Green microalgae including those from the genus Lobosphaera are exploited in biotechnology to obtain valuable fatty acids e.g., arachidonic acid (C20:4, ARA) for the production of infant formulae, food and feed additives. In nature, microalgae frequently exist in naturally immobilized state (as biofilms) with limited cell division rate and increased stress resilience. In biotechnology, immobilization of microalgae on artificial cell carriers simplifies biomass harvesting, increases culture robustness and productivity. The choice of suitable cell carrier is central to biotechnology of immobilized culture. Cell carriers based on the natural amine-containing polymer chitosan and synthetic polyethylenimine (PEI) are promising candidates for immobilization of phototrophic microorganisms. This is the first report on the effects of immobilization on PEI and chitosan on the accumulation and composition of polyunsaturated fatty acids, including ARA, in Lobosphaera sp. IPPAS C-2047. The immobilization on PEI increased ARA percentage in the total tatty acids and ARA accumulation by 72% and 81%, compared with the suspended cells cultured respectively in complete or nitrogen-deprived medium 14 days. Immobilization of Lobosphaera sp. on the chitosan-based carrier declined ARA but increased oleic and α-linoleic acid percentages. Mechanisms of the effects of immobilization on fatty acid profiles of the microalgae are discussed.

Microalgae are naturally adapted to fluctuating availability of phosphorus (P) being capable to opportunistically uptake large amounts of inorganic phosphate (Pi) and safely store it in the cell as polyphosphate. Hence, many microalgal species are remarkably resilient to high concentrations of external Pi. Here we report on an exception from this pattern comprised by a failure of the high Pi-resilience in a strain Micractinium simplicissimum IPPAS C-2056 normally coping with a very high Pi concentrations. This phenomenon occurred after abrupt re-supplementation of Pi to the M. simplicissimum culture pre-starved of P. This was the case even if Pi was re-supplemented in a concentration far below the level toxic to the P-sufficient culture. We hypothesize that this effect can be mediated by a rapid formation of the potentially toxic short-chain polyphosphate following the mass influx of Pi into the P-starved cell. A possible reason for this is that the preceding P starvation impairs the capacity of the cell of converting the newly absorbed Pi into a “safe” storage form of long-chain polyphosphate. We believe that findings of this study can help to avoid sudden culture crashes, they are also of potential significance for development of algae-based technologies for efficient bioremoval of P from P-rich waste streams.

Pharmaceuticals including antibiotics are among hazardous micropollutants (HMP) of the environment. Incomplete degradation of the HMP leads to their persistence in water bodies causing a plethora of deleterious effects. Conventional wastewater treatment cannot remove HMP completely, and a promising alternative is comprised by biotechnologies based on microalgae. The use of immobilized microalgae in environmental biotechnology is advantageous since immobilized cultures allow recycling of the microalgal cells, support higher cell densities, and boost tolerance of microalgae to stresses including HMP. Here we report on a comparative study of HMP (exemplified by the antibiotic ceftriaxone) removal by suspended and chitosan-immobilized cells of Lobosphaera sp. IPPAS C-2047 unialgal culture. We also monitored the dynamics of photosynthetic pigments content and the physiological condition of the cells as reflected by the activity of their photosynthetic apparatus. Special attention was paid to the changes in the accumulation of valuable arachidonic acid (C20:4). In addition to this, we followed the changes in the culture microbiome induced the antibiotic exposure. Collectively, our results showed that both suspended and immobilized cultures took up ceftriaxone from the culture medium. In the case of immobilized culture, a significant amount of the antibiotic was adsorbed on the chitosan carrier itself. The dynamics of the taxonomic composition of the microbiome of the microalgae was more shifted by the immobilization on the chitosan than by exposure to 20 mg/L of ceftriaxone. The possibility and limitations of the using of chitosan-immobilized Lobosphaera sp. IPPAS C-2047 for HMP removal coupled with the production of valuable long-chain polyunsaturated fatty acids is discussed.

Depression and cognitive impairment are recognized complications of COVID-19. This study aimed to assess cognitive performance in clinically diagnosed post-COVID depression (PCD) patients using neuropsychological testing. The study involved 71 post-COVID patients, with matched control groups: recovered COVID-19 individuals without complications (n=18) and individuals without prior COVID-19 history (n=19). A post-COVID depression group (PCD, n=25) was identified based on psychiatric diagnosis, a comparison group (noPCD, n=46) included participants with neurological COVID-19 complications, excluding clinical depression. The PCD patients showed significantly less scores in the MoCA test, decreased immediate memory recall in the Word Memory Test, decreased processing speed and higher accuracy in the Trail Making Test, and near to significant worse executive control and processing speed in the Stroop task compared to controls and the noPCD patients. The number of post-COVID symptoms negatively correlated with immediate word memory recall and processing speed among all post-COVID patients. In PCD patients, negative correlations between number of post-COVID symptoms and delayed recall, between time after recovery and immediate recall, and positive correlation between the number of acute symptoms and processing speed in the incongruent condition of the Stroop task were found. No differences between groups in Sniffin’s stick olfactory test was found. Overall, our study revealed cognitive impairment in PCD patients similar to those in major depressive disorder.

Depression is one of the most severe sequelae of COVID-19, with major depressive disorder often characterized by disruption in white matter (WM) connectivity , stemming from changes in brain myelination. This study aimed to quantitatively assess brain myelination in clinically diagnosed post-COVID depression using recently proposed MRI method, macromolecular proton fraction (MPF) mapping. The study involved 63 recovered COVID-19 patients (52 mild, 11 moderate, 2 severe) at 13.5±10.0 months post-recovery, with matched controls without prior COVID-19 history (n=19). A post-COVID depression group (PCD, n=25) was identified based on psychiatric diagnosis, while a comparison group (noPCD, n=38) included participants with neurological COVID-19 complications, excluding clinical depression. Fast MPF mapping revealed extensive demyelination in PCD patients, particularly in juxtacortical WM (predominantly occipital lobe and medial surface), WM tracts (inferior fronto-occipital fasciculus (IFOF), posterior thalamic radiation, external capsule, sagittal stratum, tapetum), and grey matter (GM) structures (hippocampus, putamen, globus pallidus, and amygdala). The noPCD group also displayed notable demyelination but with less magnitude and propagation. Multiple regression analysis highlighted IFOF demyelination as the primary predictor of PCD presence and severity according to Hamilton scores. The number of post-COVID symptoms was a significant predictor of PCD presence while the number acute of symptoms was a significant predictor of PCD severity. This study, for the first time, reveals extensive demyelination in numerous WM and GM structures in PCD, outlining IFOF demyelination as a key biomarker.