Accumulation of Thiophenes by Cell Cultures of Tagetes patula and the Release of 5-(4-Hydroxy-1-butynyl)-2,2′-bithiophene into the Medium

Abstract

Calli of Tagetes patula, subcultured one or two times, were used to start liquid cultures. Calli of both subcultures contained thiophene-biocides, mainly 5-(but-3-en-1-ynyl)-2,2′-bithiophene (BBT) and 5-(4-acetoxy-1-butynyl)-2,2′-bithiophene (BBTOAc). Secondary calli contained about 3 times higher concentrations of thiophenes than tertiary calli. The liquid batch cultures consisted of coarse cell aggregates (3-8 mm), the volume of which was doubled each 15 days. In contrast to callus cultures grown on solid medium, cell aggregates grown in liquid medium released thiophenes. The release into the medium was at least 2.3 mg.dm^-3 in 90 days by an average amount of 100 g of fresh cell aggregates and occurred mainly as 5-(4-hydroxy-1-butynyl)-2,2′-bithiophene (BBTOH). In callus BBTOH did hardly occur. The amount of thiophenes recovered in the medium corresponded to 0.02% of the cell dry weight. The productivity of the liquid cultures was not related to the productivity of the original calli, neither was the thiophene production related to the growth rate of the biomass in the liquid cultures. The results indicate that not the selection of calli for thiophene content, but rather the selection of calli with the ability to form cell aggregates is of relevance for the production of thiophenes in liquid cultures.