Hochiminh city International University

Thu Duc District, Vietnam

Hochiminh city International University

Thu Duc District, Vietnam

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Tu N.,Hochiminh city International University | Tu Q.,Hochiminh city International University | Tung H.,Hochiminh city International University | Hieu D.,Hochiminh city International University
World Journal of Microbiology and Biotechnology | Year: 2014

Tetrodotoxin (TTX) is a potent toxin but it could be used in pharmaceutical field. Identification of TTX producing bacteria in pufferfish is necessary for TTX yield and the pufferfish conservation. In this study, Lagocephalus was collected from Cam Ranh Sea, a central part of Vietnam during spring season. The liver and intestine were incubated in 0.9 % NaCl for TTX detection in pufferfish. To be benefited from the isolation of new TTX producing bacteria, the liver and intestine were incubated in 6.5 % NaCl. The cultures were used to test the toxin and to isolate the bacterial community that could yield TTX. Surprisingly, Providencia rettgeri T892 in intestine could produce TTX identified by biochemical test and 16S rRNA sequencing. This strain was used to test the production of TTX, based on thin layer chromatography (TLC), mouse bioassay and high performance liquid chromatography (HPLC) analysis. The bacterium was optimized for TTX production in media prepared from the meat-washing water of Auxis thazard, Megalaspis cordyla and Decapterus maruadsi. Interestingly, the TTX obtained 0.106 mg/mL and 0.055 mg/mL in medium prepared from A. thazard and M. cordyla, respectively while there was no TTX production detected in medium prepared from D. maruadsi. This paper could contribute to warn to the human health care system about a possible TTX poisoning in some cases related to eating fishes. © 2014 Springer Science+Business Media Dordrecht.


Nguyen T.H.K.,Hochiminh City International University | Thu L.B.,Hochiminh City International University
Journal of Applied Pharmaceutical Science | Year: 2015

Bacillus megaterium T04 isolated from Rach Lang stream in Vietnam was tested for antimicrobial activities. The antimicrobial activities of Bacillus megaterium T04 (57.3 × 108 cfu/mL) against Candida albicans, Salmonella typhi, Pseudomonas aeruginosa, Staphylococcus sciuri, Micrococcus luteus were detected by agar well diffusion method in different cultivation conditions at three temperatures (25, 37, and 45°C) in three incubation periods (24, 48, and 72 hours). The efficacy of antimicrobial activities of this strain were determined in comparison with ceftriaxone activity against Candida albicans, Salmonella typhi, Pseudomonas aeruginosa, Staphylococcus scuiri, Micrococcus luteus. The antimicrobial activity potency was equivalent to ceftriaxone in a range ( 3.3 0.6 μg/mL to 46.5 6.2 μg/mL) for Candida albicans (0.9 0.2 μg/mL to 35.5 7.7 μg/mL) for Salmonella typhi, (0.4 0.1 μg/mL to 28.4 4.4 μg/mL) for Pseudomonas aeruginosa, (119.8 21.2 μg/mL to 283.7 26.0 μg/mL) for Staphylococcus scuiri, (3.3 0.4 μg/mL to 64.4 7.4 μg/mL) for Micrococcus luteus. © 2015 Tu HK Nguyen and Le B Thu.


Tu N.H.K.,Hochiminh City International University | Hoang T.C.M.,Hochiminh City International University
IFMBE Proceedings | Year: 2013

Streptococcus thermophilus was isolated from ferment foods in Vietnam. This strain was determined by API 50 CHL (BioMerieux). Interestingly, we have detected and characterized the enzyme called cholesterol esterase that will be used in cholesterol diagnostic and treating the cholesterol ester storage disease in women. After culturing, the free cell supernatant was precipitated with 60% ammonium sulfate and resuspended in distilled water. After dialysis, the supernatant had been titrated with 1M sodium hydroxide and detected by thin layer chromatography (TLC). The detection was based on the determination the free fatty acid that was the product of cholesterol ester hydrolyzation by cholesterol esterase. The color changed in titration and the spot appearance compared with the standard in TLC showed the presence of cholesterol esterase. The cholesterol esterase production was also optimized in different conditions containing vitamin D, and palmitic acid as the substrates of cholesterol. The study showed that Streptococcus thermophilus should be supplied in ferment food as yogurt in order to improve the health for human. © 2013 IFMBE.


Tu N.H.K.,Hochiminh City International University | An N.T.N.,Hochiminh City International University
IFMBE Proceedings | Year: 2013

Lactic acid bacteria (LAB) have the important role in general health, providing a beneficial micro flora in the intestinal tract. The tested Lactobacillus acidophilus VTCC-B-702 and Lactobacillus rhamnosus ATCC 11443 were grown individually and co-cultured together in the same environment. Agar-well diffusion test was performed to determine the antibiotic susceptibility and antimicrobial activity. Two tested LAB exhibited the sensitivity to ampicilin and tetracycline at 5×10-3 to 1×10-2 (mg/ml), but resistant at 5×10-4 (mg/ml). L. acidophilus was resistant to erythromycin at all concentration, but L. rhamnosus was sensitivity to erythromycin at 5x10-3 to 1x10-2 (mg/ml), but resistant at 5×10-4(mg/ml). After co-cultured, both of these microrganisms were resistant to erythromycin. This action showed there were erythromycin resistant determinant from L. acidophilus to L. rhamnosus. The antimicrobial activities were also tested on Escherichia coli, Staphylococcus aureus, Salmonella typhi, Pseudomonas aeruginosa. The effects showed the synergy except on Escherichia coli. © 2013 IFMBE.


Khue N.T.H.,Hochiminh city International University | Ngoc N.H.,Hochiminh city International University
Journal of Applied Pharmaceutical Science | Year: 2013

Exopolysaccharides (EPS) from lactic acid bacteria (LAB) have many applications in food industry, and pharmaceutical field. To improve EPS production in Lactobacillus rhamnosus PN04 and Leuconostoc mesenteroides VTCC-B-643, these bacteria were co-cultured together. There were shape changes in Lactobacillus rhamnosus into curved rod. Their EPS were estimated after co-cultured. After ethanol precipitation method, the colorimetric method were done using phenol-sulfuric acid assay, the EPS from L. rhamnosus PN04 increased from 2.446 mg/l to 4.228 mg/l while Leuconostoc mesenteroides increased from 3.217 mg/l to 4.712 mg/l. By SDS-PAGE analysis in both straight and curved Lactobacillus rhamnosus, there were the expressed proteins with the estimated molecular weight of 14, 60, 66 kDa while the curved Lactobacillus rhamnosus showed another proteins with molecular weight of 14, 20, 31, 45, 60, 66, 95 kDa. The results suggested that there were the interaction between two these strains. This is the first report showed there were differences in EPS production and protein expression after co-culture of Lactobacillus rhamnosus PN04 and Leuconostoc mesenteroides VTCC-B-643.


Khue N.T.H.,Hochiminh city International University | Vo P.T.M.,Hochiminh city International University
Journal of Applied Pharmaceutical Science | Year: 2013

The hyaluronic acidproducing Streptococcus zooepidermicus ATCC 43079 was used to study the hyaluronic acid production. We used the Plackett-Burman design of optimum multifactorial experiments to estimate the level effects of different factors such as peptone, meat extract, yeast extract, glucose, tween 80, dipotassium phosphate, sodium acetate, ammonium citrate, magnesium sulphate and manganese sulphate on hyaluronic acid production. As a result, meat extract (0.2%), yeast extract (0.1%) and glucose (0.4%) gave the highest production in Streptococcus zooepidermicus at temperature (40oC). In order to confirm the estimated hyaluronic acid yield, the designated experiments were done. The maximum yield of hyaluronic acid in Streptococcus zooepidermicus ATCC 43079 was 42.38 mg/l while the predicted HA was 42.32 mg/l. The results also showed the Plackett - Burman can be used to predict the HA yield.The study was the first report of HA production affected by complex nutrient, temperature and salts. © 2013 Nguyen Tu Hoang Khue & Pham Thien Minh Vo.


Vinh D.T.T.,Hochiminh city International University | Khue N.T.H.,Hochiminh city International University
Journal of Applied Pharmaceutical Science | Year: 2013

The practice of developing molecularly targeted drugs to achieve a higher degree of cancer therapy and antibiotic resistance is indispensable. Recently, bacterially derived 400nm sized minicells was reported on the ability of encapsulation with chemotherapeutic drugs. Lactobacillus acidophilus strain participated in the anti-cancer effects and performed the high-level specificity for cancer cell lines. Here we discuss minicells generation of Lactobacillus acidophilus VTCC-B-871 for drug delivery. The present work was the first report on that L. acidophilus VTCC-B-871 formed minicells with highly significant ratio (25 %) in modified MRS broth with fructose 10 g/l carbon source concentration. The minicells were packaged with Paclitaxel (10 μg/ml) and Cephalosporin (10 μg/ml) at different times of incubation (10, 15, 24 hours) at 37°C. As a result, minicells could completely absorbed in 10 hours by detecting the extraction after drug packaged minicells on antimicrobial activities on S. aureus ATCC 25923, E. coli ATCC 9637, Salmonella typhi ATCC 19430, C. albicans ATCC 14053, P . aeruginosa ATCC 27853. © 2013 Doan Thi Thanh Vinh & Nguyen Tu Hoang Khue.


Tu N.H.K.,Hochiminh City International University | Trang P.T.T.,Hochiminh City International University
IFMBE Proceedings | Year: 2013

Hyaluronic acid (HA), one of the most potential biological materials, is increasingly widely used in pharmaceutical and cosmetics nowadays. Hyaluronic acid was produced commercially from rooster combs and the fermentation of Streptococci groups A and C. In order to contribute to the safety and cheap hyaluronic acid for human, we used rice-washing water as medium to culture Streptococcus thermophilus MR10 which was detected as hyaluronic acid production source isolated in fermented foods in Vietnam. This is the first report pointing the the effects of cheap rice-washing water on the HA production of Streptococcus thermophilus. In the medium containing ricewashing water, Streptococcus thermophilus produced HA better than the usual MRS medium for Streptococcus thermophilus growth. © 2013 IFMBE.


Tu N.H.K.,Hochiminh City International University | Thien P.V.M.,Hochiminh City International University
IFMBE Proceedings | Year: 2013

Various reactions that produce color are known to be selective for certain types of carbohydrates. It was difficult to identify N-acetyl-glucosamine in hyaluronan because the hyaluronan was produced very low in microorgansims. Besides, in the traditional methods of Morgan-Elson, using alkali borate to lysis hyaluronan to give N-acety-D-glucosamine caused the unspecific products that could not react to di-methyl-benzaldehyde (DMAB). The study developed the method to detect N-acetyl-D-glucosamine by thin layer chromatography (TLC) that showed the stable purple traces on TLC than in liquid. The study was confirmed by applying high pressure liquid chromatography (HPLC). © 2013 IFMBE.


Tu N.H.K.,Hochiminh City International University
IFMBE Proceedings | Year: 2013

A lipoprotein contains both proteins and lipids water-bound to the proteins including enzymes, transporters, structural proteins, antigens, adhesins and toxins. In the present study, a LpnS gene encoding lipoprotein from Streptomyces lividans 66 was cloned by using polymerase chain reaction, southern blot and hybridization. After sequencing, the LpnS gene had 1235 bps coding 415 amino acids that had 100% homology to lipoprotein of Streptomyces lividans TK 24 and 99 % of Streptomyces coelicolor A3(2) and 71 % Streptomyces flavogriseus ATCC 3331 and 71% of ABC transporter of Streptomyces griseoflavus. This gave more data about lipoprotein in Streptomyces lividans 66. © 2013 IFMBE.

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