While carrying out bio-remediation test with halophilic bacteria of Karnataka regions I found a few isolated were tolerating cadmium up to 700ppm. Among them some have shown pigmentation when exposed to cadmium. One of the isolates has shown a fluorescent greenish yellow pigmentation when streaked on to a nutrient plate containing 200ppm of cadmium.
Do non-pigmented organisms generally show fluoresce nature when exposed to any heavy metal..? what could be the reason for such..? which way will be the best to study this particular characteristic..?
Please do correct me if I'm wrong. I think there are a lot of Halophilic bacteria, right? So, to understand the reason on why it showed a fluorescent pigment when exposed to heavy metal, you should know what bacteria it is. And probably, it is only show the pigmented colony when exposed to Cadmium. You should try to exposed it to some other heavy metal such as Zinc, Copper, etc and observe the result. Try on doing some replication to have the best result.
Secondly, is the bacteria only showed pigmented colony when exposed to 200 ppm of cadmium? How about in higher or lower concentration?
I hope it help.
Many microbial pigments have defense anti-stress functions. The plating results of Sameer generally confirm this well-known fact. Two processes are involved: 1) nutrient media wit heavy metals select resistant organisms some [if not many] of them carrying genetic determinants for biosynthesis of anti-stress pigments and 2) presence of stress-factor stimulates pigments production through differential gene expression.
pl identify the culture .if the culture is Pseudomonas sps type this will show you pigmentation with nutrient medium and coloration depends on pH of the medium.
Thank you Chand Raina. The bacteria are gram negative cocci basically diplococcus in shape, and its also non-motile in nature.
Thank you Christine. Yes I do have a lot of halophilic bacteria but only two halophilic bacteria have shown such deviation.
They found to be gram negative diplococcus when gram staining was carried out.
I have tried them with other heavy metals but the fluorescence activity is only found in cadmium.
At 700 to 900 ppm of lead its colour changes to brown but in other metals there is no such effect.
The fluorescence activity is limited within the range at 200ppm and 300 ppm of Cadmium.
Thank you Nicolai S Panikov. Kindly suggest what will be the best to carry out with these organisms.
You can use this characteristic as an identification feature for identification. Also, you can try to extract the pigment and can analyze its potential for other biochemical activity.
I too got that fluorescent greenish yellow pigmentation... and identified them as Pseudomonas aeruginosa (NCBI-GenBank accession numbers: KF031122 , KF031123, KF447770 and KF447771).
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