Effects of carbon and organic nitrogen sources on cell
growth and cellulose production in shaking flasks It
was found from preliminary experiments that yeast
extract (YE) stimulated cellulose production. First, we
examined the effects of YE concentrations on cell growth
and cellulose production in different carbon media. The
YE was added to HS media in the range from 0.5 to
6%, while carbon sources comprised 2%. The overall
growth pattern and the specific growth rate corresponding
each carbon source of strain BRCS were not significantly
affected by the initial YE concentrations, but
growth phases were extended with increasing YE concentration
as shown in Fig. 2. This resulted in increased
final cell concentrations. Polysaccharides were produced normally with a substantial surplus of carbon source
present in the medium under conditions limited by
nutrients such as the nitrogen or phosphorous. As gluconic
acid was not produced during cultivation in fructose
and sucrose media, growth curves corresponding to
these substrates were different from that of glucose. The
amounts of cellulose produced from different carbon
sources are compared in Fig. 3. Of the substrates tested,
the highest cellulose yields were obtained in the fructose
medium, and the culture containing 4% YE yielded the
maximum value of 3.7 g/l. Cellulose production in sucrose
medium was much lower than that in fructose
medium even though the cell yield in sucrose medium
was slightly higher than that in fructose medium.