Abstract
Cupriavidus necator H16 (formerly known as Hydrogenomonas eutropha) was famous as a potential single cell protein (SCP) in the 1970s. The drawback however was the undesirably efficient accumulation of non-nutritive polyhydroxybutyrate (PHB) storage compound in the cytoplasm of this bacterium. Eventually, competition from soy-based protein resulted in SCP not receiving much attention. Nevertheless, C. necator H16 remained in the limelight as a producer of PHB, which is a material that resembles commodity plastics such as polypropylene. PHB is a 100% biobased and biodegradable polyester. Although tremendous achievements have been attained in the past 3 decades in the efficient production of PHB, this bioplastic is still costly. One of the main problems has been the recovery of PHB from the cell cytoplasm. In this study, we showed for the first time that kilogram quantities of PHB can be easily recovered in the laboratory without the use of any solvents and chemicals, just by using the cells as SCP. In addition, the present study also demonstrated the safety and tolerability of animal model used, Sprague Dawley given lyophilized cells of C. necator H16. The test animals readily produced fecal pellets that were whitish in color, as would be expected of PHB granules. The pellets were determined to contain about 82-97 wt% PHB and possessed molecular mass of around 930 kg/mol. The PHB granules recovered biologically possessed similar molecular mass compared to chloroform extracted PHB [950 kg/mol]. This method now allows the production and purification of substantial quantities of PHB for various experimental trials. The method reported here is easy, does not require expensive instrumentation, scalable and does not involve extensive use of solvents and strong chemicals.
Highlights
Despite their excellent stability, durability, weight saving and insulating properties, plastics derived from petrochemicals are fast acquiring a negative image through their ubiquitous persistence in the environment, posing a threat to our natural habitats [1]
Tolerability and safety of rats fed with the lyophilized cells of C. necator H16 as sole diet source
Biosynthesis of PHB In order to minimize the variability of biomass used for the tolerability and safety evaluations, a large amount of cells containing PHA was cultivated using a 2000 L fermenter
Summary
Durability, weight saving and insulating properties, plastics derived from petrochemicals are fast acquiring a negative image through their ubiquitous persistence in the environment, posing a threat to our natural habitats [1]. Polyhydroxyalkanoates (PHAs) are being extensively investigated as a potential candidate to replace synthetic polymers mainly due to use of renewable resources, biodegradability as well as their tunable mechanical and thermal properties by copolymerization [5,6]. Though PHAs can be technically specified to meet various applications, high production costs is a serious deterrent to their successful commercialization [2,7]. Feedstock for the biosynthesis of PHA and the subsequent recovery processes are the major cost absorbing factors which account for the overall high production cost [8]. Since PHA has been produced using microbial fermentation mostly with Cupriavidus necator H16 (previously known as Hydrogenomonas eutropha) [2,8,9], recent studies have been geared toward identifying renewable and inexpensive carbon sources in order to bring down the overall costs [10,11,12,13]. A comprehensive review on the various PHA recovery methods that have evolved is available elsewhere [14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
