Maintenance of cultures
Cultures sent to customers remain alive for at least 14 days provided that the following precautions are observed. Cultures should be unpacked immediately after receipt and stored at 15-18°C under low light intensity (north window, no direct sun light, or weak white fluorescent light). Screw caps or vessels should be loosened but not removed. Further maintenance or multiplication of cultures requires transfer into new culture media. This presupposes experience in simple microbial techniques.
Many species are cultivated and dispatched on agar media (cited in SAG Database as "Medium Ag") for safety reasons but develop their morphological characteristics only in liquid media, e.g. flagellates, colony-forming Volvocales and Chlorococcales. For teaching purposes these species should be transferred into liquid media 2-3 weeks before demonstration, e.g. into Soil Water Media, Basal Medium, or Desmidiacean Medium.
Erhalt von Algenkulturen
Kulturen mit aktiven Stoffwechsel
Mikroalgenstämme der SAG werden hauptsächlich durch routinemäßige, serielle Subkultivierung unter kontrollierten Umgebungsbedingungen aufrechterhalten. Die Kulturen werden in der späten logarithmischen/stationären Phase auf frisches, steriles Medium überführt. Ziel ist es, ein gesundes, physiologisch, morphologisch und genetisch repräsentatives Replikat zu erhalten. Ein zu berücksichtigender Schlüsselfaktor ist, dass unterschiedliche Altersstufen von Subkulturen unterschiedliche Stadien des Lebenszykluses vorweisen können. Die routinemäßige serielle Subkultivierung ist ein arbeits- und verbrauchsintensiver Prozess, was es erschwert eine große Anzahl von Stämmen aufrechtzuerhalten.
Kryokonservierung
Ein erfolgreicher alternativer Ansatz für die Ex-situ-Konservierung von Algen- und Cyanobakterienkulturen ist die Kryokonservierung. Mit Hilfe des europaweiten Forschungsprojektes COBRA wurde an der SAG die Kryokonservierung von Mikroalgen etabliert.
Seitdem werden 30 % aller terrestrischen Mikroalgenbestände der SAG kryokonserviert. Dies bedeutet einen großen Qualitätssprung für die SAG-Kulturen, denn die Kryokonservierung gewährleistet physiologisch und genetisch stabile Kulturen.
Metabolically Active Cultures
Microalgal strains at SAG are primarily preserved through routine serial subculturing under controlled environmental conditions. These cultures are transferred to fresh, sterile medium during the late log or stationary phase, resulting in metabolically active cultures that are readily available for use. The goal is to maintain specimens that are healthy and representative physiologically, morphologically, and genetically. It is important to consider that subcultures of different ages may represent various stages of the life cycle. Routine serial subculturing is both labor-intensive and resource-intensive, significantly limiting the capacity of technicians to maintain a large number of strains.
Cryopreservation
Cryopreservation offers a successful alternative method for the ex situ conservation of algal and cyanobacterial cultures. Supported by the Europe-wide research project COBRA, the SAG has established cryopreservation techniques for microalgae. Consequently, 30% of SAG's terrestrial microalgal holdings are now stored through cryopreservation, marking significant progress in enhancing the quality of SAG cultures. Cryopreservation provides a means to ensure the physiological and genetic stability of these cultures.
Culture Care and Dispatch Instructions?
Cultures sent to customers remain alive for at least 14 days provided that the following precautions are observed. Cultures should be unpacked immediately after receipt and stored at 15-18°C under low light intensity (north window, no direct sunlight, or weak white fluorescent light). Screw caps or vessels should be loosened but not removed. Further maintenance or multiplication of cultures requires transfer into new culture media. This presupposes experience in simple microbial techniques.
Many species are cultivated and dispatched on agar media (cited in SAG Database as "Medium Ag") for safety reasons but develop their morphological characteristics only in liquid media, e.g., flagellates, colony-forming Volvocales, and Chlorococcales. For teaching purposes, these species should be transferred into liquid media 2-3 weeks before demonstration, e.g., into Soil Water Media, Basal Medium, or Desmidiacean Medium.
Metabolically Active Cultures
Microalgal strains at SAG are primarily preserved through routine serial subculturing under controlled environmental conditions. These cultures are transferred to fresh, sterile medium during the late log or stationary phase, resulting in metabolically active cultures that are readily available for use. The goal is to maintain specimens that are healthy and representative physiologically, morphologically, and genetically. It is important to consider that subcultures of different ages may represent various stages of the life cycle. Routine serial subculturing is both labor-intensive and resource-intensive, significantly limiting the capacity of technicians to maintain a large number of strains.
Cryopreservation as an Alternative Strategy
In contrast to the continuous effort required for maintaining active cultures, cryopreservation stands as a pivotal alternative for the long-term conservation of algal and cyanobacterial strains. Through the collaborative efforts within the Europe-wide COBRA project, SAG has successfully implemented cryopreservation protocols for its microalgal collections. Now, 30% of the SAG's terrestrial microalgae are preserved using this method, significantly improving the stability and quality of the cultures. This advancement not only ensures the genetic and physiological integrity of the strains but also exemplifies a sustainable approach to microbial resource management.
Guidelines for Culture Care Post-Dispatch
Upon arrival, it is critical that cultures are properly cared for to ensure their viability. When cultures are dispatched to customers, they are guaranteed to remain viable for at least 14 days, assuming certain conditions are met. Immediate unpacking and appropriate storage are crucial—cultures should be kept at 15-18°C in low light conditions to prevent stress and degradation. While it is necessary to slightly loosen containers to facilitate gas exchange, removing caps entirely is not advised. Subsequent culture maintenance or propagation necessitates transferring the organisms to fresh media, a process that requires basic microbiological skills.
For educational and experimental purposes, it is recommended that cultures initially grown on solid media be transferred to liquid media well in advance of any demonstrations or analyses. This transition is crucial for the full expression of morphological and physiological traits, especially in species that exhibit distinct characteristics in different growth media. Many species, such as flagellates, colony-forming Volvocales, and Chlorococcales, are cultivated and dispatched on agar media (noted in the SAG Database as "Medium Ag") primarily for safety reasons. However, to observe their true morphological characteristics, these species should be transferred to liquid media, such as Soil Water Media, Basal Medium, or Desmidiacean Medium, 2-3 weeks before they are needed for demonstration or further study. This ensures the cultures develop adequately, allowing for a more effective and educational observation of their life processes and adaptations.