Stark Gwendolyn F, Martin Robbie M, Smith Laura E, Wei Bofan, Hellweger Ferdi L, Bullerjahn George S, McKay R Michael L, Boyer Gregory L, Wilhelm Steven W
Department of Microbiology, The University of Tennessee, Knoxville, TN, USA.
Department of Chemistry, State University of New York College of Environmental Science and Forestry, Syracuse, NY, USA.
bioRxiv. 2023 Aug 28:2023.08.28.555099. doi: 10.1101/2023.08.28.555099.
For PCC 7806, temperature decreases from 26° C to 19° C double the microcystin quota per cell during growth in continuous culture. Here we tested whether this increase in microcystin provided PCC 7806 with a fitness advantage during colder-temperature growth by comparing cell concentration, cellular physiology, and the transcriptomics-inferred metabolism to a non-toxigenic mutant strain PCC 7806 Δ. Photo-physiological data combined with transcriptomic data revealed metabolic changes in the mutant strain during growth at 19° C, which included increased electron sinks and non-photochemical quenching. Increased gene expression was observed for a glutathione-dependent peroxiredoxin during cold treatment, suggesting compensatory mechanisms to defend against reactive oxygen species are employed in the absence of microcystin in the mutant. Our observations highlight the potential selective advantages of a longer-term defensive strategy in management of oxidative stress ( making microcystin) the shorter-term proactive strategy of producing cellular components to actively dissipate or degrade oxidative stress agents.
对于集胞藻PCC 7806，在连续培养生长过程中，温度从26℃降至19℃时，每个细胞的微囊藻毒素配额增加一倍。在此，我们通过比较细胞浓度、细胞生理学以及转录组学推断的代谢情况与非产毒突变株集胞藻PCC 7806 Δ，来测试这种微囊藻毒素的增加是否为集胞藻PCC 7806在较低温度生长期间提供了适应性优势。光生理数据与转录组数据相结合，揭示了突变株在19℃生长期间的代谢变化，其中包括电子汇和非光化学猝灭增加。在冷处理期间，观察到一种谷胱甘肽依赖性过氧化物酶的基因表达增加，这表明在突变体中没有微囊藻毒素的情况下，采用了防御活性氧的补偿机制。我们的观察结果突出了在氧化应激管理中（制造微囊藻毒素）长期防御策略相对于产生细胞成分以主动消散或降解氧化应激剂的短期主动策略的潜在选择优势。
