Microalgae cultures were used for a WW treatment to remediate nutrients while producing biomass and recycling water. In these trials, raceway ponds (RWPs; 1 and 0.5 ha) were located next to a municipal (WW) treatment plant in Mérida, Spain. The ponds were used for continuous, all-year-round microalgae production using WW as a source of nutrients. Neither CO2 nor air was supplied to cultures. The objective was to validate photosynthesis monitoring techniques in large-scale bioreactors. Various in-situ/ex-situ methods based on chlorophyll fluorescence and oxygen evolution measurements were used to follow culture performance. Photosynthesis variables gathered with these techniques were compared to the physiological behavior and growth of cultures. Good photosynthetic activity was indicated by the build-up of dissolved oxygen concentration up to 380% saturation, high photochemical yield (Fv/Fm = 0.62-0.71), and relative electron transport rate rETR between 200 and 450 μmol e- m-2 s-1 at midday, which resulted in biomass productivity of about 15-25 g DW m-2 day-1. The variables represent reliable markers reflecting the physiological status of microalgae cultures. Using waste nutrients, the biomass production cost can be significantly decreased for abundant biomass production in large-scale bioreactors, which can be exploited for agricultural purposes.

• Keywords
• Micractinium, biomass, biostimulanting activity, chlorophyll fluorescence, large-scale bioreactor, microalga, oxygen production, photosynthesis, raceway pond, wastewater,
• Publication type
• Journal Article MeSH

Photosynthesis uses light as a source of energy but its excess can result in production of harmful oxygen radicals. To avoid any resulting damage, phototrophic organisms can employ a process known as non-photochemical quenching (NPQ), where excess light energy is safely dissipated as heat. The mechanism(s) of NPQ vary among different phototrophs. Here, we describe a new type of NPQ in the organism Rhodomonas salina, an alga belonging to the cryptophytes, part of the chromalveolate supergroup. Cryptophytes are exceptional among photosynthetic chromalveolates as they use both chlorophyll a/c proteins and phycobiliproteins for light harvesting. All our data demonstrates that NPQ in cryptophytes differs significantly from other chromalveolates - e.g. diatoms and it is also unique in comparison to NPQ in green algae and in higher plants: (1) there is no light induced xanthophyll cycle; (2) NPQ resembles the fast and flexible energetic quenching (qE) of higher plants, including its fast recovery; (3) a direct antennae protonation is involved in NPQ, similar to that found in higher plants. Further, fluorescence spectroscopy and biochemical characterization of isolated photosynthetic complexes suggest that NPQ in R. salina occurs in the chlorophyll a/c antennae but not in phycobiliproteins. All these results demonstrate that NPQ in cryptophytes represents a novel class of effective and flexible non-photochemical quenching.

• MeSH
• Cell Membrane metabolism   radiation effects   MeSH
• Cryptophyta cytology   enzymology   metabolism   radiation effects   MeSH
• Photosystem II Protein Complex metabolism   MeSH
• Kinetics MeSH
• Hydrogen-Ion Concentration MeSH
• Protein Structure, Quaternary MeSH
• Protein Multimerization radiation effects   MeSH
• Chlorophyll Binding Proteins chemistry   metabolism   MeSH
• Protons MeSH
• Substrate Specificity MeSH
• Light adverse effects   MeSH
• Xanthophylls metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Photosystem II Protein Complex MeSH
• Chlorophyll Binding Proteins MeSH
• Protons MeSH
• Xanthophylls MeSH

Microscopic algae and cyanobacteria are excellent sources of numerous compounds, from raw biomass rich in proteins, oils, and antioxidants to valuable secondary metabolites with potential medical use. In the former Czechoslovakia, microalgal biotechnology developed rapidly in the 1960s with the main aim of providing industrial, high-yield sources of algal biomass. Unique cultivation techniques that are still in use were successfully developed and tested. Gradually, the focus changed from bulk production to more sophisticated use of microalgae, including production of bioactive compounds. Along the way, better understanding of the physiology and cell biology of productive microalgal strains was achieved. Currently, microalgae are in the focus again, mostly as possible sources of bioactive compounds and next-generation biofuels for the 21st century.

• MeSH
• Biomass MeSH
• Biofuels MeSH
• Biotechnology history   methods   trends   MeSH
• Cell Culture Techniques MeSH
• History, 20th Century MeSH
• History, 21st Century MeSH
• Microalgae growth & development   MeSH
• Cyanobacteria growth & development   MeSH
• Check Tag
• History, 20th Century MeSH
• History, 21st Century MeSH
• Publication type
• Journal Article MeSH
• Historical Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH
• Czechoslovakia MeSH
• Names of Substances
• Biofuels MeSH