Open AccessResponse surface method for polyhydroxybutyrate (PHB) bioplastic accumulation in Bacillus drentensis BP17 using pineapple peel
Author(s) -
Watsana Penkhrue,
Dieter Jendrossek,
Chartchai Khagnuch,
Wasu Pathom-aree,
Tomoyasu Aizawa,
Rachel L. Behrens,
Saisamorn Lumyong
Publication year - 2020
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0230443
Subject(s) - polyhydroxybutyrate , bioplastic , food science , biopolymer , response surface methodology , dispersity , central composite design , materials science , biodegradable plastic , enthalpy of fusion , fermentation , polyhydroxyalkanoates , strain (injury) , melting point , chemistry , bacteria , polymer , chromatography , composite material , polymer chemistry , waste management , biology , genetics , engineering , anatomy
Polyhydroxybutyrate (PHB) is a biodegradable biopolymer which is useful for various applications including packing, medical and coating materials. An endospore-forming bacterium (strain BP17) was isolated from composted soil and evaluated for PHB production. Strain BP17, taxonomically identified as Bacillus drentensis , showed enhanced PHB accumulation and was selected for further studies. To achieve maximum PHB production, the culture conditions for B . drentensis BP17 were optimized through response surface methodology (RSM) employing central composite rotatable design (CCRD). The final optimum fermentation conditions included: pineapple peel solution, 11.5% (v/v); tryptic soy broth (TSB), 60 g/L; pH, 6.0; inoculum size, 10% (v/v) and temperature, 28°C for 36 h. This optimization yielded 5.55 g/L of PHB compared to the non-optimized condition (0.17 g/L). PHB accumulated by B . drentensis BP17 had a polydispersity value of 1.59 and an average molecular weight of 1.15x10 5 Da. Thermal analyses revealed that PHB existed as a thermally stable semi-crystalline polymer, exhibiting a thermal degradation temperature of 228°C, a melting temperature of 172°C and an apparent melting enthalpy of fusion of 83.69 J/g. It is evident that B . drentensis strain BP17 is a promising bacterium candidate for PHB production using agricultural waste, such as pineapple peel as a low-cost alternative carbon source for PHB production.