UNUSUAL MORPHOLOGY OF AGROMONAS-OLIGOTROPHICA AND THE EFFECT OF NACL AND ORGANIC NUTRIENT ON ITS FINE-STRUCTURE

Fine structure of an oligotrophic bacterium, Agromonas oligotrophica, was studied by electron microscopic observation of thin-sectioned cell s, Cells grown in 0.01% (w/v) each of peptone and meat extract (1/100 PM) showed the following three remarkable features: (1) Cytoplasm is d ivided into several compartments which are surrounded by cytoplasmic m embrane. (2) Several electron-dense cores are visible in each cell whi ch are stained by DAPI (4,6-diamidino-2-phenylindole). (3) The organis m divides not by the usual septum formation but by irregular budding a nd/or elongation and pinching off. The process is independent of the c ytoplasmic compartmentalization. Cells grown in 1/100 PM supplemented with 0.4% (w/v) NaCl or those grown in medium including 0.1% (w/v) eac h of peptone and meat extract (1/1O PM) are characterized by abnormal morphological features; deformed cell shape, incomplete development of cytoplasmic membrane, incomplete compartmentalization of cytoplasm an d the hollow space between the outer layer and cytoplasmic membrane. T he abnormal morphological appearance may relate to the halo and organo sensitivities of this organism.