Nisin is an antimicrobial peptide widely used in food industry. In this study, Nisin A production in Lactococcus lactis ATCC 11454 was improved by overexpression of Nisin A structural gene nisA through introducing a shuttle expression vector pMG36ek-nisA and an integrated vector pDG780-nisA into the host strain. The differences of growth profiles and Nisin A production level between the two obtained genetic engineering strains FMM1/FMM2 and the parent strain were investigated. Our results show that while the growth profile (the growth rate, biomass and pH) of FMM1 was similar to the parent strain, its Nisin A production increased 31%. In contrast, the biomass of FMM2 was notably lower than the parent strain, while its yield of Nisin A enhanced slightly. The transcription level of genes involved in Nisin A biosynthesis in both engineering strains was further detected by RT-PCR. We found that all the 11 Nisin A biosynthetic genes in FMM1 and FMM2 had a higher transcription level than those in the parent strain, and these genes exhibited more significant increasing degree of transcription level in FMM1 which hosted the autonomous replicating nisA gene. These data suggest that expression of nisA may act as a rate-limit factor in Nisin A biosynthesis. In conclusion, this work provides a new method to improve Nisin A production by increasing the transcription level of nisA, paving the way to further large-scale industrial production of Nisin A.
Bacterial Proteins ; genetics ; Genes, Bacterial ; Genetic Engineering ; Genetic Vectors ; Lactococcus lactis ; genetics ; metabolism ; Nisin ; biosynthesis ; genetics ; Transcription, Genetic

With the rapid development of mobile internet technology, mobile health application (mHealth APP) are increasingly widely used in the field of health management and have been proven to play an important role in the management of chronic diseases. Solid organ transplant recipients face complex health management needs after surgery, including postoperative follow-up, medication management, prevention and treatment of complications and comorbidities, and lifestyle adjustment. mHealth APP can provide solid organ transplant recipients with convenient self-management tools. Although some progress has been made in this field, there are still many challenges, such as insufficient user experience, technological dependence, and data security risks. Therefore, this article discusses the development process, main functions and current application status of mHealth APP, and analyzes its advantages in improving the self-management ability of solid organ transplant recipients, promoting doctor-patient communication and reducing the incidence of complications. At the same time, based on the practical experience of author’s team in developing the “TransMate” mHealth APP, we propose the directions that mHealth APPs should focus on in the future, in order to provide more effective support and services for the health management of solid organ transplant recipients.