Thirteen microbial isolates were evaluated for green synthesis of Mg and Mn nanoparticles. The isolates were come from soil and wastewater samples from detergent processing industry. Metallotolerance ability of isolates was assessed towards these metals. Bacterial isolate B4 Mg/W was selected as highly extremo-tolerant for Mg+2 and can grow between 800 to 15000ppm (80-1500%)and was identified as Pseudomonas stutzeri, B4 Mg/W. Fungal isolate F4 Mn/ S was selected as extremo-tolerant for Mn+2 and grow in the range 800 to 45000ppm (80-4500%) and was identified as Fusarium nygamai, F4 Mn/ S. Biosynthesis of the Mg and Mn nanoparticles was achieved in both cases extracellular and intracellular. The nanoparticles were characterized using atomic absorption spectrophotometer (AAS), dynamic light scattering (DLS) and transmission electron microscope (TEM). Pseudomonas stutzeri, B4 Mg/W nanoparticle size was ranges from (229.3-553.2 nm) with different mean number for each size, the maximum mean number 33.7% was that of the particles with size 356.2 r. nm and atomic absorption spectrophotometer (AAS) revealed uptake percentage of the metal was 35.17%. Fusarium nygamai, F4 Mn/ S nanoparticles ranges from (61.21-127.5 to 412.5 nm) with different mean numbers for each size, the maximum mean number 23.1% was that of the particle size 82.09 nm and range from 23.1 to 28.1 % and AAS was 27.07%. Antimicrobial activity against Streptococcus pyogenes RCMB010015, 31.25 and 62.5 mm followed by Candida albicans RCMB05035, 15.63 and 62.5; then Staphylococcus aureus RCMB010027 and Eschericia coli RCMB010056 gave7.81and 62.5mm for both; while for Aspergillus fumigates RCMB02564 gave the least amount of inhibition 1.95 and 15.63mm; moreover Pseudomonas aeruginosa RCMB010043 was very resistant for both Pseudomonas stutzeri, B4 Mg/W and Fusarium nygamai, F4 Mn/S inracellular nanoparticles, respectively.