Recently, the deteriorated soil areas are growing dramatically in Algeria. The application of microorganisms to these areas in order to restore them is extremely beneficial. Thus, the aim of this project was to use yeasts to exploit their metabolites to promote plant growth and stimulate their micro-symbionts. This little-studied role in yeasts, particularly in Algeria, is very interesting and can be exploited with other microorganisms in the revegetation of degraded sites. Various yeast strains have been isolated from legume soil since the plant used is a legume whose production is encountering many difficulties. Yeast strains were then selected to study their effect on micro-symbionts, namely rhizobia and mycorrhizae and their effect on plant growth by evaluating their growth, rate of mycorrhization and dry weight, respectively. The results obtained underlined a significant impact on the growth of rhizobia, particularly with Rhodotorula mucilaginosa LSF2, and on mycorrhization by improving its frequency and intensity where the best result was obtained with Debaryomyces hansenii LSF1. In addition to this indirect effect, a direct effect on the plant was revealed following the various inoculations conducted using the selected yeasts and the reference strain Saccharomyces cerevisiae, which were be able to increase the biomass of the plant. This finding is interesting because it not only clarifies the role of yeasts but also provides an opportunity for their application in different fields through simple or mixed inoculation with other biofertilizers.