Traumatic Acid and Thiamin as Growth Factors for Algae.

Bottomley and, especially, Ashby2 showed that Lemna develops well in a purely inorganic medium, although it thrives better if some organic matter , such as a soil extract, is added. The addition of soil extract and other chemically ill-defined organic matters3 to the culture medium of algae is a general practice.4 Since the chemistry of many plant hormones has become known in recent years it seemed of interest to see in which respect they affect the growth of algae. Yin5 studied the effect of auxin on Chlorella and found an inhibition of the multiplication but an increase of the individual cell size. Pratt,6 however, found just the reverse, an increase in cell number and no increase in cell size. Recently English, Bonner and Haagen-Smit7 isolated and synthesized traumatic acid (1-decene-1, 10 dicarboxylic acid), a wound hormone of plants, which causes considerable proliferation and elongation of parenchymatous tissues (bean pods and potato tubers). On the assumption that this substance might exhibit similar properties on plant cells in general, it was added to the sterile cultures of unicellular algae8 in order to determine whether it promotes the growth. Traumatic acid indeed proved to be highly effective in promoting multiplication of the culture, as is shown in the table for Scenedesmus obliquus, Sc. bijugatus, Sc. brasiliensis and Palmellococcus miniatus. Similar results were obtained with Coccomyxa subellipsoidea forma putridena, Kirchneriella spec.?, Coelastrum proboscideum var. gracilis and Stichococcus bacillaris.9 Thiamin was recognized as a growth factor for fungi by Schopfer'0 and later on also as a growth factor for higher plants."I Thiamin was found to be ineffective, or at least far less effective than traumatic acid, when added to cultures (in basic inorganic medium) of the previously mentioned algae. It proved, however, to be decidedly effective in promoting the growth of Sphaerella lacustris (Haematococcus pluvialis).l2 Traumatic acid also af