Photobioreactors enable the cultivation of phototrophic microorganisms under controlled conditions. Aerosol-based photobioreactors (abPBR) supply nutrients as fine droplets and enable the cultivation of biofilms on various substrates. Luffa is a biodegradable material with high porosity and large surface area. The combination of an abPBR and Luffa significantly improves cyanobacterial growth compared to established reactor concepts and offers a sustainable alternative to plastic-based systems.

The interdisciplinary nature of science, technology, engineering, and mathematics (STEM) offers the opportunity to implement educational approaches to biotechnology and process engineering issues. The focus should be on the promotion of scientific literacy in contexts relevant to research, industry, and society. This article specifically shows the development of suitable low-level experiments to provide a milestone for the implementation of biotechnological and process engineering issues in STEM education. The experiments show the successful transfer of inquiry-based bioprocess engineering experiments with a Do-It-Yourself (DIY) bioreactor and low-cost sensors. It was possible to achieve comparable trends of process-relevant state variables like mixing time and volumetric mass transfer coefficient (kLa) for the DIY bioreactor in comparison to established commercial systems. Furthermore, microalga Microchloropsis gaditana could be successfully cultivated under different cultivation conditions in the DIY system, and the respective growth curves could be observed. The DIY system is well suited for experimental application in schools and provides a scientifically substantiated basis for data interpretation. The scientific outreach approach and cooperation in a multiprofessional team for the transfer of process engineering questions to education can be evaluated as enriching. Experiments involving educational concepts offer a variety of connecting elements in the curriculum and opportunities to foster scientific literacy.

Cyanobacteria are promising organisms for sustainable biotechnology due to their ability to grow photoautotrophically and their wide range of products. Many cyanobacteria grow in the form of biofilms, which is why the development of photobioreactors (PBR) for the cultivation of cyanobacteria in the form of biofilms is of great interest. However, these biofilm PBR are mostly based on artificial growth surfaces, whereas biodegradable growth surfaces would be favored in terms of sustainable production and application. Luffa sponges (the dried fruit of Luffa cylindrica) are excellent biodegradable growth surfaces for cyanobacteria. Therefore, a biofilm PBR for cultivation of cyanobacteria on Luffa was developed in this study. Since many cyanobacteria grow naturally as biofilms in an air-exposed form and this should be imitated to improve growth, an aerosol-based PBR (abPBR) should be used for cultivation. This involves supplying the cyanobacteria with a nutrient mist. The abPBR was comprehensively characterized by determining the distribution of light, humidity and temperature inside the reactor. In addition, the residence time distribution of the aerosol was determined both experimentally and simulatively. In final cultivation experiments, it was shown that the abPBR is ideal for cultivating cyanobacteria and at the same time the aerosol system enables a simple imitation of drought stress. With the cyanobacteria Nostoc spec. and Desmonostoc muscorum, maximum area-time-yields (ATY) in relation to the growth surface of 6.34 and 4.19 g m-2 d-1, respectively, were achieved. Compared to previously developed abPBR, the ATY has been increased by a factor of 2.3.

Phycobiliproteins and pigments derived from cyanobacteria hold significant potential for diverse applications in the food, pharmaceutical, and chemical industries. The filamentous cyanobacterium Anabaena cylindrica serves as a valuable resource for extracting these compounds. This study develops a simplified, safe, and cost-effective extraction method that eliminates toxic solvents and minimizes processing steps. This makes the method applicable for all users and allows the easy integration of the extraction into biorefinery concepts in which the biomass is to be used as a fertilizer, for example. Utilizing salts such as ammonium sulfate and calcium chloride (15 gL−1 each) enables the effective extraction of phycocyanin (PC) and allophycocyanin, achieving a PC concentration of 192.34 mggCDW−1 and 209.44 mggCDW−1, respectively. Ethanol was introduced as a less toxic alternative to methanol for pigment extraction, increasing chlorophyll a and carotenoid recovery by 21% and 37%, respectively.

A growing world population is presenting the agricultural industry with increasing challenges. While a growing population needs to be fed, climate change means that agriculture must become more sustainable and tolerant against extreme events such as drought. Cyanobacteria are promising biofertilizers due to their nitrogen-fixing ability and biofilm formation. Therefore, the growth-promoting effect of nitrogen-fixing cyanobacteria (Anabaena cylindrica, Nostoc calcicola, and Nostoc muscorum) on wheat (Triticum aestivum) as a widely cultivated crop plant, was investigated in this study, both in hydroponic and pot culture experiments. Co-cultures of living N. calcicola with wheat were investigated for the first time in this study and showed the greatest growth-promoting effect, resulting in a significantly higher dry mass of the plants in hydroponics (+ 30%) compared to the control. In pot culture, the dry mass was increased by 44% with N. calcicola. The seedling length of the wheat plants was most strongly stimulated by co-cultivation with A. cylindrica. Co-cultures with the model plant Arabidopsis thaliana were carried out with and without the induction of drought stress. A significant increase in the dry mass of A. thaliana was achieved by co-cultivation with N. calcicola (+ 83%) without drought stress. The growth of A. thaliana was also stimulated under drought stress. Treatment with N. muscorum and N. calcicola resulted in the greatest improvement in DW, at 57% and 32%, respectively. This study highlights cyanobacteria as an effective biofertilizer that enhances plant growth and stress tolerance, reducing the need for synthetic fertilizers.

Cyanobacteria are a source of a variety of valuable substances. These include extracellular polymeric substances (EPS) and natural dyes. EPS are produced by cyanobacteria to protect themselves against environmental stresses, serve as a water reservoir, and play an essential role in the formation of biofilms. They can be used, for example, due to their antimicrobial properties. Cyanobacteria are phototrophic organisms and synthesize the pigments chlorophyll a and carotenoids for photosynthesis. However, they also possess other light-harvesting complexes in the form of phycobilisomes, which combine with proteins to form so-called phycobiliproteins (PBP). These enable cyanobacteria to utilize a larger light spectrum than plants. Both the pigments and the PBP can be used as natural colorants and offer antioxidant properties, among other things, which enables applications in medicine. Methods for the combined extraction of EPS, PBP, and pigments have already been described in the literature. Still, in this work, the methods were simplified and optimized to obtain the best possible method for use in the laboratory. The optimized downstream process is based on an extraction of the EPS with deionized water followed by an extraction of the PBP with potassium phosphate buffer and finally the extraction of the pigments with methanol. The PBP and pigments are extracted by adding fixed ratios of solvents followed by a single extraction for a certain period. The universal applicability was demonstrated over a broad biomass spectrum from 4 mg to 80 mg dry mass and the method was transferred to several cyanobacterial strains.

Microbiologically Induced Calcium Carbonate Precipitation (MICP) is a technology for improving soil characteristics, especially strength, that has been gaining increasing interest in literature during the last few years. Although a lot of influencing factors on the result of MICP are known, particle size and shape of the particles remain poorly understood. While destructive measuring of compressive strength or calcium carbonate content are important for the characterization of samples these methods give no insight into the internal structures and pore networks of the samples. X-ray microcomputed tomography (micro-CT) is a technique that is used to characterize the internals of rocks and to a certain degree MICP-treated soils. However, the impact of filtering and image processing of micro-CT Data depending on the type of MICP sample is poorly described in the literature. In this study, single fractions of local quarry were treated with MICP through the ureolytic microorganism Sporosarcina pasteurii to investigate the influence of particle size distribution on calcium carbonate content, unconfined compressive strength and the reduction of water permeability. Additionally, micro-CT was conducted to obtain insights into the resulting pore system. The impact of the Gauss filter und Non-local means filter on the resulting images and data on the pore network are discussed. The results show that particle size has a significant impact on the result of all tested parameters of biosandstone with lower particle size leading to higher strength and generally higher calcium carbonate content. Micro-CT data showed that the technology is feasible to gain valuable insights into the internal structures of biosandstone but the resolution and signal-to-noise ratio remain challenging, especially for samples with particle sizes smaller than 125 µm.

Synthetic hydrophilic polymers are an emerging yet overlooked class of anthropogenic substances. Unlike particulate plastics, synthetic hydrophilic polymers can interact with water, which complicates studying their fate and effects in the environment. This review discusses the sources, fate, and effects of these polymers across ecosystem boundaries. We identified households, agriculture, and mining as major sources. Despite wastewater treatment, synthetic hydrophilic polymers enter natural waterbodies. Agrochemical and sewage sludge applications release them to soil. Sorption and coagulation processes, influenced by polarity and molecular weight, likely define their fate through aquatic and terrestrial systems. Slow biodegradation may favor their accumulation. To advance our understanding of their fate, analytical techniques need improvement. Ecotoxicity studies found acute effects but long-term and field studies on mixtures and interactions with other pollutants are lacking. All in all, the prevailing literature emphasizes benefits of synthetic hydrophilic polymers while neglecting potential negative consequences; this calls for precaution.

Due to the global increase in the world population, it is not possible to ensure a sufficient food supply without additional nitrogen input into the soil. About 30-50% of agricultural yields are due to the use of chemical fertilizers in modern times. However, overfertilization threatens biodiversity, such as nitrogen-loving, fast-growing species overgrow others. The production of artificial fertilizers produces nitrogen oxides, which act as greenhouse gases. In addition, overfertilization of fields also releases ammonia, which damages surface waters through acidification and eutrophication. Diazotrophic cyanobacteria, which usually form a natural, stable biofilm, can fix nitrogen from the atmosphere and release it into the environment. Thus, they could provide an alternative to artificial fertilizers. In addition to this, biofilms stabilize soils and thus protect against soil erosion and desiccation. This chapter deals with the potential of cyanobacteria as the use of natural fertilizer is described. Possible partners such as plants and callus cells and the advantages of artificial co-cultivation will be discussed later. In addition, different cultivation systems for studying artificial co-cultures will be presented. Finally, the potential of artificial co-cultures in the agar industry will be discussed.

Prokaryotic and eukaryotic biofilm-forming microorganisms offer a wide spectrum of various biotechnological interesting products, which makes them promising cultivation organisms for industry, as biotechnological processes can be made simpler and more efficient. The biggest challenge is the cultivation since standard bioreactors like airlift or stirred tank reactors are not suitable for the cultivation of biofilms. Here, special biofilm bioreactors have been developed in recent years that imitate the natural habitat of biofilms. The choice of the surface plays an important role in the initial adhesion of the cells that form the basis for the subsequent biofilm formation and productivity. To enhance initial adhesion different materials were microstructured and used as a surface for the cultivation of different biofilms. It could be shown, that initial adhesion can positively be influenced by designing flow-breaker structures. Furthermore, pH and ionic strength have an impact on initial adhesion. In summary, it can be said that microstructured surfaces have an impact on biofilm thickness and structure, biomass formation, and productivity of valuable products.

Cyanobacteria are promising organisms for the sustainable production of various biotechnologi-cal interesting products. Due to their energy production via photosynthesis, the cultivation of cyanobacteria expands the CO2 cycle. Most cyanobacteria form biofilms on surfaces in their natu-ral environment by surrounding the cells with a self-produced matrix of extracellular polymeric substances (EPS) that hold the cells together. These special growth properties need special reac-tors for cultivation. By immobilizing cyanobacteria on carriers, systems currently established in industry could also be used for biofilm formers. Various artificial carriers for immobilized growth of cyanobacteria and microalgae have already been described in the literature. However, the use of waste materials or natural biodegradable carriers would be more sustainable and is, therefore, the focus of this study. Dried Luffa cylindrica, zeolite, and corn stalks were investigated for their use as carriers for cyanobacteria. L. cylindrica was shown to be an excellent natural carrier for (i) Anabaena cylindrica (ii) Nostoc muscorum 1453-12a, and (III) Nostoc muscorum 1453-12b. Higher or at least similar growth rates were achieved when cyanobacteria were cultivated with L. cylindrica compared to submerged cultivation. Additionally, the production of EPS and C-phycocyanin was increased at least 1.4-fold in all strains by culturing on L. cylindrica. The improved growth could be explained on the one hand by the high surface area of L. cylindrica and its properties, and on the other hand by the release of growth-promoting nutrients from L. cylindrica to the medium.

In the course of combining the Sustainable Development Goals (SDGs) with the science education curriculum, the relevance of the micro- and macroalgae in education is based on the biotechnological future-oriented significance and the ever-growing trend toward plant-based nutrition. So, the micro- and macroalgae are finding their way onto the food shelves and creating biotechnological solutions with regard to climate change (SDG4; SDG13). Their colored photopigments and phycobiliproteins are already established as important natural dyes in the food and textile industries. In addition to being essential in photosynthesis, photopigments have a variety of functions and effects that influence almost all aspects of our lives. The article presents experimental protocols developed based on the established methods for the extraction of photopigments from plants and optimized for the use of phototrophic micro- and macroalgae (Chlorella vulgaris, Arthrospira platensis, and Palmaria palmata). Besides the green chlorophylls and yellow-orange carotenoids in plants, cyanobacteria and red algae developed additional light antenna complexes, so-called phycobilisomes, consisting of different phycobiliproteins. For this purpose, experiments that are simple to execute have been developed to make the colorful world of photopigments visible to the students from the upper secondary level and can be used in both university and school educational settings. Furthermore, a column chromatography was developed, which allows the preparation of the pigment and phycobiliprotein extracts from A. platensis. This procedure is based on the established "supermarket column" and was optimized according to the use of powdered amounts of A. platensis. Additionally, results from a first implementation in a classroom setting will be discussed.

The terrestrial cyanobacterium Chroococcidiopsis cubana was identified as a producer of an antimicrobial substance inhibiting growth of the Gram-positive bacterium Micrococcus luteus and the yeast Candida auris. It was found that the production is initiated by nitrogen limitation, usually occurring during late exponential growth phase of the cyanobacterium. This effect was used for implementation of a continuous production set-up, which led to a significantly increased formation of the antimicrobial metabolite. The produced bioactive culture supernatant was purified by reverse phase chromatography; the most potent fraction caused a growth inhibition of over 90 % for both indicator organisms. The metabolite remained active until a temperature of approx. 45 degrees C; at increasing temperatures, the inhibiting effect decreased significantly. By identification of the trigger initiating the compound synthesis, a first scale-up could be implemented, leading to a reliable production of the antimicrobial metabolite. As Candida auris is an emerging pathogen causing serious infections, this work can be the first step to the development of a potent antifungal drug.

The sodium salicylate method for nitrate determination in liquids was adapted for the use in microtiter plates and the applicability of this quick, easy and economic test was examined for cyanobacterial mineral media. The assay was found to be suitable for a direct detection of nitrate ions up to a concentration of 450 mg L-1 within the commonly used mineral media BG-11, BBM, ASN-III and Zarrouk. The salicylate method was successfully used for the correlation of Synechococcus elongatus PCC 6301 cell growth and nitrate consumption over 17 cultivation days.

Although the handling and exploitation of cyanobacteria is associated with some challenges, these phototrophic bacteria offer great opportunities for innovative biotechnological processes. This chapter covers versatile aspects of working with cyanobacteria, starting with up-to-date in silico and in vitro screening methods for bioactive substances. Subsequently, common conservation techniques and vitality/viability estimation methods are compared and supplemented by own data regarding the non-invasive vitality evaluation via pulse amplitude modulated fluorometry. Moreover, novel findings about the influence the state of the pre-cultures have on main cultures are presented. The following sub-chapters deal with different photobioreactor-designs, with special regard to biofilm photobioreactors, as well as with heterotrophic and mixotrophic cultivation modes. The latter topic provides information from literature on successfully enhanced cyanobacterial production processes, augmented by own data.

Terrestrial cyanobacteria grow as phototrophic biofilms and offer a wide spectrum of interesting products. For cultivation of phototrophic biofilms different reactor concepts have been developed in the last years. One of the main influencing factors is the surface material and the adhesion strength of the chosen production strain. In this work a flow chamber was developed, in which, in combination with optical coherence tomography and computational fluid dynamics simulation, an easy analysis of adhesion forces between different biofilms and varied surface materials is possible. Hereby, differences between two cyanobacteria strains and two surface materials were shown. With longer cultivation time of biofilms adhesion increased in all experiments. Additionally, the content of extracellular polymeric substances was analyzed and its role in surface adhesion was evaluated. To test the comparability of obtained results from the flow chamber with other methods, analogous experiments were conducted with a rotational rheometer, which proved to be successful. Thus, with the presented flow chamber an easy to implement method for analysis of biofilm adhesion was developed, which can be used in future research for determination of suitable combinations of microorganisms with cultivation surfaces on lab scale in advance of larger processes.

AbstractIn diesem Beitrag stellt sich die Nachwuchswissenschaftlerin Dr.‐Ing. Dorina Strieth vom Lehrgebiet Bioverfahrenstechnik der TU Kaiserslautern vor. Neben aktuellen Forschungsarbeiten und Lehraktivität berichtet sie über die Notwendigkeit des Wissenstransfers in die Zivilgesellschaft. Fachlich berichtet sie von aktuellen Ergebnissen der intelligenten Nutzung phototropher Biofilme sowie dem Potenzial zur biotechnologischen Herstellung nachhaltiger Baumaterialien.

Biotechnology and BioengineeringVolume 119, Issue 6 p. 1337-1341 ISSUE INFORMATIONFree Access Biotechnology and Bioengineering: Volume 119, Number 6, June 2022 First published: 13 May 2022 https://doi.org/10.1002/bit.27828AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume119, Issue6June 2022Pages 1337-1341 RelatedInformation

Cyanobacteria are ubiquitous phototrophic prokaryotes that find a wide range of applications in industry due to their broad product spectrum. In this context, the application of cyanobacteria as biofertilizers and thus as an alternative to artificial fertilizers has emerged in recent decades. The benefit is mostly based on the ability of cyanobacteria to fix elemental nitrogen and make it available to the plants in a usable form. However, the positive effects of co-cultivating plants with cyanobacteria are not limited to the provision of nitrogen. Cyanobacteria produce numerous secondary metabolites that can be useful for plants, for example, they can have growth-promoting effects or increase resistance to plant diseases. The effects of biotic and abiotic stress can as well be reduced by many secondary metabolites. Furthermore, the biofilms formed by the cyanobacteria can lead to improved soil conditions, such as increased water retention capacity. To exchange the substances mentioned, cyanobacteria form symbioses with plants, whereby the strength of the symbiosis depends on both partners, and not every plant can form symbiosis with every cyanobacterium. Not only the plants in symbiosis benefit from the cyanobacteria, but also vice versa. This review summarizes the beneficial effects of cyanobacterial co-cultivation on plants, highlighting the substances exchanged and the strength of cyanobacterial symbioses with plants. A detailed explanation of the mechanism of nitrogen fixation in cyanobacterial heterocysts is given. Finally, a summary of possible applications of co-cultivation in the (agrar-)industry is given.