Abstract
Polyhydroxybutyrates (PHBs) are macromolecules synthesized by bacteria. Because of their fast degradability under natural environmental conditions, PHBs were selected as alternatives for the production of biodegradable plastics. Sixteen PHB-accumulating strains were selected and compared for their ability to accumulate PHB granules inside their cells. Isolate AS-02 was isolated from cattle manure and identified as Bacillus wiedmannii AS-02 OK576278 by means of 16S rRNA analysis. It was found to be the best producer. The optimum pH, temperature, and incubation period for the best PHB production by the isolate were 7, 35 °C, and 72 h respectively. PHB production was the best with peptone and glucose as nitrogen and carbon sources at a C/N ratio of (2:1). The strain was able to accumulate 423, 390, 249, 158, and 144 mg/L PHB when pretreated orange, mango, banana, onion peels, and rice straw were used as carbon sources, respectively. The extracted polymer was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and GC-MS spectroscopy, which confirmed the structure of the polymer as PHB. The isolate B. wiedmannii AS-02 OK576278 can be considered an excellent candidate for industrial production of PHB from agricultural wastes.
Highlights
Plastic materials that have been generally used in our daily lives are causing dangerous environmental problems
PHB production by bacteria is the core subject of this work, since PHB are considered to be natural polymers
B-positive isolates were subjected to quantification of PHB production, and the best isolate was further characterized and optimized for its ability to produce a maximum amount of PHB
Summary
Plastic materials that have been generally used in our daily lives are causing dangerous environmental problems. Petroleum-based plastics have serious ecological and social impacts because of their non-degradable nature and the leaching of carcinogenic substances when exposed to scratch or heat [1]. Biopolymers are generated from renewable natural sources and are often biodegradable and nontoxic. They are either produced by biological systems (microorganisms, plants, and animals) or produced from substrates obtained from living organisms such as polylactic acid, which can be synthesized from biologically obtained lactic acid [2]. PHAs are thermoplastic aliphatic polyesters with linear polymer chains that are manufactured via a microbial process on sugar-based medium, where they act as carbon and energy storage material in bacteria
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