Fibroin-like protein production method

A method for producing a fibroin-like protein, the method comprising:

• (A) culturing an Escherichia coli bacterium having a gene encoding the fibroin-like protein in a culture medium;
• (B) inducing expression of the gene encoding the fibroin-like protein;
• (C) after said inducing, a feed medium is added to said culture medium, wherein said feed medium comprises a reduced amount of or no growth factor, resulting in reduced cell proliferation;
• and
• (D) collecting the fibroin-like protein;
• wherein said reduced amount of the growth factor with respect to all ingredients in said feed medium is less than 30% (w/w),
• wherein in step (C), said reduced cell proliferation results in cumulative specific proliferation rate of 0.070 (/h) or lower,
• wherein the fibroin-like protein comprises:
• (a) a fibroin;
• or
• (b) a fibrous protein having a sequence similar to a repetitive sequence of a fibroin,
• wherein the sequence similar to a repetitive sequence of a fibroin is a sequence represented by the following formula (I),
• REP1−REP2 (I)
• wherein the protein (b) has the sequence represented by the formula (I) at the repetition number of 2 or more,
• wherein, independently for each repetition, the REP1 is an amino acid sequence consisting of a continuous sequence of one or more of the amino acids alanine and glycine, and the length of the REP1 is 2 to 20 residues, and
• wherein, independently for each repetition, the REP2 is an amino acid sequence comprising one or more of the amino acids glycine, serine, glutamine, and alanine, the total number of glycine, serine, glutamine, and alanine residues is 40% or more of the total number of amino acid residues of the REP2, and the length of the REP2 is 2 to 200 residues.