EXAMINATION OF MORPHOLOGY AND SURFACE STRUCTURE OF COCCI LACTIC ACID BACTERIA BY SCANNING ELECTRON MICROSCOPE AND IMAGE ANALYSIS

Lactic acid bacteria (LAB) widely distributed in nature and play an important role in much food fermentation. Bacteria cell morphology is useful and valuable characteristics used in the classification and identification of bacteria. Therefore, cell morphological shape and size of six strains of cocci LAB were studied in broth and milk media using scanning electron microscope (SEM) and image analysis technique. Results indicated that, Pediococcus acidilactica was the smallest strain in size and Streptococcus thermophilus was smaller than Enterococcus and lactococcus strains. Except Pediococcus acidilactica, cells of other strains were generally smaller in size when grown in milk media than in broth media. Cells of cocci LAB were not perfect spherical cells. In conclusion, cell shape and size parameters can be used for identification and classification of cocci LAB with determination of define standard conditions for growth.