Strategies for the development of a side stream process for polyhydroxyalkanoate (PHA) production from sugar cane molasses

Albuquerque, Maria da Graça Ejarque; Eiroa, M.; Torres, Cristiana A.V.; Nunes, Bruno Rafael Pereira; Reis, Maria A.M.

doi:10.1016/j.jbiotec.2007.05.011

Cited by 336 publications

(198 citation statements)

References 18 publications

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“…The experimental setup consisted of three benchscale reactors and a hollow fiber membrane filtration module (Albuquerque et al, 2007). The molasses acidogenic fermentation (stage 1) was carried out in a continuous stirred tank reactor operated under anaerobic conditions.…”

Section: Methodsmentioning

confidence: 99%

“…The molasses acidogenic fermentation (stage 1) was carried out in a continuous stirred tank reactor operated under anaerobic conditions. The conditions used to operate the acidogenic continuous stirred tank reactor are described in detail in Albuquerque et al (2007). The fermented molasses was clarified by microfiltration and used as a feedstock for subsequent culture selection and PHA accumulation.…”

Section: Methodsmentioning

confidence: 99%

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Link between microbial composition and carbon substrate-uptake preferences in a PHA-storing community

et al. 2012

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The microbial community of a fermented molasses-fed sequencing batch reactor (SBR) operated under feast and famine conditions for production of polyhydroxyalkanoates (PHAs) was identified and quantified through a 16 S rRNA gene clone library and fluorescence in situ hybridization (FISH). The microbial enrichment was found to be composed of PHA-storing populations (84% of the microbial community), comprising members of the genera Azoarcus, Thauera and Paracoccus. The dominant PHA-storing populations ensured the high functional stability of the system (characterized by high PHA-storage efficiency, up to 60% PHA content). The fermented molasses contained primarily acetate, propionate, butyrate and valerate. The substrate preferences were determined by microautoradiography-FISH and differences in the substrate-uptake capabilities for the various probe-defined populations were found. The results showed that in the presence of multiple substrates, microbial populations specialized in different substrates were selected, thereby co-existing in the SBR by adapting to different niches. Azoarcus and Thauera, primarily consumed acetate and butyrate, respectively. Paracoccus consumed a broader range of substrates and had a higher cell-specific substrate uptake. The relative species composition and their substrate specialization were reflected in the substrate removal rates of different volatile fatty acids in the SBR reactor.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Link between microbial composition and carbon substrate-uptake preferences in a PHA-storing community

et al. 2012

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“…In comparison to fermented effluent, polymer with single synthetic acid has higher M w up to 3.0 9 10 6 Da, which may be due to higher rates of polymerization [66]. M w of the copolymers was observed to be 4.5-9 9 10 5 Da with acetate and propionate, 8.5 9 10 5 Da, for P(3HB:3HV) with molasses and 3.5-4.3 9 10 5 Da for copolymer with fermented molasses [7,67]. The disruption of polymer chain by 3HV units causes the average M w to decrease with increasing monomer units, e.g.…”

Section: Substrate and Feeding Regimementioning

confidence: 99%

“…P(3HB:3HV) synthesized by mixed bacterial culture had higher 3HV up to 48 mol% at pH 9.5 in comparison to pH 8.5 and P(3HB:3HV:4HB) synthesized by Delftia acidovorans had increased 3HV (29-46 mol%) and 4HB (39-50 mol%) at pH 8.5 in comparison to pH 5.0 [71,72]. The pH can also have an indirect effect on PHA composition as the VFA profile produced under acidogenic fermentation can be manipulated by varying it [67]. In addition to this, nutrient level in media as compared to C affects the quality of PHA.…”

Section: Culture Conditionsmentioning

confidence: 99%

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

et al. 2015

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Polyhydroxyalkanoates (PHAs) as an alternative to synthetic plastics have been gaining increasing attention. Being natural in their origin, PHAs are completely biodegradable and eco-friendly. However, consistent efforts to exploit this biopolymer over the last few decades have not been able to pull PHAs out of their nascent stage, inspite of being the favorite of the commercial world. The major limitations are: (1) the high production cost, which is due to the high cost of the feed and (2) poor thermal and mechanical properties of polyhydroxybutyrate (PHB), the most commonly produced PHAs. PHAs have the physicochemical properties which are quite comparable to petroleum based plastics, but PHB being homopolymers are quite brittle, less elastic and have thermal properties which are not suitable for processing them into sturdy products. These properties, including melting point (T m ), glass transition temperature (T g ), elastic modulus, tensile strength, elongation etc. can be improved by varying the monomeric composition and molecular weight. These enhanced characteristics can be achieved by modifications in the types of substrates, feeding strategies, culture conditions and/or genetic manipulations.

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“…Mixed culture PHA production relies on a selection pressure that favors organisms with PHA storage capacity. In this case no reactor sterilization is necessary and the culture can adapt to various complex waste feed stocks (Albuquerque et al 2007;Bengtsson et al 2008;Serafim et al 2008), leading to potential environmental and economical advantages compared to both pure culture PHA production. Fermentations employing two or more microorganisms offer benefits over single culture fermentations either by commensalism or by neutralism or by conversion of substrate to a metabolite by first microorganism which is utilized by the second microorganism to produce the product (Kondo et al 1996;Shimizu et al 1999).…”

Section: Introductionmentioning

confidence: 99%