IODEGRADABLE polyesters, polyhydroxyalkanoate (PHAs)
…… are promising candidates for the development of environmentfriendly
and totally biodegradable plastics. The production of PHAs
by Pseudomonas fluorescens S48 was examined using bioreactor as
one-stage batch, two-stage batch, and fed-batch (pulsed, continuous
and high cell density) cultures. Corn oil , soybean oil (extracted from
their meal) and two types of waste frying oils (WFO) were used in
productive medium as a carbon source. The highest values of polymer
content in the one-stage bioreactor fermentation (52 % and 76.53 %)
were obtained after 60 h on media supplemented with extracted corn
oil and soybean oil, respectively. Whereas, the highest figure obtained
on WFO type 2 was 30 % under the same circumstances. Using
bioreactor as a two-stage batch culture increased the polymer content
with soybean, corn oil and WFO type 2 by 2.2 %, 32.11 % and 58 %,
respectively as compared with that obtained in one-stage batch
culture. High-cell-density (0.64 gl-1
) at continuous feeding rate
0.55mll-1
h
-1
of WFO type 2 recorded the highest polymer content,
yield and conversion coefficient after 48 h. Moreover, this application
increased the polymer content by 65.7 % than that obtained in onestage
batch culture as well as reduced the fermentation period 12 hr