Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture and Rural Affairs/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing, 100081, People's Republic of China.
Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC, 27695, USA.
Appl Biochem Biotechnol. 2021 Aug;193(8):2516-2533. doi: 10.1007/s12010-021-03502-2. Epub 2021 Mar 29.
The purpose of this study was to examine the efficacy of the algicidal bacterium Sagittula stellata on the cell lysis of Nannochloropsis oceanica, a microalga found in the marine environment, in order to extract intracellular valuables. Algicidal bacteria are capable of lysing algal cell walls while keeping lipids and proteins intact yet separated. We obtained these microbes from locations with consistent algae blooms and found that the bacterium Sagittula stellata displayed significant algicidal properties toward Nannochloropsis oceanica, achieving an algicidal rate of 80.1%. We detected a decrease of 66.2% in in vivo fluorescence intensity in algae cultures, obtained a recoverable crude lipid content of 23.3% and a polyunsaturated fatty acid (PUFA) ratio of 29.0% of bacteria-treated algae, and observed the lysis of the cell membrane and the structure of the nucleus of algae. We also identified the inhibited transcription of the ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (rbcS) gene and proliferating cell nuclear antigen (PCNA)-related genes and the upregulated heat shock protein (hsp) gene in algal cells during bacterial exposure. Our results indicate that Sagittula stellata effectively lysed microalgae cells, allowing the recovery of intracellular valuables. The algicidal method of Sagittula stellata on Nannochloropsis oceanica cells was confirmed to be a direct attack (or predation), followed by an indirect attack through the secretion of extracellular algicidal compounds. This study provides an important framework for the broad application of algicidal microorganisms in algal cell disruption and the production of intracellular valuables.
本研究旨在考察星杆藻对海洋微藻海洋卡盾藻的溶藻效果，以提取细胞内有价值的物质。杀藻细菌能够裂解藻细胞壁，同时保持脂质和蛋白质完整但分离。我们从藻类经常大量繁殖的地方获得了这些微生物，发现星杆藻对海洋卡盾藻具有显著的杀藻特性，杀藻率达到 80.1%。我们检测到藻类培养物中的体内荧光强度降低了 66.2%，获得了可回收的粗脂质含量为 23.3%和多不饱和脂肪酸（PUFA）比例为 29.0%的细菌处理藻类，并且观察到细胞膜和藻类细胞核的结构破裂。我们还鉴定出在细菌暴露期间藻类细胞中核酮糖-1,5-二磷酸羧化酶/加氧酶小亚基（rbcS）基因和增殖细胞核抗原（PCNA）相关基因的转录受到抑制，以及热休克蛋白（hsp）基因的上调。我们的结果表明，星杆藻有效地裂解了微藻细胞，从而可以回收细胞内的有价值物质。星杆藻对海洋卡盾藻细胞的杀藻方法被证实是直接攻击（或捕食），然后通过分泌细胞外杀藻化合物进行间接攻击。这项研究为广泛应用杀藻微生物裂解藻细胞和生产细胞内有价值物质提供了重要框架。
