Antibacterial Mechanisms of Berberine and Reasons for Little Resistance of Bacteria / 中草药·英文版

Objective To study the antibacterial mechanisms of berberine and try to understand the reasons why bacteria cells difficultly resisted to it. Methods Detecting the minimal inhibitory concentration (MIC) of bacterial cultures incubated under sub-MIC concentration of berberine, Huanglian, and Neomycin for more than 200 generations, in order to analyze the bacteria resistance. Detecting the binding kinetics of berberine to DNA, RNA, and proteins. Observing the changes in bacterial cell surface structure with scanning electron microscopy. Detecting the Ca2+ and K.+ released from berberine-treated bacterial cells with atomic absorption spectrum. Detection the absorption of methyl-3H-thymine (3H-dT), 3H-uridine (3H-U), and 3H-tyrosine (3H-Tyr) into berberine-treated bacterial cells. Results MICs of bacterial cultures, growing more than 200 generations in MH medium with 1/2 MIC of berberine (BA200) or Huanglian (HA200), did not increase compared to the control, while remarkably increased in MH medium with 1/2 MIC of Neomycin (NA200). In addition, from the culture NA200 it was easy to isolate resistant mutant strains which could grow in MH medium with more than four times MIC Neomycin, but from the culture BA200 and HA200 it was difficult to isolate berberine or Huanglian mutant strains could grow in MH medium with more than four times MIC berberine or Huanglian. The binding kinetics of berberine to DNA, RNA, and proteins illustrated that berberine could easily and tightly bind to DNA and RNA, and hardly dis-bind from DNA- and RNA-berberine complexes. Berberine could easily bind to protein too, but also easily dis-bind from berberine-protein complex. The bacterial cells treated with berberine sharply decreased the absorption of 3H-dT, 3H-U, and 3H-Tyr, as the radioactive precursors of DNA, RNA, and protein biosynthesis. Berberine could damage bacterial cell surface structure, especially for Gram-negative bacteria. Ca2+ and K+ released from berberine-treated cells increased significantly compared to the control. Conclusion All of above results indicate that bacterial cells could not easily become resistant mutants to berberine. The mechanisms for the bactericidal effect of berberine include: inhibiting DNA duplication, RNA transcription, and protein biosynthesis; influencing or inhibiting enzyme activities; destructing the bacterial cell surface structure and resulting in Ca2+ and K+ released from cells. All of the berberine bactericidal mechanisms are the most essential physiological functions for a live cell, if influenced any one such function, the mutation would be lethal mutation, so that it is difficult to get berberine resistant cells. The results in this paper also prefigure that berberine and its related Chinese medicines would provide a feasible way to control antibiotic resistance problem.

Effect of continuous temperature change on hydrolytic products of yeast beta-glucan by endo-beta-1,3-glucanase / 生物工程学报

In order to explore the influence of reaction temperature on the product composition, the effect of continuous temperature change (22 degrees C-60 degrees C, +/-0.1 degree C) on hydrolysis of yeast beta-glucan by endo-beta-1,3-glucanase was determined by using self-developed Biochem-temperature Characteristic Apparatus. The activation energy of enzymatic hydrolysis of yeast beta-glucan was 84.17 kJ/mol. The optimum temperature represented by accumulation of products decreased exponentially within a certain period of time. The components of the products were changed with reaction temperature. The length of oligosaccharides decreased with the increase of temperature. The main products were laminaribiose and laminaritriose at the temperature higher than 46 degrees C, while the main products were laminaripentaose and larger molecular weight components at the temperature lower than 30 degrees C. The results can provide precise parameters to control the reaction temperature of the production of 1,3-beta-D-glucooligosaccharides.

Mutagenicity of Enphorbia lunulata decoction in vitro / 中国药理学通报

Aim To assay the mutagenicity of Enphorbia lunulata(EL) decoction and to modify the Ames test for evaluation the mutagenicity of herbal medicine samples.Method The mutagenicity of EL decoction was assayed by standard Ames test; the teratogenicity was done by mammalian bone marrow chromosomal aberration test. In modified Ames test system,the influence of histidine EL decoction was excluded by additional negative control, in which the test media was supplied with histidine (histidine amount equaled to the histidine in different concentration of EL decoction).Result The mutagenicity of EL decoction was positive in the standard Ames test. The teratogenicity of EL decoction was negative in mammalian bone marrow chromosomal aberration test. By the modified Ames tests,the mutagenicity of EL decoction was negative.Conclusion The standard Ames test is not suitable for evaluating the mutagenicity of EL decoction, but the modified Ames test is. The mutagenicity in vitro and the teratogenicity in vivo of EL decoction are all negative.

Purification and characterization of a thermostable laccase with unique oxidative characteristics from Trametes hirsuta.

A laccase was purified from Trametes hirsuta. This laccase was classified as a "white" or "yellow" laccase. pH 2.4 was optimal for the oxidation of ABTS and pH 2.5 for DMP. DMP oxidation was optimal at 85 degrees C. The half-life of this laccase was 70 min at 75 degrees C, and 5 h at 65 degrees C. Non-phenolic dyes, such as Methyl Red, were oxidized by purified laccase without mediators. The enzyme was not inhibited by Cu(2+), Mn(2+), or EDTA. These are atypical laccase characteristics that make it a good candidate for theoretical and applied research.

Strategy and application of metaproteomics / 生物工程学报

Metaproteomics is an emerging proteomics technology to analyze large scale protein expression in environmental microbial ecosystem. It is termed as the large-scale characterization of the entire protein complement of environmental microbial community at a given point in time. This review focuses on the research strategies and the recent applications in this field based on the published reports and in combination with our own research experiences.

Mechanism of cellobiose inhibition in cellulose hydrolysis by cellobiohydrolase.

An experimental study of cellobiose inhibition in cellulose hydrolysis by synergism of cellobiohydrolyse I and endoglucanase I is presented. Cellobiose is the structural unit of cellulose molecules and also the main product in enzymatic hydrolysis of cellulose. It has been identified that cellobiose can strongly inhibit hydrolysis reaction of cellulase, whereas it has no effect on the adsorption of cellulase on cellulose surface. The experimental data of FT-IR spectra, fluorescence spectrum and circular dichroism suggested that cellobiose can be combined with tryptophan residue located near the active site of cellobiohydrolase and then form steric hindrance, which prevents cellulose molecule chains from diffusing into active site of cellulase. In addition, the molecular conformation of cellobiohydrolase changes after cellobiose binding, which also causes most of the non-productive adsorption. Under these conditions, microfibrils cannot be separated from cellulose chains, thus further hydrolysis of cellulose can hardly proceed.

The induction and elimination of bacteria's resistance / 中国药理学通报

AIM Objective By comparing E.coli's resistance to antibiotics and Chinese medical herbs before and after incubated in LB containing Neomycin or Chinese medical herbs, we try to understand the difference in their mechanism of resistance. METHODS We incubated E.coli cells under the culturing media with low concentration of Neomycin and Chinese medicine herbs respectively; lately, the culturing process were continued under the media with no Neomycin or Chinese medicine herbs. We tested the minimal inhibitory concentrations(MIC)of Neomycin(Kanamycin, Gentamicin, Tetracyclin etc) and Chinese medical herbs to culture cells. Result The experimental data indicated that increased resistance of population cells in the broth including Neomycin happened easily, as well as multi resistance simultaneously. As for the Chinese medical herbs, the case is different. After growing in the LB containing one of Huang Lian (rhizoma coptidis), Berberine or San-Huang-Tang of low concentrations, population cells did not increase their resistance either to antibiotics or to Chinese medical herbs. Removing the pressure of Neomycin, E.coli population cells resistance came back to the initial level. CONCLUSION The increased antibiotic resistance of population cells is unstable, and alternative using of different antibiotics maybe contribute to the alleviation of antibiotics resistance.