According to Fig. 2, at each temperature there is a time when
the ammonia content is minimal; in this paper that time is called
as tmin. In experiments, tmin was 208.4 h, 191.5 h, and 73 h at
25 ◦C, 30 ◦C and 35 ◦C, respectively. After tmin cells begin to
metabolize accumulated carbon sources due to nitrogen limitation,
reducing the yield of PHA production. At 30 ◦C the P.
fluorescens consumes 99.9% of the initial ammonia, generating
more limiting conditions and therefore more PHA accumulation
in the cytoplasm. According to studies reported by Rehm and
Steinbüchel (1999), when the levels of nitrogen source limited,
the bacteria increase the activity of PHA synthase, the enzyme
responsible of PHA production