CRYOPRESERVATION AND REVITALIZATION OF MICROBIAL CONSORTIA ISOLATED FROM APULIAN TABLE OLIVES

Background and Aims The ex-situ preservation of microbial resources as pure cultures in specific microbial Biological Research Centres (mBRCs) is crucial to ensure scientificresearch and promote biotechnological innovation. However, in light of the interest in microbiomes, studying how to preserve complex microbialcommunities in mBRCs becomes fundamental. In the food sector, microbial communities and microbiomes represent treatable model systems formicrobial ecology studies and bioresources to support fermentation processes and improve the sustainability, quality and safety of food products. Methods Within the SUS-MIRRI.IT project, this study aims to preserve the microbiota from typical Apulian table olives cv Leccino , and to evaluate the effectivenessof a cryopreservation protocol by using glycerol and DMSO as cryoprotectants and a storage temperature of -135 °C. The microbial population wasstudied before and after short and mid-term storage using a culture-dependent approach, RNA-based metabarcoding analysis, and metabolic profilingevaluation. Furthermore, a revitalization protocol of the stored microbial consortia has been tested to define appropriate methodologies to propagate thepreserved microbiome after cryopreservation. Results Results indicated that after one and six months of cryopreservation, the viability of the microbial consortium slightly decreased regardless of thecryoprotectant used. No significant changes in the metabolic profile were observed, except for γ-Amino Butyric acid. Also, the metabarcoding analysisshowed no significant differences in relative aboundances after storing periods. Conclusions Results confirmed the proper preservation of the microbial consortium and its functionality after a short and mid-term storage period and pointed outpreliminary insights on the possibility of exploiting them in fermenting processes after cryopreservation.