Effect Of Genetically Modified Lactobacillus Plantarum 590 With NisI Gene On Gut Health Of SD Rat

Application of microorganisms in food industry can be traced back thousands of years ago. Now, microorganisms play more and more important role in food-related industry. With the application of transgenic technique new varieties of genetically modified microorganisms (GMM) came into being. Different GMM can be optimized to enhance the existing good qualities, to meet the special needs. It will undoubtedly expand the scope of application of microorganisms, lower production costs. However, as artificial new products, there are some concerns on food safety of GMM existing from the date of the birth of GM products. Currently, there is no systematical, complete and practical food safety evaluation system on GMM and the marketization of GMM is limited. Therefore, developing food safety study on GMM and establishment of evaluation system is the urgent task. It will promote the regulatory progress of GMM, further expand the application.In this study non-GM probiotic Lactobacillus plantarum (Lp) as control, major factors of GM Lactobacillus plantarum 590 (Lp590) introduced with nisI gene influencing on the body health such as in vitro tolerance, sub-chronic toxicity feeding, intestinal immune and gene horizontal transfer were studied. The study according to microorganic characteristics, combined with the existing evaluation model for other genetically modified products, but not confined by other safety evaluation models. The current study was aimed at exploring the systematic, perfect and practical food safety evaluation model of GMM, laying the foundation of development and utilization of GMM.In vitro tolerance of GM Lp590 to multistresses was studied. Compared with Lp, the result of the tolerance to nisin verified that Lp590 can indeed confer resistance to higher concentration nisin, and Lp590 had the similar growth curve as Lp. The ability of Lp590 to tolerate both environmental stresses (like temperatures ranging from 52°C to 4°C, or exposure to ethanol, oxygen, and osmotic stresses) and gastrointestinal transit was assessed. Lp590 showed a tolerance to 4°C and ethanol that was similar to Lp. Notably, Lp590 can tolerate higher temperatures (52°C) and higher levels of H₂O₂ and NaCl than Lp. While, Lp590 has the same gastrointestinal transit tolerance as Lp. These above results indicated that GM Lp590 has many desirable biological characteristics and has good prospects for industrial application, transgenic technique did not lead to negative effect. These results provide the possibility that food safety of GM Lp590 was assessed through animal feeding trials.The sub-chronic toxicity feeding was performed. The results showed that compared with Lp, after feeding with Lp590, no adverse oral administration-related differences in body weight, food consumpation, behavior and condition gross and histopathological examination were observed. Compared with Lp, Lp590 had the similar effect on improving jejunal muscosal structure. These results showed that exogenous gene is not the disadvantage for body health, and GM Lp590 and non-GM probiotic Lp had the same impact on SD rats.Faece as an important metabolic indicator was comprehensively studied. Fecal major flora were studied by both plate count and quantitative PCR methods, the result demonstrated that rats fed with GM Lp590 and non-GM Lp can both increase useful bacteria, decrease harmful bacteria and promote intestinal health. Further, no differences in fecal enzyme activity, SCFA, fecal pH value and fecal water content were observed between rats being administrated Lp590 compared with rats being administrated Lp. These results demonstrated that Lp590 is as safe as Lp, the transgenic composition did not change probiotic function.By several methods such as immunohistochemistry, quantitative PCR and ELISA, intestinal permeability, intestinal mucosal immunity, antioxidant capacity of the body were studied. The results of lowered intestinal permeability, improved tight-junction integrity and mucosal immunity, enhanced antioxidant capacity made cleared that Lp590 and Lp are beneficial to the health of SD rats, there was no side effects on body from exogenous gene.With specific primers for blood, muscle, liver, spleen, kidney, results of PCR showed that transgenic composition was not found in the relevant tissues and organs.According to study, the results of present study have revealed GM Lp590 has the same improvement on body health as Lp, exogenous gene has no any bad effect on SD rats.The first systematic food safety evaluation ensures commercialization and marketization of GM Lp590.The standpoint was first proposed in this study that gut health is the key mark reflecting body health. In the evaluation process, catching microorganic characteristics the study was proceeded form in vitro tolerance to gut health. Around the key point the study performed multi-angle analysis. It made the subject clear, interlocking, highlighted on the important point of food safety evaluation of GMM, but also comprehensive reflection the effect of GMM on the body. This study established a systematic, complete and practical food safety evaluation model of GMM. It can provide scientific standard methods for the regulation and commercial production of GMM. It must be significantly meaningful to the development of GMM.