Vietnam Journal of Biotechnology

Tobacco  mosaic  virus  (TMV)  and  cucumber  mosaic  virus  (CMV)  is  one  of  the  most  important  viral pathogens  capable of affecting  to many plant  species, such as tomato, potato, tobacco, peppe etc. In order to generate fransgenic tobacco plants resistant to both TMV and CMV, RNA interference  (RNAi) technology hasbeen applied in this study. A multi-fragment  of 625 bp - CPi (including  305 bp from  nucleotide  159 - 463 of TMV  cp gene  and  313 bp  from  nucleotide  315 -  627  of  CMV cp gene)  was used  to  construct  a  expression vector  containing T-CMV-CP  RNAi  in order to silence the CP gene of both TMV and CMV. This  construct was fransformed into tobacco plants (Nicotiana tabacum, cv. K326) via grobacterium tumefaciens.  The PCRT-PCR  and ELISA  analyses indicated that the CPi multi-fragment  was stably integrated  in tobacco genome and resulted in the absence of TMV and CMV in the inoculated transgenic lines. The resistant valuation of TO fransgenic tobacco  plants  after  three  times  challenge  with  TMV  and  CMV  revealed  that  34/48  (70.8%) fransgenic  lines were completely resistant to both studied vuuses.

Cultured mammalian cells have been extensively utilized as platform for recombinant protein production because of their post-translational modifications. Several rodent- or human derived cells like CHO, HBK and HEK are frequently used for complex protein expression. Despite the plenitude of cell lines, nearly 70% of all recombinant therapeutic proteins produced today are made in CHO cells. In order to establish a protein expression system in CHO cells, the gene encoding the green fluorescence protein, GFP, was selected as the target gene of this study. pEGFP-N2 vector containing the g/^ gene -was delivered into cells by calcium phosphate or lipofectamin 2000. Forty-eight hours after transfection, the GFP expression was checked by its fluorescent intensity under a fluorescent microscopy. The fransfected cells are about 50 - 60% ofthe total cells. The stable transfected cell line named CHO/GFP expressing high level of the GFP was selected by geneticine antibiotic. These results showed the applicability of the modem cell cultured techniques for transient fransfection and stable transfected cell line development to study the expression of therapeutic recombinant proteins in the CHO cell system

Anoectochilus setaceus is a medicinal plant used as a traditional medicine as well as nutritious products for health care in China and many Asian countries. In conventional propagation, the the vessel type, material and volume lead to differences in the moisture content between the internal and external conditions which result in great impact on the quality of in vitro plantlets as well as subsequent growth at nursery. In this study, several factors affecting the multiplication and regeneration of A. setaceus cultured in vitro were investigated. The highest percentage of shoot regeneration (52.88%) from ex vitro stem nodes was obtained when explants were cultured on SH medium supplemented with 1 mg/l BA, 30 g/l sucrose with cotton wool plug as the substrate and pH of the medium was adjusted to 5.8 prior to autoclaving. In the present study, culture vessel volume and ventilation culture conditions indicated to have effect on shoot quality. Results showed that 3-liter Erlenmeyer flasks in combination with ventilation caps resulted in better shoot growth and development (shoot height: 10.75 cm; 9.45 leaves per shoot; fresh- and dry- weight of 2.45 and 0.219 g per shoot, respectively; leaf diameter: 2.85 cm and SPAD: 39.99). Results of chromatography (TLC) analysis indicated that explants gave the same Rf value as that of authentic Adenosine. Qualifying Adenosine using TLC showed that extracts of shoots cultured on solid and liquid medium (ventilation plastic bag), and that of shoots cultured in 3-liter vessel with liquid medium (with and without ventilation) gave the same pattern in the respects of color and Rf value.

Mannitol is a six-carbon sugar alcohol that is claimed to have several health promoting effects (low-caloric, low-glycemic, low-insulinemic, anticariogenic, and prebiotic). Due to its low hygroscopic character, it widely used in food and pharmaceutical industries. In food industry, mannitol is used as sugar replacers because of their taste and sweetness. It is nonmetabolizable sweeteners which do not affect insulin levels making it applicable in diabetic food products. Among mannitol production methods including: chemical, enzyme and fermentation, the conversion of fructose to mannitol by lactic acid bacteria fermentation is the best way because of no requirement for highly purified substrates, making pure product and easy to produce in industry scale. There are many groups of microorganisms capable of fermenting mannitol biosynthesis, including lactic acid bacteria group, because of their conversion of fructose to mannitol by mannitol dehydrogenase with high mannitol content and low byproducts. In the study, we researched on conditions of fermentation for mannitol biosynthesis by Lactobacillus fermentum HF08. Mannitol production of the strain was reached to the maximum 93.1-93.2 g/l after 48 hours of fermentation in an appropriate medium (g/l): pepton 7.0; glucose/fructose 50/100; yeast extract 2.0; K2HPO4 2.0; MgSO4.5H2O 0.2; MnSO4 0.01. The pH of the medium fermentation for the mannitol production was 5.0-5.5. Suitable temperature for mannitol production was 35-37oC.

Plant endophytes are an interesting group of microorganisms that colonize the internal tissues of living plants and do not cause any disease symptoms in the host plant. It exists in different parts of plants, such as roots, leaves, and stems, and significantly affects the formation of metabolic products in plants by promoting the accumulation of important secondary metabolites. The present study focused on analyzing the diversity and distribution of endophytic fungi related to different tissues from samples of the medicinal plant Dysosma difformis (Hemsl & E.H. Wilson) T.H. Wang collected in Ha Giang and Lai Chau, in which the isolates from roots were 27 strains (50.94%), 12 strains from stems (22.64%), and 14 strains from leaves (26.42%). Based on the isolates, we analyzed the fungal diversity through seven different diversity indices. The results showed that isolates’ diversity was similar to the endophytic fungal population in tissues of D. difformis distributed in different vegetation in Vietnam. Specifically, Shannon's index showed the highest diversity in roots (H′ = 2.673), followed by stems (H′ = 2.162) and leaves (H′ = 2,054). Similarly, species richness was highest in roots (Dmg = 4,551; Dmn = 3,079) and stem (Dmg = 4,024; Dmn = 3,175) and lowest in leaves (Dmg = 3.41; Dmn = 2,405). However, the Simpson diversity index showed that the endophytic fungal community was most abundance in leaves (1-D = 0.911), followed by stems (1-D = 0.897) and roots (1-D = 0.867). In addition, the Sorensen index of 0.615 shows the average similarity in species composition between the two sites, Ha Giang and Lai Chau. This is the first report on the diversity of endophytic fungi isolated from D. difformis, paving a potential way for screening endogenous fungal strains capable of producing important secondary compounds.

The COVID-19 pandemic is ongoing and spreading around the world, which means a continuous increase in the number of infections and death. SARS-CoV-2 constantly rapidly stored mutation in the Spike gene to adapt with the host cell. The Spike gene encoded spike protein directly interacts with hACE2 on the human cell surface. Herein, using the network centrality and molecular docking approaches, we detected key mutations that positively affect spike protein. Based on network centrality, we demonstrate that the A23403G (D614G) mutation in the Spike gene is the center of a network which means this mutation has a positive effect on the virus. In addition, analyzing the interaction of spike protein with hACE2, we highlighted that the mutation appeared in the RBD region by changing the electrostatic energy of the complex. Remarkably, mutations N440K, L452R, T478K, E484K, Q493R, and Q498R increased binding free energy of Spike-hACE2 complex due to the change of the side chain into a positive charge. The Eta, Delta, and Omicron variants existed in one or more of these mutations resulting in higher binding free energy and binding affinity than the Wuhan variant indicating sounder interaction with hACE2. In general, mutations appearing on the spike protein tended to cause the surface to become positively charged in order to interact easily with the negative surface of the hACE2 receptor.

Tế bào tua là tế bào trình diện kháng nguyên chuyên nghiệp nhất tới các tế bào lympho T trong quá trình đáp ứng miễn dịch. Klotho là một protein xuyên màng được tìm thấy chủ yếu trong thận. Klotho có vai trò ngăn cản quá trình lão hóa tế bào và làm tăng khả năng hấp thụ ion Ca2+ khi tế bào được hoạt hóa bởi kháng nguyên lipopolysaccharide (LPS). Nồng độ ion Ca2+ trong tế bào chất tăng lên kích hoạt tín hiệu phân tử PI3 kinase (PI3K)/Akt kéo theo ức chế sự phosphoryl hóa GSK3β, kết quả làm tăng sự phiên mã của các cytokine viêm. Trong nghiên cứu này, chúng tôi đã tiến hành xác định mức độ biểu hiện của gen klotho, nồng độ IL-10 trong môi trường dịch huyền phù và cơ chế phân tử liên quan trong tế bào tua bằng phương pháp RT-PCR, western blotting và ELISA. Vật liệu sử dụng là tế bào tủy xương chuột được nuôi cấy 8 ngày cùng hormone GM-CSF. Kết quả nhận được cho thấy, khi sử dụng chất LY294002 để ức chế tín hiệu PI3K/Akt hoặc nuôi cấy tế bào trong môi trường đói huyết thanh đều làm tăng quá trình phosphoryl hóa GSK3β dẫn đến mức độ biểu hiện mRNA của gen klotho tăng lên. Bên cạnh đó, LY294002 làm giảm sự giải phóng cytokine IL-10 từ 570 pg/ml xuống 306 pg/ml. Ảnh hưởng của LY294002 đến mức độ biểu hiện mRNA gen klotho và sự tiết IL-10 bị ngăn chặn bởi chất ức chế đặc hiệu SB16763 của GSK3β. Kết quả nghiên cứu cho thấy tín hiệu phân tử PI3K/Akt ức chế biểu hiện gen klotho và làm tăng khả năng tiết IL-10 thông qua điều hòa sự phosphoryl hóa phân tử GSK3β trong tế bào tua.

In biofertilizer production, carriers and substrates have an important role in maintaining an efficacy of the commercial biofertilizer by-product. The aim of this study was to select the best carrier material and substrate and as well substrate’s moisture to sustainably store biofertilizer by-product containing three halophilic plant growth promoting bacterial strains. They are Bacillus aquimaris KG6-3 (KG6-1), Burkholderia sp. BL1-10 (BL1-10) and Bacillus megaterium ST2-9 (ST2-9) with a function of non-symbiosic nitrogen fixer, phosphorous solubilizing bacteria and IAA producing bacteria, respectively. All the experiments in this study were conducted under the laboratory conditions. Spent coffee ground and domestic coal ash were used as carrier materials. Besides that, rice bran, banana peel, banana flesh, cocopeat and brown sugar were used as substrate materials. The results showed that the domestic coal ash was able to sustain the highest viable cell number of ST2-9 and KG6-3 strains after 16 incubation hours whilst BL1-10 was found to be highest viable cell number in carrier material of spent coffee ground and the viable cell number of mixed inoculum including three bacterial strains was shown to be not significantly different among the three tested carrier materials. Moreover, the viable cell number of all three bacterial strains regardless of single or mixed inoculation was found to be highest during 15 weeks in rice bran substrate with 50% of moisture content. The mixed viable cell number of bacterial consortium achieved highest in the substrate containing rice bran + brown sugar (15:1, w/w) and when taking into account a comparion between two inoculation means, it was shown that the viable cell number in treatments with bacteria immobilized in domestic coal ash was always higher than that in treatments with free cell bacteria inoculation method. Thus, it was concluded that domestic coal ash and rice bran + brown sugar mixture (15:1) was the best carrier material type and substrate for biofertilizer by-product containing the three holophilic plant growth promoting bacteria and the immobilization technique to inoculate bacteria via carrier material was the best option for microbial inoculation.

Tạp chí Công nghệ Sinh học 3(1): 15-22, 2005

The researchs on the biomass spectra - a functional characteristic of biotic communities is still limited. In this study, the nematode biomass spectra in the bottom of Ba Lai estuary was investigated at six subtidal stations from the sea toward the upstream. The result showed that nematode biomass spectra ranged between -8 and 1 being significantly different between stations, and the lowest biomass of those spectras was in station BL4 (< 2 µg) which is upwardly closed to the Ba Lai dam. BL4 was also characterized by the lowest nematode abundance in the studied area. In addition, station BL3 downwardly closed to the dam exhibited low number of individuals. The heterogeneity in the nematode biomass spectra of BL3 and BL4 might due to the disturbance in the sedimentary environment of Ba Lai estuary related to the dam impact. This research again supports the important role of biomass spectra as bioindicator tool for biomonitoring and environmental quality assessment. Therefore, applying nematode biomass spectra is recommended for environmental assessment due to their advantages such as timesaving, not taxonomical expertise-requirement.