Encapsulation of Trichoderma reesei and Neurospora crassa in calcium alginate capsules for fungi-mediated self-healing concrete: An explorative study on the protocol, survival of the organisms and CaCO3 biomineralization

Concrete, a predominant building material, is known for its material degradation due to crack formation. The associated durability concerns initiated the use of microorganisms to self-heal concrete cracks by promoting CaCO3 precipitation on their cell walls. Filamentous fungi grow in mycelial networks that provide abundant nucleation sites for the precipitation. As demonstrated by the research on bacteria, protection of the microorganism in the concrete mix is crucial to safeguard its survival. In this work, an encapsulation method based on sodium alginate and calcium lactate was identified in the bacteria-based literature and adapted to the fungi Trichoderma reesei and Neurospora crassa. Results showed spore survival after the encapsulation procedure, however survival was negated when immersed in concrete-relevant conditions. Simultaneously, biomass formation and CaCO3 biomineralization were quantified in liquid media. This study features possibilities to optimize the encapsulation procedure and aids the identification of optimal biomineralization conditions.