Characterization of magnetotactic bacteria (MTBs) isolated from different habitats in Egypt

The aim of this work is the characterization of some efficient magnetotactic bacterial strains (MTBs) were isolated from different iron contaminated sites. A total of 21 MTBs cultures were from sewage sludge specimen (8 isolates), iron-contaminated agricultural soil (10 isolates) and (3 isolates) from water wells. Twelve bacterial isolates show a magnetic response individually to the applied external magnetic stimulus by the two methods either microscopic or semi solid plate technique. Three distinguished morphologies of MTB (cocci, large slow moving rods and small actively moving rods) out of 21 isolates were dominant. From anaerobiosis selection step only 8 isolates show the ability to grow in sodium sulfide plates. TEM analysis revealed that these bacterial isolates contained numerous mineral crystals similar to magnetosomes. From the previous successive purification steps only one isolates showed the best iron uptake as the iron concentration was completely consumed from the medium during the growth period, as and cell biomass productivity (OD600: 0.229). Based on their morphological and microscopy characteristics as well as 16S rRNA genes sequence analysis, the isolate was identified as Pseudomonas aeruginosa.