Compare the following: bacterial species, bacterial strain, and bacterial type. Explain the relationship and development of strains and types to a species. Solution Bacterial species: It is a group of prokaryotic organisms which are ecologically distinct where many ecotypes of bacteria are grouped under a genous. These bacteria show a certain level of phenotypic identity, above 95% pair-wise average nucleotide identity (ANI) and over 97% 16S rRNA identity. bacterial strain: A strain is a low level taxonomically characterized micro-organism within a particular species that show genetic variance. Bacterial types: Bacteria can be classified based on cell wall type, and shape into different types. Based on cell wall type: gram positive, cells take up purple gram stain due to peptidoglycan rich cell wall egs (Streptococcus pneumoneae). Gram-negative bacteria such as vibrio cholerae which cause cholera take up pink stain due to thick peptidoglycan layer in their cell wall. Based on shape bacteria are classified into coccus (spherical shaped bacteria, egs.streptococcus), bacillus (rod-shaped bacteria egs. Ecoli), Vibrio (spiral or comma-shaped bacteria egs. Vibrio cholerae), spirillum (Spiral shape bacteria with more rigid structure egs: Heliobacter Pylori corkscrew shaped bacteria), Spirochete (Long thin flexible bacteria which are corkscrew shaped egs: Treponema pallidum) A species is a higher taxonomical classification which further breaks down into different strains that are genetically different. A type of bacteria shows which morphological differences and cell wall characteristics of a bacteria. The lowest level of classification would be based on type of species. A group of organisms of the different type, different morphological feature and virulence carrying out similar function would be classified under a strain. These strain would have micro-organisms, with genetic variance egs. A species of bacteria E. coli lives in the intestine and is good for human but it can also turn out to be pathogenic due to the 5% genetic variance among strains. Enteropathogenic and enterotoxigenic bacteria cause diarrhea in humans particularly children. Many such strains are grouped together under species egs E. Coli species. Which contains all the pathogenic and nonpathogenic E.Coli bacteria. These bacteria have 97% 16s rRNA identity, therefore falling under one species..

1. Compare the following: bacterial species, bacterial strain, and bacterial type. Explain the
relationship and development of strains and types to a species.
Solution
Bacterial species: It is a group of prokaryotic organisms which are ecologically distinct where
many ecotypes of bacteria are grouped under a genous. These bacteria show a certain level of
phenotypic identity, above 95% pair-wise average nucleotide identity (ANI) and over 97% 16S
rRNA identity.
bacterial strain: A strain is a low level taxonomically characterized micro-organism within a
particular species that show genetic variance.
Bacterial types: Bacteria can be classified based on cell wall type, and shape into different types.
Based on cell wall type: gram positive, cells take up purple gram stain due to peptidoglycan rich
cell wall egs (Streptococcus pneumoneae). Gram-negative bacteria such as vibrio cholerae which
cause cholera take up pink stain due to thick peptidoglycan layer in their cell wall.
Based on shape bacteria are classified into coccus (spherical shaped bacteria, egs.streptococcus),
bacillus (rod-shaped bacteria egs. Ecoli), Vibrio (spiral or comma-shaped bacteria egs. Vibrio
cholerae), spirillum (Spiral shape bacteria with more rigid structure egs: Heliobacter Pylori
corkscrew shaped bacteria), Spirochete (Long thin flexible bacteria which are corkscrew shaped
egs: Treponema pallidum)
A species is a higher taxonomical classification which further breaks down into different strains
that are genetically different. A type of bacteria shows which morphological differences and cell
wall characteristics of a bacteria. The lowest level of classification would be based on type of
species. A group of organisms of the different type, different morphological feature and
virulence carrying out similar function would be classified under a strain. These strain would
have micro-organisms, with genetic variance egs.
A species of bacteria E. coli lives in the intestine and is good for human but it can also turn out to
be pathogenic due to the 5% genetic variance among strains. Enteropathogenic and
enterotoxigenic bacteria cause diarrhea in humans particularly children.
Many such strains are grouped together under species egs E. Coli species. Which contains all the
pathogenic and nonpathogenic E.Coli bacteria. These bacteria have 97% 16s rRNA identity,
therefore falling under one species.