The global increase in obesity has significant health implications, with an increased BMI as a known risk factor for diseases such as type 2 diabetes, cardiovascular diseases, or different cancer types. Long-term effectiveness of diet therapy in addressing morbid obesity is extremely limited with no adequate pharmaceutical agents available as treatment option resulting in bariatric surgery as being the only viable option to achieve and maintain significant long-term weight loss. One important role in the overall human health plays the gut microbiome and its complex composition, which is usually altered and reduced in complexity/diversity in severely obese patients. In this study, the influence of bariatric surgery and the resulting weight-loss on the gut microbiome composition of twelve morbid obese (BMI ≥ 40) female adult central European patients was investigated by comparing the relative abundances of the major microbial phyla Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria prior- and post-surgery. We also aimed to give insight into the major changes of individual prominent and promising future probiotic bacteria characterized by an overall increase in abundance accompanied by a switch of enterotypes. Identifying specific microbial alterations associated with successful weight-loss outcomes may contribute to the development of future therapeutic interventions by supplementation with next-generation probiotics.