Kokushu (sake, shochu, and awamori), an alcohol of Japanese origin, is traditionally brewed from rice and other materials. It is brewed by saccharification of koji and alcoholic fermentation of yeast. Since the 19th century, many strains of yeast have been isolated and studied taxonomically for kokushu brewing. Since the book “The yeasts, a taxonomic study” was published in 1952, all the original names assigned to these yeast strains are the synonym of Saccharomyces cerevisiae. Nonetheless, kokushu can be fermented exclusively by specific kokushu yeast strains. To confirm this, 96yeast strains were collected, taxonomically characterized, and used for comparison with other strains of the genus Saccharomyces. Then, seven tests were performed as described as “Key to species” of the book “The yeasts, a taxonomic study (5th ed.)” most of the kokushu yeast strains formed a homogeneous cluster and were separated from other species of the genus Saccharomyces. Of the 96 kokushu yeast strains that were studied and grown on vitamin-free medium, growth difference from Saccharomyces cerevisiae was observed in 90 strains. These results showed that kokushu yeast strains are unique in their phenotypic characteristics; thus, more information can be obtained from these strains for taxonomic studies on genomics and selection of yeast strains possessing specificity for kokushu brewing.

Cellulolytic myxobacteria cultured using filter paper as the only carbon source were isolated from soils in Japan. To purify isolated strains, fruiting bodies of cellulolytic myxobacteria formed on Stanier agar medium were incubated at 60℃ for 1-7 days and/or at room temperature for 3-6 months. Purified 120 strains were cultured in P- and E-liquid media for 4-6 weeks at 28℃. Approximately 75% of the strains were found to produce metabolites with antimicrobial activity, and 63% of extracts showed growth inhibitory activity against Aspergillus niger. Based on LC-MS analysis, we estimated that 34 known natural products of the genus Sorangium were produced by 100 isolates, including spirodienal, ambruticin, disorazole, and epothilone. Also, many products whose molecular weights did not match those of known products from the genus Sorangium were detected.

Oomycetes are difficult to preserve in culture using ordinary slow freezing on agar disks. Here we tested a vitrification method as an alternative approach for long-term preservation of oomycete strains. Selected seeds were used as a culture substrate before preservation at ultra-low temperature. Rape or sesame seeds were inoculated with oomycete strains, then vitrified and cryopreserved in liquid nitrogen. Thirteen out of 20 strains tested were successfully revived from the cryopreserved infested seeds with a viability of >50%. Viability was better on sesame seeds than on rape seeds. The possibility of cryopreservation using seeds was also investigated for the ordinary slow freezing method. Though viability was not stable among the conditions tested and varied among isolates, the oomycete strains examined were well preserved and showed higher viability when seeds were used rather than agar-culture disks. Also, when infested seeds were used, viability was higher for the slow freezing method than for the vitrification method in most cases. These results suggest that seeds after infestation can be a useful substrate for long-term cryopreservation of oomycetes.