Milk and dairy products from dairy farms around Hanoi greatly contribute to the consumed milk quantity in Hanoi. The use of fresh milk or pasteurized milk becomes more and more popular in the daily life of local people. Milk and dairy products were widely sold in numerous stores, particularly in Xuan Mai, Ba Vi, Phu Dong and Gia Lam. However, there have not yet been any studies to assess the pathogenic bacterial contamination of these products. In our study, 49 samples including 23 raw milk samples, 12 pasteurized milk samples, and 14 yogurt samples were collected in order to examine the presence of food­born pathogenic bacteria such as Listeria monocytogenes, Staphylococcus aureus, Salmonella spp. using PCR method. This fast and accurate method works based on the specific amplification of tested bacterial DNA. The results showed that one of the samples may contain Staphylococcus aureus while another may be contaminated with Listeria monocytogenes. None of the samples was contaminated with Salmonella spp. The results were confirmed by gene sequencing.

As one of probiotic bacteria, Bifidobacterium is supplement in food industry such as in milk and yogurt. The advantageous impact of these bacteria for human health was reported. However, in Vietnam, supplement of these bacteria as probiotic source to the food was not much in food industry. In our experiment, Bifidobacterium are isolated from a feces sample of 7 days-child which only had mother milk. The bacterial isolated from infant intestinal tract was Bifidobacterium infantis (B. infantis, closest to Bifidobacterium longum ssp. infantis strain Bi-26 with gene bank accession CP054425.1). The techniques to identify these bacteria were MALDI Biotyper, PCR and sequencing. This experiment is original for further study the characters of these bacteria to apply them in our daily life.

Phellinus linteus is known to be a medicinal mushroom which is very good to human health. They are used as medicinal mushroom in many Asian countries such as Japan, Korea, China, Thailand and Vietnam. Because of long time growth and over-havest by humans in natural conditions, they are artificially cultured in these countries. There were advances of liquid culture of mushroom such as time saving and scaleable in culture in comparison with culturing of mushroom in decaying wood. In this study, Phellinus linteus is cultured in optimum liquid medium, lyophilized, ground into fine powder and evaluated for microbiological and total of Asen and Lead to ensure the biomass product will meet safety standards for users. Results are as follows: Total of anaerobic bacteria 2,2 × 10­4 CFU/g, Coliforms< 1,0 × 101 CFU/g, Coagulase positive with Staphylococci <1,0×101 CFU/g, total amount of yeast-mold < 1,0 × 101 CFU/g, not detected of E.coli, Clostridium perfringens and Salmonella spp.. Furthermore, we did not find any Asen and Lead which are supposed to remain in our sample.

Là một trong những vi khuẩn probiotic, Bifidobacterium được sử dung để bổ sung vào thực phẩm trong công nghiệp thực phẩm như sữa và sữa chua. Những ảnh hưởng tốt của các vi khuẩn này đến sức khỏe con người đã được công bố. Tuy nhiên, ở Việt Nam, việc bổ sung những vi khuẩn này làm nguồn probiotic trong thực phẩm chưa được chú trọng trong ngành công nghiệp thực phẩm. Trong thí nghiệm này, Bifidobacterium được phân lập từ phân của trẻ bảy ngày tuổi chỉ bú sữa mẹ. Vi khuẩn phân lập được từ đường ruột của một trẻ 7 ngày tuổi tại Việt Nam là Bifidobacterium infantis (B. Infantis gần nhất là Bifidobacterium longum phân loài infantis chủng Bi-26, trình tự trên ngân hàng gene là CP054425.1). Các kỹ thuật được sử dụng để xác định các vi khuẩn này là MALDI Biotyper, PCR, và đọc trình tự gene. Thí nghiệm này là tiền đề cho các nghiên cứu tiếp theo để xác định đặc tính của các vi khuẩn này cho các ứng dụng vào cuộc sống con người.

Bifidobacterium is anerobic bacterium which is popular in human and animal intestine. B. infantis was successfully isolated from a new-born child’s fecal sample previously. In this study, the probiotic characteristics of this strain such as: extracellular enzyme production ability; antibiotic activity against food-born pathogen like E. coli, S. aureus; organic acid production and bile-salt sufferance were evaluated. The results showed that the isolated can produce amylase and protease enzyme, do not produce cellulase enzyme; the organic acids also were produced during development of bacterium. The bacterium can against E. coli and S. aureus and can grow in the media containing up to 1% of bile salt. Results of this study are the basis for further studies to apply these bacteria as a source of probiotic beneficial to human health in Vietnam.