alkaline picrate test - (May/05/2009 )
hi every 1 
, I'm new here so I'm hoping I'm doing it right
in a article from "Letters in Applied Microbiology" i run in to a test to detect HCN by "alkaline picrate test as described by Lorck (1948)"
HCN is Hydrogen cyanide and is highly toxic,so what it's function in bacteria? (is it like Penicillin )
and how alkaline picrate test detect HCN ?
(the only References for this test is from 1948 so it's a dead end for me )
tnk for reading, guy
can you give us the ref (I'm too lazy to track it down).
guyfubis on May 5 2009, 05:26 PM said:
, I'm new here so I'm hoping I'm doing it rightin a article from "Letters in Applied Microbiology" i run in to a test to detect HCN by "alkaline picrate test as described by Lorck (1948)"
HCN is Hydrogen cyanide and is highly toxic,so what it's function in bacteria? (is it like Penicillin )
and how alkaline picrate test detect HCN ?
(the only References for this test is from 1948 so it's a dead end for me )
tnk for reading, guy
Cyanide is a secondary metabolite produced in a number of bacteria including some Pseudomonas sp.
The method of Lorck (Lorck, H (1948). Production of hydrocyanic acid by bacteria. Physiol Plant 1: 142-146) has more recently been modified (Alstrom, S., and R.G. Burns (1989). Cyanide production by rhizobacteria as a possible mechanism of plant growth inhibition. Biol Fertil Soils 7: 232-238).
The modified method is qualitative. Bugs are incubated on nutrient agar supplemented with glycine (4.4 g/L) in parafilm-sealed petri dishes. The production of cyanide is detected using picrate/Na2Co3 paper fixed to the under side of the Petri-dish lids. After 24h incubation a change in the paper colour from yellow to orange/red indicates cyanide production.
Picrate paper: Moist picric acid (1.4 g) is weighed out and dissolved in 100 ml of
2.5 % (w/v) sodium carbonate. A square (about 10 cm x 10 cm) of Whatman 3MM filter
paper is immersed in the yellow picrate solution for about 20 sec and hung up to dry in air. It is then cut in strips and stored dark at - 20 oC
Hope this helps
Ahh , tnk for the help that is what I need .
And no one in my university have any record going that far back , tnk again 
Sorry for the extremely late replay I was extremely busy the last few weeks .
GeorgeWolff The text is :"Characterization of a new isolate of Pseudomonas fluorescens strain Psd as a potential biocontrol agent" , Letters in Applied Microbiology 47 (2008) 98–105.
If u wont the full text mail me a request on guyfubis@gmail.com, and I will be happy to send u the pdf