Abstract:

Two anaerobes isolated from the feces of female vegetarians, LJ-G1 and LJ-Q2, were demonstrated to capable
of metabolizing soybean isoflavones to produce equol. The number of colonies, optical density and equol production was
plotted against culture period for either of the two strains. The impact of MnSO4, ZnSO4, CaCl2, Na2CO3 and KNO3 on
bacterial growth was explored. Meanwhile, the utilization of different carbon sources such as lactose, maltose, sucrose,
corn starch and glucose by the anaerobic strains was screened. The culture conditions for equol production were optimized
by single factor and orthogonal array designs. The results showed that LJ-G1 and LJ-Q2 were preferred to grow at 37 ℃
under anaerobic conditions. Their growth was at the exponential phase after 6 h of cultivation, the stationary phase after 21 h
and the decline phase after 39 h. All investigated metal salts could inhibit the growth of the strains, with MnSO4 being the
strongest inhibitor, whereas glucose had a positive effect on the growth of these intestinal strains. The optimized culture
conditions that provided a higher equol production of 11.89 μg/mL were 7 g/L glucose and 2 g/L NaCl in the medium with
an initial pH of 7.2.

Key words: vegetarians, intestinal bacteria, equol