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Council Directive 93/85/EECShow full title

Council Directive 93/85/EEC of 4 October 1993 on the control of potato ring rot

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Version Superseded: 07/07/2006

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EU Directives are published on this site to aid cross referencing from UK legislation. Since IP completion day (31 December 2020 11.00 p.m.) no amendments have been applied to this version.

Nitrate reductase activity and denitrification (Bradbury, 1970)U.K.

Culture medium:

KNO3 (nitrite free)1 g
Difco bacto yeast extract1 g
K2HPO45 g
Distilled water1 litre

Dispense into 10 ml volumes in 20 ml bottles. Sterilize by autoclaving at 121 oC for 15 minutes.

Reagent A:

H2SO48g
5N acetic acid1 litre

Reagent B:

naphthylamine5 g
5N acetic acid1 litre

Inoculate the nitrate medium in duplicate. Test after 10 and 20 days, by adding one drop of Lugol's iodine, 0,5 ml reagent A and 0,5 ml reagent B. If medium does not turn reddish, add approximately 50 mg zinc powder. Observe the colour reaction.

Positive reaction:
Colour reaction
Stage 1Stage 2
No reduction of nitratecolourlessred
Reduction of nitrate as far as nitrite (nitrate reductase only)red
Reduction of nitrate beyond nitrite (denitrification — nitrate and nitrite reductase)colourlesscolourless

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