Two field experiments were executed during the seasons of 2012 and 2013 to test response of common bean to inoculation with rhizobia plus soil yeast strains Saccharomyce cerevisiae, Candida sake, Saccharomyces exiguous, Pichia membranifaciens and Cryptococcus lourentii. The results showed an the improvement of bean nodulation and plant growth parameters by the mixed inoculation treatments with Rhizobium plus the yeast strains. The highest improvement was recorded for yeast strain S. cerevisiae or S. exiguous. Inoculation with the yeast strain S. cerevisiae mixed with Rhizobium induced the following increases in nodule numbers, straw and seed yield: 51.94 %,10.92 % and 16.65 % in the firest season, and 50.94 %, 10.32 and 31.37 % in the second season, respectively over the inoculation with Rhizobium alone. The recorded enhancements are probably due to yeast hormonal production like indol acetic acid (IAA) on root growth and lateral roots leading to increased nodulation and nutrient uptake and subsequently increased yield. Also, by increasing mineral nutrients solubilization like phosphorous and iron.

Bacillus megaterium mutants selected after NTG treatments were evaluated for their efficiency in improving growth, p-uptake and Fe-uptake by tomato in greenhouse. Only five mutants out 1000 colonies were found to solubilize phosphates more than wild type strain on the basis of the solubilization index on Pikovskyaya's solid medium. They designed as M1, M2, M3, M4, M5 and their solubilization index were 2.56, 2.42, 2.28, 2.49 and 2.31, respectively. The highest phosphate solubilization index was recorded by mutant strain M1 compared with the wild type strain (2.13). The results show that all tested strains produced; in their cultures; organic substances that chelated iron in the calcareous soil. In greenhouse experiment the results showed that inoculation of tomato cultivar Super marmand with wild strain or mutant M1 with or without the addition of rock phosphate had a significant effect on shoot and root dry weights, p-uptake and Fe-uptake in shoot compared with uninoculated treatment (control), or amended with rock phosphate alone. Similar results were recorded with Burchard cultivar, but in general, the cultivar Super marmand was more responsive to wild type and mutant M1 inoculation than the cultivar Burchard. Application of both mutant and rock phosphate resulted in the highest availability of P and Fe in the soil, resulted in increases about 26 % in P and 36 % in Fe as compared to control

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