Microbial Resources and Systematics
Online ISSN : 2759-2006
Print ISSN : 1342-4041
Current issue
Displaying 1-15 of 15 articles from this issue
  • —History of genomic information and microbial taxonomy—
    Takuro Nunoura
    2023 Volume 39 Issue 2 Pages 61-68
    Published: 2023
    Released on J-STAGE: July 26, 2024
    JOURNAL FREE ACCESS

    Molecular biology techniques have had an impact on microbial taxonomy since the discovery of Archaea based on rRNA fingerprinting. Now, the development of DNA sequencing technology and bioinformatics has enabled us to use whole genome sequences in prokaryotic taxonomy including with previously uncultivated lineages. In fact, the genome taxonomy database (GTDB) is one of the most reliable databases with which to identify the taxonomy of individual microbes including uncultured lineages based on genomic information. However, the International Code of Nomenclature of Prokaryotes does not officially accept genome-based taxonomy, and a genome-based taxonomy scheme called the SeqCode Initiative has been launched. Here, I summarize the history of the impact of molecular biology techniques and subsequent genomic information on prokaryotic taxonomy since the discovery of Archaea (archaebacteria), and the recent changes in microbial taxonomy to understand the current situation.

    Download PDF (476K)
  • —Current status and future prospects in the social implementation of 'microalgae'—
    Tsuyoshi Takeshita, Masaki Yoshida, Yuuhiko Tanabe, Jun Abe
    2023 Volume 39 Issue 2 Pages 69-76
    Published: 2023
    Released on J-STAGE: July 26, 2024
    JOURNAL FREE ACCESS

    Microalgae are phototrophic organisms ranging in size from a few to several tens of micrometers, so they are rarely observed in daily life. Nevertheless, they possess the potential to catalyze transformative changes in the global environment. Microalgae harness light energy, carbon dioxide, and water during photosynthesis to yield sugar, while generating starch, protein, and lipids via metabolic processes. Recent endeavors have focused on harnessing microalgae to produce valuable compounds such as carotenoids and fatty acids. Algal Bio Co., Ltd., which was established as a university-affiliated venture company in 2018, is dedicated to utilizing algae to address diverse societal challenges. Our commitment revolves around pursuing sustainable development across three core domains: health, food, and the environment. We are actively engaged in developing a "market-in" business model, which encompasses the utilization of a wide spectrum of microalgae species. We explore and cultivate microalgae to align with societal and customer demands, thus contributing to the advancement of production technology. To facilitate the global adoption of this business model, we are steadfastly working towards making Algal Bio's technology a cornerstone of clean tech worldwide through the establishment of an "algae platform," thus effectively addressing global societal issues through the innovative use of algae.

    Download PDF (15726K)
  • Fumi Mori, Yoko Tanaka, Ryo Matsuzaki, Hisayoshi Nozaki, Haruyo Yamagu ...
    2023 Volume 39 Issue 2 Pages 77-87
    Published: 2023
    Released on J-STAGE: July 26, 2024
    JOURNAL FREE ACCESS

    Multicellular members of the volvocine green algae represent a unique model lineage in which both sex evolution and multicellularity can be studied experimentally. However, with the exception of Gonium and Astrephomene, methods for cryopreservation of these algae have not been well evaluated. To establish cryopreserved culture strains of the multicellular volvocine algae, we investigated optimal cryopreservation conditions in eight multicellular genera without reproductive cell differentiation, Pandorina, Volvulina, Yamagishiella, Colemanosphaera, Eudorina, Platydorina, Basichlamys, and Tetrabaena. Survival rates by the most probable number (MPN) method were compared among three cryoprotectants [6% N,N-dimethylformamide (DMF), 3% hydroxyacetone, and 5% methanol] after 2 ml cryotubes containing actively growing vegetative colonies mixed with the cryoprotectant were subjected to two-step cooling and freezing in liquid nitrogen. We obtained ≥ 0.1% MPN survival for each of the eight genera when culture samples were subjected to cryogenic treatment with 6% DMF and/or 5% methanol. Using the optimized cryopreservation conditions obtained for each genus, 88 cryopreserved strains belonging to the eight genera were established in the Microbial Culture Collection at the National Institute for Environmental Studies (MCC-NIES).

    Download PDF (1152K)
  • Toyozo Sato, Ryoki Asano
    2023 Volume 39 Issue 2 Pages 89-94
    Published: 2023
    Released on J-STAGE: July 26, 2024
    JOURNAL FREE ACCESS

    The spoilage of rough rice with a musty odor occurred after harvest, drying and storage in an area of Niigata prefecture in 2020. Both surface sterilized and unsterilized husked rice and the rice hull were incubated on four kinds of agar media in darkness at 25℃ for 10-15 days to discover the microbes causing the odor. Although many fungi and several bacteria were isolated, they did not have a musty odor. In contrast, an actinomycete that ranged in color from pale yellow to white and with a powdery texture and a strong musty odor grew on unsterilized rice grains and hull pieces on water agar. The spoilage was reproduced by an inoculation with a representative isolate of the actinomycete on milled rice grains. The isolate grew up to 10 mm in diameter after being cultured on nutrient agar in darkness at 25℃ for 50 days. The surface side of the colony was conical and pale-yellow in color with radial wrinkles and a white frilled margin. The isolate produced abundant spiral spore chains from aerial hyphae. The cause of the musty odor of the rice was identified as a species of Streptomyces based on the properties of colonies, microscopic morphology, and the DNA sequence of the 16S rRNA gene. The spoilage in 2020 was assumed to be caused by rice plants often falling over before the harvest, and consequently the musty Streptomyces sp. appeared to contaminate the ears and propagate on rough rice.

    Download PDF (1854K)
  • [in Japanese]
    2023 Volume 39 Issue 2 Pages 95-97
    Published: 2023
    Released on J-STAGE: July 26, 2024
    JOURNAL RESTRICTED ACCESS
    Download PDF (4314K)
feedback
Top