Aims: Microorganisms play a vital role in the breakdown of natural organic compounds and are valuable objects for worldwide enzyme production. The aim of this study was to identify favorable production conditions for Bacillus amyloliquefaciens D19 protease, followed by the purification and chemical characterization of this novel enzyme to assess its potential applications in various fields. Methodology and results: In this study, favorable conditions of protease production from B. amyloliquefaciens D19 were determined using a medium containing soluble starch (1.5%), earthworm extract (1.0%), yeast extract (0.5%), NaCl (1.0%), at pH 7.0-8.0, 37 °C for 36 h with 150 rpm shaking condition. The protease was purified and had a molecular weight of about 23 kDa. The optimum condition for casein hydrolysis was at 40 °C and pH 6.5-7.0 in the presence of 1.0 mM Na+ or 5.0 mM Zn2+. The enzymatic activity was maintained at 75-100% at 30-50 °C and in pH 6.0-10.0. The values of Vmax and KM were also determined as 1547 U/mg and 6.33 mg/mL, respectively. Conclusion, significance and impact of study The identified optimal conditions will serve as the foundation for the production of the 23 kDa B. amyloliquefaciens D19 protease, one of the smallest proteases within the Bacillus genus. Moreover, its notable heat resistance, broad pH tolerance, high substrate catalysis and moderate substrate binding affinity make this enzyme a promising candidate for various applications in the food-feed and brewing industries.

Artichoke (Cynara scolymus L.) is a perennial plant belonging to the Asteraceae family originating from the Mediterranean region. In Vietnam, there are some varieties of artichoke which are extensively cultivated and propagated in highland areas, however, there have been limited detailed scientific publications on the chemical composition and biological activity of artichoke grown in Vietnam. Therefore, this study provides a detailed description of the extraction, isolation, and structural determination of 20 natural secondary metabolites present in harvested artichoke. The antioxidant activity of the extract and the 9 isolated compounds are tested in 1,1-diphenyl-2-picrylhydrazyl radical scavenging and ex vivo malondialdehyde model. Among the selected compounds, 1-caffeoylquinic acid, 3-caffeoylquinic acid, chlorogenic acid, 4-caffeoylquinic acid, cynarin, 1,5-dicaffeoylquinic acid, 4,5-di-caffeoylquinic acid, cynaroside, and scolymoside exhibited strong radical scavenging activity with IC50 values ranging from 5.7 to 61.6 µM. In the malondialdehyde assay, 1,3-dicaffeoylquinic acid (or cynarin) showed the strongest activity with an IC50 value of 24.7 µM, followed by 1,5-di-caffeoylquinic acid (66.8 µM), and 4,5-di-caffeoylquinic acid (127.3 µM). This outcome contributes to establishing a database on the phytochemical and antioxidant activity of the Vietnamese artichoke.

Objectives: Vibrio parahaemolyticus is a major foodborne pathogen in aquatic animals and a threat to human health worldwide. This study investigated the prevalence, antimicrobial resistance, antimicrobial resistance genes (ARGs), and biofilm formation of V. parahaemolyticus strains isolated from fish mariculture environments in Cat Ba Island, Vietnam. Methods: In total, 150 rearing water samples were collected from 10 fish mariculture farms in winter and summer. A polymerase chain reaction assay was used to identify V. parahaemolyticus, its virulence factors, and ARGs. The antimicrobial resistance patterns and biofilm formation ability of V. parahaemolyticus strains were investigated using the disk diffusion test and a microtiter plate-based crystal violet method, respectively. Results: Thirty-seven V. parahaemolyticus isolates were recovered from 150 samples. The frequencies of the tdh and trh genes among V. parahaemolyticus isolates were 8.1% and 21.6%, respectively. More than 90% of isolates were susceptible to ceftazidime, cefotaxime, and chloramphenicol, but over 72% were resistant to ampicillin, tetracycline, and erythromycin. Furthermore, 67.57% of isolates exhibited multidrug resistance. The presence of ARGs related to gentamicin (aac(3)-IV), tetracycline (tetA) and ciprofloxacin (qnrA) in V. parahaemolyticus isolates was identified. Conversely, no ARGs related to ampicillin or erythromycin resistance were detected. Biofilm formation capacity was detected in significantly more multidrug-resistant isolates (64.9%) than non-multidrug-resistant isolates (18.9%). Conclusion Mariculture environments are a potential source of antibiotic-resistant V.parahaemolyticus and a hotspot for virulence genes and ARGs diffusing to aquatic environments. Thus, the prevention of antibiotic-resistant foodborne vibriosis in aquatic animals and humans requires continuous monitoring.

In this study, twenty-five yeast strains were isolated from soil samples collected in the gold mining ore in Gia Lai, Vietnam. Among them, one isolate named GL1 T could highly tolerate Cu 2+ up to 10 mM, and the isolates could also grow in a wide range of pH (3–7), and tem perature (10–40 ℃). Dried biomass of GL1 was able to remove Cu 2+ effectively up to 90.49% with a maximal biosorption capacity of 18.1 mg/g at pH 6, temperature 30 ℃, and incuba tion time 60 min. Sequence analysis of rDNA indicated this strain was closely related to Rhodotorula mucilaginosa but with 1.53 and 3.46% nucleotide differences in the D1/D2 domain of the 28S rRNA gene and the ITS1-5.8S rRNA gene-ITS2 region sequence, respect ively. Based on phylogenetic tree analysis and the biochemical characteristics, the strain appears to be a novel Rhodotorula species, and the name Rhodotorula aurum sp. nov. is pro posed. This study provides us with more information about heavy metal-tolerant yeasts and it may produce a new tool for environmental control and metal recovery operations.

Background: Psychological factors such as anxiety and depression have been recognized as the etiology of temporomandibular disorders. Objectives: The study aimed to evaluate the prevalence of temporomandibular disorders in dental students and describe the state of depression and anxiety and related factors in the students with the disorders. Materials and methods: 323 students at the Faculty of Odonto-Stomatology, Hue University of Medicine and Pharmacy, were examined to detect temporomandibular disorders, using the DC/TMD axis I. Then GAD-7 and PHQ-9 questionnaires were used to screen for anxiety and depression in the group with the disorders. Results: The proportion of students with temporomandibular disorders was 38.1%, intra-articular disorders accounted for the highest rate (80.5%). The percentages of depression and anxiety among students with the disorder were 28.4% and 55.3%, respectively. 41.5% of TMD students had mild anxiety and the same proportion of students had risk of depression. Risk factors associated with depression and anxiety were economic status and excercise, respectively (p < 0.05). Conclusions: The percentage of students with temporomandibular disorders is relatively high. The majority of students with the disorders are at risk for depression and low level of anxiety. There is a link between the economic status and depression, between exercise and anxiety.

Background: The genus Alpinia is one of the diverse genera in Thua Thien Hue province, in which many species have been used as medicine. But until now, studies on A. vietnamica have rarely been reported. Objectives: The present study was aimed at the determination of microscopic characteristics and chemical compositions as well as evaluating the antioxidant and acetylcholinesterase inhibitory activities of A. vietnamica. Materials and methods: A. vietnamica was collected in Phong Dien district, Thua Thien Hue province. Anatomic structures and powder properties were determined by the microscopic method. Phytochemical screening was conducted by specific chemical reactions. The Folin-Ciocalteau method and the aluminum chloride-flavonoid assay, respectively, were used to quantify the total polyphenol (TPC) and total flavonoid contents (TFC). Antioxidant activity was assessed using the DPPH assay, while acetylcholinesterase (AChE) inhibitory activity was evaluated using the Ellman method. Results: The microscopic characteristics of this species have been described. Phytochemical analysis results revealed the presence of flavonoids, coumarins, and tannins in A. vietnamica. The ethanol extract from the aerial part of A. vietnamica had higher polyphenol and flavonoid contents than the underground part extract. Moreover, this extract also displayed a stronger DPPH radical scavenging and exhibited AChE inhibitory activities. Conclusion: This is the first report on the microscopic characteristics, chemical compositions, and biological activities of A. vietnamica.

As part of our continued study on the chemical constituents of Willughbeia edulis stems, a new dimeric lignan named edulignan (1) was isolated from its EtOAc-soluble extract. Based on NMR spectroscopic interpretation, the planar structure of 1 has been suggested to have two 2-substituted 4-chromanone subunits with different stereochemical configurations. In addition, the MS/MS analysis of the products obtained by acidcatalyzed hydrolysis of 1 was supportive of its structure. Unfornatually, the new compound 1 did not show α-glucosidase inhibitory activity with an IC 50 value > 250 μM.

Papiliotrema huenov was previously reported to be highly tolerant of a range of extremely toxic heavy metals. This study aimed to identify the potential of P. huenov to remove manganese and copper from aqueous solution. Physical conditions which affect removal of Mn(II) and Cu(II) were determined. Optimal temperature for adsorption of both metal ions was 30°C, and optimal pH for maximum uptake of Mn(II) and Cu(II) were 5 and 6, respectively. Under these conditions, living cells of P. huenov accumulated up to 75.58% of 110 mg/ L Mn(II) and 70.5% of 128 mg/L Cu(II) over 120 h, whereas, the removal efficiency of metal ions by dead cells over 1 h was 60.3% and 56.5%, respectively. These results indicate that living cells are more effective than dead biomass for bioremediation, but that greater time is required. The experimental data extends the potential use of P. huenov in biosorption and bioaccumulation of toxic heavy metals to copper and manganese, two of the most common industrial contaminants.

Three yeast strains (Hue-1, Hue-8, and Hue-19) with strong heavy metal tolerance were isolated from mangosteen from Hue city, Vietnam. They exhibited identical phenotype and phylogeny. Sequence analysis of the D1/D2 region of the LSU rRNA gene and the internal transcribed spacer (ITS) region demonstrated that the closest relative of these strains is Papiliotrema sp. with 2.12% and 3.55–3.7% divergence in the D1/D2 domain, and ITS domain, respectively. Based on the physiological, biochemical, and molecular data, the three strains belong to a novel species of Papiliotrema genus, for which the namePapiliotrema huenov sp. nov. is proposed. These strains are highly tolerant of heavy metals compared to other yeasts, being able to grow in the presence of 2 mM Pb (II), 2 mM Cd (II), and up to 5 mM Ni (II), but no growth was observed in the presence of 1 mM As (III).

Introduction: Hospitals are a key source of information for the early identification of emerging disease outbreaks and acute public health events for risk assessment, decision-making and public health response. The objective of this study was to identify potential facilitators and barriers for event reporting from the curative sector to the preventive medicine sector in Viet Nam. Methods: In 2016, we conducted 18 semi-structured, in-depth interviews, as well as nine focus group discussions, with representatives from the curative and preventive medicine sectors in four provinces. We transcribed the interviews and focus group discussions and used thematic analysis to identify the factors that appeared to affect public health event reporting. Results: We identified five major themes. First, the lack of a legal framework to guide reporting meant hospital staff relied on internal procedures that varied from hospital to hospital, which sometimes delayed reporting. Second, participants stated the importance of an enabling environment, such as leadership support and having focal points for reporting, to facilitate reporting. Third, participants described the potential benefits of reporting, such as support provided during outbreaks and information received about local outbreaks. Fourth, some challenges prohibited timely reporting such as not perceiving reporting to be the task of the curative sector and hesitancy to report without laboratory confirmation. Finally, limited resources and specialist capacities in remote areas hindered timely detection and reporting of unusual events. Discussion: This study identified potential opportunities to promote the detection and reporting of unusual events from health-care workers to the public health sector, and thus to improve the overall health security system in Viet Nam.The influenza virus is a respiratory pathogen that is transmitted through respiratory droplets.1 During seasonal influenza epidemics, high attack rates cause a significant public health burden.2 The infection is usually self-limited in young adults but can lead to severe infections in people in high-risk groups, including elderly people (> 65 years old), pregnant women, children aged 6–59 months and adults with chronic illnesses.3