Shabbir Usama, Zahra Itrat, Liaqat Ayesha, Arshad Ayesha, Nawaz Shahid, Betenbaugh Michael, Ijaz Roohi, Ibrahim Awais, Arooj Tuba, Muneer Bushra, Ali Nazish Mazhar, Ramzan Uzma, Rasheed Sammi, Ghauri Ayesha, Ali Manel Ben, Hedfi Amor, Shakoori Abdul R, Shakoori Farah R
Institute of Zoology, University of the Punjab, New Campus, Lahore, 54590, Pakistan.
Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA.
Biotechnol Lett. 2025 Aug 11;47(4):88. doi: 10.1007/s10529-025-03629-w.
Paramecium caudatum is a well-known ecotoxicological indicator for monitoring heavy metal pollution, including lead contamination. This study investigates P. caudatum's stress response to lead nitrate through the accumulation of polyhydroxyalkanoates (PHAs), biopolymers with potential applications in sustainable bioplastic production. The effect of lead nitrate stress (23.1 g/L) on PHA synthesis was compared with glucose supplementation (180 g/L) and unsupplemented controls. PHA was extracted at 24, 48, and 72 h from both glucose- and metal-treated cultures. Intracellular PHA granules were visualized using Sudan Black B and Nile Blue A staining. Extracted polymers were characterized by FTIR and GC-MS, confirming their chemical identity and structural similarity to poly(3-hydroxybutyrate) (PHB). Scanning electron microscopy (SEM) was used to examine the polymer microstructure. Lead nitrate treatment induced the highest PHA yield (4.8 g/L) after 24 h, significantly exceeding glucose-supplemented (3.8 g/L) and control (1.8 g/L) cultures. FTIR spectra revealed characteristic O-H, C-H, and ester carbonyl (C = O) absorption bands typical of PHB, while GC-MS identified 3-hydroxybutyrate as the dominant monomer along with minor medium-chain-length components. SEM imaging showed a porous, pseudospherical, and interconnected polymer morphology. P. caudatum responds to heavy metal stress by enhancing PHA accumulation, producing high-quality biopolymers structurally comparable to PHB. These findings highlight the dual potential of P. caudatum for bioplastic production and environmental remediation, offering a novel green biotechnology approach to valorize pollutant stress responses.
尾草履虫是一种著名的生态毒理学指标，用于监测包括铅污染在内的重金属污染。本研究通过聚羟基脂肪酸酯（PHA）的积累来研究尾草履虫对硝酸铅的应激反应，PHA是一种生物聚合物，在可持续生物塑料生产中具有潜在应用价值。将硝酸铅胁迫（23.1 g/L）对PHA合成的影响与葡萄糖补充（180 g/L）和未补充对照组进行了比较。在24、48和72小时从葡萄糖处理和金属处理的培养物中提取PHA。使用苏丹黑B和尼罗蓝A染色观察细胞内PHA颗粒。通过傅里叶变换红外光谱（FTIR）和气相色谱-质谱联用（GC-MS）对提取的聚合物进行表征，确认其化学特性以及与聚（3-羟基丁酸酯）（PHB）的结构相似性。使用扫描电子显微镜（SEM）检查聚合物微观结构。硝酸铅处理在24小时后诱导产生了最高的PHA产量（4.8 g/L），显著超过葡萄糖补充组（3.8 g/L）和对照组（1.8 g/L）培养物。FTIR光谱显示了PHB典型的特征性O-H、C-H和酯羰基（C=O）吸收带，而GC-MS鉴定出3-羟基丁酸酯是主要单体，同时还有少量中链长度成分。SEM成像显示聚合物形态为多孔、假球形且相互连接。尾草履虫通过增强PHA积累来应对重金属胁迫，产生结构上与PHB相当的高质量生物聚合物。这些发现突出了尾草履虫在生物塑料生产和环境修复方面的双重潜力，提供了一种新颖的绿色生物技术方法来利用污染物应激反应。
