PURPOSE: To produce an L-amino acid in high efficiency from N-carbamoylamino acid having high concentration, by using Alcaligenes NS 540 stain and performing a reaction in an alkaline region in which the solubility of N- carbamoylamino acid increases.

CONSTITUTION: The objective Alcaligenes sp NS 520 (FERM P-9544) is a Gram- negative bacillus having locomotivity, positive to catalase, positive to oxidase, free from acid fastness, free from sporulation, having aerobic nature, non- fermentative in OF test and negative to VP reaction and arginine decomposition activity, etc. An L-amino acid is produced by culturing said NS 540 strain in a medium containing carbon source, nitrogen source, inorganic salt, etc., at pH5W10 and 10W35°C for 1W3 days and reacting N-carbamoylamino acid of 1W20% concentration with the obtained cultured product as an enzyme source at pH8W10 and 15W50°C. The reaction liquid is preferably added with 0.1W10mM of manganese sulfate, cobalt chloride, etc.