Hue University Journal of Science: Natural Science

Isolation of endogenous bacteria from wild orchids

Huu Tho Nguyen — 2024-10-09

Endophytic bacteria reside in plant tissues without causing damage to the host and enhance plant growth under both normal and adverse conditions. In this study, 30 strains of endophytic bacteria were isolated from different wild orchids, including Dendrobium anosmum, Aerides falcata, Dendrobium thyrsiflorum, Dendrobium lindleyi, and Cymbidium finlaysonianum. The colony morphology of the isolated strains was mainly white (73.4%), and slimy (60%), with regularly rounded edges (63.3%), a few had a dry or glossy surface and a wavy edge. The results of biochemical characterization studies showed that 18/30 strains could decompose phosphorus; 15/30 strains could produce producing IAA; 16/30 strains could fix nitrogen; and 18/30 strains were likely to generate NH₃. Among them, three isolated strains, named L4, L6, and C4, as outstanding characteristics than other strains, were selected for identification and identified as Burkholderia sp., Bacillus cereus, and Pseudomonas boreopolis, respectively. These microbes are potential strains that can be used as microbial products for agricultural applications, especially in growing orchid seedlings.

Establishment of undergroundwater quality index (GWQI) and application to Hai Lang district, Quang Tri province

Kiên Trương Trung — 2024-10-09

In this study a Ground Water Quality Index (GWQI) was established and applied to Hai Lang district in Quang Tri province. Ten basic water quality parameters selected for establishment of the GWQI consisted of: pH, TDS, hardness (HARD); SO4, COD, N-NH4, N-NO3, Fe, Mn and Total coliform (TC). Principal component analysis (PCA) was applied to the monitoring data set of the period 2015-2018 in the district to determine the weights (w_i) of the parameters. The linear sub-index functions (q_i) were set up basing on the allowable limits of the parameters specified in the National Technical Regulation on Domestic Water Quality (QCVN 01-1:2018/BYT) issued by the Ministry of Health. Three (3) different methods were used to calculate index GWQI_M (multiplicate form), GWQI_A (additive form) and GWQI_Ref (reference form) for the water quality data set. The indexes were all funtions of sub-index q_i and weights w_i. The obtained results show that the index GWQI_M is more suitable than GWQI_A and GWQI_Ref in reflecting the groundwater quality. Applying the GWQI_M to the water quality data set of the period 2019 - 2021 in the district indicated that there are 89% of GWQI_M values classified as Very good or Good water quality, 7% as Medium 1% as Poor and 3% as Very poor (or Unfit for drinking).

Simultaneous determination of Amlodipine and Atovastatin in a multicomponent drug using infrared spectroscopy coupled with multivatiate analysis

Duy Luu Nguyen — 2024-09-30

The development and validation of a UV spectroscopy method combined with multivariate analysis methods including classical least squares, principal component regression, and partial least squares were performed to simultaneously quantify Amlodipine (AML) and Atorvastatin (ATO). A central composite design experimental method was used to construct calibration and validation sets. UV absorption spectra were measured in the wavelength range of 230-260 nm. Multivariate regression methods were constructed based on the measured spectra of the calibration and validation sets, resulting in: R² > 0.9927, RMSEC_AML < 1 ppm, RMSEC_ATO < 2 ppm, and relative prediction error (REP) < 5%. The recovery ranged from 99.20% - 108.13% for AML and 99.10% - 107.19% for ATO for all three methods. The repeatability (RSD) was smaller than the Horwitz value. ANOVA analysis compared the mean values of the methods with the HPLC method, and no significant differences were found. The simultaneous quantification of AML and ATO in Zoamco-a tablets resulted in AML and ATO content within the range of 90-110% of the labeled content, which complies with the regulations of the Vietnamese Pharmacopoeia V.

Isolation and evaluation of antioxidants from leaves of Uvaria rufa (Dunal) Blume – Annonaceae

Thị Minh Tâm Trần — 2024-09-30

Uvaria rufa (Dunal) Blume is exclusively utilized for postpartum women in certain traditional medicine hospitals. This study was carried out to isolate the compounds with antioxidant effects in the leaves to use this medicinal plant more effectively. Extraction, seperation, isolation and purification were done as routine work. Structure elucidation was based on ultraviolet spectroscopy, mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy methods. The in vitro antioxidant activity of isolated compounds was performed on DPPH (2,2- diphenyl-1-picrylhydrazyl) free radical quenching method on 96 well plates. From ethyl acetate fraction, 2 compounds, ie. isoquercitrin and rutin were isolated, exhibited antioxidant activity with IC₅₀ values of 3.33 µM and 16.42 µM, respectively. These results will be the basis for further testing of other biological activities of the plant.

Evaluation of Antibacterial Activity Properties of Carbon Quantum Dots Synthesized from Orange Juice

Thị Bảo Chi Lê — 2024-09-30

In this study, carbon quantum dots (CDs) were synthesized through plasma processing of orange juice at atmospheric pressure and low temperature. The resulting CDs exhibited an average size of approximately 4.7 nm with a narrow distribution. A blue emission was observed with a peak wavelength of 460 nm under excitation at 390 nm. The formation of CDs was confirmed by UV-Vis absorption spectra and Raman scattering analyses. The antibacterial activities of the CDs were evaluated against Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922 strains. Results indicated that inhibitory effects on bacterials strains were observed after 30 seconds of exposure for Escherichia coli ATCC 25922 and 5 minutes for Staphylococcus aureus ATCC 29213. The average antibacterial efficiency of the CDs sample against Staphylococcus aureus and Escherichia coli strains was found to be 62.1% and 57.0%, respectively.

Extraction and isolation of compounds from chloroform extract of Goniothalamus donnaiensis leaves, Annonaceae

Thi Thu Hong Lê — 2024-09-30

Two compounds including a stylryl lactone: goniodiol, and a phytosterol: daucosretol were isolated from the chloroform extract of the leaves of Goniothalamus donnaiensis. Leaves of G. donnaiensis were collected in Vinh Cuu district, Dong Nai province in November 2019. Their chemical structures were elucidated by ESI-mass, 1 H- NMR, 13 C-NMR, DEPT, HSQC and HMBC spectra. These two compounds were first isolated from the leaves of Goniothalamus donnaiensis.

Cloning and expression nahC gene encoding 1,2-dihydroxynaphthalene dioxygenase of Paenibacillus naphthalenovorans 4B1

Le Thi Ha Thanh — 2024-09-30

Polycyclic aromatic hydrocarbon compounds used in many industries have caused environmental pollutions and left consequences to human health. Naphthalene, the simplest polycyclic aromatic hydrocarbon, is widely used as a model compound for biodegradation studies in bacteria. The 1,2-dihydroxynaphthalene dioxygenase, a benzene ring-cleavage enzyme, converts intermediate compounds in the naphthalene degradation pathway into less toxic compounds. In this study, the nahC gene encoding 1,2-dihydroxynaphthalene dioxygenase from the moderate thermophilic Paenibacillus naphthalenovorans strain 4B1 was cloned into pGEM-T Easy vector. Subsequently, the gene after confirming the correct DNA sequence was ligated into pCold^TM II expression vector and transformed to Escherichia coli BL21. The SDS-PAGE results showed that the nahC gene was successfully expressed in E. coli BL21 with 0.5 mM IPTG. The molecular weight of resulting recombinant enzyme was approximately 35 kDa. These results are the basis for enzyme purification and characterization.

Antioxidant activity of collagen/chitosan/ Archidendron clypearia extract composite materials

Ngọc Nguyễn Hoàng Lương — 2024-09-30

In this study, we have synthesized a new material with good antioxidant activity. For the first time, Archidendron clypearia extract was included in the collagen/chitosan/TEOS mixture, the resulting material had antioxidant capacity evaluated through DPPH and ABTS radical scavenging and the total antioxidant capacity method, with low IC₅₀ values (IC₅₀ = 43.60 μg/mL and 46.57 μg/mL for DPPH and ABTS radical scavenging capacity) and the total antioxidant capacity was 83.06 ± 0.56 mg GA/g. The total content of phenolic and flavonoid compounds in Coll-Cs-TEOS-MD 0.5 is 36.87 ± 0.18 mg GA/g and 28.12 ± 0.15 mg QE/g, respectively. Material characteristics are examined through infrared spectroscopy (IR) and scanning electron microscope (SEM). Coll-Cs-TEOS-MD 0.5 material shows good antioxidant activities, which is very promising as a biocompatible material for biomedical applications.

Synthesis and photocatalytic activity of ZnO/biochar composite for the degradation of doxycycline under visible light irradiation

Văn Hưng Nguyễn — 2024-09-30

In this study, ZnO/biochar (ZBC) materials were successfully synthesized by simple hydrolysis of a mixture of Zn(NO₃)₂ salt and biomass derived from reed stems. The synthesized materials were characterized by XRD, SEM, TEM, BET, FT-IR and UV-Vis-DRS methods. The photocatalytic degradation of doxycycline (DC) was studied from the influencing factors of pH and concentration. Characterization shows that ZnO is well dispersed on the biochar surface. The presence of biochar helped improve the specific surface area, narrow the band gap and enhance the optical absorption in the visible light region of ZnO. The ZBC composite at ZnO/biochar mass ratio = 1/0.25 showed the highest photodegradation efficiency, about 3.5 times higher than pure ZnO in DC decomposition. Kinetic studies showed that DC degradation followed an apparent first-order kinetic model with rate constant k_app = 2.03×10^-2 min^-1 at DC concentration of 9.0 mg/L. Research shows that ZnO/biochar material has great potential in treating antibiotic-contaminated wastewater.

Research on enhancing marine microalgae biomass Tetraselmis sp. for nitrogen and phosphorus removal from brakish-salt water rich in nutrients

Thanh Lộc Đặng Thị — 2024-09-30

This study investigates the cultivation of Tetraselmis sp., a marine microalgae species, in seawater enriched with elevated levels of nutrient salts (N, P). The primary objective was to determine the suitable growth conditions for Tetraselmis sp., considering variations in nutrient composition, pH levels, initial inoculum density, and differing initial TN:TP ratios. Results indicate robust growth of Tetraselmis sp. in F/2 seawater medium with a salinity of 30 ‰ and pH 8, with initial inoculum densities ranging from 5% to 10%. Tetraselmis sp. exhibited strong growth potential in environments with elevated nutrient salt concentrations (N, P). Specifically, as TN concentration increased from 9.7 to 56.3 mg/L and TP concentration rose from 0. 1 to 3.7 mg/L, cell density increased from 6.98×10⁵ (cells/mL) to 1.34×10⁶ (cells/mL) after a 15-day cultivation period. Total phosphorus treatment efficiency ranged from 82% to 100%. Total nitrogen treatment efficiency ranged from 97% to 83% for initial T-N concentrations of 10 to 25 mg/L. However, with higher T-N concentrations (~56 mg/L), the treatment efficiency reached only 58% after 15 days of cultivation. These findings highlight the significant potential of cultivating Tetraselmis sp. for N and P removal from brackish-salt water rich in nutrients in Vietnam.

The Spin-Coater, Hydrothermal Synthesis and Characterizations of MoS2/TiO2 Nanoflake for Photoelectrochemical Application

Nguyễn Tiến Đại — 2024-09-30

MoS₂/TiO₂ nanoflakes (NFs) have been synthesized using the spin-coater and hydrothermal method at a temperature of 180 ^oC for photoelectrochemical application. The thick-MoS₂ nanoflakes are about a few nano to tens of nano for 4 – 8 h, which consist of highly active sites at edges and planes to improve photoconversion efficiency. XRD pattern of MoS₂/TiO₂ NFs showed both hexagonal and anatase phases for MoS₂ and TiO₂, respectively, with a high crystal quality. At room temperature, the photoluminescence spectra of MoS₂ NFs exhibited an asymmetric shape and good emission peak at 688 nm. The photoelectrochemical cell of the MoS₂/TiO₂nanostructure obtained a photocurrent density of 3.5 mA. cm^–2 at –0.8 V (vs. SCE), using 0.5 M H₂SO₄ electrolyte. As a result, we propose a potential fabrication of high-efficiency optoelectronic devices through the synthesis of MoS₂ NFs hybrid with traditional photocatalyst oxide materials by the one-step hydrothermal approach.

Synthesis of nano materials on the base of rice husk ash and CeO2 for application as a growth stimulant for bell peeppers plan (capsicum annuum L.)

Huỳnh Xuân Trường — 2024-09-30

In this study, CeO₂/SiO₂ material was synthesized and applied as a growth stimulant for bell pepper plants from Ce(NO₃)₄ precursor and rice husk ash using gamma irradiation method. Material morphology and structure were confirmed through physicochemical characterization methods including: XRD, EDX, IR and SEM characterization. The results of surveying the effects of CeO₂/SiO₂ materials on the growth and development of bell pepper plants show that CeO₂/SiO₂ significantly affects the growth and development of bell pepper plants. Experimental data obtained showed that bell pepper yield increased by 22 tons/ha, average root length increased by 3.6 cm and harvest time was 11 days less than the control sample. In addition, bell pepper plants supplemented with CeO₂/SiO₂ are stronger and do not have yellow leaves. This shows that CeO₂/SiO₂ has a growth stimulating effect on bell pepper plants.

A Sexual size difference and microhabitat use of Amolops ricketti group (Anura, Ranidae) in Bach Ma national park, Thua Thien Hue province, Vietnam

Đức Lợi — 2024-09-30

Amolops ricketti (group) is a species with nutritional and medicinal value. However, little is known about sexual size dimorphism (SSD), microhabitat use, and the mode of action of this species. We observed the behavior of this species in the field at Bach Ma National Park, combined with analyzing morphological characteristics in the laboratory. Based on 97 adult Rock Frog samples (44 males and 53 females), assessments and comparisons of morphological measurements and calculations of the SSD index were performed. The results showed that the average trunk length (SVL) of adult females was longer than that of adult males, with an SSD index of 0.23. This species lives in fast-flowing stream water, also known as torrential environments, with microhabitats mainly on high-slope rocks dominating (52.58%), followed by rocks with low-slope (34.02%). This species used the highest proportion of time for lying and waiting activities (77.78%). The mode of activity of this species is more suitable for the sit-and-wait model than the wide forager model. Some environmental, physical, and chemical indicators in the species' living area were also surveyed in this study.

Molecular detection methods for Pasteurella multocida and Mannheimia haemolytica

Cong Tuan Le — 2024-09-30

P. multocida and M. haemolytica are the main bacteria causing pasteurellosis in household animals, leading to extensive economic losses for the livestock industry. Different traditional methods have been used since the 1980s to detect P. multocida and M. haemolytica infection. Although these methods help diagnose pasteurellosis in the early stages, they are limited in sensitivity and specificity. Therefore, modern diagnostic methods that rely on bacterial genomics to improve sensitivity, specificity, and stability have developed. This report is based on our team’s results and published papers related to diagnosis, typing, and polymorphism of pasteurellosis via PCR, Multiplex PCR, real-time PCR, and LAMP and analyze the advances and drawbacks of each method to provide a comprehensive view of pasteurellosis diagnosis.

Study on reducing power of Morinda citrifolia L. Fruit Extract (McFE) as a reduced agent in the green synthesis of gold nanoparticles

Dang Xuan Du — 2024-09-30

The reducing power of Morinda citrifolia L. Fruit Extract (McFE) for the green synthesis of gold nanoparticles was evaluated by ferricyanide method, infrared spectroscopy (FT-IR) and ABTS•+ free radical scavenging activity. The results showed that the extract sample at the concentration of 75 mg/mL (McFE75) stored for 2 days gave the highest reducing power. FTIR spectroscopy indicated the involvement of carboxyl, amine and hydroxyl groups in the the composition of McFE75. Gold nanoparticles (AuNPs) were green synthesized using McFE75 as a reducing agent with a volume ratio of McFE75/Au³⁺ 1 mM of 1:10. The UV-vis spectroscopy, TEM and SEM methods were used to monitor the formation and morphology of AuNPs. The Zeta potential method was used to evaluate the stability of the gold colloidal system. The results showed that the time of 110 minutes was suitable to fabricate the gold nano colloidal system at room temperature. The size of obtained AuNPs was of about 17 nm, Zeta potential = -14.2 mV. The obtained nano gold colloidal system was quite stable. After 2.5 months of storage, the size and Zeta potential of AuNPs were 26 nm and -6.5 mV, respectively.

In vitro and in silico studies of compounds extracted from Elsholatzia cillata against bacteria Streptococcus pneumoniae and Streptococcus pyogenes

Vĩnh Phú Nguyễn — 2024-09-30

The Elsholatzia cillata essential oil was extracted and characterized by gas chromatography-mass spectrometry (GC-MS) for compositional specificity. GC-MS analysis revealed the presence of 13 natural components in the essential oil (E1 - E13). The ability of active components that inhibit Streptococcus pneumoniae with 5XU1 protein and Strepcococcus pyogene with 4XCH protein was identified using in vitro and in silico studies. Evaluating the antibacterial ability of compounds in the Elsholatzia cillata essential oil under in vitro conditions that against S. pneumoniae and S. pyogenes exhibited that the results of inhibition zone diameter and minimum concentration inhibition (MIC) was 45 mm and 0.15625 µL.mL^-1 on S.pneumoniae strain and 34 mm and 0.15625 µL.mL^-1 on S. pyogenes strain, respectively. Molecular docking simulations confirmed the most effective inhibitors against proteins 5XU1 and 4XCH into the order of ligand-protein complexes E12, E9, E5, E11, E8 and E8, E11, E9, E10, E12.