Resemblance of Immobilized Trichoderma viride Fungal Spores in an Alginate Matrix to a Composite Material

Trichoderma uiride fungal spores were immobilized in alginate gels. The mechanical properties of these gels were tested by compression using a universal testing machine. The properties of the immobilized preparations are presented in terms of their corrected stress at failure, Hencky's strain at failure, and the modulus of deformability. Results are also presented as the ratio between mechanical properties of gels with or without microorganisms, and the occupied volume of the tested gel. A simple mathematical model for composite materials was found to properly describe the relative stress at failure vs the phase volume of the fungal spores. Random loose packing of the spores in the matrix is proposed.