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Comparative growth characterization of frequently used substrains of the model cyanobacterium Synechocystis sp. PCC 6803 under varying culture conditions
Zavřel, Tomáš ; Očenášová, Petra ; Sinětova, M. A. ; Červený, Jan
Cyanobacteria have gained increased attention as ideal candidates for biotechnological applications due to their capacity to produce valuable molecules ranging from therapeutic proteins to biofuels. Their natural phenotypic plasticity in highly dynamic environments enables easy deployment of new biotechnologies as well as opening possibilities for genetic engineering. This contribution presents a new approach to fast and reliable characterization of cyanobacteria growth in a flat panel photobioreactor that enables examination of changing light, temperature, and nutrient availability. The utilization of semi-continuous automatic cultivation with real-time culture growth monitoring provides a strong experimental basis for both characterization and optimization of cyanobacteria cultures in photobioreactors. We first characterized the autotrophic growth of the substrain of Synechocystis sp. PCC 6803 denoted as GT-L. This strain is capable of efficient growth under a wide range of environmental conditions with doubling time as fast as 5 h under favorable conditions. However, differences among Synechocystis sp. PCC 6803 substrains have been identified on both the genotype and phenotype levels. We therefore aimed to utilize the experimental platform to characterize multiple commonly used Synechocystis sp. PCC 6803 substrains. This method will enable us to identify substrains capable of robust growth and high production yields as reliable biotechnological candidates.
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Development of methods for breeding high-lipidcontent algal strain Chlamydomonas reinhardtii using fluorescence-activated cell sorting
Fedorko, Jan ; Búzová, Diana ; Červený, Jan
Green microalgae are among the most widely distributed microorganisms in the biosphere. They are significant contributors to global photosynthetic productivity and are interesting for biotechnology due to their large variety of high-value compound accumulation and range of applications. To achieve profitable microalgae cultures for biotechnology, one wants to combine antagonistic properties: rapid growth and high accumulation of specific compounds. Here, we focus on development of advanced cultivation strategies and breeding methods applied to the model algae Chlamydomonas reinhardtii for optimized production of lipids. For identification, isolation, and subsequent selection of an optimal subpopulation with high lipid content, we used high-throughput fluorescenceactivated cell sorting in combination with imaging flow cytometry on cells stained with lipid-specific fluorescent dye. We observed that post-sort cell viability was not negatively influenced by external parameters used during the sorting procedure (pressure, light quality and quantity, influence of the sorting electromagnetic field, toxic effects of both fluorescent marker and microfluidic system medium composition).
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Spatial heterogeneity of soil CO2 efflux in four different ecosystems
Dařenová, Eva
Manual measurements of soil CO2 effl ux on a larger number of positions can give precise estimation of CO2 effl ux from the investigated area and together with temporal dynamics, observed in continuous measurements, can provide a good view on the ecosystem carbon balance. In this study we investigated the spatial heterogeneity of soil CO2 effl ux in four diff erent ecosystems (spruce forest, beech forest, wetland, grassland). Soil CO2 was measured on a net of 25–65 positions using a manual measurement system. We tried to fi nd responsible factors for the heterogeneity and to determine a measurement protocol for the most precise estimation of soil CO2 effl ux. Th e highest respiration activity was observed in the spruce forest, the lowest in the wetland ecosystem, where it was caused by a high water table. In the wetland ecosystem, there was the highest spatial heterogeneity of respiration activity, which reached almost 60 %. Th is high heterogeneity was caused by the gradient of the water table depth. Contrary to this, the lowest heterogeneity was found in the grassland where it was only about 15 %. In the spruce and beech forest the heterogeneity ranged between 35 and 45 %. As infl uencing factors we investigated e.g. soil moisture, tree distance and amount of the above ground biomass.
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