Abstract: A method is described for producing an L-amino acid or a nucleic acid by culturing a microorganism having an ability to produce the L-amino acid or nucleic acid in a liquid medium in a fermentation tank containing a stirring impeller, and optionally adding seed crystals to the medium as required to produce and accumulate crystals of the L-amino acid or nucleic acid in the medium, and collecting crystals of the L-amino acid or nucleic acid from the culture. The power density of the stirring impeller is controlled to be 2.4 kW/m3 or lower after either precipitation of the crystals or addition of the seed crystals.

Abstract: A method is described for producing an L-amino acid or a nucleic acid by culturing a microorganism having an ability to produce the L-amino acid or nucleic acid in a liquid medium in a fermentation tank containing a stirring impeller, and optionally adding seed crystals to the medium as required to produce and accumulate crystals of the L-amino acid or nucleic acid in the medium, and collecting crystals of the L-amino acid or nucleic acid from the culture. The power density of the stirring impeller is controlled to be 2.4 kW/m3 or lower after either precipitation of the crystals or addition of the seed crystals.

Abstract: A coryneform bacterium which has enhanced intracellular pyruvate carboxylase activity obtained by increasing copy number of a gene encoding the intracellular pyruvate carboxylase, or by enhancing function of a expression regulatory sequence for the gene, and has L-glutamic acid-producing ability is cultured in a medium so that L-glutamic acid should be produced and accumulated in the culture, and L-glutamic acid is collected from the culture.

Abstract: L-serine is produced by cultivating in a medium a coryneform bacterium having L-serine productivity in which an activity of at least one of phosphoserine phosphatase and phosphoserine transaminase is enhanced, preferably, further having introduced therein a gene coding for D-3-phosophoglycerate dehydrogenase in which feedback inhibition by L-serine is desensitizied, allowing L-serine to accumulate in the medium, and collecting the L-serine from the medium.

Abstract: A coryneform bacterium which has enhanced intracellular pyruvate carboxylase activity obtained by increasing copy number of a gene encoding the intracellular pyruvate carboxylase, or by enhancing function of a expression regulatory sequence for the gene, and has L-glutamic acid-producing ability is cultured in a medium so that L-glutamic acid should be produced and accumulated in the culture, and L-glutamic acid is collected from the culture.

Abstract: Disclosed is a coryneform bacterium having resistance to azaserine or &bgr;-(2-thienyl)-DL-alanine and having L-serine productivity.

Abstract: Disclosed is a coryneform bacterium having resistance to azaserine or &bgr;-(2-thienyl)-DL-alanine and having L-serine productivity.

Abstract: L-serine is produced by cultivating in a medium a coryneform bacterium having L-serine productivity in which an activity of at least one of phosphoserine phosphatase and phosphoserine transaminase is enhanced, preferably, further having introduced therein a gene coding for D-3-phosophoglycerate dehydrogenase in which feedback inhibition by L-serine is desensitized, allowing L-serine to accumulate in the medium, and collecting the L-serine from the medium.