Waste tire rubbers accumulation for disposal is a considerable environmental challenge in many countries. These solid wastes contain sulfur, zinc oxide, stearic acid, carbon black, proprietary additives, and bead wires. An emerging safe technology under consideration for recycling waste tire rubbers is their use as an effective and safe fertilizer source for supplying Zn with no risk of Cd contamination in agricultural lands. Bacterial inoculation of ground rubber has been shown to be effective in hastening degradation of rubber and increase in DTPA-extractable Zn in calcareous soil. In the first part of the present study (batch experiment), for the first time, we evaluated the ability of Pseudomonas putida and different strains of Thiobacillus alone or in combination with rubber-detoxifying bacteria ( Rhodococcus erythropolis and Acinobacter calcoaceticus ) in degradation of tire rubber and Zn release into the soil. In the second part of the study (pot experiment), the effect of endophytic symbiosis on hastening Zn release from tire rubber into the soil and its uptake by plant was investigated. Two rates of ground tire rubber (0 and 200 mg kg -1 ) (2.0 mg Zn kg -1 ) were incorporated into a Zn-deficient calcareous soil. Before addition to the soil, the rubber samples were given 24 microbial treatments including: No Inoc (no microbial inoculation), Af ( A. ferrooxidans TCC 1647), Tt, ( T. thioparus TCC 1668), Mt (a mix of Thiobacillus strains), P1 ( P. putida P41), P2 ( P. putida P168), RA ( R. erythropolis TCC hyhy; 1767 + A. calcoaceticus PTCC 1318), P1+Af, P1+Tt, P1+Mt, P2+Af, P2+Tt, P2+Mt, RA+Af, RA+Tt, RA+Mt, RA+P1, RA+P2, RA+P1+Af, RA+P1+Tt, RA+P1+Mt, RA+P2+Af, RA+P2+Tt and RA+P2+Mt. Soil pH and DTPA-extractable Zn and Fe concentrations were measured at weeks 1, 3, 6, and 10. All microbial treatments significantly reduced soil pH at week 3; although this reduction was greatest at the RA+P2+Mt treatment. In the presence of tire rubber, soil pH at week 10 was still significantly lower than the initial soil pH. At the microbial inoculated-rubber treatments, available Fe concentration was increased up to week 3 and thereafter it was decreased; although soil DTPA-Fe concentration was still higher than the initial concentration of this metal in soil. The RA+P2+Mt and RA+P2+Tt were the most effective bacteria treatments in increasing the availability of Fe in tire rubber-treated soil. With tire rubber, soil DTPA-Zn concentration increased until week 6 and then remained unchanged or slightly reduced at week 10. With application of ground tire rubber, greatest increase in DTPA-extractable Zn concentration was found at the presence of RA microbial treatment. By using cluster analysis, microbial inoculation treatments were classified into 8 groups based on soil pH and concentrations of Fe and Zn. Group 8, produced the lowest pH and the highest DTPA- extractable concentrations of Fe (on average 6.92 mg kg -1 ) and Zn (on average 2.67 mg kg -1 ). In the first pot experiment, roots of one bread ( Triticum aestivum cv. Roshan) and one durum wheat cultivars ( Triticum durum cv. Durum) were inoculated or non-inoculated with Piriformospora indica fungal endophytes and were exposed to two rates of ground rubber (0 and 284 mg kg -1 ) or 15 mg kg -1 ZnSO 4 . Before addition to the soil, ground rubber and ZnSO 4 were inoculated or non-inoculated with RA and RA+P1+Tt. Application of tire rubber into the soil, increased shoot dry mass of wheat cultivars over the commercial Zn-sulfate. Microbial inoculation of ground tire rubber resulted in significant increase of shoot growth and Zn content of both wheat cultivars. In the second pot experiment, two genotypes of Festuca ( arundinacea cvs. 75b and 75c) were with or without endophytic fungi ( Neotyphodium sp.) and RA+P2+Mt. Application of microbial inoculated tire rubber resulted in increase of shoot and root dry matter yield of Festuca plants. According to the results obtained, the RA and RA+P1+Tt were most effective microbial treatments in hastening increase in DTPA-extractable Zn and in enhancing Zn uptake by wheat plants while P2 and RA+P2+Mt were most effective treatments in hastening decrease in soil pH and increase in Fe concentration.