Vietnam Journal of Biotechnology

Contamination of heavy metals (As, Cd, Hg, Pb and Sn) in honeybee products (Apis cerana) from Northern Vietnam is determined. The study was carried out in two main harvesting seasons of beekeeper farms (April and October), over two years (2018-2019). A total of 72 samples from 24 honeybee hives from 8 provinces and one city were collected. The results showed that the quality of three products in nearly all research sites were met the standards in accordance with the national technical regulation on the limits of heavy metal contamination in food of the Vietnamese Health Ministry, except for the pollen and beeswax from HY2 site. The concentration of Pb was most notably value in this study, which was determined at fairly high levels in pollen (3,767 mg/kg) and beeswax (5,840 mg/kg) from HY2 site. This can be a warning for this metal significant contamination in the habitat. Specially, Hg was not detected in most samples or only recorded without significant. For the environmental types, the mean value of As and Sn in all honeybee’s product types in semi-rural area were higher than that in rural area. Thus, the detection of the heavy metals proves that honeybee’s products could be good indicators to detect the environmental contaminants and monitor the habitat quality of a particular area

Berberine has been known as a traditional component for treatment of intestinal-related diseases in Asian countries. Additionally, it possesses a variety of pharmacological properties, which were studied for treating tumor, diabetes, cardiovascular disease, hyperlipidemia, inflammation, bacterial and viral infections, cerebral ischemia trauma, and mental disease. Moreover, berberine has been known as an anti-osteoporotic agent by controlling both osteoclast (bone resorption cells) and osteoblast (bone-forming cells) functions. Beside the beneficial effects of berberine, it has some drawbacks that hindered its applications and resulted in low bioavailability. One of the most drawback characteristics of berberine is that it has poor watery solubility. To overcome these limits, nanotechnology has been used as the primary approach to deliver berberine in different nano-formulations. In this study, a novel berberine nanoparticle (nanoberberine, NBB) with good water dispersion was synthesized to enhance its bioavailability. The result showed that NBB was successfully developed in spherical shape and approximately 559 nm of mean size. Besides, in vitro release study revealed that berberine content release from NBB was 3 to 4 times higher than that from free berberine. Moreover, no cytotoxicity was observed for both NBB and berberine on osteoblast MC3T3-E1 cells at the tested concentrations. Additionally, alkaline phosphatase (ALP) activity, a marker for osteoblast differentiation process, was significantly higher in NBB compared to free berberine at the same test concentrations. This result indicated that NBB could be a potential biological agent for inducing bone formation. Overall, our data indicated that NBB could improve bioavailability, especially osteogenesis activity in vitro compared to free berberine.

Most of the rice cultivars exhibit suspension of growth when submerged to overcome the reduced availability of oxygen. When the situation continues, majority of the cultivars unable to recover after the flood recedes. However, there are fortunately some rice genotypes that can withstand such submerged condition for up to two weeks by adapting two totally opposite mechanisms. One type of cultivars elongates enormously at a very short span of time and the leaves come above the water level. In the second type, they remain under water without any growth. Cultivars of both types tolerate the submergence but the first category easily lodges when flood water recede. In those lines, yields are reduced drastically. In this study, we focus on characterize the genetic variation at the Sub1 locus and to associate its relevance, if any, to submergence tolerance among the deep water landraces. As a first step, seeds of some rice cultivars collected from North-east Indian regions were initially selected for the characterization of genetic variation. The PCR based analysis involving several genes known to be associated with submergence tolerance did not reveal much difference. However, Southern hybridization revealed certain differences between submergence tolerant and susceptible cultivars. Although we did not notice major difference with regard to Sub1 genes when tried with EcoRI and BamHI, differences were noticed with adh1 and RAmy3C genes. Representative, Southern analysis showed the genetic variation among the deep-water cultivars as compared to Swarna and Sub1-Swarna. It is possible that deep-water rice cultivars may not differ in their genome at Sub1 locus but they respond through SNORKEL genes under submergence.

Soybean (Glycine max) is one of the crops which have high economic value and serve for food, feed and process of many countries around the world. However, there are many factors affecting the productivity of soybean, of which insect pests and diseases are the most harmful agents. Therefore, an application of biotechnology to transfer insect resistance genes derived from a species of bacteria Bacillus thuringiensis can contribute to increase soybean yield and significantly reducing pesticide use. Currently, there are many insecticidal proteins detected from B. thuringiensis such as Cry, Cyt and Vip with a broad and specific spectrum belonged to several orders Lepidoptera, Diptera, Coleoptera, Homopera, and Nematoda. Numerous studies have been implemented over the world to transfer genes encoding these proteins in combination or modified forms to increase their toxicity. Several events of genetically engineered soybean with stacked traits of insect resistance and herbicide tolerance are commercialized and approved to be cultured in many countries such as MON 87701 × MON 89788 or DAS-81419-2. In Vietnam, studies on genetically engineered soybean with insect resistance trait has been carried out. Moreover, the exploitation, screening and selection of high biodiversity and indigenous B. thuringiensis strains which habors specific genes capable of killing targeted insects and serve as materials for plant transformation are great scientific meaning and potential practical application. This will be an important source of materials to create many soybean cultivars with good ability of insect resistance in order to meet specific needs.

Tạp chí Công nghệ Sinh học 3(1): 57-66, 2005

Currently, scientific publications are focusing on the pharmacological actions of Citrus limon's extract and essential oil. Its essential oil is rich in bioactive monoterpenoids, such as D-limonene, β-pinene, γ-terpinene. Citrus limon essential oils have been recognized as the potential source of natural insecticides because of their selectivity, ability to be biologically degraded into non-toxic compounds, low impacts on biodiversity and the environment. Many previous studies have reported anti-bacterial, anti-fungal, anti-inflammatory, anti-cancer, hepato-regenerative, and cardio-protective activities of Citrus limon essential oil. In this study, we collected the discarded Citrus limon peel source in Gia Lai province to utilize as a material to build an optimized extraction process with the following criteria: extraction solvent, solvent/sample ratio, extraction temperature, and extraction time. The results showed a stable extraction process with a maximum extraction efficiency of 4.02%, at 40°C, for 3 hours, with two extraction times using 95% ethanol for solvent. Using GC/MS method, the determined limonene content accounted for 12.2% of the extract. The Citrus limon peel extract exhibited potency against Aedes aegypti (arbovirus vector) at a concentration of 0.01 mL, with protection time of 70 minutes and biting percentage of 0.9%, compared to negative control with statistically significant (P < 0.05). The above results correspond with the most recent publications about the effects of mosquito repellence of certain plant-based essential oils. This study has proven that Citrus limon peel in this locality signifies a promising candidature for future studies regarding its main active compound, limonene, in the control of dengue-transmitting vectors. Therefore, Citrus limon peel extract brings hope to develop new mosquito repellency products in the future.

Cytokinin (CK) is an important phytohormone, which not only plays significant role in plant development but also involves in mediating plant stress tolerance. Previous studies showed that the drought tolerance can be improved by stress-inducible overexpression of adenine isopentenyl transferase (IPT), which is a critical enzyme in CKs biosynthesis. To study the role of soybean GmIPT10 in regulating plant tolerance, we successfully generated GmIPT10-overexpressing transgenic soybean plants and screened a line carrying homozygous, single copy of transgene. Analyzing several physiological traits of this line demonstrated that it possessed stress tolerance characteristics, including increased primary root and shoot lengths, better production of shoot biomass, higher number of trifoliate leaves, and higher survival rate than the non-transgenic plants under drought condition. The net house experiments also showed that the GmIPT10-overexpressing transgenic soybean had a greater relative water content compared to the control genotype under applied drought condition. Therefore, this report indicated that plant drought tolerance might be enhanced via regulating expression of GmIPT10.

In the present study, silver nanoparticles were synthesized by chemical reduction method route into the lamellar space of bentonite (Ag/CTS/Bentonite). Silver nitrate (AgNO3) was taken as a metal precursor, sodium borohydride (NaBH4) as a reducing agent, reduction of Ag+ ions and the subsequent formation of Ag nanoparticles, chitosan as a natural polymeric stabilizer and was sticked silver nanoparticles to the surface of bentonite particles, respectively. Manipulating the size and shape of Ag/CTS/Bentonite nanomaterial was characterized using transmission electron microscopy (TEM), spherical silver nanoparticles, as depicted by TEM, were found to have a wide particle size distribution from 5 nm to 90 nm. Meanwhile, the X-Ray flourescence (XRF) spectrum indicated the presence of silver on bentonite particles. Antifungal activity of the synthesized Ag/CTS/Bentonite nanomaterial was investigated against crop pathogenic fungi (Fusarium oxysporium (F. oxysporium) and Rhizoctonia solani (R. solani)) isolated from infected soybean plant in Bac Ninh province by the Plant Protection Research Institute. The assessment of fungicidal activity of the Ag/CTS/Bentonite nanomaterial showed that this product exhibited strong antifungal activity towards soybean pathogenic fungi. At highest nanosilver concentration of the Ag/CTS/Bentonite nanocomposite (400 ppm) sclerotial germination of F. oxysporum was almost inhibited, after 7 days the inhibition effect on sclerotial germination attained 66.70%. For the case of R. solani, after 2 days at 400 ppm silver nanoparticles concentration the inhibition effect on sclerotial germination attained 92.82%. The obtained results suggested that the synthesized Ag/CTS/Bentonite nanomaterial acts as an effective antifungal agent. Thus, it could be used in developing novel antifungal agents for potential applications in agriculture.

A large amount of spent yeast as by-product is annually generated from brewing industry and it contains about 50-55% protein with good balance of amino acids. The hydrolysate produced from spent brewer’s yeast may be used in food application. The yield of proteolylic hydrolysis for spent brewer’s yeast and amino acid contents of hydrolysates depend on factors such as temperature, pH value, type of used enzyme and ratio enzyme/substrate, time. Besides, applied hydrolysing methods (batch-, or continuous method) has effected on degree of hydrolysis. With the purpose of how proteolytic hydrolysis having effects on the spent brewer’s yeast for food application in industrial scale, continuous overflow method was used in this study. Bitterness of hydrolysate and the yield of continuous overflow proteolytic hydrolysis process are the two interested factors for protein hydrolysis. In this report, it is dealt with determination for optimal conditions to obtain the highest yield of hydrolysis process and the lowest bitterness of hydrolysate. Response surface methodology (RSM) was used to determine optimal condition for continuous overflow proteolytic hydrolysis of spent brewer’s yeast. The optimal conditions for obtaining high degree of hydrolysis and low bitterness are determined as followings: ratio of enzyme mixture (alcalase 7.5 U/g and flavourzyme 10 U/g), pH at 7.5, hydrolysis temperature at 51oC and hydrolysis time of 9 hours. Under the optimal conditions, the yield of hydrolysis was 59.62% ± 0.027 and the bitterness equivalently with concentration of quinine was 7.86 ± 0.033 μmol /ml.

In this study, three chloroplast genes (matK, rbcL and rpoC1) and one nuclear gene (ITS) were used to assess the nucleotide diversity for nine individuals of Canarium nigrum species in Bac Giang, Hoa Binh and Phu Tho provinces (three individuals from each province). The nucleotide sequence of the four regions (ITS, matK, rbcL and rpoC1) of C. nigrum were determined with the results showing their size to be 696 bp, 798 bp, 702 bp and 522 bp, respectively. Results of nucleotide sequence comparison for the studied samples exhibited 100% similarity for all the four gene regions. Sequence comparison with other species in the Canarium genus available in the GenBank revealed that the nucleotide diversity level (π) was the highest for the ITS gene (0.02), followed by matK (0.007), and the lowest for rbcL (0.003). The phylogenetic tree of C. nigrum with the species in Canarium genus indicated that the separation of species was the clearest for the rpoC1 gene, followed by rbcL, matK and ITS gene, with the bootrap values obtained from the branching nodes of each species ranging from 98 to 99%, 35 to 67%, 65 to 98% and 98 to 99%, respectively. The species C. nigrum had the closest nucleotide similarity to C. tramdenum (KP093200) and C. album (KP093198) for the ITS gene and to species C. subulatum (KR530509), C. acutifolium (KR530512) for matK gene region. These results suggests the rpoC1 gene region could be used as barcode for the species in genus Canarium.