Methylene Blue Reduction
DESCRIPTION
Some bacteria are able to reduce some organic colorants  (methylene blue, malachite green, Janus green) to colorless substances
that regain initial color in oxygen presence.
MEDIUM PREPARATION: to every 5 ml nutritive broth medium, add 1 drop of
methylene blue 1% solution.

PROCEDURE:
Inoculate a medium tube with bacterial culture then add paraffin oil to create low
oxygen growth conditions. Incubate at 37 ˚C, 24 hours.

RESULTS:
Full discoloration indicates a positive reaction.  
Green color indicates a weak positive reaction.
Reaction is negative if blue color persists.

REFERENCES:
1. H. Raducanescu, V.Bica-Popii,1986. Bacteriologie veterinara, Ed. Ceres, Bucuresti.
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(c) Costin Stoica
R E G N U M
PROKARYOTAE
Methylene blue decomposition test
positive (left) & negative (right)
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