ABSTRACT
The discovery and use of antibiotics is one of the most important breakthroughs in medical history.However, the uprising and spread of the drug-resistance bacterial pathogens have posed a great threat on human health once again.There is an urgent need to develop new antibiotics.Traditional Chinese medicine contains a large volume of bioactive substances suited for novel antibiotic development.However, clinical use of antibiotics of Chinese medicine originis are very rare despite the fact that Chinese medicine has been used for infectious diseases for many years.In this paper, we propose a new mechanism of action for Chinese medicine in treating infectious diseases based on our experimental data.Unlike conventional antibiotics which kill pathogens or inhibit their growth, the traditional Chinese medicine probably function through repressing bacterial pathogenicity.That is, they are actually “antipathogenic drugs”.There are several advantages these antipathogenic drugs possess over traditional antibiotics, including that pathogens are less likely to develop resistance and the drugs have less effect on normal members of the human microbe.
ABSTRACT
Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants that exist extensively in the environment. Microbial degradation is the main pathway of PAHs eradication in natural environment and therefore is of importance to investigate. Advancement has been made in recent years regarding the PAHs molecular degradation mechanisms in bacteria. In this review, we summarized some of the research progresses in microbial PAHs biodegradation pathways (including salicylate pathway and protocatechuate pathway), key enzymes (nah-like, phn, phd, nid and nag) and genes involved. Emphasis was given on naphthalene and phenanthrene which were often used as the representatives of PAHs. It is likely that the new information will promote further research and applications of microbial PAHs biodegradation technology.
Subject(s)
Bacteria , Genetics , Metabolism , Biodegradation, Environmental , Environmental Pollutants , Metabolism , Naphthalenes , Metabolism , Phenanthrenes , MetabolismABSTRACT
We designed and constructed an antibiotic screening system by using antibiotic responsive genes as reporters. Plasmid pCS26 carrying a promoterless luminescence reporter, luxCDABE, was used as the vector and the promoter regions of antibiotic responsive genes/operons from Escherichia coli were cloned upstream of the lux reporter to form the first part of the screening reporter array. Random promoter library of Salmonella enterica and Pseudomonas aeruginosa were screened for antibiotic responsive clones which consist of the second part of the screening array. The selected final reporter array responded to different antibiotics in distinct patterns and enabled in vivo high-throughput screening for antibiotics. Unknown antibiotics could, in general, be classified by analyzing the response patterns. This screening system is both sensitive and efficient and should prove to be a useful tool for screening new antibiotic compounds.
Subject(s)
Anti-Bacterial Agents , Pharmacology , Drug Evaluation, Preclinical , Methods , Gene Expression Regulation, Bacterial , Promoter Regions, Genetic , Genetics , Pseudomonas aeruginosa , Genetics , Salmonella enterica , GeneticsABSTRACT
Quorum sensing is an important gene regulatory mechanism in Pseudomonas aeruginosa and controls the expression of numerous virulence factors. We designed and constructed a screening system for quorum-sensing inhibitors. We developed the system by using the lasI and rhlA promoters fused with promoterless sacB as reporters. Using this system we screened a number of Chinese herb extracts, and identified three herb extracts containing inhibitors to the quorum-sensing system and to its regulated genes. The screening system developed was highly efficient and sensitive. It could serve as a useful tool to identify herb compounds that block infections but unlikely render antibiotic resistance in pathogens.