As far as I understand bacteria of order Lactobacillales are all LAB (Lactic acid bacteria). So often "Lactobacillales" and "LAB" are used interchangeably.

But I also thought that this is not the whole truth, because there are LAB which are not of order Lactobacillales.

Can anyone elaborate on this topic and is there a paper/review explaining the consensus on this topic?


Lactic acid fermentation is the most common type of fermentation among Eubacteria, and it's found on several genera.

Actually, regarding the fermentation types, we can say as a general rule:

  • Ethanol fermentation: found in Plants and Fungi.
  • Lactic acid fermentation: found in Bacteria and Animals.

That being said, according to the Todar's Online Textbook of Bacteriology,

Although many genera of bacteria produce lactic acid as a primary or secondary end-product of fermentation, the term Lactic Acid Bacteria is conventionally reserved for genera in the Order Lactobacillales.

And according to Lactic Acid Bacteria: Microbiological and Functional Aspects, Fourth Edition:

They [LAB] belong to the Phylum Firmicutes, Class Bacilli and Order Lactobacillales.

These genera are: Lactobacillus, Leuconostoc, Pediococcus, Lactococcus, Streptococcus, Carnobacterium, Enterococcus, Oenococcus, Tetragenococcus, Vagococcus and Weisella.

The problem here is that not all lactic acid producing bacteria are called a LAB. Therefore, Lactobacillales and LAB can be used interchangeably. However, you cannot say that all bacteria that perform lactic acid fermentation are LAB.


  • $\begingroup$ Thanks a lot for your reply. I found this sources already. Is there any review/paper confirming this as the consensus among taxonomists? $\endgroup$
    – Michael
    May 3 '17 at 12:30
  • $\begingroup$ Have a look at this book, page 2: books.google.com.au/… $\endgroup$
    – user24284
    May 3 '17 at 12:46

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