In the category of Gram-negative bacteria, is there any non-pathogenic species? Is such a list of non-pathogenic gram-negative bacteria's available? Can you give maximum 5 examples of such bacteria which has been proved to be non-pathogenic and is gram-negative?

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    $\begingroup$ Well, most of them are not pathogenic. It would be quite a long list. $\endgroup$ – canadianer Mar 29 '18 at 6:05
  • $\begingroup$ The most diverse, yet phylogenetically coherent, bacterial phylum is the Proteobacteria, and its members are Gram-negative. If you go through the list of bacterial genera and species belonging to Proteobacteria, and if you look into the papers that describe them, you will always find the information about the source, i.e., the environment from which the bacteria were isolated, and from that you can infer about the pathogenic potential. bacterio.net/-classifphyla.html#proteobacteria $\endgroup$ – user37894 Mar 31 '18 at 5:59
  • $\begingroup$ Another strategy is to make the list of all pathogenic bacteria, remove them from the list of all bacteria, and exclude Gram-positive ones. You will be left with all Gram-negative bacteria for which pathogenicity is not known. $\endgroup$ – user37894 Mar 31 '18 at 6:02

As Canadianer already mentioned in the comments, the majority of bacteria (this includes gram-negative bacteria) are non-pathogenic.

I think a prime example is the human gut flora. You can find loads of bacterial species living in your gut without doing you any harm, if anything they are doing you a favour by breaking down food.

Here some examples of gram-negative genera:

  • Bacteroides
  • Escherichia

Most species within those genera are non-pathogenic, however, there are exceptions.

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  • $\begingroup$ So bacteroides vulgatus is gram-negative and non-pathogenic? $\endgroup$ – girl101 Mar 29 '18 at 10:02
  • $\begingroup$ It would appear so.. Here is a study (jb.asm.org/content/193/15/4025.full) that refers to Bacteroides vulgatus as one of "the most commonly isolated microbes from the human gastrointestinal tract, and it has been found to constitute part of the core gut microbiota in healthy humans". $\endgroup$ – Johnny Mar 29 '18 at 10:43
  • $\begingroup$ I should add, however, that infections may have been reported for said organism. This happens when they grow in environments where they shouldn't be growing. The questions of pathogenicity isn't always as black and white as we would like it to be. Generally, Bacteroides vulgatus is considered commensal. $\endgroup$ – Johnny Mar 29 '18 at 10:50

There are more than 15,758 named bacterial species, and the majority of them are Gram-negative, and most of them are non-pathogenic.

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  • $\begingroup$ the document is password protected, how to open ? $\endgroup$ – girl101 Aug 6 '18 at 8:43
  • $\begingroup$ The password for "Bacteria I. Taxonomy: Genera and Species" is: 1 $\endgroup$ – user37894 Aug 7 '18 at 17:56

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