**7. Conclusion**

Fermented milks especially which use intestinal microflora, known as probiotic cultures link to many aspects of host health. Dairy-based matrix is suitable for proliferation of probiotics due to supplying a rich source of carbon and essential amino acids as a consequence of lactose hydrolyzing and proteolytic systems involved casein utilization. However, we still have limited understanding within the mechanisms involved in these systems, particularly with regard to colonization resistance. Despite a lot of research to date, many questions still remain as to how the modulations of the microflora are able to offer benefits for the host in either good health or illness. Knowledge of its composition and activities are central to this, as is a better understanding of how influence the toleration of microflora. Colonization of the gut may not be an absolute necessity since the healthy host influence the toleration of the strain becoming tolerant, thereby removing its immunological capacity to be a probiotic. Since different probiotic strains are known to have different immunological and microbiological properties, molecular studies should enable specific components of bacterial phenotype, and so identify strains that can benefit the host with diarrhea or inflammatory diseases as well as their role to fight Covid-19.

*Fermentation - Processes, Benefits and Risks*
