Abstract

BIOPLASTIC (POLY -3-HYDROXYBUTYRATE) PRODUCTION BY LOCAL PSEUDOMONAS AERUGINOSA ISOLATES UTILIZING WASTE COOKING OIL

Dr. Eman H. Gatia*, Nadhim H. Haider and Saad H. Khudair

Abstract

Disposal of domestic wastes, such as waste cooking oil (WCO),without pretreatment, contributes to the deterioration of theenvironment and creating severs problems. Synthetic plastic posesthreat to the environment, because it is non-biodegradable are nowaccumulate in the environment at great millions of tons per year.Bioplastic are polymers such as Poly -3-hydroxybutyrate (PHB), whichhas gained importance since it can be easily degrade in nature. Thepresent study was aimed to isolate a promising microbial producer of(PHB), and optimization experiment to evaluate the best environmentaland physiological factors that lead to maximum (PHB) production.Seventy Pseudomonas species were isolated from differentcontaminated soil and water samples. The isolates thereafter were screened for (PHB)production using Sudan black and Nile blue as indicators stains to investigate the bacterialisolates for PHB production. It was found that 50 of them were capable of producing PHB.The isolate Pseudomonas aeruginosa Dw7 exhibit higher production of PHB, therefore it'sselected for further studies. The isolate DW7 is definitively identified as Pseudomonas aeruginosa Dw7 after complete 16S rRNA gene sequences method. Highest accumulation ofPHB and DCW were at 30°C, recorded 0.65 g/L and 1.78 g/l respectively with deletion ofsurface tension to 28mN/m with yield of PHB ranged between (35.6 and 36.5 %). DifferentWCO were tested as the sole carbon sources. The highest cell growth was observed on thepolymer samples produced from corn oil, followed by the polymer produced using sunfloweroil. The isolate yielded a relatively good dry weight 1.78 g/l with 0.72 of PHB yielding 40% (PHB/dry weight of biomass) when grown on corn oil waste with an initial concentration of 1%. Ammonium sulphate was found to be the best nitrogen source with initial concentration at 1gm/ l which raises the production of dry weight biomass to 2.6 g/l with 1.33 g/l of PHB (yield 51%). Optimum oil concentration was 3% with best DCW, highest PHB accumulation and yield which were 3.7, 1.98 and 53 % respectively. The highest PHB yield was observed as an intracellular product in P aeruginosa Dw7 accumulating as high as 4.32 g\l dry weight with 2.30 g/l of PHB (yielding 53.2 %) in C\N ratio of 30:1 in culture medium. Using WCO as a carbon source for synthesis of PHB is an economic process, turns polluting wastes into a valuable biodegradable product. This renewable source of waste oil can thus be exploited as low cost materials for PHB production.

Keywords: Pseudomonas aeruginosa; Poly-3-hydroxybutyrate; Oil waste; Bioplastic.