In the United States of America, the physician group practice has become one of the most common practice models, and has a relatively perfect and clear system of laws and regulations in its monitoring.In view of the policy side, the federal government has published the Stark Law to regulate the registration, properties, operation, service contents in details for the physician group practice.Taking the market side, it is practiced to protect the physician groups and medical practice behaviors through medical insurance policies.In China, the emergence of physician group has received widespread attention and concern.But since the short development time and unclear development path, the relevant laws and regulations for physician groups are still are not perfect.This paper aims to summarize the development and status quo of the American physician group as well as the regulations related to the groups` operating system, which will provide a good reference to China.The purpose is to provide policy recommendations for the standardized development and perfect regulations of physician groups in China.The following recommendations were put forward: improve the relevant laws and regulations;promote the establishment of the corresponding security policies;speed up and enhance the research and development of medical liability insurance;do continuous tracking and timely summarize practices.

L-tryptophan, one of the aromatic amino acids, is widely used in the fields of medicine, food and feed additives. The phosphoenolpyruvate-carbohydrate phosphotransferase system (PTS) plays an important role in glucose transport and phosphorylation in Escherichia coli. PTS-mediated regulation dominates the carbohydrates' uptake and metabolism in E. coli. We constructed L-tryptophan-producing bacteria containing two typical PTS mutations (ptsHIcrrglf⁻ glk⁺ and ptsG⁻) by Red homologous recombination system, and studied in 50 L jar fermenter using fed-batch fermentation. Both PTS system mutants had a great impact on the biomass (increasing 47.0% and 17.6%, respectively), L-tryptophan production (increasing 25.9% and 9.4%, respectively), glucose conversion rate (increasing 26.5% and 17.4%, respectively) and byproduct acetic acid generation (slightly increased and decreased，respectively).