TABLE 1.

Frequency of rugose EPS production by V. cholerae strains^a

Strainb	Serogroup/biotype	Origin	Sourcec (year)	% Rugose coloniesd,e,f
				Flask		Tube
				30°C	37°C	30°C	37°C
N16961	O1/E1 Tor	Bangladesh	C (1971)	31 (1.5)	47 (0.9)	70 (0.7)	74 (1.9)
C6709	O1/E1Tor	Peru	C (1991)	1	23	15	70
NCTC 6585	O1/classical	India	C (1943)	43 (1.4)	44 (0.2)	0	0
AMS20A73	O1/classical	China	C (1945)	3	4	0	0
Aldova	O37	Czechoslovakia	C (1965)	0	1	72 (0.2)	41 (2.8)
1803	Non-O1	Brazil	C (1992)	0	0	16	87
1837	O139	Bangladesh	C (1992)	0	0.2	0	0 to 2
P44	Non-O1	Peru	E (2000)	12	0	0	2
1085-93	O37	Germany	E (1993)	0	0	0.1	0
141-94	O70	Germany	E (1994)	0	0	0.3	0
928-93	O6	Argentina	E (1993)	0	0.2	0.4	0

^aA smooth colony was inoculated into glass tubes containing 3 ml of APW#3 or into flasks containing 45 ml of APW#3, and the cultures were incubated statically for 48 and 72 h at 30°C and 37°C, respectively.

^bListed are only strains showing HFRP or spontaneous rugose colonies under each condition.

^cC, clinical; E, environmental.

^dValues represent the average percentages of cells shifting to a rugose colony morphology.

^eReadings were taken at 72 h for all strains except N16961, for which the reading was taken at 48 h.

^fValues in parentheses represent standard errors and are shown only for specific strains showing high levels of HFRP.