Lactoferrin (LF) is a multifunctional protein found in mammals, and it shows broad-spectrum antimicrobial activity. To improve the functional properties of specific probiotics in order to provide both the beneficial characteristics of lactic acid bacteria and the biological activity of LF, cDNAs of bovine LF (BLF), human LF (HLF), or porcine LF (PLF) were cloned into a nisin-inducible plasmid. These were then transformed into the selected eight probiotics, which are LF-resistant hosts. Expression of recombinant LFs (rLFs) was analyzed via SDS-PAGE and Western blot analysis. Although the selected host strains may not contain the nisRK genes (NisK, the sensor kinase; NisR, the regulator protein), the components of autoregulation, a low level of LFs expression can be successfully induced by using nisin within bacterial cells in a time-dependent manner in three engineered clones, including Lactobacillus delbrueckii/HLF, L. delbrueckii/BLF, and L. gasseri/BLF. Lactobacillus delbrueckii and Lactobacillus gasseri originate from yogurt and human milk, respectively, and both strains are functional probiotic strains. Therefore, we further compared the antibacterial activities of disrupted recombinant probiotic clones, conventional strains (host control), and vector control ones by using agar diffusion and broth inhibition analysis, and the expression of rLFs in the above three clones considerately improved their antibacterial efficacies against four important food-borne pathogens, namely, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, and Salmonellaenterica. In conclusion, this study provides a simple strategy for the production of functional LFs (BLF and HLF) in both functional and LF-resistant hosts for applications in the field.

中文翻译：

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乳链菌素抗性益生菌菌株表达增强的抗菌活性的乳链菌肽控制的牛和人乳铁蛋白的单个质粒。

乳铁蛋白（LF）是一种在哺乳动物中发现的多功能蛋白质，它具有广谱抗菌活性。为了改善特定益生菌的功能特性，以提供乳酸菌的有益特性和LF的生物学活性，将牛LF（BLF），人LF（HLF）或猪LF（PLF）的cDNA克隆到乳链菌肽诱导的质粒。然后将它们转化为选定的8种益生菌，它们是LF抗性宿主。重组LF（rLFs）的表达通过SDS-PAGE和蛋白质印迹分析进行了分析。尽管选定的宿主菌株可能不包含nisRK在细菌细胞中使用乳酸链球菌素以时间依赖的方式成功地诱导乳清蛋白基因（NisK，传感器激酶； NisR，调节蛋白），自动调节的成分，低水平的LFs表达，可以在三个工程克隆（包括德氏乳杆菌）中以时间依赖性方式成功诱导/ HLF，德氏乳杆菌/ BLF，并加氏乳杆菌/ BLF。德氏乳杆菌和乳杆菌分别来自酸奶和人乳，两种菌株均为功能性益生菌菌株。因此，我们通过琼脂扩散和肉汤抑制分析进一步比较了被破坏的重组益生菌克隆，常规菌株（宿主对照）和载体对照的抗菌活性，上述三个克隆中rLFs的表达均显着提高了它们的抗菌效力。四个重要的食源性致病菌，即大肠埃希氏菌，金黄色葡萄球菌，粪肠球菌，和沙门氏菌肠炎。总而言之，这项研究为在功能性和耐LF宿主中生产功能性LF（BLF和HLF）提供了一种简单的策略，可用于该领域。