The present research had as its main objective to learn about the microbiological composition of rhizosferes from several mountain crops: coffee (Coffea arabica L.), banana (Musa sapientum), yam (Dioscorea alata), malanga (Xantosoma sagitifolium,), higuereta (Ricinus communis) and cocoa (Theobroma cocao L.), in a brown soil with carbonates to find out if any of these habitats could become microbial sources for the isolation of bacterial inoculants for biofertilizer production. Also, to study the in vitro efficiency of 18 phosphorous-solubilizing strains isolated from rhizospheric soils in two culture media, Pikovskaya and Ramos-Callao, and, lastly, to study the influence of biofertilizers prepared from strains indigenous to Sabaneta, Municipality of El Salvador, Guantanamo Province, Cuba, in tomato (Lycopersicum sculentum Mill.) and cucumber (Cucumis sativus). Rhizospheres that were microbiologically abundant were those originating from banana and coffee. From the study on in vitro efficacy, the most efficient phosphorous-solubilizing strains in both culture media used were Sabaneta 27-1 (Sab 27-1) and Sabaneta 28-1 (Sab 28-1), which we recommended for its application in the aforementioned mountains under natural conditions. The most effective strain in tomato was Sab 28-1, and, under these same conditions, the most efficient strains were Sab 28-1 and the symbiotic nitrogen-fixing strain Sab-27 for cucumber.