Hoda M Elzeini
Cairo University, Egypt
Title: Morphological identification of rod lactic acid bacteria using scanning electron microscope and image analysis
Biography
Biography: Hoda M Elzeini
Abstract
Lactic Acid Bacteria (LAB) widely distributed in nature and play an important role in much food fermentations. Bacterial cell morphology is useful and valuable characteristics used in the identification of any organism in order to classify. Therefore, cell morphological shape and size of four strains of rod LAB grown in two different media (MRS and RSM) were studied using Scanning Electron Microscope (SEM) and image analysis technique. Topographical images reveal rectangular shapes with smooth corners and height profiles and variation in size which occurred singly or in pairs or chains. Rod cells had a wide range of breadth (0.40-1.07 μm) with cells' perimeters of 4.64 up to 11.7 μm and the elongation varies between 0.572 and 0.790 µm. Both areas of Lb. helveticus 764N and Lb. casei 761N were reduced when grown in RSM than in broth medium. On the contrary, cells' areas of Lb. acidophilus 791N and Lb. paracasei 72MP increased when grown in RSM than in broth medium. RSM lowered the compression on cells walls either by the adsorbed water to the surface of the cells or by extra nutrients provides. All the aseptic ratios measured were higher than 1. Rod cells had a different orientation angles and surfaces seem to have heights or extrudes with external boundary was either a sharp outline or a rough surface. Cells hardness and wall thickness affected negatively or positively depending on the strain and growing medium. In conclusion, image analysis of SEM could be a good and accurate tool for measuring many morphology, shape and size parameters for the viable bacterial cells which can be used for identification and classification of rod LAB with determination of defined standard conditions for optimum growth