S. SEN, H.P.S. MAKKAR, S. MUETZEL AND K. BECKER. 1998. Escherichia coli K-12 was exposed
to Quillaja saponaria saponins from various commercial firms (Sigma, Roth and Nor-feed)
and to an extract of Yucca schidigera plant powder (DK Sarsaponin 30) at different
concentrations (0·05–1·0% w/v). A concentration-dependent response was
observed. Quillaja saponaria saponins from Sigma increased growth up to 0·1% (w/v)
level, whereas Nor-feed and Roth saponins produced maximum growth at a much
higher level (0·5 and 0·75%, w/v, respectively). These results suggest that quillaja
saponins from various sources differ in their biological activity, although all three
saponins had the same content of vanillin-sulphuric acid reactive moieties. The
lyophilized water extract from the DK Sarsaponin powder showed maximum growth at 0·1%
(w/v) level. The levels at which maximum growth was observed did not change on
subjecting the quillaja or yucca saponins to heat treatment in an autoclave (121 °C
for 30 min). All the saponins and the plant extract increased growth of Escherichia coli
up to a certain concentration and thereafter decreased growth. In spite of the
decreased growth at higher levels of saponins, it was higher compared to the control
(without saponin) up to levels of 1% (w/v) for all saponins except Quillaja
saponins from Sigma, for which the growth was lower at levels of 0·25% (w/v) and
higher. Saponins have the potential to modulate microbial growth in natural and
artificial fermenters.
INTRODUCTION