Growth and thiophene accumulation by hairy root cultures of Tagetes patula in media of varying initial pH.

Hairy roots of Tagetes patula were grown for 24 days in modified Murashige and Skoog's liquid medium at different initial pH levels of 4.0, 5.0, 5.7, 6.0 and 7.0. Irrespective of the initial pH, after 12 days, the pH of the culture medium was approximately 4.5. However the final pH, after 24 days of growth, did depend weakly on the initial pH of the medium. The biomass yield was lowest at an initial pH of 4.0, possibly due to lower utilization of ammonium at this pH. Similar patterns of thiophene accumulation was observed at all pH levels tested. Maximum thiophene accumulation occurred in root cultures which were 12-16 days old.