In this work, the antibacterial activity of the lipopeptides produced by Bacillus amyloliquefaciens M1 was examined against multidrug-resistant Vibrio spp. and Shewanella aquimarina isolated from diseased marine animals. A new and cheap medium which contained 1.0 % soybean powder, 1.5 % wheat flour, pH 7.0 was developed. A crude surfactant concentration of 0.28 mg/ml was obtained after 18 h of 10-l fermentation and diameter of the clear zone on the plate seeded with Vibrio anguillarum was 34 mm. A preliminary characterization suggested that the lipopeptide N3 produced by B. amyloliquefaciens M1 was the main product and contained the surfactin isoforms with amino acids (GLLVDLL) and hydroxy fatty acids (of 12-15 carbons in length). The evaluation of the antibacterial activity of the lipopeptide N3 was carried out against S. aquimarina and nine species of Vibrio spp.. It was found that all the Vibrio spp. and S. aquimarina showed resistance to several different antibiotics, suggesting that they were the multidrug resistance. It was also indicated that all the Vibrio spp. strains and S. aquimarina were sensitive to the surfactin N3, in particular V. anguillarum. The results demonstrated that the lipopeptides produced by B. amyloliquefaciens M1 had a broad spectrum of action, including antibacterial activity against the pathogenic Vibrio spp. with multidrug-resistant profiles. After the treatment with the lipopeptide N3, the cell membrane of V. anguillarum was damaged, and the whole cells of the bacterium were disrupted.

Cyclooxygenase-2 (COX-2) participates in cancer invasion and metastasis by decreasing the expression of E-cadherin. However, the molecular mechanisms through which COX-2 regulates E-cadherin expression and function have not yet been fully elucidated. The aim of this study was to investigate the possible molecular mechanisms through which COX-2 regulates E-cadherin expression in gastric cancer. The mRNA and protein expression of COX-2, nuclear factor-κB (NF-κB), Snail and E-cadherin was detected in gastric cancer cells by quantitative PCR and western blot analysis, respectively. The expression of these genes was also detected in healthy gastric mucosa and gastric cancer tissues by immunohistochemistry. We detected various levels of COX-2, nuclear factor-κB (NF-κB), Snail and E-cadherin expression in the normal gastric mucosa and cancer tissues; however, the expression patterns differed: the increased expression of COX-2, NF-κB and Snail was observed in the gastric cancer tissues, whereas there was a considerable reduction in E-cadherin expression in the cancer tissues compared to the normal gastric mucosa. The expression patterns of COX-2, NF-κB and Snail were similar. The increased expression of COX-2 in the gastric cancer tissues closely correlated with the increased expression of NF-κB and Snail, but inversely correlated with the expression of E-cadherin. Treatment of the SGC7901 cells (which express high levels of COX-2) with celecoxib, a COX-2 inhibitor, not only led to a marked dose- and time-dependent decrease in the expression of COX-2, NF-κB and Snail, but also led to a significant increase in the expression of E-cadherin, and this was associated with a reduction in cell invasion. By contrast, the same treatment did not alter the expression of these genes in another gastric cancer cell line, MGC803 (which barely expresses COX-2). These data suggest that COX-2 regulates the expression of E-cadherin through the NF-κB and Snail signaling pathway in gastric cancer.

The bacterium Bacillus amyloliquefaciens anti-CA isolated from mangrove system was found to be able to actively kill Candida albicans isolated from clinic. The bacterial strain anti-CA could produce high level of bioactive substance, amylase and protease in the cheap medium containing 2.0 % soybean meal, 2.0 % wheat flour, pH 6.5 within 26 h. After purification, the main bioactive substance was confirmed to be a cyclic lipopeptide containing a heptapeptide, L-Asp→L-Leu→L-Leu→L-Val→L-Val→L-Glu→L-Leu and a 3-OH fatty acid (15 carbons). In addition to C. albicans, the purified lipopeptide can also kill many yeast strains including Metschnikowia bicuspidata, Candida tropicalis, Yarrowia lipolytica and Saccharomyces cerevisiae. After treated by the purified lipopeptide, both the whole cells and protoplasts of C. albicans were destroyed.

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Purpose: As one of the classic anti-Canidia albicans (CA) and vulvovaginal candidiasis (VVC) drugs, nystatin (NYS) is limited by poor water solubility and easy aggregation. Traditional NYS vaginal delivery formulations do not fully adapt to the specific environment of the vaginal cavity. The use of exopolysaccharides (EPS) has great application potential in emulsifiers, but its use has not been reported in nanoemulsions. In this work, an EPS/NYS nanoemulsion (ENNE) was developed to improve the activities of NYS against CA and VVC Methods: The ENNE was prepared by ultrasonic method using EPS as an emulsifier, liquid paraffin oil as an oil phase, PEG400 as a co-emulsifier, and NYS as the loaded drug. ENNE preparation was optimized by response surface method. After optimization, in vitro and in vivo analysis of the anti-CA activity; animal experiments; staining with propidium iodide (PI), periodic acid-schiff (PAS), and hematoxylin-eosin (H&E); and cytokine experiments were performed to investigate the therapeutic ability against VVC. Results: The optimal formulation and preparation parameters of ENNE were determined as follows: EPS content of 1.5%, PEG400 content of 3.2%, NYS content of 700 μg/mL, paraffin oil content of 5.0%, ultrasonic time of 15 min, and ultrasonic amplitude of 35%. The ENNE showed an encapsulated structure with an average particle size of 131.1 ± 4.32 nm. ENNE exhibited high storage and pH stability, as well as slow release. The minimum inhibitory concentration (MIC) of ENNE against CA was only 0.125 μg/mL and the inhibition zone was 19.0 ± 0.5 mm, for greatly improved anti-CA effect. The prepared ENNE destroyed the membrane of CA cells, and exhibited good anti-CA effect in vivo and therapeutic ability against VVC. Conclusion: The results of this study will promote the application of EPS in nanotechnology, which should lead to new and effective local drug formulations for treating VVC.