Journal of Pure and Applied MicrobiologyVol. 4 No. 2

Microaerophilic Magnetotactic Bacteria from Lonar Lake, India

Mahesh S. Chavadar and Shyam S. Bajekal

Department of Microbiology, Yashwantrao Chavan College of Science, Karad Vidyanagar, Karad– 415 124 , India.

Received on 19 February 2010 and accepted on 25 March 2010

 

ABSTRACT

Magnetotactic bacteria (MTB), the major constituents of natural microbial communities in sediments and chemically stratified water columns. The hallmark feature of MTB is the presence of unique, nanometer sized, intracellular inclusions the ‘magnetosomes’ that confers ‘magnetotaxis ’to these cells. The ‘magnetosomes’, the ‘magnetotaxis’ and the possible applications of these bacteria grown curiosity about the MTB. Presently they received the celebrity status, as MTB might be tool for searching extraterrestrial life. Lonar Lake is the only meteorite impact crater in the world formed basaltic rock. The closed basin lake has a unique environment characterized by high alkalinity and salinity. Evidences of magnetic activity in the surrounding rocks and soil are also found, and reported. The role of MTB in biomineralization encouraged us to find such bacteria in this unique environment. The sediments samples collected from the lake were used to isolate the microaerophilic magnetotactic bacteria (mMTB). The mMTB were enriched by ‘magnetic collection’ method, isolated by the ‘capillary racetrack’ (CRT) method and cultivated under microaerophilic conditions using a chemically defined medium. The three isolated mMTB showed were tested for response to the magnetic field using magnetic field in a ‘hanging drop’ under a microscope and also the on semisolid agar medium. They showed migration towards the South Pole of the magnet and precise alignment at the edge of the hanging drop. On semisolid agar also they showed migration toward magnetic South Pole. The intracellular iron content of the isolated mMTB cultures was measured using atomic absorption spectroscopy (AAS), which indirectly confirms the presence of magnetosomes in these the isolated MTB; similar result was obtained by R.P. Blakemore during discovery of MTB.

Keywords : Magnetosome, Magnetotaxis, Magnetic collection, Capillary race track method.