We further examined the optimal initial CSL concentration
in agitated culture conditions. In tests in a fermentor,
the maximum cellulose yield was obtained in
8% CSL medium, different from the results shown in
Fig. 4. It was, therefore, preferential to perform agitated
cultures in 8% CSL medium. As shown in Fig. 5 and
Table 2, the fermentation process, which involved cellulose
production by A. xylinum BRCS, aerobically cultivated
in 8% CSL medium containing 2% glucose, comprised
the following: a) Lag phase or induction phase
(O-22 h) in which cells did not grow, but substantial
amount of gluconic acid accumulated almost proportionally
to the same amount of glucose being consumed. b)
Accumulation phase of gluconic acid (22-30 h) in which
almost all glucose was rapidly metabolized to gluconic
acid and the cells began to grow exponentially. c) Cell
growth/cellulose production phase (30-43 h) in which the
cells continued to grow and cellulose began to be
produced rapidly with decreasing amounts of accumulated
gluconic acid. d) Stationary phase (43-49 h) in which
both cell growth and cellulose production ceased even
though considerable amount of gluconic acid still remained.