Microalgae are possible sources of antiviral substances, e.g. against cyprinid herpesvirus 3 (CyHV-3). Although this virus leads to high mortalities in aquacultures, there is no treatment available yet. Hence, ethanolic extracts produced with accelerated solvent extraction from six microalgal species (Arthrospira platensis, Chlamydomonas reinhardtii, Chlorella kessleri, Haematococcus pluvialis, Nostoc punctiforme and Scenedesmus obliquus) were examined in this study. An inhibition of the in vitro replication of CyHV-3 could be confirmed for all six species, with the greatest effect for the C. reinhardtii and H. pluvialis crude extracts. At still non-cytotoxic concentrations, viral DNA replication was reduced by over 3 orders of magnitude each compared to the untreated replication controls, while the virus titers were even below the limit of detection (reduction of 4 orders of magnitude). When pre-incubating both cells and virus with C. reinhardtii and H. pluvialis extracts before inoculation, the reduction of viral DNA was even stronger (> 4 orders of magnitude) and no infectious viral particles were detected. Thus, the results of this study indicate that microalgae and cyanobacteria are a promising source of natural bioactive substances against CyHV-3. However, further studies regarding the isolation and identification of the active components of the extracts are needed.

Electronic waste contains high amounts of gold and is therefore an important secondary source of this raw material. While conventional metal recovery processes are associated with environmental and health risks along with high energy demand, bio-based methods represent a sustainable alternative of growing importance. In our previous work, we discovered that the moss Physcomitrella patens not only selectively binds Rare Earth Elements (REEs) but can also bind gold with even higher efficiency. This prompted us to conduct a comparative study on the biosorption of gold by P. patens and two further moss species (Physcomitrium eurystomum and Physcomitrium sphaericum). Sorption capacities from model gold solutions reached 1.2 ± 0.4 mmol g-1, 1.1 ± 0.6 mmol g-1 and 0.8 ± 0.1 mmol g-1, respectively, and were up to 3.7-folds higher than these obtained for selected REEs. As expected, the efficiency of gold removal was affected by the pH of the metal solution. Furthermore, reduction of gold ions seems to play an important role in the gold recovery by mosses. Thus, although further studies on the mechanisms of gold recovery by moss species are needed, the work presented here provides important insights into the use of moss for the re-valorisation of e-waste as a secondary source of gold.

Microalgae often stand out for their high biodiversity as well as their associated large number of potent bioactives. Therefore, they are interesting candidates as possible sources of antiviral substances, e.g. against cyprinid herpesvirus 3 (CyHV-3). Although this virus leads to high mortalities in aquacultures, there is no treatment available yet. Hence, ethanolic extracts produced with accelerated solvent extraction from six microalgal species (Arthrospira platensis, Chlamydomonas reinhardtii, Chlorella kessleri, Haematococcus pluvialis, Nostoc punctiforme and Scenedesmus obliquus) were examined in this study for inhibitory effects on viral replication. An inhibition of the in vitro replication of CyHV 3 in common carp brain cells could be confirmed for all six species, with the greatest effect for the C. reinhardtii and H. pluvialis extracts. At still non-cytotoxic concentrations viral DNA replication was reduced by over 3 orders of magnitude (> 99.9 %) each compared to the untreated replication controls, while the virus titers were at or even below the limit of detection. When pre-incubating cells and virus with C. reinhardtii and especially H. pluvialis extracts before inoculation, the reduction of viral DNA and virus titer was even stronger. Based on these results, an intervention in the initial replication steps like viral adsorption or membrane fusion is assumed. Moreover, a protection mechanism preventing the production of viral proteins and the assembly of mature virions is also possible. All in all, the results show that microalgae are a very promising source of natural antiviral substances against CyHV-3.