## 4 Discussion
Such a personalised approach takes into account specific patterns of dysbiosis associated with individual patients and their unique disease characteristics and focuses on targeted and more effective therapeutic interventions. Many studies [38,39] analysed the microbial profile of donors and made an effort to relate it to the clinical and laboratory results of patients with UC. The obtained clinical results and immunological changes following the FMT therapy in patients with UC were significantly related to variations in several specific strains in faecal microbiota recipients [38,39]. For example, the study that included patientswith refractory UC who were subjected to preliminary antibiotic treatment followed by repeated FMT treatment with a transplant exhibiting high bacterial abundance and high relative proportion of species _AKERmansia muciniphila_, non-classified Ruminococcaceae, and _Ruminococcus_ spp., revealed a higher probability of induction of remission in comparison with therapy by antibiotics alone [40,41]. [PERSON] et al. [42] conducted metagenomics and metabolomics analyses of patients and found out that the patients in remission after FMT showed increased counts of _Eubacterium hallii_ and _Roseburia involurans_ and increased levels of biosynthesis of short-chain fatty acids (SCFAs) and secondary biliary acids. These results indicated the importance of the diversity of donor's microbiota for the effectiveness of FMT treatment. Presumably, just as described in the studies by some authors [41,43], the selection of donors based on taxonomic composition of their intestinal microbiota, particularly low or high abundance of specific strains, could become a subject of future studies involving treatment of UC or CD. These results indicate the importance of thorough inspection of each transplant of donor's faecal microbiota by complex analysis including NGS analysis and various laboratory tests. Such analyses effectively define bacterial composition, identify harmful bacteria, and accurately determine genes resistant to medicaments. These strict analyses should be consistently carried out within each FMT procedure [44]. When looking for the rational approach to FMT preparation, the common assumption is to obtain an FMT product that captures the maximum amount of microbiota from the fresh stool of a healthy donor. Consequently, the majority of studies aimed at developing FMT production methods focus on processes that minimise the reduction in bacterial viability or diversity [45]. In the process of confirmation of standard quality of the prepared FMT it is important to select correct method for determination of viability of faecal microbiota. Characterisation of the composition of microbiome in the processed material obtained from FMT donor is not always performed, or the investigations are usually based on NGS analyses [46]. These analyses are based on detection of DNA derived from viable and non-viable organisms, and thus they cannot accurately indicate which bacteria in the recipient are viable and capable of replication. A number of studies investigated the viability of bacteria present in fresh forms of FMT subjected to various processes [47, 48, 49, 50], but only a few of them referred to their stability in storage [47,51]. In the second stage of our experiments, we investigated the viability of microbiota in the frozen and lyophilised administration form of FMT from a healthy donor stored under various conditions. During the period of 9 months, we investigated frozen faecal material at \(-70\)\({}^{\circ}\)C, and lyophilised faecal material stored at \(-70\)\({}^{\circ}\)C, 4 \({}^{\circ}\)C, and 20 \({}^{\circ}\)C. An important factor affecting the viability of bacteria is the methodical procedure used for processing of FMT. Many bacteria found in the large intestine, that seem to be associated with positive results at CD and UC therapy, such as _Faecalibacterium prausnitzii_, are strict anaerobes that may be reduced by aerobic processing of FMT [52].