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Classification and Cell Structure

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Classifications and Species Characteristics



This section discusses Leuconostoc mesenteroides’ scientific classification and its basic background characteristics, as well as Leuconostoc mesenteroides’ classification as a lactic acid bacteria.



Scientific Classification and Cell Characteristics


Scientific classification is a means by which scientists group organisms with common characteristics.  Leuconostoc meseneroides’ scientific classification is below (the classification becomes more specific going from “Kingdom” to “Species.”)


  • Leuconostoc meseneroides is a species, and can be divided further into subspecies. 


  • Subspecies for example include Leuconostoc meseneroides subsp. meseneroides and Leuconostoc meseneroides subsp.cremoris.


  • Each subspecies has its own characteristics.









TABLE 1: Scientific Classification of Leuconostoc meseneroides





























Leuconostoc mesenteroides





Classified in the Kingdom Bacteria, Leuconostoc mesenteroides share some characteristics with all bacteria: 





  • They have no nucleus surrounded by membranes.
  • They have no organelles surrounded by membranes.
  • They have a DNA strand.
  • They have a cell wall. 



In addition to the basic characteristics they share with others as members of the Bacteria Kingdom, Leuconostoc mesenteroides show the following characteristics. 








All bacteria do not have the same shape. Typical shapes are cocci, rods, and spirals. When Leuconostoc mesenteroides develop on solids, they are shaped as rods.  In liquids, Leuconostoc mesenteroides are shaped as cocci.  These cocci can be by themselves, with a few others, or joined together in long chains as shown below. 






FIGURE __: Leuconostoc mesenteroides Cocci







Source: JGI Genome Analysis and System Modeling Group of the Life Sciences Division of



 Oak Ridge National Laboratory. "Leuconostoc mesenteroides ATCC 8293." JGI Microbes . 7 Dec. 2008 <http://http://genome.jgi-psf.org/ finished_microbes/leume/leume.home.html>.


Photo: Fred Breidt, North Carolina State University




 Cell Wall


Leuconostoc mesenteroides are Gram positive.  This means that they have an outer cell wall made of peptidoglycan.  To determine if a cell is gram positive or negative, the bacteria is stained with a crystal violet dye.  A purple color indicates peptidoglycan.  Peptidoglycan is a material made of a combination of sugars and amino acids.   Following are examples of Gram positive and negative bacteria.  Following also is a larger illustration of a typical Gram positive bacteria.


Figure ___: Gram Positive and Negative Bacteria












Source: "Gram stain: bacteria isolated and coloured with Gram stain." Online Photograph. Encyclopædia Britannica Online School Edition. 13 Dec document.write(new Date().getFullYear()); 2008  <http://school.eb.com/eb/art-709









a)      FIGURE __


Diagram of a Typical Gram + Bacteria





Source: Bacteria: More on Morphology, http://www.ucmp.berkeley.edu/bacteria/bacteriamm.html


Plasma Membrane: This allows the transfer of material in and out of the cell.


Plasmid: These are loops of DNA, capable of being transmitted to other cells. They can also code proteins to make antibiotics inactive.


DNA: DNA is not surrounded by a membrane.


Ribosome: They produce proteins, although they are smaller than the eukaryotic cells of plants and animals.





Facultative Anaerobe


Another way in which bacteria are grouped is based on how they are affected by gaseous oxygen.  Aerobic bacteria require oxygen to live, grow and reproduce.  Anaerobic bacteria are just the opposite.  Leuconostoc mesenteroides is a facultative anaerobe.  Facultative anaerobes can grow whether or not oxygen is present.




Bacteria are either autotrophs or heterotrophs.  Autotrophs manufacture their own food by fixing carbon dioxide.  Their energy source is either from light or from oxidation of elements such as nitrogen.  Heterotrophs are opposite to autotrophs.  Heterotrophs do not make their own food.    Leuconostoc mesenteroides are heterotrophs.  They break down compounds from the environment for energy.  In the case of Leuconostoc mesenteroides,




 Leuconostoc mesenteroides is not a motile species.  Some bacteria do have flagella that help them to move, and an example is shown below.




Source: "Proteus vulgaris." Online Photograph. Encyclopædia Britannica Online School Edition. 13 Dec.  2008  <



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