To improve the efficiency of -PL production by Streptomyces sp.
M-Z18, batch and fed-batch co-fermentations with mixed carbon
sources, glucose, and glycerol were performed [20].
The batch fermentations
showed that the initial ratio of glucose to glycerol plays
an important role in glucose/glycerol co-fermentation.
The optimal
glucose/glycerol weight ratio was found to be 30/30, which resulted
in a maximum -PL productivity of 5.26 g/l/d. The results of the
experiment indicated that the initial glucose/glycerol weight ratio
plays an important role in glucose/glycerol co-fermentation.
These
results suggested that glucose and glycerol were consumed synergistically
during the co-fermentation process and that substrate
utilization time was shortened in comparison to utilization of a
single substrate.
Under optimized conditions, fed-batch fermentations
with glucose and glycerol as a mixed carbon source achieved
maximum -PL concentration and productivity values of 35.14 g/l
and 4.85 g/l/d, respectively [20].
These values were, respectively,
1.43-fold & 1.39-fold, and 1.17-fold & 1.16-fold higher than those
obtained from fermentations with glucose and glycerol and suggested
that glucose/glycerol co-fermentation may be an efficient
strategy for -PL production by Streptomyces sp. M-Z18.