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.
Cyanobacteria obtain their energy through photosynthesis and live embedded in a matrix of extracellular polymeric substances (EPS) containing valuable products, e.g., polysaccharides, lipids, ...proteins, and antimicrobials. Besides chlorophyll a and carotenoids, they have light-absorbing compounds in the form of light-harvesting complexes, the so-called phycobilisomes, consisting of different phycobiliproteins. Together they close the “green gap” whereby cyanobacteria can use light more effective than higher plants. Cultivation of cyanobacteria on a lab-scale results in small amounts of biomass for their characterization or a comprehensive screening. EPS are, for example, produced as a protection against suboptimal culture conditions. Carotenoids are essential light-harvesting pigments for photosynthesis, play a key role in photoprotective reactions, and are produced for cell wall stabilization. Essentially, the pigment composition of cyanobacteria depends on the available light spectrum, nitrogen content, and temperature. Especially the production of EPS and pigments are indicators for the cell-condition. Therefore, different EPS extraction methods were tested including the determination of inhibitory effects of extracts against
Escherichia coli
. Based on the best EPS extraction method, a new strategy for downstream processing (DSP) was developed to determine EPS, the pigments chlorophyll
a
and carotenoids, and phycobiliproteins from only one sample. As cyanobacterial model organisms
Trichocoleus sociatus
and
Nostoc flagelliforme
were used, and DSP strategy was successfully transferred to four additional cyanobacteria. The final DSP includes the following steps: (i) EPS extraction, (ii) lyophilization of biomass, (iii) extraction of phycobiliproteins, and a final (iv) chlorophyll a and carotenoid extraction. The new strategy allows a comprehensive characterization of cyanobacterial cells.
Due to the emerging rise of multi‐drug resistant bacteria, the discovery of novel antibiotics is of high scientific interest. Through their high chemodiversity of bioactive secondary metabolites, ...cyanobacteria have proven to be promising microorganisms for the discovery of antibacterial compounds. These aspects make appropriate antibacterial screening approaches for cyanobacteria crucial. Up to date, screenings are mostly carried out using a phenotypic methodology, consisting of cyanobacterial cultivation, extraction, and inhibitory assays. However, the parameters of these methods highly vary within the literature. Therefore, the common choices of parameters and inhibitory assays are summarized in this review. Nevertheless, less frequently used method variants are highlighted, which lead to hits from antimicrobial compounds. In addition to the considerations of phenotypic methods, this study provides an overview of developments in the genome‐based screening area, be it in vivo using PCR technique or in silico using the recent genome‐mining method. Though, up to date, these techniques are not applied as much as phenotypic screening.
Due to the emerging rise of multi‐drug resistant bacteria, the discovery of novel antibiotics is of interest. Through their high chemodiversity of bioactive secondary metabolites, cyanobacteria have proven to be promising microorganisms for the discovery of antimicrobial compounds. This review deals with the screening, including in vivo approaches like bioactivity assays as well as in silico approaches using contemporary genome‐mining tools in connection with cyanobacteria. The summarized tools are not only applicable for cyanobacteria and can be transferred to other microorganisms.
Cyanobacteria are promising organisms for the sustainable production of various biotechnological 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 natural 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 reactors 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.
When using microbiologically induced calcium carbonate precipitation (MICP) to produce calcium carbonate crystals in the cavities between mineral particles to consolidate them, the inhomogeneous ...distribution of the precipitated calcium carbonate poses a problem for the production of construction materials with consistent parameters. Various approaches have been investigated in the literature to increase the homogeneity of consolidated samples. One approach can be the targeted application of ureolytic organisms by 3D printing. However, to date, this possibility has been little explored in the literature. In this study, the potential to use MICP to print calcium carbonate layers on mineral particles will be investigated. For this purpose, a dispensing unit was modified to apply both a suspension of Sporosarcina pasteurii and a calcination solution containing urea and calcium chloride onto quartz sand. The study showed that after passing through the nozzle, S. pasteurii preserved consistent cell vitality and therefore its potential of MICP. Applying cell suspension and calcination solution through a printing nozzle resulted in a layer of calcium carbonate crystals on quartz sand. This observation demonstrated the proof of concept of printing calcium carbonate by MICP through the nozzle of a dispensing unit. Furthermore, it was shown that cell suspensions of S. pasteurii can be stored at 4°C for a period of 17 days while maintaining its optical density, urease activity and cell vitality and therefore the potential for MICP. This initial concept could be extended in further research to printing three‐dimensional (3D) objects to solve the problem of homogeneity in consolidated mineral particles.
The cultivation of cyanobacteria with the addition of an organic carbon source (meaning as heterotrophic or mixotrophic cultivation) is a promising technique to increase their slow growth rate. ...However, most cyanobacteria cultures are infected by non-separable heterotrophic bacteria. While their contribution to the biomass is rather insignificant in a phototrophic cultivation, problems may arise in heterotrophic and mixotrophic mode. Heterotrophic bacteria can potentially utilize carbohydrates quickly, thus preventing any benefit for the cyanobacteria. In order to estimate the advantage of the supplementation of a carbon source, it is essential to quantify the proportion of cyanobacteria and heterotrophic bacteria in the resulting biomass. In this work, the use of quantitative polymerase chain reaction (qPCR) is proposed. To prepare the samples, a DNA extraction method for cyanobacteria was improved to provide reproducible and robust results for the group of terrestrial cyanobacteria. Two pairs of primers were used, which bind either to the 16S rRNA gene of all cyanobacteria or all bacteria including cyanobacteria. This allows a determination of the proportion of cyanobacteria in the biomass. The method was established with the two terrestrial cyanobacteria
Trichocoleus sociatus
SAG 26.92 and
Nostoc muscorum
SAG B-1453-12a. As proof of concept, a heterotrophic cultivation with
T. sociatus
with glucose was performed. After 2 days of cultivation, a reduction of the biomass partition of the cyanobacterium to 90% was detected. Afterwards, the proportion increased again.
Diazotrophic cyanobacteria are able to fix N2 from the atmosphere and release it as bioavailable nitrogen what other organisms can utilize. Thus, they could be used as living nitrogen supplier ...whereby the use of fertilizer could be reduced in agricultural industry what results in a decrease of laughing gas released during fertilizer production. The diazotroph cyanobacterium Desmonostoc muscorum (D. muscorum) was characterized in shake flasks cultivated in nitrogen‐free and nitrogen‐containing medium. Similar growth rates were reached in both cultivations and the release of ammonium by D. muscorum was detected under nitrogen depletion. Subsequently, D. muscorum was co‐cultivated with Arabidopsis thaliana (A. thaliana) in nitrogen‐free medium. Additionally, the plant was cultivated in nitrogen containing and nitrogen‐free medium without D. muscorum as reference. A co‐cultivation led to higher growth rates of the cyanobacterium and similar growth of A. thaliana with similar maximum photochemical efficiency of photosystem II compared to the growth of nitrogen containing medium. Further, accumulation of cyanobacterial cells around the roots of A. thaliana was detected, indicating a successfully induced artificial symbiosis. Based on these results, D. muscorum could be a promising cyanobacterium as living nitrogen supplier for plants.
Abstract
In 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.
Abstract
In this article, young scientist Dr.‐ng. Dorina Strieth from the Chair of Bioprocess Engineering at the TU Kaiserslautern introduces herself. In addition to current research work and teaching activities, she reports on the need for knowledge transfer to civil society. On a scientific level, she presents recent results on the intelligent use of phototrophic biofilms as well as the potential for biotechnological production of sustainable building materials.
In 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.
In this article, young scientist Dr.‐ng. Dorina Strieth from the Chair of Bioprocess Engineering at the TU Kaiserslautern introduces herself. In addition to current research work and teaching activities, she reports on the need for knowledge transfer to civil society. On a scientific level, she presents recent results on the intelligent use of phototrophic biofilms as well as the potential for biotechnological production of sustainable building materials.
Nachwuchswissenschaftlerin Dr.‐Ing. Dorina Strieth von der TU Kaiserslautern gibt Einblick in die aktuellen Forschungsfragen mit Bezug zur Nachhaltigkeit. Neben ihren aktuellen Forschungs‐ und Lehraktivitäten berichtet sie über die Notwendigkeit des Wissenstransfers in die Zivilgesellschaft.
The original version of this article unfortunately contains mistake introduced during the publishing process. The names of the authors were interchanged in the author group. The corrected author ...group is shown above.
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