Lu Xiao, Liu Jie, Xiao Xinfeng, Xue Jianliang, Cheng Dongle, Zhang Linlin
College of Safety and Environment Engineering, Shandong University of Science & Technology, Qingdao, 266510, China.
Institute of Yellow River Delta Earth Surface Processes and Ecological Integrity, Shandong University of Science & Technology, Qingdao, 266510, China.
World J Microbiol Biotechnol. 2025 Apr 28;41(5):150. doi: 10.1007/s11274-025-04372-0.
The emerging contaminant 2, 6-di-tert-butyl-p-cresol (BHT) is a kind of synthetic phenolic antioxidant and can pose negative effects on the aquatic organism. However, the mechanism of phycosphere bacteria coordinating with microalgae in response to BHT stress remains poorly understood. Herein, the effect of BHT on the microalgae Phaeodactylum tricornutum was comprehensively analyzed. BHT exposure led to a dose-dependent inhibition of P. tricornutum growth and the photosynthetic pigment biosynthesis. BHT also led to an increase in the content of malondialdehyde, therefore microalgae responded to the oxidative stress by enhancing activities of antioxidant enzymes, including superoxide dismutase, catalase and peroxidase, to eliminate excess reactive oxygen species in the cells. Furthermore, transcriptome analysis revealed that genes related to photosynthesis, TCA cycle, oxidative phosphorylation, and indole-3-acetic acid (IAA) synthesis were up-regulated in response to BHT stress, which are crucial for the microalgae's adaptation to stresses. In addition, high-throughput Illumina MiSeq sequencing results demonstrated a significant increase in the relative abundance of bacteria affiliated with Halomonas, Marivita and Oceanicaulis. Microbiological assays demonstrated that Halomonas can thrive by using BHT as the sole energy source and exhibit a chemotactic response to IAA. Therefore, we conclude that the increased content of IAA secreted by microalgae in the phycosphere environment promoted the enrichment of BHT-tolerant bacterium Halomonas, thereby it is helpful for environmental pressures adaptability of P. tricornutum. Overall, this study provided a comprehensive understanding of the physiological and biochemical effects of BHT on microalgae, and we highlight the potential functional significance of IAA in establishing an interaction between microalgae and algae-associated bacteria in adverse environments.
新兴污染物2,6 -二叔丁基对甲酚（BHT）是一种合成酚类抗氧化剂，会对水生生物产生负面影响。然而，目前对藻际细菌与微藻协同应对BHT胁迫的机制仍知之甚少。在此，我们全面分析了BHT对微藻三角褐指藻的影响。BHT暴露导致三角褐指藻生长及光合色素生物合成受到剂量依赖性抑制。BHT还导致丙二醛含量增加，因此微藻通过增强抗氧化酶（包括超氧化物歧化酶、过氧化氢酶和过氧化物酶）的活性来应对氧化应激，以消除细胞内过量的活性氧。此外，转录组分析表明，与光合作用、三羧酸循环、氧化磷酸化和吲哚 - 3 - 乙酸（IAA）合成相关的基因在BHT胁迫下上调，这些基因对微藻适应胁迫至关重要。此外，高通量Illumina MiSeq测序结果显示，与嗜盐单胞菌属、海栖菌属和海洋茎杆菌属相关的细菌相对丰度显著增加。微生物学分析表明，嗜盐单胞菌可以利用BHT作为唯一能源生长，并对IAA表现出趋化反应。因此，我们得出结论，藻际环境中微藻分泌的IAA含量增加促进了耐BHT细菌嗜盐单胞菌的富集，从而有助于三角褐指藻适应环境压力。总体而言，本研究全面了解了BHT对微藻的生理生化影响，并强调了IAA在恶劣环境中微藻与藻相关细菌之间建立相互作用的潜在功能意义。
