The Madre de Dios region in southeastern Peru, known for its biological and cultural diversity, is threatened by alluvial gold mining, which has led to deforestation and ecosystem degradation. This article focuses on the nodulation capacity of symbiotic nitrogen-fixing bacteria in the plant Stylosanthes guianensis in areas degraded by alluvial gold mining in Madre de Dios. The objectives were to characterize bacterial strains, evaluate their nodulation capacity and their influence on plant growth in mining substrate. The results indicate that the inoculation of these bacteria had a positive impact on the development of S. guianensis, promoting growth and the formation of effective nodules in all test conditions. In addition, it was observed that the slow-growing strains in vitro had a more beneficial effect on plant growth than the fast-growing strains. These findings suggest that inoculation of nitrogen-fixing bacteria may be an effective strategy for the restoration of degraded areas, highlighting the importance of symbiosis between these bacteria and the plant in the recovery of degraded ecosystems, and raises the need for further research to better understand the species involved in biological nitrogen fixation and to determine the best inoculants to increase forage yields of S. guianensis.