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Abstract:
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Polyhydroxybutyrate (PHB) is known to have applications
as medical implants and drug delivery carriers and
is consequently in high demand. In the present study the
possibilities of harnessing potential PHB-producing vibrios
from marine sediments as a new source of PHB was investigated
since marine environments are underexplored. Screening
of polyhydroxyalkanoate (PHA)-producing vibrios from
marine sediments was performed using a fluorescent plate
assay followed by spectrophotometric analysis of liquid cultures.
Out of 828 isolates, Vibrio sp. BTKB33 showed maximum
PHA production of 0.21 g/L and PHA content of
193.33 mg/g of CDW. The strain was identified as Vibrio
azureus based on phenotypic characterization and partial
16S rDNA sequence analysis. The strain also produced several
industrial enzymes: amylase, caseinase, lipase, gelatinase,
and DNase. The FTIR analysis of extracted PHA and its
comparison with standard PHB indicated that the accumulated
PHA is PHB. Bioprocess development studies for enhancing
PHA production were carried out under submerged fermentation
conditions. Optimal submerged fermentation conditions
for enhanced intracellular accumulation of PHA production
were found to be 35 °C, pH −7, 1.5 % NaCl concentration,
agitation at 120 rpm, 12 h of inoculum age, 2.5 % initial
inoculum concentration, and 36 h incubation along with supplementation
of magnesium sulphate, glucose, and ammonium
chloride. The PHA production after optimization was
found to be increased to 0.48 g/L and PHA content to426.88 mg/g of CDW, indicating a 2.28-fold increase in
production. Results indicated that V. azureus BTKB33 has
potential for industrial production of PHB. |