乳酸菌表達重組吳郭魚抗菌肽Tilapia piscidin 4之功能性分析

Abstract

因應海洋漁業資源匱乏，水產養殖業日益興盛，成為食用水產品的主要供應來源。然而高密度養殖及環境管理不當，容易使養殖生物緊迫，導致水產養殖面臨許多疾病爆發的挑戰，進而造成極大的經濟損失，並使產業發展受到限制。面對細菌性病原，養殖業者通常於飼料中添加抗生素作為預防，感染亦施用抗生素及消毒劑進行治療，過度依賴抗生素的情況，造成抗藥性菌株產生以及藥物殘留的問題，故歐盟、美國及日本等經濟體近年來逐步或全面性禁止食用動物飼料中添加抗生素。抗生素之禁用，可能使得養殖動物較容易受到細菌感染，因此開發提升養殖動物抗病力之機能性添加物作為因應措施是極為需要的。 在自然環境中，生物體為了避免受到病原的侵害，發展出多種對抗及保護機制。除了傳統的免疫調控機制外，抗菌肽 (antimicrobial peptide)在先天性免疫系統中也扮演著重要的角色。抗菌肽廣泛存在於各種生物體中，具有殺死細菌、真菌或是病毒等微生物之功能。此外許多研究中也指出在病原菌感染過程，抗菌肽具有免疫調節之功能，因此是良好的飼料機能性添加物候選之一。 本研究選用開發成本低廉、具可食用性及生物安全性的乳酸乳球菌NIsin Controlled gene Expression system (NICE expression system)表達系統生產吳郭魚抗菌肽Tilapia piscidin 4 (TP4)，並研究最佳誘導條件與抗菌活性，以評估重組抗菌肽TP4作為飼料添加劑的發展潛力。

With a lack of natural marine resources, aquaculture has become the main source of fish in the food supply. However, high-density breeding and improper environmental management often results in disease outbreaks that cause great economic losses and limit industrial development. Breeders usually use antibiotics in animal feed as preventive agents and administer antibiotics and disinfectants for treatment of infections. However, overreliance on antibiotics has led to the emergence of drug-resistant strains and persistent exposure to drug residues. Therefore, the European Union, the United States, Japan, and other economies have gradually or comprehensively banned the use of antibiotics in animal feeds in recent years. The ban on antibiotics may make the farmed animals more susceptible to bacterial infections, so the development of functional additives can increase disease resistance should be considered as a countermeasure. In the environment, organisms have developed various operational and protective mechanisms to respond to attacks by pathogens. In addition to traditional immunomodulatory mechanisms, antimicrobial peptides also play an important role in the innate immune system. Antimicrobial peptides are widely present in various organisms and exhibit antibacterial, antifungal and/or antiviral activity. Furthermore, many studies have shown that antimicrobial peptides have immunoregulatory functions during pathogen infection. Thus, these molecules are good candidates for feed functional additives. In this study, we utilize the NIsin-controlled gene expression system, which has low development cost, edible products and good biosafety, for production of the antimicrobial peptide tilapia piscidin 4 (TP4). We investigate the optimal induction conditions and antimicrobial activity, which are key considerations for feed additives.