Accumulation of non-degradable plastic waste in the environment might be prevented by the use of biodegradable polyhydroxyalkanoate (PHA). In this study, the thermophile Schlegelella thermodepolymerans produced up to 80 wt% PHA based on dry cell mass. The largest PHA granules were found in the cells within 48 h using 20 g/L xylose, a C/N ratio of 100, an initial pH of 7, at 50 °C. The substrate consumption, pH changes, and cell growth were monitored, revealing the time dependency of PHA production in S. thermodepolymerans. The metabolic pathways from xylose to PHA were identified based on proteomic analysis, revealing involvement of classic phaCAB, de novo fatty acid biosynthesis, and fatty acid β-oxidation. In addition, it was shown that S. thermodepolymerans degraded extracellular PHA with a high efficiency at 50 °C.
For the future circular economy, renewable carbon feedstocks manifest considerable promise for synthesizing sustainable and biodegradable polyhydroxyalkanoate (PHA). In this study, 16 wt% and 30 wt% PHA (cell dry weight) are respectively produced by thermophilic Caldimonas thermodepolymerans from beechwood xylan and wheat arabinoxylan as the sole carbon source. Moreover, an in silico study of the potential xylan-degrading proteins was conducted using proteome sequencing and CAZyme specialized bioinformatic tools. This study demonstrates the feasibility of utilizing complex polysaccharide substrates for PHA biosynthesis, thereby potentially eliminate additional processing steps and reducing overall production costs for sustainable plastic.
MULTIFILE
Worldwide, plastic cups are used for serving drinks. Some typical examples of large-scale consumption are large concerts and festivals. As a part of the BIOCAS project, which focusses on the valorization of biomass through various routes, a PHA biobased festival cup was developed and created to reduce the impact of current fossil plastics. The role of VHL was to assess the environmental impact. The aim of the report is to inform the BIOCAS-partners about the use of plastic cups, and address the environmental impact in comparison with other types of biobased plastic cups and fossil-based cups. This report can serve as a basis for making choices within all different types of (plastic/biobased) cups. Besides, it can be used as a public communication tool about the environmental impact of different types of (plastic/biobased) cup applications.
MULTIFILE
The valorization of biowaste, by exploiting side stream compounds as feedstock for the sustainable production of bio-based materials, is a key step towards a more circular economy. In this regard, chitin is as an abundant resource which is accessible as a waste compound of the seafood industry. From a commercial perspective, chitin is chemically converted into chitosan, which has multiple industrial applications. Although the potential of chitin has long been established, the majority of seafood waste containing chitin is still left unused. In addition, current processes which convert chitin into chitosan are sub-optimal and have a significant impact on the environment. As a result, there is a need for the development of innovative methods producing bio-based products from chitin. This project wants to contribute to these challenges by performing a feasibility study which demonstrates the microbial bioconversion of chitin to polyhydroxyalkanoates (PHAs). Specifically, the consortium will attempt to cultivate and engineer a recently discovered bacterium Chi5, so that it becomes able to directly produce PHAs from chitin present in solid shrimp shell waste. If successful, this project will provide a proof-of-concept for a versatile microbial production platform which can contribute to: i) the valorization of biowaste from the seafood industry, ii) the efficient utilization of chitin as feedstock, iii) the sustainable and (potentially low-cost) production of PHAs. The project consortium is composed of: i) Van Belzen B.V., a Dutch shrimp trading company which are highly interested in the valorization of their waste streams, hereby making their business model more profitable and sustainable. ii) AMIBM, which have recently isolated and characterized the Chi5 marine-based chitinolytic bacterium and iii) Zuyd, which will link aforementioned partners with students in creating a novel collaboration which will stimulate the development of students and the translation of academic knowledge to a feasible application technology for SME’s.
