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Chemical Compositionand Staphylococcus aureusInhibitory Activity of the Ethanol Extract from Mahonia nepalensisDC.

Trinh Dinh Kha, Ha Thi Thanh Hoan, Nguyen Thi Thu Hien

Date Received: 26-11-2015 / Date Accepted: 29-05-2016
An investigation was conducted to determine the chemical composition and inhibitory effect against Staphylococcus aureus of Mahonia nepalensis DC. (M. nepalensis) extract. Chemical analysis showed that the extract contained alkaloids, tannins, flavonoids, saponins and terpenoids. The growth of Staphylococcus aureus strain was inhibited by the different extract concentrations. The diameter of inhibition zones varied from 10 to 15 mm for the extract concentrations from 20-40 mg/ml. The MIC, IC50 and MBC values were 0.05; 4.17 and 21.67 mg/ml, respectively. It is, therefore, suggested that the extract from M. nepalensis could be used as an anti-Staphylococcus agent in particular and a promising antibacterial agent in general.
Study on the Anti-bacterial Activity of EssentialOils from Perilla Leaves

Nguyen Thi Hoang Lan, Bui Quang Thuat, Le Danh Tuyen, Nguyen Thi Ngoc Duyen

Date Received: 26-08-2014 / Date Accepted: 10-03-2015
The experiment was carried out to examine the anti-bacterial effects of essential oil from perilla leaves on eight spoilage and food poisoning bacteria strains (Escherichia coli, Salmonella, Pseudomonas fluorescens, Pseudomonas aeruginosa VTCC-B-657, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Streptococcus feacium). The results indicated that perilla essential oil had anti-bacterial effects against all the above bacterial strains, except P. aeruginosa. The effect of perilla essential oil on gram-positive bacteria was stronger than that on gram-negative bacteria. The pure essential oil completely inhibited four strains of gram-positive bacteria, including Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Streptococcus feacium, and one strain of gram-negative bacteria, namely P. fluorescens. The Minimum Inhibitory Concentration (MIC) was more than 8192 µg/ml for both Escherichia coli and Salmonella and from 1024 µg/ml to 4096 µg/ml for the other five studied strains.
Isolation, Selection, and Characterisation of Enterococcus faecalisET04Capable of Producing Bacteriocin

Duong Van Hoan, Dang Thi Thanh Tam, Dinh Truong Son, Nguyen Xuan Truong, Pham Thi Dung, Nguyen Xuan Canh

Date Received: 19-09-2022 / Date Accepted: 29-06-2023
The study was carried out to identify Enterococcusstrains capable of producing bacteriocins, orienting the applications as a supplement to aquaculture feeds and replacing the current use of antibiotics. In this study, bacterial strain ET04 was isolated and evaluated for its ability to antagonize against Staphylococcus aureus and Aeromonas jandaei. The research results showed that the bacterial strain ET04 was determined to have the ability to produce bacteriocin that inhibited the growth of the tested microorganisms. The bacteriocin compound produced by strain ET04 was stable at pH 2.0 to 8.0 and most of the antibacterial activity was lost at pH 10; at pH 12.0 the antibacterial activity was completely lost. On MRS medium supplemented with 3% glucose and yeast extract, bacterial strain ET04 showed the best bacteriocin production ability. Combining morphological, physiological, biochemical, and sequence analysis of 16S rRNA genes, strain ET04 was identified as Enterococcusfaecalis ET04.
Optimization of Parameters in PolysaccharideExtraction and Bioactive Analysis from Myxopyrum smilacifolium(Wall.) Blume Roots

Luu Hong Son, Vu Thi Hanh, Nguyen Thi Tinh, Ta Thi Luong, Dinh Thi Kim Hoa, Ngo Xuan Binh

Date Received: 26-02-2021 / Date Accepted: 04-06-2021
It has been demonstrated that roots ofMyxopyrum smilacifolium(Wall.) contain many bioactive compounds including polysaccharides, saponin, flavonoids. This study aimed to determine the effects of the single-factor model on the amount of polysaccharide extracted from roots of Myxopyrum smilacifolium(Wall.) Blume), as a basis on a fractional factorial design at three levels through the Box–Behnken experimental design. Extracts obtained from optimized conditions were used for evaluation of their antibacterial, antioxidant, and anti-inflammatory ability. The results of the single-factor showed that the time of using ultrasound, the ethanol concentration, solvent/ material ratio, and extraction temperature were 60 seconds at 37 kHz, 80%, 15/1 (ml/g), and 80C for 90 min respectively. Under the optimized conditions by using the Box–Behnken experimental design, the results showed that the time of using ultrasound, the ethanol concentration, solvent/ material ratio, and extraction temperature were 64.67 seconds at 37 kHz, 81.56%, 15.33/1 (ml/g), and80C for 90 min respectively; and the total polysaccharide content was 16.1948 mg/g of the root. The extracts of total polysaccharides were able to inhibit Staphylococcus aureusK, Staphylococcus aureus, Shigella flexneri, Bacillus subtilis, Escherichia coli, Pseudomonas spp with antibacterial ring diameters as follow: 8.01; 18.06; 8.03; 6.84; 15.33; 9.39, and 10.13 mmrespectively. There was an IC50value of 168.94 ± 5.28 (µg/ml) when evaluating antioxidant activity. The anti-inflammatory ability was 28.31 ± 1.04; 33.76 ± 1.06; 50.04 ± 2.03 and 71.14 ± 2.81 (% BSA denaturation) corresponds to the extract concentration of 0.78125; 1.5625; 3.125 and 6.350 (μg/ml) respectively.
INVESTIGATION OF THE POTENTIAL UTILITY OF PERILLA ESSENTIAL OIL IN PRESERVATION OF FRESH PORK

Nguyen Thi Hoang Lan, Le Danh Tuyen, Bui Quang Thuat

Date Received: 12-04-2016 / Date Accepted: 10-08-2016 / Date Published: 10-08-2016
This study examined the effects of perilla essential oil treatments on pH, NH3, and thiobarbituric acid (TBA), and microbiological indices, including total aerobic counts, E. coli, and Staphylococcus aureus, on the shelf-life of fresh pork. Fresh sirloin pork was sprayed with perilla oil at two concentrations of 1% (v/v) and 2% (v/v) and stored at 5°C. Results revealed that compared to the control samples stored in the same refrigerated cold condition, the shelf-life of the treated sirloin pork was extended to 6 and 9 days, respectively to the two concentrations of perilla oil applied. This indicates that perrila essential oil might play an important role as antioxidant and antibacterial agent in prolonging the shelf-life of refrigerated fresh pork. The treatment with 1% perilla oil had less effect on color and flavor of the fresh pork sample compared to concentration of 2%.
DOI: https://doi.org/10.31817/tckhnnvn.2016.14.7.
ISOLATION, IDENTIFICATION, AND PRELIMINARY CHARACTERIZATION OF Bacillus subtilisWITH BROAD-RANGE ANTIBACTERIAL ACTIVITY FROM MUONG KHUONG CHILLI SAUCE

Nguyen Thi Thanh Thuy, Vu Thi Huyen Trang, Vu Quynh Huong, Trinh Thi Thu Thuy, Nguyen Thi Lam Doan, Tran Thi Na, Nguyen Hoang Anh

Date Received: 24-05-2016 / Date Accepted: 10-08-2016 / Date Published: 10-08-2016
Bacillus subtilis is usually found in foods such as dry cured sausages, cheeses, traditional fermented milks, etc., in which they cooperate with other microorganisms during fermentation, release amylases, lipases and proteases… B. subtilis not only play with probiotic role but also produce antimicrobial substance. Muong Khuong chilli sauce is a naturally fermented product derived from Muong Khuong special peppers without heat treatment and is able to be preserved in ambient conditions for 1.5-2 years. Amongst 512 types of colonies, 48 Bacillus sp. strains were isolated from 80 chilli samples. Their ability against pathogenic bacteria was determined using the agar-well diffusion method through measuring the inhibition zone diameter. The four pathogenic bacteria strains tested were Escherichia coli RG1.1, Salmonella typhi GT4.3, Listeria monocytogenes MI2.6, and Staphylococcus aureus TS1.9. The results of 16S rRNA genotype sequencing for the two strains, TO43.13 and TO53.2, that had broad-range antimicrobial activity indicated that the TO43.13 sequence was homologous up to 95% with B. subtilis BcX1 (JX504009.1) and B. subtilis EPP2 2 (JQ308548.1). The TO53.2 strain sequence was homologous up to 94% with the two strains B. subtilis Pe-Lg-1 (FR687210.1) and B. subtilis YT2 (HQ143571.1). The optimal conditions for the growth and development of these two strains were with a 0.6% concentrations of NaCl, a pH of 7, and a temperature of 35°C.
DOI: https://doi.org/10.31817/tckhnnvn.2016.14.7.
Biological Characteristics of Race VD111 of Streptomyces albogriseolus

Pham Thu Trang, Pham Thanh Huyền, Le Gia Hy, Phi Quyet Tien, Ho Tuyen, Nguyen Van Giang, Nguyen Phuong Nhue

Date Received: 12-06-2014 / Date Accepted: 20-09-2014 / Date Published: 06-08-2025
The inappropriate use of antibiotics might cause the development and wide spread of drug-resistance. Therefore, finding new antibiotics from marine microorganisms has been receiving attention by the scientists. This article presents the taxonomical characterization and antimicrobial activity of marine actinomycet strain VD111 isolated from Vietnam’s seawater. Based on Bergey’s classification and method of International Streptomyces Project (ISP), the strain VD111 was classified as Streptomyces albogriseolus since it had biological characteristics similar to the standard strain Streptomyces albogriseolus ISP 5003. The favourable conditions for the growth of the strain VD111 were established; temperature of 370C, pH of 7-8 and NaCl of 7-10%. The suitable medium and fermentation conditions for producing antimicrobial substances by the strain VD111 were A4H medium with the following substances expressed in g/l: 15g glucose, 15g soybean powder, 5g NaCl, and 1g CaCO3 and, pH=7. The preculture supplement was of 5.0% (v/v) and inoculum age of 48 hours. Maximal antibacterial compound yield (diameter of inhibition zone against Bacillus subtillis ATCC 6633: 30,2 mm) and biomass (10,6 mg/ml) were achieved after 60 hours of fermentation. Especially, the bioactive compound from strain Streptomyces albogriseolus VD111 exhibited antimicrobial activity against gram-positive, gram-negative bacteria and yeast (Candida albicans ATCC 10231).
DOI: https://doi.org/10.31817/tckhnnvn.2014.12.8.
Properties of Biological Waterproof Films Combination Chitosan and Lignin Extracted from Sugarcane Bagasse

Chu Thi Thanh, Nguyen Thi Tuyet, Nguyen Ngoc Kien, Ngo Thi Thuong, Nguyen Thi Bich Thuy, Le Thi Thu Huong

Date Received: 25-11-2019 / Date Accepted: 23-04-2021
Currently, the global demand for development of biodegradable films to replace synthetic plastic materials has been rapidly increased. In this study, we aimed to extract lignin from sugarcane bagasse by-products of the sugarcane industry in order to fabricate biological membranes from chitosan and lignin to reduce environmental pollution. The results revealed that lignin was successfully extracted from sugarcane bagasse by alkaline hydrolysis method in 2h with weight ratio NaOH/ sugarcane bagasse of 1:10 w/w and precipitation at pH = 2 by acidic solution. Properties of films were measured: moisture, film thickness, tensile strength and waterproof. The biological waterproof films were synthesized from chitosan and lignin with a volume ratio (1C:1L v/v), the film thickness of 27,19-30,13µm and the tensile strength of 259.000-312.000 N/m2and antimicrobial activity with Escherichia coliandStaphylococcus aureus.

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