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THE TOXIC CYANOBACTERIUM NOSTOC SP. STRAIN 152 PRODUCES HIGHEST AMOUNTS OF MICROCYSTIN AND NOSTOPHYCIN UNDER STRESS CONDITIONS 1
Author(s) -
Kurmayer Rainer
Publication year - 2011
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2010.00931.x
Subject(s) - cyanobacteria , biology , microcystin , nostoc , microcystin lr , metabolite , irradiance , secondary metabolite , strain (injury) , environmental factor , photosynthesis , botany , food science , zoology , biochemistry , bacteria , genetics , physics , anatomy , quantum mechanics , gene
The understanding of how environmental factors regulate toxic secondary metabolite production in cyanobacteria is important to guarantee water quality. Very little is known on the regulation of toxic secondary metabolite production in benthic cyanobacteria. In this study, the physiological regulation of the production of the toxic heptapeptide microcystin (MC) and the nontoxic related peptide nostophycin (NP) in the benthic cyanobacterium Nostoc sp. strain 152 was studied under contrasting environmental conditions. A 2 k levels factorial design was used, where k is the number of four factors that have been tested: reduction in temperature (20°C vs. 12°C), irradiance (50 vs. 1 μmol · m −2 · s −1 ), P‐PO 4 (144 vs. 0.14 μM P‐PO 4 ), and N‐NO 3 (5.88 mM versus N‐NO 3 free). While the growth rate was reduced >100‐fold under most severe conditions of temperature, irradiance, and phosphate reduction, the production of MC and NP never ceased. The MC and NP contents per cell varied at maximum 5‐ and 10.6‐fold each; however, the physiological variation did not outweigh the highly significant linear relationship between the daily cell division rate and the MC and NP net production rates. Surprisingly, the MC and NP contents per cell showed a maximum under P‐PO 4 ‐reduced and irradiance‐reduced conditions. Both intra‐ and extracellular MC and NP concentrations were negatively related to P‐PO 4 and irradiance. It is concluded that the proximate factor behind maximal cellular MC and NP contents is physiological stress.