Cryopreservation of the human gut microbiota: Current state and perspectives

The human intestinal microbiota is a complex ecosystem that consists of thousands of bacterial species that are responsible for human health and disease. The intestinal microbiota is a natural resource for production of therapeutic and preventive medicals, such as probiotics and fecal transplants. Modern lifestyles have resulted in the extinction of evolutionally selected microbial populations upon exposure to environmental factors. Therefore, it is very important to preserve the human gut microbiota to have the opportunity for timely restoration with minimal safety risks. Cryopreservation techniques that are suitable for the preservation of viable, mixed microbial communities and a biobanking approach are currently under development in different countries. However, the number of studies in this area is very limited. The variety of morphological and physiological characteristics of microbes in the microbiota, the different cryopreservation goals, and the criteria for the evaluation of cryopreservation effectiveness are the main challenges in the creation of a universal and standardized cryopreservation protocol. In this review, we summarized the current progress of the main cryopreservation techniques for gut microbiota communities and the methods for the assessment of the effectiveness of these techniques in the context of practical application.