Strain Gf398 is an improved methanol-tolerant mutant of Gluconobacter frateurii NBRC 103465. Comparative genome analysis of Gf398 and NBRC 103465 revealed 18 mutated genes as potentially related to the methanol tolerance of Gf398. These mutated genes included enzyme-related, cell membrane-associated, cellular maintenance, and hypothetical protein-encoding genes, as well as one regulatory gene (ompR). The methanol tolerances of a recombinant NBRC 103465 strain expressing mutated ompR and one expressing the wild-type ompR were compared; the mutant showed slightly better cell growth in 2% (v/v) methanol-containing glycerol medium.

In this study, we constructed a method for preparing microbial black-dirt model on a glass plate under laboratory condition. It clearly demonstrated that indigenous bacterial biofilms function as scaffolds for fungal spore adhesion followed by black-dirt formation by a fungus, Cladosporium halotolerans. This black-dirt model should be a useful tool not only for development of the methods for its prevention and removal but also for studying fungi-bacteria complex biofilm formation.