Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection, National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China.
Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection, National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China.
J Hazard Mater. 2024 Sep 15;477:135152. doi: 10.1016/j.jhazmat.2024.135152. Epub 2024 Jul 20.
Raphidiopsis raciborskii (R. raciborskii) forms harmful cyanobacterial blooms globally, and poses a great threat to the safety of drinking water and public health. There is a great need to develop eco-friendly biological alternative measures to mitigate mass blooms of R. raciborskii. However, previous rare studies on algicidal microorganisms against R. raciborskii restricted this aim. Recently, an algicidal bacterium Streptomyces sp. HY (designated HY) was identified with flavones producing ability, and could remove up to 98.73 % of R. raciborskii biomass within 48 h by directly attacking the cyanobacterium and release of algicidal substances (i.e., flavonoids) with a inoculum ratio of 5 %. Algicidal rate of HY was enhanced by 88.05 %, 89.33 % under dark and light, and full-light conditions respectively, when compared with the dark condition. Its algicidal substances were stable in a broad range of temperature (-80-55 °C) and pH (3-11) conditions, and all treated groups exhibited ≈ 100 % algicidal rate at day 3. HY treatment disrupted the photosynthesis system and triggered serious oxidative stress resulting in severe morphological injury. Thereby, HY treatment significantly affected expression levels of several essential genes (i.e., psbA, psaB, rbcL, ftsZ, recA, grpE), and simultaneously inhibited the biosynthesis and release of cylindrospermopsin. Yet, HY treatment didn't show any toxicity to zebrafish test embryos. Such results indicate that HY is a promising algicidal candidate strain to control global R. raciborskii blooms, and holds great promises for an effective biological measure to sustain water safety.
裂须盘藻（R. raciborskii）在全球范围内形成有害的蓝藻水华，对饮用水安全和公共健康构成巨大威胁。开发环保的生物替代措施来减轻裂须盘藻的大规模水华非常有必要。然而，之前针对裂须盘藻的杀藻微生物的罕见研究限制了这一目标的实现。最近，一种具有产生类黄酮能力的杀藻细菌链霉菌 sp. HY（命名为 HY）被鉴定出来，可以在 48 小时内通过直接攻击蓝藻和释放杀藻物质（即类黄酮）将裂须盘藻的生物量去除高达 98.73%，接种比例为 5%。与黑暗条件相比，HY 在黑暗、光照和全光照条件下的杀藻率分别提高了 88.05%、89.33%。其杀藻物质在较宽的温度（-80-55°C）和 pH（3-11）条件下稳定，所有处理组在第 3 天的杀藻率均约为 100%。HY 处理破坏了光合作用系统，引发严重的氧化应激，导致严重的形态损伤。因此，HY 处理显著影响了几个必需基因（即 psbA、psaB、rbcL、ftsZ、recA、grpE）的表达水平，并同时抑制了柱孢藻毒素的生物合成和释放。然而，HY 处理对斑马鱼试验胚胎没有显示出任何毒性。这些结果表明，HY 是一种有前途的杀藻候选菌株，可以控制全球裂须盘藻水华，为维持水安全提供了一种有效的生物措施。
