In this study, muscle protein gel-formation during fermentation by lactic acid bacteria at 4℃ was investigated using myofibrillar protein as a model gelation system. Protein fermentation by the two strains of psychrotrophic lactic acid bacteria Lactobacillus sakei D-1001 and Lactobacillus sakei No. 4 was performed at 4℃. Physical properties and microstructure of gels were examined after treatment at 70℃ for 30 min. Both myofibrillar protein gels showed higher gel strength and syneresis rate than non-fermented gels. Whereas protein distributions did not significantly differ between fermented and non-fermented gels, a finer strand-like microstructure was more apparent in fermented gels.