2种肠道微生物抗菌肽的特性研究(英文)

A Study on Characteristics of Two Antibacterial Peptides from Gut Bacteria

本研究旨在对从鸡肠道里分离到的2种抗菌肽进行生物学性质研究。从鸡盲肠内容物中分离得到2株菌,通过生理生化法和16S rRNA测序分析进行鉴定。采用牛津杯法对抗菌肽的抗菌谱进行研究;通过调节培养基的碳源、氮源、及初始pH研究培养条件对抗菌肽产量的影响。分离鸡盲肠内容物得到2株菌,鉴定为植物乳酸杆菌CLP29和粪肠球菌CLE34,它们可以产生2个蛋白酶敏感的抗菌肽(植物乳酸菌素CLP29,粪肠球菌素CLE34,3.5ku)。在MRS(Mann Rogosa Sharpe)培养基中,当初始pH为5.0、6.0和7.0,且培养温度为37℃时,2种抗菌肽的抗菌活性均达到最大值,为6400AU/mL。碳源和氮源均影响植物乳酸杆菌素CLP29和粪肠球菌素CLE34的产量。可溶性淀粉可以刺激植物乳酸杆菌素CLP29的表达,但是当氮源为柠檬酸铵或蛋白胨加牛肉浸膏时,植物乳酸杆菌素CLP29产量则大大降低。对粪肠球菌素CLE34而言,碳源为半乳糖时,产量可达到最大(6400AU/mL),但是当碳源为可溶性淀粉或蔗糖时,产量则降低50%～70%。综上,本研究从鸡的肠道中成功地分离得到可产生抗菌肽的2株菌,且通过改变培养基组成和条件实现对抗菌肽产量的调节。

The main objectives of this study were to isolate and characterize the two antibacterial peptides from gut of poultry.Two bacterial strains were isolated from chicken cecal contents and identified basing on physiological and biochemical characteristics determination,and 16S rRNA sequencing analysis.Oxford cup test was conducted to assay the antimicrobial spectrum.Carbon sources,nitrogen sources,and the initial pH in cultural media were modified and adjusted to assay their effects on antibacterial peptides expression.Two bacteria were confirmed as Lactobacillus plantarum CLP29 and Enterococcus faecium CLE34,and found to express two protease-sensitive antibacterial peptides（plantaricin CLP29 and enterocin CLE34,3.5 ku）,respectively.The optimum conditions for production of both peptides were recorded in MRS（Mann Rogosa Sharpe） broth at pH 5.0,6.0 and 7.0,and at 37 ℃,with their antimicrobial activities being 6 400 arbitrary units per mL（AU/mL）.Both carbon and nitrogen sources affected production of plantaricin CLP29 and enterocin CLE34.Plantaricin CLP29 production was increased when L.plantarum CLP29 was cultured in the presence of amidulin combined with most nitrogen sources,but reduced when ammonium citrate or peptone＋beef extract being the nitrogen source in medium.The highest yield（6 400 AU/mL） of enterocin CLE34 was obtained when E.faecium CLE34 were cultured in the presence of galactose,but the yield of enterocin CLE34 was reduced by 50%~75% with the supplementation of amidulin or sucrose in medium.In conclusion,two antibacterial peptides producing bacterial strains were successfully isolated from gut of poultry,and the production of antibacterial peptides could be adjusted by changing the components in cultural media.