As we use selective media (for example Pikovskaya media). Many researchers use the media for isolation of phosphate solubilizing bacteria from environmental samples. Some bacteria grow in the media but doesn't make any clear zone. But some researchers isolate phosphate solubilizing bacteria in modified media. If agar contain phosphorus then it does not make any sense to isolate PSB without zone formation. If anyone has any idea please inform me.
@ Chandra, the agar use to prepare microbial media is a jelly like substance, obtained from red algae. Agar is a mixture of two components such as linear polysaccharide agarose and a heterogenous mixture of smaller molecule called agaropectin. Therefore, agar as such does not have any phosphorus content.
Pikovskayas agar medium contains calcium phosphate. Since phosphorus is a major nutrient for cellular metabolism, microorganisms cannot grow unless the phosphate is solubilized to provide a source of phosphorus for growth. Clear zones are not formed but flocculant precipitate opaque gel surround colonies of phosphate-solubilizing bacteria. If you do not see this precipitation gel around some colonies in a mixed culture, then those colonies developed by syntrophism.
@ Chandra, the agar use to prepare microbial media is a jelly like substance, obtained from red algae. Agar is a mixture of two components such as linear polysaccharide agarose and a heterogenous mixture of smaller molecule called agaropectin. Therefore, agar as such does not have any phosphorus content.
Hi Chadra,
The issue with using the Pikovskaya medium to isolate the PSB is that this Medium contains Phosphorus (P2O5) from the yeast extract included in its composition. This is why you can notice the growth of bacteria without the hallo zone (Phosphate solubilization activity). That`s why I recommend the use of the NBRIP medium. This one Doesn`t contain Phosphorus.
Moreover, this is a qualitative approach. You need to add another qualitative approach (or test) by using the NBRIP liquid Medium to assess the Phosphate solubilization activity of your isolated bacteria. Let me tell you that you might find some bacteria that are PSB (-) in the qualitative test and PSB(+) in the quantitative test. Bear in mind that you can rely only on the qualitative test.
I hope this answer brought you some help.
Wish you good luck.
Agar does not contain phosphorus and I advise you check your selective media
Pikovskayas Agar contains calcium phosphate (5.000 g/L) and it is recommended for detection of phosphate-solubilizing soil microorganisms. Phosphate-solubilizing bacteria will grow on this medium and form a clear zone around the colony, formed due to phosphate solubilization in the vicinity of the colony. However if you don’t see hallo formation it may be due to short-distance metabolite transfer by micro-organism or cross-feeding.
So if you are not getting hallo better you can pick few colonies and check in Pikovskaya s broth medium with tricalcium phosphate and then quantify the available Phosphorous with standard KH2PO4 using colorimeter at 410 nm.
Good luck!
It contains phosphorus as a form of calcium phosphate. It is an essential nutrient for microbes especial PDB.
- Badges
- Science topic
- Similar topics
- Biological Science
- Microbiology