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Differences and similarities in the structure of salmonella enterica and lactococcus lactis.
The structural makeup of L.lactis makes it compatible with both aerobic and anaerobic reactions which makes it an important microbe for food production. It is a non-pathogenic bacterium with peptidoglycan component in their cell wall. They have cocci shape unlike salmonella enterica that is a rod shaped bacteria. The cocci of these bacteria come in pairs or short chains. The bacteria size is smaller than that of S. enterica. The size is 0.5-1.5 micrometer in length. The Lactococcus lactis is also non motile because of the absence of flagellum or any other motility device.
The presence of peptidoglycan layer in the wall of lactococcus makes it distinguishable from salmonella enterica which is a gram negative organism. The peptidoglycan layer protect the bacteria and make it more stable and rigid (Pascal et al, 2006). Other major characteristic present in the bacteria is cytoplasmic lipid membrane and single periplasmic space which is lacking in gram negative species. A unique presence of teichoic acids also makes gram positive organism different. The similarities among the two organisms are the fact that both have plasma membrane.
Salmonella enterica is an enteric bacteria which is mobile by means of peritrichous flagella attached onto the cell surface. The flagella are made up of protein structure which lack microtubules (Todar, 2012). It is a gram negative bacteria with rod shapes. It is a non-sporing rod with a cell size of about 0.7-1.5 by 2.0-5.0 micrometers in size. The organism has a cell structure that enable production of lipopolysaccharides. The cell produces proteins that caused disruption of the cells of the walls of the intestine causing some form of disruption to the intestinal wall.
The main energy source for salmonella enterica is hydrogen and this hydrogen are being broken down by the enzymes produced by the bacteria itself. Some of the flagella are very long compared to the others on the cell of the organism. There are three specific cell surface antigens found on the cell wall of salmonella enterica. These are the flagella "H” antigen, the oligosaccharide "O"antigen and the polysaccharide "Vi" antigen. Adhesins is another important component of salmonella which distinguishes it from lactococcus lactis.
Characteristics that make one pathogenic and other non-pathogenic
Presences of antigens and lipopolysaccharides on the cell wall of salmonella enterica are a factor that contributes to its pathogenicity. This is because of the ability of those antigens and lipopolysaccharides that are being produced to result in the cell wall damage of the host cell (Marina-Devyatyarova et al, 2000). Those factors are usually produced within the host cell and then result in cellular wall damage. Another importance factor that contributes to the pathogenicity of the bacteria is the presence of flagella.
Flagella in salmonella enterica is a strong hold towards achieving effective attachment to host cells and also allows movement around when compared to non-motile organism such as L. lactis. The presence of adhesins which are either fimbral or non-fimbral complement the ability of the microorganism in attaching easily with host cells or mediating formation of biofilm. The lactococcus lactis are usually considered being opportunistic in it role. The absence of flagella and non-spore formation makes it nonpathogenic.
References
Marina Devyatyarova et al, (2000). The Lipopolysaccharide Structures of Salmonella enterica Serovar Typhimurium and Neisseria gonorrhoeaeDetermine the Attachment of Human Mannose-Binding Lectin to Intact Organisms.
Retrieved 9 April, 2012 from http://iai.asm.org/content/68/7/3894.full
Pascal et al (2006). Peptidoglycan Structure Analysis of Lactococcus lactis Reveals the Presence of an l,d-Carboxypeptidase Involved in Peptidoglycan Maturation . Journal of bacteriology.
Retrieved 10 April, 2012 from http://jb.asm.org/content/188/14/5293.abstract
Todar, K, (2012). Structure and function of bacterial cells (page 2). Todar's Online textbook of bacteriology.
Retrieved 10 April, 2012 from http://textbookofbacteriology.net/structure_2.html
