Blue color formation of cyanobacteria with beta-cyclocitral.
Volatile compounds, such as beta-cyclocitral, geosmin, and 2-methylisoborneol, from cyanobacteria showed a lytic activity against cyanobacteria. Particularly, beta-cyclocitral caused an interesting color change in the culture broth from green to blue during the lysis process. In the present study, the lytic behavior of various cyanobacteria with beta-cyclocitral was investigated, and a mechanism for the blue color formation was developed. beta-Cyclocitral lysed both the laboratory strains of any genera and bloom samples including many species of cyanobacteria, and caused the characteristic color change from green to blue. beta-Cyclocitral provided a characteristic behavior, such that the absorption maxima of chlorophyll-a and beta-carotene disappeared, but that of phycocyanin still remained after 12 h, which indicated that beta-cyclocitral decomposed chlorophyll-a and beta-carotene rapidly, so that the inherent colors from the tolerant water-soluble pigments became observable in the cultured broth. This phenomenon was confirmed by another experiment using Phormidium (NIES-611), which showed a pink color derived from phycoerythrin. beta-Cyclocitral was more easily oxidized when compared with similar aldehyde compounds, so that the pH of the solution quickly decreased to 4.5. An oxidation product of beta-cyclocitral in water solution was isolated and identified as 2,6,6-trimethylcyclohexene-1-carboxylic acid. This study provides support that beta-cyclocitral derived from cyanobacteria plays an important role in the lysis of cyanobacteria and participates in the blue color formation under natural conditions.
Harada
Ken-Ichi
K
Graduate School of Environmental and Human Science and Faculty of Pharmacy, Meijo University, Tempaku, Nagoya 468-8503, Japan. kiharada@ccmfs.meijo-u.ac.jp
Ozaki
Keiko
K
Tsuzuki
Sayaka
S
Kato
Hajime
H
Hasegawa
Masateru
M
Kuroda
Emilia K
EK
Arii
Suzue
S
Tsuji
Kiyomi
K
D000042:Absorption; D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology*; D003116:Color; D003470:Culture Media; D000458:Cyanobacteria / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D004224:Diterpenes / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D010788:Photosynthesis / Q000187:drug effects; D010858:Pigmentation / Q000187:drug effects*; D013057:Spectrum Analysis
D000447:Aldehydes; D003470:Culture Media; D004224:Diterpenes; C516118:beta-cyclocitral