Identification and enrichment of anaerobic digestion consortia was performed towards the construction of an advanced composite bioaugmentation inocula. Batch acclimatisation experiments were performed at lab scale to develop hydrolytic and methanogenic consortia. Ammonia-tolerant methanogens were successfully acclimatised and enriched (≥5 g/L NH4+-N). Targeted strategies were implemented with stepwise additions of artificial ammonia sources such as ammonium chloride and consecutive/sequential inoculations for the next acclimatisation step. Different growth parameters (i.e., methane production, VFA levels, pH, maximum growth rate, etc.) were used in order to evaluate the performance and robustness of the enriched cultures to identify the optimal cultures under high lignocellulose or ammonia conditions. However, the initial hydrolytic bacteria acclimatisation experiments were not conclusive, and thus, known strains of well-performed hydrolytic bacteria from DSMZ were ordered (contingency plan) to be used for the upcoming hydrolysis experiments.
Next steps include the implementation of lyophilisation experiments with varying parameters to evaluate and develop an optimum lyophilisation method for the consortia. For methanogenic consortia and hydrolytic bacteria, lyophilisation provides a way to preserve these microbial communities while maintaining their viability and functionality (lyophilised composite inocula) through individual steps (Pre-preservation growth, Lyophilisation, Rehydration. Developing an optimal lyophilisation method ensures that these microorganisms can be stored long-term without significant loss of activity or adaptability, enabling further application opportunities.