-8 and menaquinone-8. The major cellular fatty acids were C(18 : 1)ω7c, C(16 : 1)ω7c and C(16 : 0) and the hydroxy acids were C(10 : 0) 3-OH and C(12 : 0) 3-OH. The DNA G+C content was 48.3-48.7 mol%. Phylogenetic analysis of 16S rRNA gene sequences placed the isolates within the radiation of the genus Endozoicomonas in a broad clade of uncultured clones recovered from various marine invertebrates. The isolates exhibited 96.5-96.9 % 16S rRNA gene sequence similarity with Endozoicomonas elysicola MKT110(T) and Endozoicomonas montiporae CL-33(T), with which the isolates formed a monophyletic cluster with 100 % bootstrap support. The phenotypic features (carbohydrate fermentation, quinone system and some major cellular fatty acids) differed from those of members of the genus Endozoicomonas, which are aerobic, produce little or no menaquinone under aerobic conditions and possess different amounts of C(14 : 0) and C(18 : 1)ω7c. Although some phenotypic differences were identified, the isolates should be assigned to the genus Endozoicomonas on the basis of congruity of phylogeny and should be classified as representatives of a novel species, for which the name Endozoicomonas numazuensis sp. nov. is proposed. The type strain is HC50(T) ( = NBRC 108893(T)  = DSM 25634(T)). An emended description of the genus Endozoicomonas is presented.

Unnarmicins A and C, New Antibacterial Depsipeptides Produced by Marine Bacterium Photobacterium sp. MBIC06485

AbstractTwo new antibiotic depsipeptides, unnarmicins C (1) and A (2), were isolated from the fermentation broth of a marine bacterium, Photobacterium sp. strain MBIC06485. The structure of 1 was established by spectroscopic studies and chiral analyses of its chemical degradation/conversion products, and that of 2 by comparing its NMR, MS, and CD data with those of 1. Both compounds selectively inhibited the growth of two strains belonging to the genus Pseudovibrio, one of the most prevalent genera in the marine environments within the class Alphaproteobacteria.

Urukthapelstatin A, a novel cytotoxic substance from marine-derived Mechercharimyces asporophorigenens YM11-542. I. Fermentation, isolation and biological activities.

Urukthapelstatin A, a novel cyclic peptide, was isolated from the cultured mycelia of marine-derived Thermoactinomycetaceae bacterium Mechercharimyces asporophorigenens YM11-542. The peptide was purified by solvent extraction, silica gel chromatography, ODS flash chromatography, and finally by preparative HPLC. Urukthapelstatin A dose-dependently inhibited the growth of human lung cancer A549 cells with an IC50 value of 12 nM. Urukthapelstatin A also showed potent cytotoxic activity against a human cancer cell line panel.

Structural Determination and Proposed Biosynthesis of Alcanivorone, a Novel α-Pyrone Produced by Alcanivorax jadensis

A novel α-pyrone designated as alcanivorone was found in a culture broth of the marine bacterium, Alcanivorax jadensis, and its structure was determined by an analysis of 1D NMR, 2D NMR and MS data. Alcanivorone was produced by A. jadensis only when sodium pyruvate was added to the culture medium as a carbon source. Incorporation experiments using stable isotope-labeled pyruvate indicated that alcanivorone was biosynthesized from four molecules of pyruvate.

Psychromonas heitensis sp. nov., a psychrotolerant bacterium isolated from seawater in Japan

Four bacterial strains, 04HE-4-40, A4I-9, A4I-21 and AK15-027(T), were isolated from Heita Bay off Kamaishi in Japan. Based on 16S rRNA gene sequence analysis, the isolates were placed as a new lineage within the genus Psychromonas. The 16S rRNA gene sequence similarity values between the isolates and type strains of recognized Psychromonas species were less than 97 %. The DNA G+C contents of the isolates were about 38 mol%. The major respiratory quinone was Q-8, and the predominant cellular fatty acids were 16 : 1omega7c and 16 : 0. The isolates were able to grow at 30 degrees C, unlike other Psychromonas species. Based on the results of the phylogenetic analysis and phenotypic characteristics and DNA-DNA hybridization data, the isolates represent a novel species, for which the name Psychromonas heitensis sp. nov. is proposed. The type strain is AK15-027(T) (=MBIC 06898(T)=NCIMB 14416(T)).