Mechanical Analysis of the Injury of Spores by Reciprocal Pressurization

Abstract

Mechanical analysis of injury of spores of B. subtilis by quick decompression was investigated. The stress on the stress concentration point of germinated spores under 200, 300 and 400 MPa treatment was calculated to be 800 MPa, 1200 MPa and 1600 MPa, respectively, where this point was the highest point of stress concentration on the sporecoat. The stress showed values 4 times larger than treatment pressure. Sporecoat is a keratin-like scleroprotein. The tensile strengths of some polymers were 70 MPa (polyester), 50 MPa (vinyl chloride), 70 MPa (nylon) and 20 MPa (polyethylene). From stress analysis, minimum stress of the spore model on the stress concentration point (800 MPa) was higher than the tensile strength of the above polymers. It was indicated that the sporecoat is disrupted by the stresses produced by expansion of inner-spore-water with quick decompression.