Again, less than 25 % of the added glucose
was consumed. It seemed possible that the fall off in FA
production and the incomplete glucose consumption may
have been due to FA toxicity inhibiting the metabolism of
the production strain, BE1576 (Nunn et al., 1979). Given
that low pH increases the toxicity of FAs, we looked at
butyrate production on TB plus 2 % glucose while controlling
the pH in a range between 7.0 and 7.1. This was
done over a 24 h period, followed by anaerobic incubation
without pH control for an additional 20 h. After the initial
24 h period, 68.18 % of the glucose had been consumed
and butyrate, hexanoate and octanoate had been produced
at 7.47, 0.37 and 0.043 g l21
, respectively