Polyhydroxyalkanoates (PHAs) form a highly promising class of bioplastics for the transition from fossil fuel-based plastics to bio-renewable and biodegradable plastics. Mixed microbial consortia (MMC) are known to be able to produce PHAs from organic waste streams. Knowledge of key-microbes and their characteristics in PHA-producing consortia is necessary for further process optimization and direction towards synthesis of specific types of PHAs. In this study, a PHA-producing mixed microbial consortium (MMC) from an industrial pilot plant was characterized and further enriched on acetate in a laboratory-scale selector with a working volume of 5 L. 16S-rDNA microbiological population analysis of both the industrial pilot plant and the 5 L selector revealed that the most dominant species within the population is Thauera aminoaromatica MZ1T, a Gram-negative beta-proteobacterium belonging to the order of the Rhodocyclales. The relative abundance of this Thauera species increased from 24 to 40% after two months of enrichment in the selector-system, indicating a competitive advantage, possibly due to the storage of a reserve material such as PHA. First experiments with T. aminoaromatica MZ1T showed multiple intracellular granules when grown in pure culture on a growth medium with a C:N ratio of 10:1 and acetate as a carbon source. Nuclear magnetic resonance (NMR) analyses upon extraction of PHA from the pure culture confirmed polyhydroxybutyrate production by T. aminoaromatica MZ1T.
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In the production of fermented foods, microbes play an important role. Optimization of fermentation processes or starter culture production traditionally was a trial-and-error approach inspired by expert knowledge of the fermentation process. Current developments in high-throughput 'omics' technologies allow developing more rational approaches to improve fermentation processes both from the food functionality as well as from the food safety perspective. Here, the authors thematically review typical bioinformatics techniques and approaches to improve various aspects of the microbial production of fermented food products and food safety.
In the field of ‘renewable energy resources’ formation of biogas is an important option. Biogas can be produced from biomass in a multistep process called anaerobic digestion (AD) and is usually performed in large digesters. Anaerobic digestion of biomass is mediated by various groups of microorganisms, which live in complex community structures. However, there is still limited knowledge on the relationships between the type of biomass and operational process parameters. This relates to the changes within the microbial community structure and the resulting overall biogas production efficiency. Opening this microbial black box could lead to an better understanding of on-going microbial processes, resulting in higher biogas yields and overall process efficiencies.
To treat microbial infections, antibiotics are life-saving but the increasing antimicrobial resistance is a World-wide problem. Therefore, there is a great need for novel antimicrobial substances. Fruit and flower anthocyanins have been recognized as promising alternatives to traditional antibiotics. How-ever, for future application as innovative alternative antibiotics, the full potential of anthocyanins should be further investigated. The antimicrobial potential of anthocyanin mixtures against different bacterial species has been demonstrated in literature. Preliminary experiments performed by our laboratories, using grape, rose and red cabbage anthocyanins against S. aureus and E. coli confirmed the antimicrobial potential of these substances. Hundreds of different anthocyanin entities have been described. However, which of these entities hold antimicrobial effects is currently unknown. Our preliminary data show that an-thocyanins extracted from grape, rose and red cabbage contain different collections of anthocyanin entities with differential antimicrobial efficacies. Our focus is on the extraction and characterization of anthocyanins from various crop residues. Grape peels are residues in the production of wine, while red rose and tulip leaves are residues in the production of tulip bulbs and regular horticulture. The presence of high-grade substances for pharmacological purposes in these crops may provide an innovative strategy to add value to other-wise invaluable crop residues. This project will be performed by the collaborative effort of our institute together with the Medi-cal Microbiology department of the University Medical Center Groningen (UMCG), 'Wijnstaete', a small-scale wine-producer (Lemelerveld) and Imenz Bioengineering (Groningen), a company that develops processes to improve the production of biobased chemicals from waste products. Within this project, we will focus on the antimicrobial efficacy of anthocyanin-mixtures from sources that are abundantly and locally available as a residual waste product. The project is part of a larger re-search effect to further characterize, modify and study the antimicrobial effects of specific anthocy-anin entities.
In the context of global efforts to increase sustainability and reduce CO2 emissions in the chemical industry, bio-based materials are receiving increasing attention as renewable alternatives to petroleum-based polymers. In this regard, Visolis has developed a bio-based platform centered around the efficient conversion of plant-derived sugars to mevalonolactone (MVL) via microbial fermentation. Subsequently, MVL is thermochemically converted to bio-monomers such as isoprene and 3-methyl-1,5-pentane diol, which are ultimately used in the production of polymer materials. Currently, the Visolis process has been optimized to use high-purity, industrial dextrose (glucose) as feedstock for their fermentation process. Dutch Sustainable Development (DSD) has developed a direct processing technology in which sugar beets are used for fermentation without first having to go through sugar extraction and refinery. The main exponent of this technology is their patented Betaprocess, in which the sugar beet is essentially exposed to heat and a mild vacuum explosion, opening the cell walls and releasing the sugar content. This Betaprocess has the potential to speed up current fermentation processes and lower feedstock-related costs. The aim of this project is to combine aforementioned technologies to enable the production of mevalonolactone using sucrose, present in crude sugar beet bray after Betaprocessing. To this end, Zuyd University of Applied Sciences (Zuyd) intends to collaborate with Visolis and DSD. Zuyd will utilize its experience in both (bio)chemical engineering and fermentation to optimize the process from sugar beet (pre)treatment to product recovery. Visolis and DSD will contribute their expertise in microbial engineering and low-cost sugar production. During this collaboration, students and professionals will work together at the Chemelot Innovation and Learning Labs (CHILL) on the Brightlands campus in Geleen. This collaboration will not only stimulate innovation and sustainable chemistry, but also provides starting professionals with valuable experience in this expanding field.
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.
