Expression of the TetA gene encoding TetA efflux protein in E. coli contributes to its increased bacterial resistance toward berberine.

Berberine (BBR) is a traditional Chinese medicine in various applications due to its antibacterial effect. Here we investigated the increased bacterial resistance of E. coli toward BBR. The median effective concentration (EC50) of BBR against E. coli was increased when TetA efflux protein (TEP) was introduced. Sixty-five percent of the intracellular BBR was expelled and molecular docking demonstrated the intensive interaction of TEP to BBR. Finally, the combined antibacterial experiment identified that BBR acted as an inhibitor of TEP in detoxification of tetracycline. TEP is the first discovered protein that was related to the bacterial susceptibility to BBR.

Evaluation of berberine as a natural fungicide: biodegradation and antimicrobial mechanism.

Berberine (BBR) is a traditional Chinese medicine which recently was applied as a biological pesticide. Here, we studied the antimicrobial mode of BBR and its impact on soil bacterial diversity. BBR was more effective against fungi than bacteria due to the specific interaction between BBR and glucan. Also, BBR was degraded rapidly in soil, leading to the limited effect on soil bacterial diversity. Collectively, BBR is an environment-friendly pesticide and it is promising in dealing with fungal plant diseases.

Insights into 3-hydroxypropionic acid biosynthesis revealed by overexpressing native glycerol dehydrogenase in Klebsiella pneumoniae.

In Klebsiella pneumoniae, glycerol dissimilation involves parallel oxidation and reduction pathways. Oxidation pathway provides adenosine triphosphate (ATP) and cofactors to sustain cell growth, while reduction pathway presents 3-hydroxypropionic acid (3-HP) and 1,3-propanediol(1,3-PDO), which are commercially attractive platform chemicals. Previous metabolic engineering of K. pneumoniae focused on the intensification of reduction pathway; however, it failed to overproduce 3-HP or 1,3-PDO. Contrary to this strategy, here we show that overexpression of glycerol dehydrogenase (dhaD), the first functional enzyme in oxidation pathway, can efficiently stimulate cell growth and facilitate 3-HP accumulation. Under microaerobic conditions, although metabolic burden arising from plasmid replication, the recombinant K. pneumoniae overexpressing dhaD grew actively and showed 60% enhancement of 3-HP compared to the control. In particular, overexpression of dhaD increased the activity of glycerol dehydratase, indicating the concerted action of two enzymes and the interdependence between glycerol oxidation and reduction pathways. Moreover, the strain overexpressing dhaD produced more lactic acid yet less acetic acid than the control, implying the interplay between dhaD expression and the formation of byproducts. Together, not only showing that intensifying glycerol oxidation pathway is beneficial to 3-HP production, this study also reveals the structural rigidity of dha operon that mediates glycerol dissimilation in K. pneumoniae.

[The influence of soybean isoflavone on expression of low density lipoprotein receptor (LDLR) mRNA in ovariectomied rats].

OBJECTIVE: To investigate the effect of soybean isoflavone on blood lipid and the expression of LDLR mRNA in ovariectomied rats. METHODS: Forty eight Sprague-Dawley rats were divided randomly into four groups: Sham group (sham), OVX group (OVX), OVX + gemifibrozil (G) group (OVX + G) and OVX + isoflavone (ISO) group (OVX_ISO). in which the rats were treated with G or ISO for three months starting from two weeks after both sides of rat' s ovarietomy. Blood sample were taken out for determination of blood lipid. The liver tissue were taken out quickly, Isothiocyanate guanidine-phenol-chloroform was used to extract the total RNA from the liver and RT-PCR was used to detect the expression of LDLR mRNA. RESULTS: Compared with the OVX group, contents of TG, LDL-C and OX-LDL in serum in OVX + ISO group decreased remarkably, and the contents of HDL-C increased. LDLR mRNA in OVX + ISO group increased distinctively compared with OVX group and OVX + G group. CONCLUSION: The level of mRNA of LDLR in liver decreas after ovariotormy and the soybean isoflavone may increase it by regulating the expression level of LDLR through transcription.

[Effect of tonifying shen recipe on advanced glycosylation end products in aorta and serum lipids in ovariectomized rats].

OBJECTIVE: To investigate the effect of tonifying Shen recipe (TSR) on levels of advanced glycosylation end products (AGEs) in aorta, serum lipids and lipid peroxidation in ovariectomized rats. METHODS: Rats were randomly divided into the sham group, the ovariectomized group and the TSR group, in which the rats were treated with TSR for 13 weeks starting from 2 weeks after ovariectomy. Blood sample was taken out from rat at the end of the experiment after 24 hrs fasting for determination of lipids and lipid peroxidation, and the animal was sacrificed, the aorta was taken out for detecting AGEs. RESULTS: No significant difference was found between groups in levels of total cholesterol and low density lipoprotein cholesterol. In comparing with the sham group, levels of aortic AGEs, serum triglyceride (TG), oxidized low density lipoprotein (OX-LDL) and malondialdehyde (MDA) in the ovariectomized group were obviously higher (P < 0.05 or P < 0.01), and levels of high density lipoprotein cholesterol (HDL-C), apo-lipoprotein A-I (apoA-I) and activity of superoxide dismutase (SOD) were lower (all P < 0.01). While in the TSR group, as compared with the ovariectomized group, the above-mentioned abnormal changes, excepting for TG, were all reversed to certain degree (P < 0.05 or P < 0.01). CONCLUSION: TSR displays its cardiovascular protecting effect in ovariectomized rats through lowering the AGEs content in aorta, reducing the serum levels of OX-LDL and MDA, raising the levels of serum HDL-C and apoA-I and increasing SOD activity.