Culturing method for genus Rhizobium bacteria

A method for inhibiting an increase in viscosity of a culture solution of Rhizobium bacteria and improving viable cell count of the Rhizobium bacterium in the culture solution, the method comprising:

• culturing a Rhizobium bacterium by liquid culture using a medium comprising one or more carbon sources, wherein a disaccharide accounts for at least 25 mass % of the one or more carbon sources in the medium while maintaining a pH of 5.0 to 7.0 in a culture solution from a beginning of the culturing to an end of the culturing;
• and
• concentrating and/or separating viable bacteria from the culture solution,
• wherein the disaccharide is at least one selected from the group consisting of maltose, trehalose, and lactose, and
• wherein the Rhizobium bacterium is a Rhizobium vitis ARK-1 strain with accession number FERM BP-11426, a Rhizobium vitis ARK-2 strain with accession number FERM BP-11427, a Rhizobium vitis ARK-3 strain with accession number FERM BP-11428, or an Agrobacterium radiobacter K84 strain.

A method for inhibiting an increase in viscosity of a culture solution of Rhizobium bacteria,

• the method comprising culturing a Rhizobium bacterium by aeration-agitation culture using a medium comprising one or more carbon sources, wherein a disaccharide accounts for at least 25 mass % of the one or more carbon sources in the medium while maintaining a pH of 5.0 to 7.0 in a culture solution from a beginning of the culturing to an end of the culturing,
• wherein the disaccharide is at least one selected from the group consisting of maltose, trehalose, and lactose, and
• wherein the Rhizobium bacterium is a Rhzizobium vitis ARK-1 strain with accession number FERM BP-11426, a Rhizobium vitis ARK-2 strain with accession number FERM BP-11427, a Rhizobium vitis ARK-3 strain with accession number FERMI BP-11428, or an Agrobacterium radiobacter K84 strain,
• whereby, at the time of culturing a Rhizobium bacterium, and, at the time of isolating and recovering a viable cell thereof, the viscosity of culture solution of Rhizobium bacteria is maintained by inhibiting the increase in viscosity.