# Council Directive 98/57/EC of 20 July 1998 on the control of Ralstonia solanacearum (Smith) Yabuuchi et al., Division 7.1: Biovar determination

Extent: E+W+S+N.I.

R. solanacearum is separated into biovars on the basis of the ability to utilise and/or oxidise three disaccharides and three hexose alcohols (Hayward, 1964 and Hayward et al. , 1990). Growth media for the biovar test is described in Appendix 2. The test can be successfully performed by stab inoculating the media with pure cultures of R. solanacearum isolates and incubating at 28 °C. If the media are dispensed into sterile 96 well cell culture plates (200 µl per well) colour change from olive green to yellow can be observed within 72 hours, indicating a positive test result.
Biovar
1
2
3
4
5
Utilisation of:
Maltose
–
+
+
–
+
Lactose
–
+
+
–
+
D (+) Cellobiose
–
+
+
–
+
Mannitol
–
–
+
+
+
Sorbitol
–
–
+
+
–
Dulcitol
–
–
+
+
–
Additional tests differentiate biovar 2 sub-phenotypes
See Lelliott and Stead (1987)
Biovar 2A (Worldwide distribution)
Biovar 2A (Found in Chile and Colombia)
Biovar 2T (Found in tropical areas)
Utilisation of trehalose
–
+
+
Utilisation of meso -inositol
+
–
+
Utilisation of D ribose
–
–
+
Pectolytic activity
low
low
high

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Source: https://www.legislation.gov.uk/eudr/1998/57/annex/II/section/VI/division/B/division/7/division/7.1 (the official version)
Page: https://openlegislation.uk/eu-directive-1998-57/annex-II/section-VI/division-B/division-7/division-7.1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.