Editing Coliform bacteria (section)

=== Detection of coliform bacteria in drinking water ===

==== PCR ====
Amplification of the [[beta-galactosidase]] gene is used to detect coliforms in general, because all coliform organisms produce this compound.<ref name=":1">{{cite journal | vauthors = Rompré A, Servais P, Baudart J, de-Roubin MR, Laurent P | title = Detection and enumeration of coliforms in drinking water: current methods and emerging approaches | journal = Journal of Microbiological Methods | volume = 49 | issue = 1 | pages = 31–54 | date = March 2002 | pmid = 11777581 | doi = 10.1016/S0167-7012(01)00351-7 }}</ref> The [[Amplification of DNA|amplification]] of the beta-D glucuronidase is used to detect ''E. coli,'' or the amplification of their [[verotoxin]] gene(s) to detect verotoxin-producing ''E. coli.''<ref name=":1" /><ref>{{cite journal | vauthors = Holland JL, Louie L, Simor AE, Louie M | title = PCR detection of Escherichia coli O157:H7 directly from stools: evaluation of commercial extraction methods for purifying fecal DNA | journal = Journal of Clinical Microbiology | volume = 38 | issue = 11 | pages = 4108–4113 | date = November 2000 | pmid = 11060076 | pmc = 87549 | doi = 10.1128/JCM.38.11.4108-4113.2000 }}</ref>

==== Chemiluminescent in-situ hybridization ====
Specific areas of the [[16S rRNA]] in the ''Enterobacteriaceae'' genus are bound by [[oligonucleotide]] probes, which aids in monitoring the quality of drinking water.<ref name=":1" /> Specifically, ''E. coli'' is labelled with a soybean peroxidase-labeled peptide nucleic acid (PNA) probes that bind to a specific sequence in their 16S rRNA. When used in conjunction with a [[Chemiluminescence|chemiluminescent]] substrate, light is produced where each colony of ''E. coli'' is located, indicating that they are present in the sample.<ref>{{cite journal | vauthors = Stender H, Broomer AJ, Oliveira K, Perry-O'Keefe H, Hyldig-Nielsen JJ, Sage A, Coull J | title = Rapid detection, identification, and enumeration of Escherichia coli cells in municipal water by chemiluminescent in situ hybridization | journal = Applied and Environmental Microbiology | volume = 67 | issue = 1 | pages = 142–147 | date = January 2001 | pmid = 11133438 | pmc = 92533 | doi = 10.1128/aem.67.1.142-147.2001 | bibcode = 2001ApEnM..67..142S }}</ref>

==== Violet red bile agar ====
The solid medium is used to grow lactose-fermenting coliforms and utilizes a neutral red [[pH indicator]]. Pink colonies appear when lactose is fermented and are surrounded by [[bile]] that has [[Precipitation (chemistry)|precipitated]] out. To confirm if these colonies are coliforms, they are transferred to brilliant green lactose bile (BGLB) and incubated. If gas is visible after incubation, it can be confirmed that the sample had coliforms present.<ref name=":2">{{Citation |title=Water quality. Enumeration of Escherichia coli and coliform bacteria |url=http://dx.doi.org/10.3403/bseniso9308 |publisher=BSI British Standards |doi=10.3403/bseniso9308 |access-date=2022-03-03|url-access=subscription }}</ref>

==== Membrane filter method ====
Test samples are filtered through standard filter paper and then transferred to M-endo or LES Endo Agar mediums. Colonies appear pinkish-red with green metallic sheen after 22–24 hours of incubation. These colonies can be confirmed as coliforms if they are inoculated in [[Lauryl tryptose broth|lauryl tryptose]] (LST), produce gas, and then inoculated in BGLB. If there is gas production in the BGLB tubes, the test is positive for the presence of coliform bacteria.<ref name=":2" />{{clear}}