Роль витамина В12 в сукцессии морских фитоценозов

• Main Author: Пропп, Луиза
• Format: Text
• Language: unknown
• Published: Федеральное государственное унитарное предприятие «Тихоокеанский научно-исследовательский рыбохозяйственный центр» 2009
• Subjects: ВИТАМИН В12; АУКСОТРОФИЯ; ФИТОПЛАНКТОН; ДИАТОМОВЫЕ; ЦВЕТЕНИЕ; БИОМЕТОД; МОРСКАЯ СРЕДА; БИОЛОГИЧЕСКАЯ ПРОДУКТИВНОСТЬ; БАКТЕРИИ; Barents Sea
• Online Access: http://cyberleninka.ru/article/n/rol-vitamina-v12-v-suktsessii-morskih-fitotsenozov; http://cyberleninka.ru/article_covers/10101186.png

Обсуждается роль витамина В12 в морских биоценозах. Приводится обзор работ о продуцентах и консументах витамина, методах его определения. Излагается разработанная автором ионообменная техника концентрирования витамина с последующим микробиологическим определением его содержания с использованием штамма кишечной палочки Escherichia coli. Результаты наблюдений над сезонной динамикой витамина В12 в прибрежных водах Баренцева моря, сопоставление их с видовым составом и численностью фитопланктона согласуются с ранее высказанной в литературе гипотезой о связи сукцессии доминирующих видов фитопланктона с изменением в воде содержания витамина В12. Vitamins, as cobalamin (B12), thiamin, biotin, are required absolutely for alga growth in axenic culture that is known as auxotrophy. That's why vitamins have to determine which species can develop and dominate in a phytoplankton community. Publications on producers and consumers of the vitamin B12 and methods of its determination are reviewed. New ion-exchange technique to concentrate the vitamin with a subsequent microbiological determination using Escherichia coli strain, elaborated by the author, is presented that doesn't require a long incubation period like algal bioassay and has higher sensitivity than extraction techniques. Seasonal succession of phytoplankton and B12 variation in coastal waters of the Barents Sea are described. Although the maximal content of B12 (before spring bloom) reached 2 ng/l, it was completely exhausted during the peaks of bloom with domination of Sceletonema costatum and later S. costatum and Leptocylindrus danicus. In the second case, two auxotrophs competed for the B12. Cellular requirements on B12 are very small, so it is probably important for growth mainly. Auxotrophic algae form a significant portion of phytoplankton population; from the other hand, concentration of B12 is often sufficient to allow the maximum growth rates. So, auxotrophs can compete successfully with autotrophs, and the vitamin hypothetically can be a limiting factor for some species in certain seasons. Their blooms can deplete the content of B12 in the sea water but the concentration usually rises again by activity of bacteria that develop on organic substratum formed by algae excretion and cell breakage. Author's observations over seasonal dynamics of B12 in relation with phytoplankton species composition and abundance confirm this hypothesis because the succession of phytoplankton dominating species and variations of vitamin B12 content are well correlated. Turnover of B12 in marine environment is suggested on the base of this hypothesis.