Optimization of Bioplastic Production by Exiguobacterium sp. and Klebsiella sp. Using Molasses as Carbon Source

Author(s) : Rameesa Sadaat and Nazia Jamil

Abstract:

Bioplastics are the ecofriendly, biodegradable and biocompatible plastics originated from many living bodies including bacteria. Two bacterial strains Exiguobacterium sp. and Klebsiella sp. were screened for PHA production by Nile Blue Staining and Sudan Black B Staining. Both strains exhibited PHA production ability. Time profiling for the growth of two strains was performed using four different culture media. The two strains were optimized for PHA production for different pH conditions using three different carbon sources as glucose (control), sodium gluconate and molasses. Molasses sample was estimated containing 59.2% carbohydrate and 5.89% protein content by Phenol-Sulfuric Acid Method and Bradford Protein Assay respectively. Sodium Hypochlorite Method was used for PHA extraction. Exiguobacterium sp. showed exponential growth in molasses in 2% concentration and produced 54.0g/L biomass, 7.2 gL-1 or 13.3% PHA at 78 hours. With molasses as carbon source, biomass production by Klebsielliasp.was recorded optimal with 2% supplementation producing 88.7g/L biomass and 8.5g/L or 9.58% PHA, after 78 hours of incubation at 37 ºC. Fourier Transform Infra-Red Spectroscopy analysis showed that Exiguobacterium sp. produced poly (3-hydroxybutyrate) in medium supplemented with glucose as well as molasses as confirmed by the presence of C = O group at 1624.712 cm-1 and 1385.783 cm-1 respectively.