TABLE 2.

Toxin production in V. cholerae wild-type and mutant strains^a

Strain	Relevant genetic map	Avg toxin production (ng/ml/OD600) ± SDb
O395 (wild type)		1,370 ± 130
toxTΔhth mutant		0.038 ± 0.015
toxTΔpro mutant		0.027 ± 0.0021
tcpAΔpro mutant		760 ± 150
ΔtcpP/pMMB66EH mutantc		0.043 ± 0.031
ΔtcpP/ptcpPH mutantc		5,670 ± 720
ΔtcpH mutant		19 ± 3

^aStrains were grown overnight in LB medium, and supernatants were assayed by GM₁-ganglioside ELISA. 

^bToxin levels represent three individual experiments. 

^cPlasmid experiments included 1 mM IPTG for induction of genes under tac promoter control.