Growth conditions have been frequently studied in optimizing polyhydroxybutyrate (PHB) production, while few studies were performed to unravel the dynamic mixed microbial consortia (MMCs) in the process. In this study, the relationship between growth conditions (C/N ratios and pH) and the corresponding key-microbes were identified and monitored during PHB accumulation. The highest PHB level (70 wt% of dry cell mass) was obtained at pH 9, C/N 40, and acetic acid 10 g/L. Linking the dominant genera with the highest point of PHB accumulation, Thauera was the most prevalent species in all MMCs of pH 9, except when a C/N ratio of 1 was applied. Notably, dominant bacteria shifted at pH 7 (C/N 10) from Thauera (0 h) to Paracoccus, and subsequently to Alcaligenes following the process of PHB accumulation and consumption. Further understanding of the relationship between the structure of the microbial community and the performance will be beneficial for regulating and obtaining high PHB accumulation within an MMC. Our study illustrates the impact of C/N ratios and pH on microbial prevalence and PHB production levels using a mixed microbial starter culture. This knowledge will broaden industrial perspectives for regulating high PHB production and timely harvesting.
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High-pressure anaerobic digestion is an appealing concept since it can upgrade biogas directly within the reactor. However, the decline of pH caused by the dissolution of CO2 is the main barrier that prevents a good operating high-pressure anaerobic digestion process. Therefore, in this study, a high-pressure anaerobic digestion was studied to treat high alkalinity synthetic wastewater, which could not be treated in a normal-pressure anaerobic digester. In the high-pressure reactor, the pH value was 7.5 ~ 7.8, and the CH4 content reached 88% at 11 bar. Unlike its normal-pressure counterpart (2285 mg/L acetic acid), the high-pressure reactor ran steadily (without volatile fatty acids inhibition). Furthermore, the microbial community changed in the high-pressure reactor. Specifically, key microbial guilds (Syntrophus (11.2%), Methanosaeta concilii (50.9%), and Methanobrevibacter (26.8%)) were dominant in the high-pressure reactor at 11 bar, indicating their fundamental roles under high-pressure treating high alkalinity synthetic wastewater.
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Sportverenigingen in Nederland dragen bij aan een gezonde leefstijl, sociale cohesie en inclusieve sportdeelname. Ondanks dat de sportparticipatie toeneemt, hebben de clubs het moeilijk om hun ledental op peil te houden. Diverse ontwikkelingen spelen daarbij een rol. De focus van het onderzoek in dit proefschrift richt zich op twee maatschappelijke ontwikkelingen, ‘individualisering’ en ‘digitalisering’. In zeven studies wordt antwoord gegeven op twee onderzoeksvragen: 1) hoe het clubgevoel van leden van sportvereniging kan worden geconceptualiseerd in termen van definitie, voorspellers en opbrengsten en 2) hoe sociaalnetwerksites van sportverenigingen kunnen bijdragen het ontwikkelen van het clubgevoel van leden? Die studies vormen samen een multimethode onderzoek. Resultaten laten zien dat clubgevoel verwijst naar de gevoelsband van leden met hun club op basis van participatie, relevantie en de sociale wereld van de club. Clubgevoel hangt samen met bindingsaspecten zoals de intentie om je in te zetten voor de club en te blijven. Sociaalnetwerksites van sportverenigingen kunnen helpen om dit clubgevoel te ontwikkelen, bij voorkeur door de kanalen in te zetten voor informatie en interactie over de club, de sport en de leden. De online kanalen vormen samen de virtuele community van de vereniging die, afhankelijk van de aanpak door de club en de leden, verschillende verschijningvormen kan hebben. Met hun virtuele community bieden sportverenigingen, naast de accommodatie, ook een ónline ontmoetingsplek voor sport en andere activiteiten waarmee ze het clubgevoel onder hun leden kunnen bevorderen. Met dit proefschrift geeft Nanny Kuijsters inzichten voor de ontwikkeling van virtuele community’s voor verenigingen, professionals en geïnteresseerden in de georganiseerde sport.
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Water treatment companies are more and more interested in chemical-free water treatment. This is a solution that might not only decrease costs of chemicals, but also decrease possible formation of by-products and contribute to decreasing the introduction of emerging contaminants in the environment. A possible route for this is the use of magnetic fields based treatment. Magnetic fields exist around us (our planet is surrounded by such fields) but are not broadly used in water treatment. A reason for this situation isthe fact that water treatment is a rather traditional market and magnetic treatment, conversely, a rather controversial and (still) not completely understood. Even with such resistance, recently it has been shown that magnetic fields applied to drinking water resulted in significant structural change of its microbiome [1]. This community structural change was clearly detected with a newly developed flow cytometry method, where the phenotypic characteristics of the entire microbial community could be analysed instantly [2-9]. Lab-scale batch experiments have shown that magnetic fields can selectively boost the growth of smaller bacteria [1][3] and indicated as a next step that the same principle could be addressed in pilot scale tests. ISusMag is structured to apply the robust and instant flow cytometry method to examine the effect of magnetic fields on drinking water at pilot scale under realistic field conditions. For this purpose, groundwater will be evenly distributed into two (pipe)lines of the same length: one will be magnetically treated, and one will be used as control. Samples will be taken at the end of the two pipes for flow cytometry examination. Measurement results can help drinking water companies to understand whether a magnetic treatment is an alternative to control the growth of pathogenic bacteria instead of classical chemical treatment (disinfection).
The message we intend to communicate is that in the future, our cities can (partly) feed themselves with healthy foods grown in microbial gardens, which can be part of a household kitchen or community garden for providing fresh green "vegetables" where the energy for the artificial LED lighting for the microbial garden is coming from solar panels on roofs thereby making this system free from fossil energy.For Floriade 2022, we would like to introduce the Urban Microbial garden pop-up restaurant for feeding and greening the city. The menu will include a speciality microbiota vegan burger made from algae, seaweed, fungi and fava beans served on dishes made from baked mycelium. Our objective is to elicit consumer perception and opinion on the future of our new microbial food chain, which is fully sustainable and safer for the environment. Consumer opinions will be video recorded and compiled into a short movie/video for further inspiration and analysis for product/service development. This pop-up restaurant is a logical extension of the Art-Work by 4F.STUDIO (Kim van den Belt, Joshua Kelly, Steven Wobbes) already present in Kavel 123 at Floriade as part of the Light Challenge. The artwork depicts a future object for community gardens which supports the idea of locally produced microbes. Since we already have work at Floriade, this living-lab project has the benefit of broadening the vision of their work through more in-depth and visceral feedback.
