聚乙烯微塑料对尼罗罗非鱼(Oreochromis niloticus)生长、抗氧化、免疫和肠道微生物的影响

Effect of High Density-polyethylene on Growth Performance,Antioxidant Capacity,Immune Functions and Intestinal Microbiota of Oreochromis niloticus

近年来,微塑料作为一类新型污染物引起了国内外的广泛关注。笔者研究了0、0.01、0.1和5 mg·L^(-1)的高密度聚乙烯微塑料(high-density polyethylene,HDPE,61~83μm)胁迫尼罗罗非鱼(Oreochromis niloticus)28 d后的毒性效应。结果表明,HDPE微塑料暴露28 d后,尼罗罗非鱼的成活率、增重率、肝体比与对照组相比无显著差异(P>0.05)。尼罗罗非鱼肝脏丙二醛(MDA)含量在0.01 mg·L^(-1)和5 mg·L^(-1)HDPE暴露组中显著高于对照组(P<0.05);谷胱甘肽转移酶(GST)活性在5 mg·L^(-1)暴露组中显著高于对照组(P<0.05);与对照组相比,暴露组尼罗罗非鱼肝脏的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和碱性磷酸酶(AKP)活性,以及鱼脑的乙酰胆碱酯酶(AChE)活性无显著差异(P>0.05),而在0.1 mg·L^(-1)暴露组中酸性磷酸酶(ACP)活性显著高于对照组(P<0.05)。尼罗罗非鱼暴露于HDPE微塑料28 d后,肠道菌群16S rDNA测序结果表明,样品中共获得465336条优化序列,操作分类单元(OTU)总数854个;与对照组相比,微塑料暴露组尼罗罗非鱼肠道中变形菌门、厚壁菌门、拟杆菌门和蓝细菌门的丰度减少,放线菌门丰度增加,但无显著性差异;在5 mg·L^(-1)HDPE微塑料暴露组中,衣原体门的丰度显著高于对照组(P<0.05)。综上可知,高浓度微塑料暴露能够对尼罗罗非鱼产生氧化胁迫并影响肠道菌群群落结构。研究结果可为揭示聚乙烯对水生生物的毒性效应及其潜在的生态风险评估提供科学依据。

In recent years,microplastics pollution has become an emergency issue,which has attracted extensive attention in the global environment.We studied the toxic effects of 0,0.01,0.1 and 5 mg·L^(-1)high-density polyethylene(HDPE,61~83μm)on Oreochromis niloticus(O.niloticus)after 28 d exposure.According to the results,after 28 d of exposure to HDPE,the survival rate,weight gain rate and hepatosomatic index of O.niloticus were not significantly different from those of the control group(P>0.05).The malondialdehyde(MDA)content in the liver of O.niloticus in the 0.01 mg·L^(-1)and 5 mg·L^(-1)HDPE groups were significantly higher than that in the control group(P<0.05),and the gultathione S-transferases(GST)activity of 5 mg·L^(-1)group was significantly higher than control group(P<0.05).The activities of superoxide dismutase(SOD)catalase(CAT),acetylcholinesterase(AChE)and alkaline phosphatase(AKP)in O.niloticus were not significantly different from those in the control group(P>0.05).The acid phosphatase(ACP)activity in the 0.1 mg·L^(-1)group was significantly higher than that in the control group(P<0.05).In addition,the 16S rDNA sequence results of intestinal microbiota showed that a total of 465336 optimized sequences were obtained after 28 d of HDPE exposure,and the total number of Operational Taxonomic Units(OTU)was 854.Compared to the control group,the abundance of Proteobacteria,Firmicutes,Bacteroides and Cyanobacteria in the intestine was decreased,while Actinomyces was increased without significant difference.The abundance of Chlamydia in the 5 mg·L^(-1)treatment group was significantly higher than that in the control group(P<0.05).In summary,high-level HDPE exposure could induce oxidative stress and cause adverse effect on the intestinal microbiota structure of O.niloticus.All findings in this study could provide scientific evidence of toxic effect and potential risk assessment of polyethylene on aquatic organisms.