Digital holographic interferometric in-vitro imaging of Escherichia coli (E. coli) bacteria

Escherichia coli (E. coli), a micro size, hazardous bacteria which is responsible for various life-threatening diseases in animals and humans. Generally, E. coli bacteria can be found naturally in the animals and human intestinal tracts which provide necessary synthesis of vitamins. However, E. coli O157:H7 is one of the most dangerous pathogenic strain which produces toxins. E. coli contaminate in number of drinks and food products. Hence early identification and treatment of E. coli O157:H7 is very necessary in order to prevent various diseases. In this work, Digital Holographic Interferometric Microscopy (DHIM) system is used for non-destructive, in-vitro imaging of E. coli bacteria. The major advantage of using the DHIM over the conventional microscopy is that in DHIM both amplitude and phase coming from the specimen can be reconstructed from recorded hologram. It provides three dimensional information of the specimen under test. In DHIM system distortions due to the aberrations are minimized by the interferometric comparison of reconstructed phase with and without the object. The phase reconstruction of recorded object and reference wavefront is calculated by Fourier Transform method. DHIM system is non-invasive, non-contact type and has the potential for fast detection of E. coli.