The research aimed to develop an advanced process for production of
biodegradable PHAs by using renewable resource as the feedstock. It is known
that the cost of raw materials for the production of bioplastic is one of the
limiting economic factors in the scaling up of such process. Therefore, this study
was constructed to examine the feasibility of using oil extracted from soybean
meal, corn meal as well as two types of WFO to produce PHAs using bioreactor
as one-stage batch, two-stage and fed-batch cultures techniques.
Batch culture (one-stage)
In one-stage batch culture, where any of the oils were used as the sole carbon
source, increasing the fermentation period led to a gradual increase in cell dry
weight of Ps. fluorescens S48 (Fig. 1). On the other hand, PHAs production was
started during the exponential phase of growth (after 12 h) then sharply increased
to achieve the highest figures of yield and content (26.09, 52 % and 36.71,
76.53%) during stationary phase after 60 h fermentation period on media
supplemented with extracted corn oil and extracted soybean oil, respectively.
The corresponding figures of productivity were 0.03 and 0.044 gl-1
h
-1
,
respectively.
Using any of the two types of WFO as the sole carbon source for PHAs
production by Ps. fluorescens S48, recorded the lowest values of cell dry weight,
PHAs concentration, content, yield and productivity than that obtained on media
containing meal oils. It is also interesting to notice that PHAs production was
delayed to start after 30 hr of fermentation period in medium contained WFO