Characterization of polyhydroxybutyrate biosynthesized from crude glycerol waste using mixed microbial consortia

Abstract

This study focused on the characterization of polyhydroxybutyrate (PHB) produced from crude glycerol (CG) using mixed microbial consortia (MMC). PHB recovered from two biomass drying treatments (65°C oven drying and lyophilization) was characterized comparatively along with a commercially sourced PHB (PHB‐C). Characterization results showed that oven‐drying method caused PHB partial hydrolysis, as indicated by its lower molecular weight (Mw) (PHB‐O, 144,000 g mol−1), which further affected its physical and chemical properties. Lyophilization helped alleviate PHB hydrolysis during drying process, leading to PHB (PHB‐L) of higher Mw (309,000 g mol−1) and material properties comparable with commercial PHB. Furthermore, crystallization and morphological studies showed that PHB‐L featured faster crystallization rates and smaller spherulites as compared with PHB‐C, probably due to its lower Mw. In general, the results from this study suggested that CG‐MMC‐derived PHB‐L possessed material properties comparable with those of pure substrate/culture produced PHB. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Peroxide induced cross‐linking by reactive melt processing of two biopolyesters: Poly(3‐hydroxybutyrate) and poly(l‐lactic acid) to improve their melting processability

“…The crystalline morphologies of PHB and PLLA samples were analyzed by HS‐POM after isothermal crystallization from the melt at 90°C (above their T c as shown in Table ). Figures (a) and (a) show micrographs of solvent casted PHB and PLLA films showing spherulites with typical birefringent Maltese cross pattern . The control PLLA 0 has smaller spherulites (radius about 240 μm) than PHB 0 (radius about 560 μm), while straight boundaries were observed between neighboring spherulites for both of them, indicating the spherulite growth follows the heterogeneous nucleation mechanism .…”

“…Figures (a) and (a) show micrographs of solvent casted PHB and PLLA films showing spherulites with typical birefringent Maltese cross pattern . The control PLLA 0 has smaller spherulites (radius about 240 μm) than PHB 0 (radius about 560 μm), while straight boundaries were observed between neighboring spherulites for both of them, indicating the spherulite growth follows the heterogeneous nucleation mechanism . If the isothermal temperature was set about 30°C higher than the T c then the diameter of PHB 0 spherulite tends to reach to 3000 μm before they impinge each other because the nuclei site are limited.…”

“…Hot Stage-Polarized Optical Microscopy (HS-POM) PHB 0 and PLLA 0 films (cast from CHCl 3 solution $ 1 mg mL 21 ) and the cross-linked PHB 0.25-1gel and PLLA 0.25-1gel films were prepared by hot pressing at 180 C. Films were used for morphological studies on isothermally formed crystals using an Olympus BX51 microscope [103 objective, polarized light filters and digital camera (Olympus DP70)] equipped with a Mettler Toledo FP900 Thermosystem (FP90 central processor and FP84 hot stage). Samples were first heated at 20 C min 21 to 190 C, held for 2 min, then cooled at 220 C min 21 to the desired temperature (90 C), and held isothermally for 1 h. 23 All images were processed using the Olympus MicroSuite (TM)-SE 3.2 software.…”

Extraction of polyhydroxyalkanoates from mixed microbial cultures: Impact on polymer quality and recovery

“…Until now, chlorinated compounds (Bengtsson et al, 2010;Serafim et al, 2008a;Dai et al, 2007;Lemos et al, 1998) or a mixture of chlorinated and non-chlorinated solvents (Hu et al, 2013;Patel et al, 2009) DMC resulted as efficient as CH 2 Cl 2 in the extraction of PHA, with polymer recoveries of 49±2 and 52±1 %, respectively (corresponding to PHA extraction yields of 20±1 and 22±1 wt%, respectively, calculated on biomass weight basis). PHA purities above 94%…”

Conversion of polyhydroxybutyrate (PHB) to methyl crotonate for the production of biobased monomers

“…PHB can be obtained in several ways since many different groups of bacteria can store carbon from biomass feedstocks to produce PHB . All metabolizable carbon, ranging from CO 2 to crude glycerol, which can be used as a carbon source and PHB can also be produced in plants . On a pilot and large scale, the production of PHB mainly uses glucose, sucrose, fatty acids, and lauric acid as carbon sources and aims to produce materials for packaging, disposables, and biomedical applications.…”