EFFECTS OF THE ADDITION OF XAD-7 AND OF ELICITOR TREATMENT ON GROWTH, THIOPHENE PRODUCTION, AND EXCRETION BY HAIRY ROOTS OF TAGETES-PATULA

The effect of the addition of a solid adsorbent, XAD-7, on the growth of hairy roots of Tagetes patula and on their production and excretion of thiophenes is described in this article. Together with this, it was investigated whether or not the refreshment of the XAD and the medium makes any difference and finally, the combination of the above treatments with the addition of an elicitor (extract of Aspergillus niger) was tested for its effects. The growth of the hairy roots was slightly increased by the addition of XAD, but slightly decreased by the addition of the elicitor. The specific production of thiophenes remained unaffected in most cases; an increase in production was observed only when XAD and elicitor were added together. The excretion of the thiophenes, on the other hand, was strongly influenced by the addition of XAD-7 to the cultures. Without this resin, there was no measurable excretion at all, whereas the presence of XAD raised the excretion to 50% of the total thiophenes produced. When these experiments were extended to bubble columns, the same results came out, although there was a surprising difference between the reactor configuration with the XAD present in the medium in the reactor and the reactor configuration with an external column containing the XAD, through which the medium was constantly circulated. In the former, about 20% of the total production was excreted, while in the latter no thiophenes could be detected outside the hairy roots.