A transformant is prepared by introducing into a coryneform a DNA fragment containing a gene coding for a novel cell cortex protein originating in Brevibacterium lactofermentum and having the following two sequences in its molcule and a molecular weight of about 63,000 D: (1) Thr-Leu-Arg-Gln-His-Tyr-Ser-Ser-Leu-Ile-Pro-Asn-Leu-Phe-Ile-Ala-Ala-Val-Gly-Asn-Ile-Asn-Glu-Leu-Asn-Asn-Ala-Asp-Gln-Ala-Ala-Arg-Glu-Leu-Phe-Leu-Asp-Trp-Asp-Thr, (2) Asn-Lys-Thr-Asp-Phe-Ala-Glu-Ile-Glu-Leu-Tyr-Asp-Val-Leu-Tyr-Thr-Asp-Ala-Asp-Ile-Ser-Gly-Asp-Ala-Pro-Leu-Leu-Ala-Pro-Ala-Tyr-Lys. This transformant or a strain deficient in the novel cell cortex protein, which has been newly prepared, is used for producing valuable substances including L-amino acids by the L-amino acid fermentation method.
