I have two strains from a single patient. Both have been confirmed as Ps. aeruginosa by PCR. One of them produces a dense brown pigment but the other produces no pigment....has anyone come across this before?
Thanks,
Bruno
Hi Bruno,
I work with P. aeruginosa and I see the same situation in some strains, mainly those isolated from Cystic Fibrosis patients. The pigmentation of strain will depend of which pigmentation genes (pyoverdin, pyocyanin, pyomelanin, pyorubin) they have. You can proceed a Pulsed Field Gel Electrophoresis (PFGE) to know how similiar these two strains between each other and/or a PCR to investigate the pigment genes in these strains.
Best regards,
Renata.
Thanks Renata. I have send them for whole genome analysis :D but was wondering if anything like that existed? We always learn 'normal pigment production' but other strains can exist!!
Thanks for you reponse
Dear Bruno, that's right. Although it's considered as a criterium of clasification the production of pigment depends on growth conditions.
Dense brown pigment is Pyocyanin...possibly Tyrosine was present in the media..
I also have isolated and identified Pseudomonas that does not produce the usual pigment. I have also seen organisms that produce the usual pigment but are not Pseudomonas. Is used Microbact for my tests so far.
Dear Bruno, first production of pigments by Ps aeruginosa is not necessary it is one of virulence factors, second My master degree was with Ps.aeruginosa and it was found many strains are not pigment producer but they were of environmental origin
Hello Mr Bruno, I'm working on P. aeruginosa and I have found some special cases of clinical strains that are not pigment producer.
Pigment is usual but not always present, depends on the isolate, growth media, and temperature.
For example green flourescent pigment pyoverdine is a siderophore used to capture iron when is scarce.
Some strains don't produce the pigment but the percentage is comparatively low
I have isolated a pseudomonas strain from the environment. It produces a pigment sometimes and sometimes doesnt produce. Why is that
Annika, may be because that gene is expressed under specific conditions. First you need to find out what is the responsible gene and what kind of pigment it produces then you can look at what impact it has on the strain
the brown pigment is probably pyomelanin. I have seen something similar in other species, but interestingly the pigment turns brown upon exposure to air, a bit like an apple browning after being cut. The pigment is formed where there are chromosomal deletions in genes associated with tyrosine metabolism, that leads to an accumulation of the pigment.
Yes I came across this strain of pseudomonas sp which is brown large colony with not smooth edges. But the most strains produse pigment
The population of a bacterial species ...could really have in them subpopulations, many events could explain that; mutations, dysfunction in quorum sensing or other signalling mechanisms......and when the phenotype is under the control of several determinants--- that exponentially increases the possibility of heterogeneous expression even with a population of bacterial species as in your case.
Are there any reference regarding Pseudomonas producing pyoviredin? If yes what is the extraction process?
Not all of them produces this pigment. Sometimes in the environment, they belong to certain factors may lead to production while some may lose this ability due to mutation and other factors so it is not a new thing
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