Abstract: In order to study the effect of heat stress on the inner membrane proteins of Clostridium perfringens spores, the physicochemcial changes in the inner membrane proteins after heat treatment at different temperatures (25, 37, 75 or 95 ℃) for 20 minutes were characterized by measuring particle size distribution, surface hydrophobicity, ultraviolet absorption spectrum, endogenous fluorescence spectrum and Raman spectrum. The results showed that heating temperature had a significant effect on C. perfringens spore inner membrane proteins. Compared with the control group (treated at 25 ℃), treatment at 37 ℃ had no significant effect on the inner membrane proteins, and did not cause any significant changes in the particle size distribution, amino acid microenvironment, surface hydrophobicity or secondary structure. After heat stress at 75 ℃, the particle size distribution was uniform and stable, the UV absorption and fluorescence intensity was significantly enhanced, and the surface hydrophobicity was significantly increased. The percentage of α-helix decreased by 3.17%, the percentage of β-sheet decreased by 3.94%, and the proportion of random coil increased by 8.31%. After heat stress at 95 ℃, the proteins’ structure was damaged, the proteins were obviously aggregated or denatured, and the particle size distribution moved significantly to larger particle size. The above results indicated that heat stress at 75 ℃ could effectively affect the physicochemical properties of C. perfringens spore inner membrane proteins, leading to the exposure of hydrophobic sites and amino acid residues and significant secondary structural changes. This study provides a theoretical basis for further research on the effect of heat stress on the functional properties of C. perfringens spore inner membrane proteins.

Key words: Clostridium perfringens; heat stress; spore; inner membrane proteins; structure