Carob fruit as source of carbon and energy for production of saccharomyces cerevisiae

Abstract EN

Carob (Ceratonia siliqua L.) aqueous extracts were prepared from carob pods and kibble (pods minus seeds) particles of 0.5 to 1.0 cm diameter, at 45 °C for 2hr.

Saccharomyces cerevisiae cells were grown on extracts by fed-batch method at 32 ºC, an optimal pH 5.5, and shaking at 300 rpm for 10 h.

The cell yield and yield coefficient were 12.6 % and 0.27 g / g sugar utilized, respectively.

Aeration effect and continuous feeding on the yield of Saccharomyces cerevisiae were studied on extracts prepared from carob pod powder or from chopped kibble.

The biomass yield coefficient was about 0.27 g- yeast / g sugar utilized for both the pod and the kibble extracts.

The cells maintained the availability of reducing sugars on the expense of non-reducing sugar present in carob extract ; therefore, reducing sugars were maintained at their initial level.

However, aeration and continuous feeding increased the yield to 113 %.

Instantaneous growth rate constant after 10 h-period was 0.18 h-1 which decreased with time.

Supplementation of Ca, Mg, N, and P salts to extract in a continuous fedbatch culture did not significantly increase the cell mass above the yield in the control.

These nutrients were important in fixed batch culture.

This indicates that, in cell division, the carbon source in the extract is not limiting factor, while the above additives become the limiting factor.

Comparing the yield of the yeast grown on carob kibble extract with other substrates, previously and currently employed in the industry, reveals that the carob kibble extract is more economical substrate for industrial production of baker’s yeast.