Abstract:

To test the stimulatory effects of three ingredients of Rhizoma gastrodiae on the biosynthesis of exopolysaccharide
(EPS) by Grifola frondosa in submerged culture, gastrodin (GA), p-hydroxybenzyl alcohol (HA) and p-hydroxylbenzaldehyde
(HBA) were separately added at various concentrations into the culture medium. The EPS concentration in the culture
supernatant was determined by phenol-sulphuric acid assay. The results showed that all three additives had an effective
stimulatory effect on mycelial growth and EPS production. Among them, the addition of p-hydroxylbenzaldehyde at 0.15 g/L
exhibited the best effect, although slightly inferior to 7% (V/V) of the 75% ethanol extract of R. gastrodiae. Furthermore,
kinetic analysis suggested that the EPS production curves with 0.15 g/L p-hydroxybenzaldehyde and 7% (V/V) of the
R. gastrodiae extract over the entire fermentation process were substantially same, producing significantly more EPS than
the blank group from the 7th day onwards (P < 0.05). As determined by high performance liquid chromatography (HPLC),
dynamic changes in the concentration of p-hydroxylbenzaldehyde during the fermentation process showed that on the 5th
day, p-hydroxylbenzaldehyde was completely absorbed and EPS began to accumulate in large quantity. Therefore, Grifola
frondosa could utilize p-hydroxylbenzaldehyde to promote the biosynthesis of EPS.

Key words: p-hydroxylbenzaldehyde, ingredients of Rhizoma gastrodiae, Grifola frondosa, exopolysaccharide