Takeshi Terahara

Hyaluromycin, a New Hyaluronidase Inhibitor of Polyketide Origin from Marine Streptomyces sp.

Hyaluromycin (1), a new member of the rubromycin family of antibiotics, was isolated from the culture extract of a marine-derived Streptomyces sp. as a HAase inhibitor on the basis of HAase activity screening. The structure of 1 was elucidated through the interpretation of NMR data for the compound and its 3″-O-methyl derivative in combination with an incorporation experiment with [1,2-13C2]acetate. The compound’s absolute configuration was determined by the comparison of its circular dichroism (CD) spectrum with those of other rubromycins. Hyaluromycin (1) consists of a γ-rubromycin core structure possessing a 2-amino-3-hydroxycyclopent-2-enone (C5N) unit as an amide substituent of the carboxyl function; both structural units have been reported only from actinomycetes. Hyaluromycin (1) displayed approximately 25-fold more potent hyaluronidase inhibitory activity against hyaluronidase than did glycyrrhizin, a known inhibitor of plant origin.

7-Chlorofolipastatin, an inhibitor of sterol O-acyltransferase, produced by marine-derived Aspergillus ungui NKH-007.

A new depsidone, named 7-chlorofolipastatin, and five known structurally related depsidones were isolated from the culture broth of the marine-derived fungus Aspergillus ungui NKM-007 by solvent extraction and HPLC using an octadecylsilyl column. The structure of 7-chlorofolipastatin was elucidated by various spectroscopic data including 1D and 2D NMR spectroscopy. 7-Chlorofolipastatin inhibited sterol O-acyltransferase (SOAT) 1 and 2 isozymes in cell-based and enzyme assays using SOAT1- and SOAT2-expressing Chinese hamster ovary (CHO) cells.

Diketopiperazines, inhibitors of sterol O-acyltransferase, produced by a marine-derived Nocardiopsis sp. KM2-16

Diketopiperazines, inhibitors of sterol O -acyltransferase, produced by a marine-derived Nocardiopsis sp. KM2-16

Characterization of lactic acid bacteria distributed in small fish fermented with boiled rice in Myanmar

AbstractThis study is a detailed description of the microflora of a traditional fishery product in Myanmar which is fermented with boiled rice. We approached this analysis from two viewpoints; namely, the culture-dependent and culture-independent methods. In Southeast Asia, there are various types of traditional fermented fishery products. In this study, we isolated and characterized lactic acid bacteria (LAB) from small freshwater fish (tinfoil barb) fermented with boiled rice, a typical Myanmar fermented product, to contribute to the understanding of its fermentation process. Eight fermented fishery products were purchased from different markets in Yangon. Forty-three of the 46 isolates were identified as LAB, and they were classified into two groups: 40 homofermentative and three heterofermentative isolates, on the basis of their phenotypic characteristics. From the results of PCR-restriction fragment length polymorphism (RFLP) analysis and 16S rRNA gene sequencing, our isolates were identified as Lactobacillus plantarum-group, Lactobacillus farciminis, Lactobacillus futsaii, Lactobacillus reuteri,Weissella paramesenteroides, and Pediococcus pentosaceus. In addition, L. plantarum and L. farciminis were identified as γ-aminobutyric acid (GABA)-producing LAB. Terminal restriction fragment length polymorphism (T-RFLP) analysis was also carried out using DNA samples extracted from these fermented products. In comparison with culture-dependent methods, the results of T-RFLP analysis did not seem to have major contradictions.

Lysinimicrobium sediminis sp. nov., an actinobacterium isolated from estuary sediment

A novel Gram-stain-positive actinobacterium, designated HT7-17T, was isolated from a sediment sample collected from the estuary of the Tama River, Japan, and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain HT7-17T was closely related to members of the genus Lysinimicrobium, with a similarity range of 97.1-98.2 %. The peptidoglycan type of strain HT7-17T was A4α, the predominant menaquinone was demethylmenaquinone DMK-9(H4) and the major fatty acids were anteiso-C15 : 0, C16 : 0 and iso-C16 : 0. The DNA G+C content was 69.9 mol%. These chemotaxonomic features corresponded to those of the genus Lysinimicrobium. Meanwhile, the differences in some phenotypic characteristics, along with the result of DNA-DNA hybridization, indicated that strain HT7-17T should be distinguished from the recognized species of the genus Lysinimicrobium. Therefore, strain HT7-17T represents a novel species of the genus Lysinimicrobium, for which the name Lysinimicrobium sediminis sp. nov. is proposed. The type strain is HT7-17T (=NBRC 112286T=TBRC 7037T).

Malachite-green-removing properties of a bacterial strain isolated from fish ponds in Thailand

Malachite green (MG) has been focused on as a biotreatment target and its biological properties have also been an issue in food fish aquaculture. An MG-removing bacterium was isolated from aquaculture fish pond sediment samples in Thailand. The isolate, strain T-5-2, is a Gram-negative, aerobic rod-shaped bacterium, and has been identified as a member of the Pseudomonas putida group. Proton nuclear magnetic resonance spectroscopy (1H-NMR) analysis of a broth culture medium containing MG showed that the concentration of MG decreased markedly and that other molecules, including leucomalachite green (LMG), were generated. Moreover, liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis showed that the MG concentration in the broth culture medium continuously decreased. This analysis also demonstrated that the concentration of LMG initially increased and then gradually decreased. Furthermore, gas chromatography–mass spectrometry (GC–MS) analysis showed 4-(dimethylamino)benzophenone (4DABP) as a degradation component of MG, which was confirmed by 1H-NMR and LC–MS/MS analysis. These findings suggest that this bacterial strain can remove MG in broth culture and degrade it to certain metabolites, including LMG and 4DABP. This study is the first detailed evaluation by the combination of LC–MS/MS, GC–MS, and 1H-NMR analyses of an MG-removing bacterium isolated from Thai aquaculture fish ponds.

Bacterial community structures of deep-sea water investigated by molecular biological techniques

The aim of the present study was to investigate the bacterial community structures of deep-sea water (DSW) and surface seawater (SSW) samples in Japan by molecular biological techniques. DGGE analyses and pyrosequencing analysis revealed that bacterial community structures of DSW were diverse and differed from those of SSW. This is the first report on the horizontal variation of bacterial community structures of DSW throughout Japan. In addition, pyrosequencing analysis revealed that the number of phyla in DSW was larger than that in SSW, and specific phyla, such as Firmicutes and Planctomycetes, were characterized by a higher proportion of the bacterial community structure in DSW than in SSW. Taken together, these results indicate that a variety of bacteria that are specifically adapted to the DSW environments can be expected to be found in DSW, and DSW would thus be a potential resource for novel or unique microorganisms and compounds.