Kurmayer Rainer
Austrian Academy of Sciences, Institute for Limnology, Mondseestrasse 9, 5310 Mondsee, Austria.
J Phycol. 2011 Feb;47(1):200-207. doi: 10.1111/j.1529-8817.2010.00931.x.
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 non-toxic related peptide nostophycin (NP) in the benthic cyanobacterium Nostoc sp. strain 152 was studied under contrasting environmental conditions. I used a 2(k) levels factorial design, where k is the number of four factors that have been tested: Reduction in temperature (20 vs. 12°C), irradiance (50 vs. 1 μmol · m(-2) · s(-1)), P-PO(4) (144 vs. 0.14 μM P-PO(4)), N-NO(3) (5.88 mM vs. N-NO(3) free). While the growth rate was reduced more than hundred 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.
了解环境因素如何调节蓝藻中有毒次生代谢产物的产生对于保证水质至关重要。目前对于底栖蓝藻中有毒次生代谢产物产生的调控知之甚少。在本研究中，在不同环境条件下研究了底栖蓝藻 Nostoc sp. 菌株 152 中有毒七肽微囊藻毒素（MC）和无毒相关肽 nostophycin（NP）产生的生理调控。我采用了 2(k) 水平析因设计，其中 k 是已测试的四个因素的数量：温度降低（20 对 12°C）、辐照度（50 对 1 μmol·m(-2)·s(-1)）、P-PO(4)（144 对 0.14 μM P-PO(4)）、N-NO(3)（5.88 mM 对无 N-NO(3)）。虽然在温度、辐照度和磷酸盐降低的最严苛条件下生长速率降低了一百多倍，但 MC 和 NP 的产生从未停止。每个细胞的 MC 和 NP 含量各自最多变化 5 倍和 10.6 倍，然而生理变化并未超过每日细胞分裂速率与 MC 和 NP 净产生速率之间高度显著的线性关系。令人惊讶的是，每个细胞的 MC 和 NP 含量在 P-PO(4) 降低和辐照度降低的条件下达到最大值。细胞内和细胞外的 MC 和 NP 浓度均与 P-PO(4) 和辐照度呈负相关。得出的结论是，细胞内 MC 和 NP 含量最高背后的直接因素是生理胁迫。
