The present invention relates to a novel obligately symbiotic thermophile Symbiobacterium toebii SC-1(Accession NO: KCTC 0685BP), and a thermostable L-tyrosine phenol-lyase and L-tryptophan indole-lyase produced by Symbiobacterium toebii SC-1. The present invention also relates to a pure culture method of Symbiobacterium toebii SC-1, a method of growth measurement for Symbiobacterium toebu SC-1 and its relative symbiotic bacteria showing low-growth yield using nitrate respiration, and a screening method of relative symbiotic strains of Symbiobacterium toebii SC-1 from the environment using a specific antibody to it. Therefore, the thermostable L-tyrosine phenol-lyase and L-tryptophan indole-lyase produced by Symbiobacterium toebii SC-1 in this invention can provide more stable catalysts in enzymatic biotransformation processes which enzymatically produce valuable medico-amino acids 3,4-dehydroxy-L-phenylalanine (L-DOPA) and L-tryptophan.