Changes in the chemical composition of carbohydrates and proteins in surface water during a bloom ofMicrocystis in Lake Suwa |
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Authors: | Yumiko Amemiya Kenji Kato Tokio Okino Oki Nakayama |
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Institution: | (1) Department of Envorinmental Engineering, Yamanashi University, Takeda 4, 400 Kofu, Japan;(2) School of Allied Medical Sciences, Shinshu University, Asahi 3, 390 Matsumoto, Japan;(3) Suwa Hydrobiological Station, Shinshu University, Kogandori 5, 392 Suwa, Japan;(4) Department of Environmental Engineering, Yamanashi University, Takeda 4, 400 Kofu, Japan |
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Abstract: | Carbohydrates and proteins in surface water during a bloom ofMictrocystis, which is the dominant summer phytoplankton in Lake Suwa, were analyzed in order to evaluate the function ofMicrocystis in organic matter metabolism. Glucose was the predominant sugar constituent of the cellular carbohydrate fraction and decreased
in quantity from inside towards the outside of the cell through the slime layer. Other constituent sugars, on the other hand,
were present in larger proportions in the lake water. Although the sugar composition of the cells did not change in July and
August, during the first period of theMicrocystis bloom, it changed appreciably in September when the water temperature decreased below 20°C accompanied by the decrease in
solar radiation and a marked change in nutrient concentration.
It appears that the sugar composition of the cells may change in response to some environmental stresses. In addition, a temporal
change in the sugar composition was found, particularly in the fraction containing the slime extracted by shaking. Among the
constituent amino acids of the cells, the percentage of arginine, aspartic acid and leucine decreased from inside toward the
outside of the cell, while glutamic acid, threonine, serine and glycine showed an opposite trend. In contrast to the carbohydrates,
the percentage composition of each amino acid varied little throughout the period of the bloom. |
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Keywords: | Amino acid composition Environmental stress Microcystis Sugar composition |
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