ALGAESOL - D3.2 - Microbial contamination control strategies - V1

Deliverable D3.2 outlines strategies for detecting and controlling microbial contamination in Chlorella sorokiniana closed cultivation systems, developed within the ALGAESOL project. Routine monitoring using light microscopy and flow cytometry was identified as the most effective approach, combining qualitative and quantitative detection of contaminants such as bacteria, protozoa, and ciliates. For sterilization, laboratory-scale autoclaving is reliable, while multi-stage filtration is preferred for large volumes or media containing organic components. Despite rigorous sterilization, ciliate contamination remains a challenge, especially at pilot scale. Initial attempts to isolate and study ciliates were hampered by culture loss, but reference strains have been acquired for ongoing research. The strategies presented here are practical and scalable, and further optimization will focus on industrial application and validation in pilot photobioreactors.