Sintayehu, Nibret (PhD)Adane, Bazezew2022-06-182023-11-282022-06-182023-11-282022-02http://etd.aau.edu.et/handle/12345678/32054Bacteria produces Polyhydroxyalkanoates (PHAs), which are macromolecules. They are inclusion bodies that build up as reserve resources while bacteria grow under various stress situations. PHAs have been chosen as alternatives for the development of biodegradable polymers due to their rapid degradability under natural environmental circumstances. The purpose of this study was to produce reducing sugars from lignocellulosic Napier grass and examine PHA production by the impact of temperature, pH, and culture time on growth yields by employing the produced reducing sugars as carbon sources using response surface methodology via Box- Behnken design BBD). Burkholderia Sacchari strain was chosen from more than 300 bacterial strains capable of PHA accumulating strains based on its ability to consume both hexose and pentose sugars and has a capacity of accumulating high mass PHA granules inside its cells. At 200 rpm, optimal pH, fermentation temperature, and incubation time for the isolate to produce the highest PHA were 7, 35 °C, and 48 hour, respectively. When hydrolysates of Napier grass was employed as carbon sources and ammonium sulphate as nitrogen sources, the strain was able to collect 62.1% PHA from its total biomass. The extracted PHAs' FTIR spectra show strong peaks at wavenumbers that are unique to PHAs as C–H, CH2, O-H, C=O, and C–O groups. The extract's resemblance appropriateness for bioplastic production were validated by UV–Vis spectrophotometric analysis.en-USPolyhydroxyalkanoateNapier grassGlucose-rich hydrolysateBox Behnken designPHA productivityBurkholderia SacchariFTIRThesis