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- ItemEvaluating stress resilience of cyanobacteria through flow cytometry and fluorescent viability assessment(Sringer, 2024-11-06) Kroupová, Zuzana; Slaninová, Eva; Mrázová, Kateřina; Krzyžánek, Vladislav; Hrubanová, Kamila; Fritz, Ines; Obruča, StanislavCyanobacteria are prokaryotic organisms characterised by their complex structures and a wide range of pigments. With their ability to fix CO2, cyanobacteria are interesting for white biotechnology as cell factories to produce various high-value metabolites such as polyhydroxyalkanoates, pigments, or proteins. White biotechnology is the industrial production and processing of chemicals, materials, and energy using microorganisms. It is known that exposing cyanobacteria to low levels of stressors can induce the production of secondary metabolites. Understanding of this phenomenon, known as hormesis, can involve the strategic application of controlled stressors to enhance the production of specific metabolites. Consequently, precise measurement of cyanobacterial viability becomes crucial for process control. However, there is no established reliable and quick viability assay protocol for cyanobacteria since the task is challenging due to strong interferences of autofluorescence signals of intercellular pigments and fluorescent viability probes when flow cytometry is used. We performed the screening of selected fluorescent viability probes used frequently in bacteria viability assays. The results of our investigation demonstrated the efficacy and reliability of three widely utilised types of viability probes for the assessment of the viability of Synechocystis strains. The developed technique can be possibly utilised for the evaluation of the importance of polyhydroxyalkanoates for cyanobacterial cultures with respect to selected stressor-repeated freezing and thawing. The results indicated that the presence of polyhydroxyalkanoate granules in cyanobacterial cells could hypothetically contribute to the survival of repeated freezing and thawing.
- ItemEffect of stabilized organic amendments on biodegradability of poly-3-hydroxybutyrate, soil biological properties, and plant biomass(Springer, 2024-09-27) Brtnický, Martin; Holátko, Jiří; Hammerschmiedt, Tereza; Mustafa, Adnan; Kameníková, Eliška; Kintl, Antonín; Radziemska, Maja; Baltazár, Tivadar; Malíček, Ondřej; Kučerík, JiříPoly-3-hydroxybutyrate (P3HB) is a biodegradable polymer with a potential extensive use in agriculture. However, while P3HB biodegradation boosts microbial enzyme activity, it significantly reduces plant biomass due to nutrient competition. In this study, we test the hypothesis that these detrimental effects can be mitigated though the co-application of nutrient-rich organic amendments, such as compost and digestate. A pot experiment with lettuce (Lactuca sativa), grown in soil amended with P3HB lone or combined with either compost or digestate. Six variants were tested: Control, Compost, Compost + P3HB, Digestate, Digestate + P3HB, and P3HB alone. We evaluated degradation of the P3HB polymer, biological soil properties, and both the dry and fresh biomass of the lettuce. We observed that adding P3HB alone enhanced dehydrogenase and urease activities, as well as all types of respiration, except for L-arginine-induced respiration. However, it strongly and negatively affected the biomass of lettuce (both aboveground and root). The strong adverse effects of P3HB on plant growth were also observed when compost was co-applied, although this combination enhanced all enzyme activities except for suppressed beta-glucosidase. Conversely, co-applying digestate with P3HB alleviated the negative effect of P3HB on both the dry and fresh biomass together lettuce. Additionally, this combination increased the activity of several enzymes (dehydrogenase, arylsulfatase, N-acetyl-beta-D-glucosaminidase, urease), and enhanced all types of respiration, except for L-arginine-induced respiration. The use of biodegradable plastics in agriculture is on rise, but it may be compromised, because their biodegradation my negatively impact plant growth. The results showed that co-application of digestate is an effective solution to alleviate these effects, while co-application of compost failed. Generally, organic amendments seem to be an option to alleviate the negative effects of bioplastics biodegradation, and offers options how to handle the treatment of waste bioplastics or their residues, but further investigation is needed to understand the underlaying mechanisms involved.
- ItemTemperature effect on the kinetic profile of Ziegler-Natta catalyst in propene polymerization(SPringer Nature, 2024-09-10) Kolomazník, Vít; Cejpek, Igor; Skoumal, MiroslavPropene polymerization kinetic profiles with a diether-based Ziegler-Natta MgCl2-supported catalyst were investigated in a stainless-steel batch reactor. The initial 10 min period characterizes various temperature levels with a constant volume of liquid propene. The lowest temperature level corresponds to the usual prepolymerization temperature (10 degrees C), and the highest level corresponds to the usual main polymerization temperature (70 degrees C). The effects of the starting temperature levels were evaluated through polymerization kinetic patterns computed namely from the second polymerization period carried out at 70 degrees C for the next 90 min. Based on the heat transfer data, the kinetic profiles were fitted to suitable semi-empirical equations derived from fundamental kinetic approaches using the first and second orders of the catalyst active sites decay. Both approaches adequately describe the dependence of the initial activities and deceleration constants on the temperature during the initial period.
- ItemAssessing Lettuce Exposure to a Multi-Pharmaceutical Mixture in Soil: Insights from LC-ESI-TQ Analysis and the Impact of Biochar on Pharmaceutical Bioavailability(AMER CHEMICAL SOC, 2024-09-04) Fučík, Jan; Jašek, Vojtěch; Hamplová, Marie; Navrkalová, Jitka; Zlámalová Gargošová, Helena; Mravcová, LudmilaAgricultural practices introduce pharmaceutical (PhAC) residues into the terrestrial environment, potentially endangering agricultural crops and human health. This study aimed to evaluate various aspects related to the presence of pharmaceuticals in the lettuce-soil system, including bioconcentration factors (BCFs), translocation factors (TFs), ecotoxicological effects, the influence of biochar on the PhAC bioavailability, persistence in soil, and associated environmental and health risks. Lettuce (Lactuca sativa L.) was exposed to a mixture of 25 PhACs in two scenarios: initially contaminated soil (ranging from 0 to 10,000 ng center dot g(-1)) and soil irrigated with contaminated water (ranging from 0 to 1000 mu g center dot L-1) over a 28-day period. The findings revealed a diverse range of BCFs (0.068-3.7) and TFs (0.032-0.58), indicating the uptake and translocation potential of pharmaceuticals by lettuce. Significant ecotoxicological effects on L. sativa, including weight change and increased mortality, were observed (p < 0.05). Interestingly, biochar did not significantly affect PhAC uptake by L. sativa (p > 0.05), while it significantly influenced the soil degradation kinetics of 12 PhACs (p < 0.05). Additionally, the estimated daily intake of PhACs through the consumption of L. sativa suggested negligible health risks, although concerns arose regarding the potential health risks if other vegetable sources were similarly contaminated with trace residues. Furthermore, this study evaluated the environmental risk associated with the emergence of antimicrobial resistance (AMR) in soil, as medium to high. In conclusion, these findings highlight the multifaceted challenges posed by pharmaceutical contamination in agricultural environments and emphasize the importance of proactive measures to mitigate the associated risks to both environmental and human health.
- ItemA Comparison of the Effects of Continuous Illumination and Day/Night Regimes on PHB Accumulation in Synechocystis Cells(MDPI, 2024-07-20) Fleischhacker-Daffert, Christina; Zerobin, Antonia; Hummel, Ferdinand; Slaninová, Eva; Kroupová, Zuzana; Obruča, Stanislav; Mrázová, Kateřina; Hrubanová, Kamila; Krzyžánek, Vladislav; Nebesářová, Jana; Ludwig, Katharina; Fritz, InesPoly(3-hydroxybutyrate) (PHB) is a biobased and biodegradable polymer with properties comparable to polypropylene and therefore has the potential to replace conventional plastics. PHB is intracellularly accumulated by prokaryotic organisms. For the cells PHB functions manly as carbon and energy source, but all possible functions of PHB are still not known. Synechocystis (cyanobacteria) accumulates PHB using light as energy and CO2 as carbon source. The main trigger for PHB accumulation in cyanobacteria is nitrogen and phosphorous depletion with simultaneous surplus of carbon and energy. For the above reasons, obtaining knowledge about external factors influencing PHB accumulation is of highest interest. This study compares the effect of continuous light exposure and day/night (16/8 h) cycles on selected physiology parameters of three Synechocystis strains. We show that continuous illumination at moderate light intensities leads to an increased PHB accumulation in Synechocystis salina CCALA 192 (max. 14.2% CDW - cell dry weight) compared to day/night cycles (3.7% CDW). In addition to PHB content, glycogen and cell size increased, while cell density and cell viability decreased. The results offer new approaches for further studies to gain deeper insights into the role of PHB in cyanobacteria to obtain bioplastics in a more sustainable and environmentally friendly way.