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The poultry industry in Vietnam is vulnerable to many viral diseases. Since antibiotics and vaccination provide inadequate protection, it will be beneficial to have alternative immunostimulants to boost non-specific immunity in poultry. Chicken interferon-alpha (ChIFNα) has been described previously with antiviral activity against many pathogens. Therefore, the purpose of this study is to clone and express recombinant ChIFNα in Escherichia coli. The ChIFNα gene was successfully cloned into the pET32a(+) vector, then expressed in the E. coli Rosetta strain. Different expression conditions were tested for the best yield of the expressed protein. Results showed that recombinant ChIFNα was expressed in Rosetta E. coli as inclusion bodies with a yield of 30 mg/100 L culture after induction with 0.5 mM IPTG in 4 hours at 37 oC. The recombinant protein was purified using affinity column chromatography under denaturing conditions with the purity > 94%. Western blot analysis indicated that recombinant ChIFNα reacted specifically with its antibody. Further studies will be carried out to characterize the biological activities of recombinant ChIFNα and its application in the poultry industry.

The attenuated porcine reproductive and respiratory syndrome virus (PRRSV) strain Hanvet1.vn was developed by Hanvet Pharmaceutical Co., Ltd. by inoculating the virulent strain 02HYon Marc-145 cells for 80 generations and used to produce PRRS vaccine. In this study, we published the results of sequencing, analyzing and comparing the genome of the attenuated PRRSV strain Hanvet1.vn compared with the original pathogenic strain 02HY. The genomes of strains Hanvet1.vn and 02HY have 8 reading frames, coding for 8 non-structural and structural proteins: NSP1a, NSP1b, GP2, GP3, GP4, GP5, MP, NP. After sequencing and translating into proteins, the gene sequence of each open reading frame (ORF) of strain Hanvet1.vn was compared with the sequence of pathogenic strain 02HY to find nucleotide and amino acid changes. The results showed that the Hanvet1.vn pathogenic strain genome (Genbank Accession KU842720) when compared with the pathogenic strain 02HY genome (Submission2490633) had89 nucleotide mutations that changed 51 amino acids in 7 ORFs and 7 proteins, respectively. Particularly, ORF6 encoding for the M protein is completely unchanged. The size of each reading frame is also exactly the same. It showed that there were no insertion and deletion (Indel) mutations in the ORFs of the attenuated strain after 80 generations of inoculation. There was a change in the genome that made the strain Hanvet1.vn become attenuated, but the gene encoding for the GP5 protein that induces the production of neutralizing antibodies only changed two nucleotides at position 471 (A->G), causing the TCA codon to turn into a TCG codon. This is a silent mutation and both codons code for the amino acid Serine (S). The second mutation at position 587 (A->T) causes Glutamine (Q) to transform into Leucine (L). However, this modification does not belong to the GP5 antigenic epitopes. In clonclusion, after 80 passages, despite changes occurred in genes of Hanvet1.vn strain for becoming an attenuated strain, the GP5 protein of the attenuated strain did not change its antigenic amino acids.

Minute intestinal flukes, Haplorchis taichui and H. pumilio, belong to the family Heterophyidae (Trematoda: Platyhelminthes), which have been studied very limited, especially the molecular markers of the mitochondrial genomes (mtDNA) and the ribosome transcription units (rTU or rDNA). We have obtained the complete mitochondrial genome of H. taichui and the coding part of ribosome transcription unit of H. taichui and H. pumilio of Vietnam. Nucleotide and amino acid data were compared between H. taichui and Metagonimus yokogawai for genomic/gene composition, codon usage (skew/skewness), and tandem repeat units (TRU). The complete mtDNA of H. taichui (strain Htai-QT3-VN) with the length of 15,120 bp and M. yokogawai (15,258 bp; Korea; KC330755) contains 36 genes, including 12 protein-coding genes (cox1, cox2, cox3, nad1, nad2, nad3, nad4L, nad4, nad5, nad6, atp6 and cob), 2 ribosomal RNA genes (rRNA); 22 transfer RNA (tRNA or trn) and a noncoding region (NCR) between trnE and trnG, divided into 2 sub-regions containing 5 TRUs (182–183 bp/TRU). H. taichui (Vietnam and Laos) uses A = 19.56%, T = 39.71%, G = 28.34%, C = 12.39% (A + T is 59.27% ​​and G + C is 40.73%) for mtDNA construction, whose skew/skewness value at A+T is negative (–0,340) and G+C is positive (0.392); for 12 protein-coding genes (PCGs) is similar; but for the mito-ribosomal genes (MRGs, of 16S/rrnL and 12S/rrnS) it is less for A+T (57.22%) and more for G+C (42.78%). M. yokogawai had lower A+T (mtDNA/55.68%; PCGs/55.96%; MRGs/54.15%) and higher G+C usage rate than H. taichui. H. taichui of Vietnam and Laos has 10,164 bp encoding for 3,376 amino acids to construct 12 PCGs with the mostly used codons as Phenylalanine (Phe-TTT) and Leucine (Leu-TTG), and the leastly used codonsas Glutamine (Gln-CAA), Arginine (Arg-CGC). Additional condon, Thr-ACA/ACC can be added as the least used in M. yokogawai. The rTU (from 5 '18S to 3' 28S) of H. taichui (7,268 bp) and H. pumilio (7,416 bp) were identified with 5 genomic regions including 18S rDNA, ITS1, 5.8S rDNA, ITS2 and 28S rDNA. The 18S and 5.8S genes of both species were of the same length (1,992 bp for 18S, 160 bp for 5.8S), but different for 28S genes (3,875 bp for H. taichui and 3,870 bp for H. pumilio). ITS1 in H. taichui (797 bp) and ITS2 in H. pumilio (280 bp) do not contain TRUs, whilst ITS1 in H. pumilio (1,106 bp) contains 5 TRUs(136 bp for 3 TRU and 116 bp for 2 TRUs); and ITS2 in H. taichui (444 bp) contain 3 TRUs (83–85 bp/each).

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of a pandemic of acute respiratory disease in humans. This pandemic has now spread worldwide and caused more than 2,000,000 deaths by 15 January 2021. The complexity and the ongoing pandemic of coronavirus SARS-CoV-2 make it difficult to control the disease. Sequence analysis on some open reading frames (ORFs) of a SARS-CoV-2 virus strain isolated in Vietnam in February 2020 (SARS-CoV-2/NIHE/human/2020/VIE strain) revealed some single nucleotide polymorphisms (SNPs) that only appeared in the Vietnamese strain in comparison to those of the isolates in other countries, including: (1) a change in ORF8-Nucleocapsid (accession number MT127114.1) at nucleotide (nt) 691 (CTC in SARS-CoV-2/NIHE/human/2020/VIE strain, TTC in all other isolates) but it does not change the encoded amino acid, (2) ORF3a-EM-ORF6-ORF7a region (accession number MT127115.1) has four-point changes, three of which lead to changes in the amino acid sequences, being nt 479 (GTA encoding Valine changed into TTA encoding Leucine), nt 575 (CGC encoding Arginine changed to GGC encoding Glycine) in the M gene, and nt 1126 (GTG encoding Valine changed to GAG encoding Glutamic acid) in ORF6. Taken together, the results provided useful information for the SARS-CoV-2 diagnostic kit and vaccine development.

Heterophyidiasis caused by minute intestinal flukes becomes of public concern in many countries worldwide. Haplorchis taichui and H. pumilio, belonging to the family Heterophyidae (Platyhelminthes: Trematoda) are two of many infecting humans and commonly found in Vietnam. Sequence study of these two small intestinal flukes is still very limited, hence we need more prospective markers for taxonomic identification and classification. This study provides complete coding sequence of the ribosomal transcription units (rTU) from H. taichui and H. pumilio (Vietnamese samples) and demonstrates the use of complete 28S rDNA sequences for phylogenetic analysis.The complete coding sequence of the rTU (from 5' 18S to 3' 28S), consisting of complete 18S, ITS-1, 5.8S, ITS2 and complete 28S rRNA genes and spacers, from H. taichui (7,268 bp) and H. pumilio (7,416 bp) from human hosts in Vietnam, were determined and annotated. The 18S and 5.8S genes of both species were of the same length (1,992 bp/18S, 160 bp/5.8S), but 28S genes differed (3,875 bp/H. taichui and 3,870 bp/H. pumilio). ITS-1 in H. taichui (797 bp) and ITS-2 in H. pumilio (280 bp) do not contain tandem repeat units (TRUs), while ITS-1 in H. pumilio (1,106 bp) contains 3 TRUs of 136 bp/each and 2 TRUs of 116 bp/each and ITS-2 in H. taichui (444 bp) contain 3 TRUs (83–85 bp/each). A phylogenetic tree inferred from the alignment of complete 28S rDNA sequences of 32 trematode strains/species, including 2 Vietnamese Haplorchis spp. and 24 species of 8 families in the suborders Xiphidiata (families Nanophyetidae, Paragonimidae, Collyriclidae), Opisthorchiata (Heterophyidae, Opisthorchiidae), and Echinostomata (Echinostomatidae, Fasciolidae). and Schistosoma japonicum of the family Schistosomatidae is used as an outgroup. The topology of the phylogenetic tree clearly confirmed the status of the Vietnamese H. taichui and H. pumilio species. These species gathered in a group (in the family Heterophyidae) clearly identified in the position of "sister” group to those in the family Opisthorchiidae (suborder Opisthorchiata, superfamily Opisthorchioidea).

Porcine epidemic diarrhea (PED) is known as a serious disease infecting all ages of pigs, with a mortality rate of up to 100% in piglets. The spike protein (S) of porcine epidemic diarrhea virus (PEDV), in particular, the S1-CTD (C-terminal domain), which contains the conservative neutralizing epitopes CO­26K equivalent (COE) (aa 499–638), exhibits a high degree of genetic and antigenic diversity. We obtained 26 Vietnamese PEDV-S1-CTD sequences (630 bp) from samples collected from seven northern provinces from June 2018 to January 2019 and analyzed them with 35 sequences from previous studies, representing the G1a and 1b, G2a and 2b, and recombinant (G1c) genotypes, and PEDV vaccines. The majority (73.1%) of strains (19/26) belonged to the subgroup G2b. With strong nodal support (98%), seven strains were clustered into an independent, “distinct subgenogroup” (named dis-subG), separate from both G1a and G1b and other G2a, 2b, and 1c (recombinant strains). When compared with the prototype CV777 strain (AF353511), sequence analysis revealed distinct changes of 513T>S, 520G>D, 527V>(I/L/M), 591L>F, 669A>(S/P), 691V>I in the COE and S1D regions of the S1-CTD protein that were only identified in these Vietnamese strains. This cluster is a new antigenic variant subgroup and further studies are required to investigate its anigenicity. The results in this study revealed the continuous evolution in the S1 region of the Vietnamese PEDV strains, which emphasizes the need for frequent updates of the vaccines for effective protection.

Conjugated linoleic acid (CLA) have been shown to exert numerous health benefits, including anti-carcinogenic, anti-atherogenic, anti-diabetic, antiobesity, cholesterol reducing, antioxidant, anti-microbial, immune system modulator and growth-stimulating properties. In human, CLA is produced from Linoleic acid (LA) by gut bacteria. In this study, nineteen Lactobacillus (Lac.) strains isolated from human feces were studied to determine their ability to metabolize LA. The bacteria were grown in the liquid form of anaerobic MRS medium supplemented with 0.5 mg/mL LA. The linoleate isomerase activity in bacteria grown on MRS medium was determined by Gas chromatograpy. The results indicated that 4 out of 19 strains, including strains Lac.02, Lac.05, Lac.14 and Lac.16 are capable of producing about 40-50 μg/mL CLA from LA. Among them, the highest ability to produce CLA from LA is Lac.02 strain. In the production of CLA from LA, enzymes involved in this metabolism in Lactobacillus act as catalysts of hydration/dehydration (CLA-HY), oxidation of hydroxy groups/reduction of oxo groups (CLA-DH), migration of carbon-carbon double bonds (CLA-DC), and saturation of carbon-carbon double bonds (CLA-ER). The cla-dh, cla-dc, cla-hy and cla-er genes that encode enzymes CLA-DH, CLA-DC, and CLA-ER had been found in all Lac.02, Lac.05, Lac.14 and Lac.16 strains. Gas chromatography traces indicated that these strains produced the same compounds, which was subsequently identified as cis-9, trans-11, and trans-10, cis-12 CLA. In the next study, we will optimize the conditions such as substrate concentrations, pH values, temperature and culture time of each strain to obtain the best rerults.

Aromatic hydrocarbons such as naphthalene, pyrene are recalcitrant compounds found in oil contaminated areas including petroleum storage tanks, oil exploiting companies. These components are difficult to be degraded/transformed in the lack of oxygen conditions. Among anaerobic and micro-aerobic microorganisms, photosynthetic purple bacteria are the dominant group. Photosynthetic purple bacteria (PPB) are considered as aquatic organisms which are able to grow in anaerobic conditions by photosynthesis but without oxygen. This bacterial group has flexible metabolic types depending on living conditions, then they are widely distributed in nature. There are numerous publications on planktonic PPB which could use naphthalene and pyrene as carbon and energy sources. However, there is no publication on biofilm formed by PPB to degrade their aromatic compounds. In this research, 4 biofilm-forming PPB strains including DQ41, PY2, PY6 and DG12 were screened and estimated their pyrene and napthalene degradation capacity. These organisms demonstrated high biofilm forming ability. As biofilm types, their utilization efficiencies were upper 79% with the initial concentrations of naphthalene and pyrene of 200 and 250 ppm, respectively. These results may contribute to enlarge the number of biofilm-forming microorganisms to degrade/transform aromatic hydrocarbons in polluted area treatment in Vietnam.

Meningococcal bacterium Neisseria meningitidis is one of the major causes of meningitis worldwide. Currently in Vietnam, N. meningitidis B and C are the most prevalent invasive serogroups. N. meningitidis expresses two major transmembrane proteins, PorA and PorB, of which PorA showed high levels of polymorphism among strains and has been studied as one component of vaccines against N. meningitidis B. Polymorphisms in porA gene clustered into three variable regions VR1, VR2 and VR3. In this study, we sequenced the entired porA gene of 19 N. meningitidis strains isolated from military units in northern Vietnam during the period 2008 – 2017 in order to: (1) evaluate the polymorphism of porA gene at nucleotide level and predict its immuno-reactivity from annotated amino acide sequences; and (2) compare porA variants of Vietnamese strains with known strains worldwide. Our results showed a high level of polymorphisms among Vietnamese strains, with the highest polymorphism found in VR1, followed by VR2 and VR3. Notably, 5/19 strains in this study showed novel variants at VR2 with unknown immunological reactivity. This result suggested potential novel immunological characteristics of meningococcal strains from Vietnam.

Oil pollution in marine environment caused by oil spillage has been a main threat to the ecosystem including the ocean life and to the human being. In this research, three indigenous purple photosynthetic strains Rhodopseudomonas sp. DD4, DQ41, and FO2 were isolated from oil-contaminated coastal zones in Vietnam. The cells of these strains were immobilized on different carriers including cinder beads (CB), coconut fiber (CF), and polyurethane foam (PUF) for diesel oil removal from artificial seawater. The mixed biofilm formed by using CB, CF, and PUF as immobilization supports degraded 90, 91, and 95% of diesel oil (DO) with the initial concentration of 17.2 g/L, respectively, after 14 days of incubation. The adsorption of DO on different systems was accountable for the removal of 12-16% hydrocarbons for different carriers. To the best of our knowledge, this is the first report on diesel oil degradation by purple photosynthetic bacterial biofilms on different carriers. Moreover, using carriers attaching purple photosynthetic bacteria to remove diesel oil in large scale is considered as an essential method for the improvement of a cost-effective and efficient bioremediation manner. This study can be a promising approach to eliminate DO from oil-contaminated seawater.

Background Porcine epidemic diarrhea virus (PEDV) is a dangerous virus causing large piglet losses. PEDV spread rapidly between pig farms and caused the death of up to 90% of infected piglets. Current vaccines are only partially effective in providing immunity to suckling due to the rapid dissemination and ongoing evolution of PEDV. Methods In this study, the complete genome of a PEDV strain in Vietnam 2018 (IBT/VN/2018 strain) has been sequenced. The nucleotide sequence of each fragment was assembled to build a continuous complete sequence using the DNASTAR program. The complete nucleotide sequences and amino acid sequences of S, N, and ORF3 genes were aligned and analyzed to detect the mutations. Results The full-length genome was determined with 28,031 nucleotides in length which consisted of the 5′UTR, ORF1ab, S protein, ORF3, E protein, M protein, N protein, and 3′UTR region. The phylogenetic analysis showed that the IBT/VN/2018 strain was highly virulent belonged to the G2b subgroup along with the Northern American and Asian S-INDEL strains. Multiple sequence alignment of deduced amino acids revealed numerous mutations in the S, N, and ORF3 regions including one substitution 766P > L766 in the epitope SS6; two in the S0subdomain (135DN136 > 135SI136 and N144> D144); two in subdomain SHR1 at aa 1009L > M1009 and 1089S > L1089; one at aa 1279P > S1279 in subdomain SHR2 of the S protein; two at aa 364N > I364 and 378N > S378 in the N protein; four at aa 25L > S25, 70I > V70, 107C > F107, and 168D > N168 in the ORF3 protein. We identified two insertions (at aa 59NQGV62 and aa 145N) and one deletion (at aa 168DI169) in S protein. Remarkable, eight amino acid substitutions (294I > M294, 318A > S318, 335V > I335, 361A > T361, 497R > T497, 501SH502 > 501IY502, 506I > T506, 682V > I682, and 777P > L777) were found in SA subdomain. Besides, N- and O-glycosylation analysis of S, N, and ORF3 protein reveals three known sites (25G+, 123N+, and 62V+) and three novel sites (144D+, 1009M+, and 1279L+) in the IBT/VN/2018 strain compared with the vaccine strains. Taken together, the results showed that mutations in the S, N, and ORF3 genes can affect receptor specificity, viral pathogenicity, and the ability to evade the host immune system of the IBT/VN/2018 strain. Our results highlight the importance of molecular characterization of field strains of PEDV for the development of an effective vaccine to control PEDV infections in Vietnam.

Vibriosis in farmed animals is a serious threat to aquaculture worldwide. Using probiotics and anti-Vibrio antimicrobial substances in aquaculture systems can be a means of preventing Vibrio infections. Therefore, we aimed to characterize and compare 16 potential anti-Vibrio probiotics (Vi+) isolated from marine sponges and fish intestines collected from the Vietnam Sea, as well as an anti-Vibrio bacteriocin to fully explore their application potentials. 16S rRNA sequencing confirmed all Vi+ to be Bacillus species with different strain variants across two sample types. An obvious antimicrobial spectrum toward Gram-negative bacteria was observed from intestinal Vi+ compared to sponge-associated Vi+. The reason was the higher gene frequency of two antimicrobial compounds, non-ribosomal peptides (NRPS) and polyketide type-I (PKS-I) from intestinal Vi+ (66.7%) than sponge-associated Vi+ (14.3% and 0%, respectively). Additionally, a three-step procedure was performed to purify an anti-Vibrio bacteriocin produced by B. methylotrophicus NTBD1, including (i) solvent extraction of bacteriocin from cells, (ii) hydrophobic interaction chromatography, and (iii) reverse-phase HPLC. The bacteriocin had a molecular weight of ~2–5 kDa, was sensitive to proteolysis and thermally stable, and showed a broad antimicrobial spectrum, all of which are essential properties for promising feed additives. This study provides necessary information of the potential of probiotic Bacillus species with anti-Vibrio antimicrobial properties to study their further use in sustainable aquaculture.

The discovery of antibiotics is considered to be one of the greatest medical achievements in the early part of 20th. Over the past six decades, these ‘wonder drugs’ have played a critical role in reducing the global burden of communicable diseases. As a country in the tropical zone, Vietnam faces numerous infectious disease outbreaks every year. In addition, the overuse of antibiotics in healthcare and the misuse of antibiotics as growth promoter in agriculture these past decades have led to serious antibiotic-resistance in bacterial pathogens of human, crops and livestock in Vietnam. This poses an urgent need for alternative strategies to fight against these pathogens. Lysins are phage-encoded peptidoglycan hydrolases which were recently demonstrated the strong potential in human and veterinary medicine to control and treat pathogens on mucosal surfaces and in systemic infections. These enzymes when applied exogenously to Gram-positive bacteria, bring about rapid lysis and death of the bacterial cell and therefore promise an effective alternative therapy against antibiotic-resistant bacterial pathogens. In this study, we applied the DNA technology to produce a recombinant S. aureus lysin (LysK). LysK was PCR amplified from phage S. aureus and cloned into a pET32a(+) expression vector. The recombinant fusion protein (LysK-Trx) was successfully expressed in E. coli, purified through nickel column chromatography, and further digested with Thrombin protease. The cleaved protein (intact LysK) was purified by nickel column again. The recombinant LysK was tested for its ability to kill S. aureus by a spot inoculation assay. The results showed that recombinant LysK induced the lysis of host bacteria, indicating that the protein was expressed and functionally active. Data from the current study can be used to develop therapeutic tools for treating diseases caused by drug-resistant S. aureus strains in Vietnam.

Oil pollution which results from industrial activities, especially oil and gas industry, has become a serious issue. Cinder beats (CB), coconut fiber (CF) and polyurethane foam (PUF) are promising immobilization carriers for crude oil biodegradation because they are inexpensive, nontoxic, and non-polluting. The present investigation was aimed to evaluate this advanced technology and compare the efficiency of these immobilization carriers on supporting purple phototrophic bacterial (PPB) strains in hydrocarbon biodegradation of crude oil contaminated seawater. The surface of these biocarriers was supplemented with crude oil polluted seawater and immobilized by PPB strains, Rhodopseudomonas sp. DD4, DQ41 and FO2. Through scanning electron microscopy (SEM), the bacterial cells were shown to colonize and attach strongly to these biocarriers. The bacteria-driven carrier systems degraded over 84.2% supplemented single polycyclic aromatic hydrocarbons (PAHs). The aliphatic and aromatic components in crude oil that treated with carrier-immobilized consortia were degraded remarkably after 14 day-incubation. Among the three biocarriers, removal of the crude oil by CF-bacteria system was the highest (nearly 100%), followed by PUF-bacteria (89.5%) and CB-bacteria (86.3%) with the initial crude oil concentration was 20 g/L. Efficiency of crude oil removal by CB-bacteria and PUF-bacteria were 86.3 and 89.5%, respectively. Till now, the studies on crude oil degradation by mixture species biofilms formed by PPB on different carriers are limited. The present study showed that the biocarriers of an oil-degrading consortium could be made up of waste materials that are cheap and eco-friendly as well as augment the biodegradation of oil-contaminated seawater.

Background Neisseria meningitidis remains the main cause of sporadic meningitis and sepsis in military camps in Vietnam. Yet, very limited molecular data of their genotypic and epidemiological characteristics are available from Vietnam, and particularly the military environment. Whole genome sequencing (WGS) has proven useful for meningococcal disease surveillance and guiding preventative vaccination programs. Previously, we characterized key genetic and epidemiological features of an invasive N. meningitidis B isolate from a military unit in Vietnam. Here, we extend these findings by sequencing two additional invasive N. meningitidis B isolated from cerebrospinal fluid (CSF) of two meningitis cases at another military unit and compared their genomic sequences and features. We also report the sequence types and antigenic profiles of 25 historical and more recently emerged N. meningitidis isolates from these units and other units in proximity. Methods Strains were sequenced using the Illumina HiSeq platform, de novo assembled and annotated. Genomes were compared within and between military units, as well as against the global N. meningitidis collection and other isolates from the Southeast Asia region using PubMLST. Variations at the nucleotide level were determined, and phylogenetic relationships were estimated. Antigenic genotypes and vaccine coverage were analyzed using gMATS and PubMLST. Susceptibility of isolates against commonly used antibiotic agents was examined using E-test. Results Genome comparison revealed a high level of similarity among isolates both within and between units. All isolates showed resistance to chloramphenicol and carried identical catP gene with other Southeast Asian isolates, suggesting a common lineage. Their antigenic genotypes predicted no coverage by either Bexsero®or Trumenba®, and nucleotide variation analysis revealed diverse new, unassigned alleles at multiple virulence loci of all strains. Groups of singleton and unique novel sequence types extending beyond individual camps were found from epidemiological data of 25 other isolates. Our results add to the sparse published molecular data of N. meningitidis in the military units in Vietnam, highlight their diversity, distinct genetic features and antibiotic resistance pattern, and emphasize the need for further studies on the molecular characteristics of N. meningitidis in Vietnam.

Lactobacillus sp. in the digestive tract are capable of producing H2O2 to inhibit the growth of harmful bacteria and balance the gut microflora. In this study, we have isolated 115 strains of Lactobacillus spp. from stool samples of healthy people in Ha Noi. Of the 50 tested Lactobacillus strains, 9 strains were capable of producing H2O2, of which the Lac.VFE-14 strain produced highly H2O2 with a concentration of 2.183 mM, followed by Lac.VFE-08 strains (2.081 mM) and Lac.VFE-04 (2.067 mM). All three strains grew well in MRS medium supplemented with bile salts or adjusted to low pH value. With 0.3% of bile salt, the survival rates of these 3 strains were 99%, 95% and 97%, respectively. At pH 3.0, after 3 hours of cultivation, the survival rates of the three strains were 98.54%, 94.15% and 95.27%, respectively. In addition, each of the cell-free culture supernatants of these three strains that inhibit the growth of S. aureus ATCC-23235. The inhibition zone diameters of the three strains were 19.0±1.0 mm, 14.0±1.0 mm and 11.7±1.3 mm, respectively. The results of 16S rRNA gene analyses showed that Lac.VFE-14, Lac.VFE-08 and Lac.VFE-04 had high similarity scores with L. plantarum ZZU 23 (100%), L. rhamnosus JCM 1136 (99%) and L. plantarum S7 (98.65%), respectively. This study indicates that all three strains have the potential to be used as probiotics in the future.

In this study, the gut microbiome of healthy adult honeybees, Apis cerana, was investigated by sequencing the V3 – V4 region in 16S rRNA gene using Illumina Miseq platform. The total of 37,853 reads for 16S rRNA gene were obtained and 30,121 (79.6%) reads were valid with 25,291 (84.0%) reads that were classified into 116 species belonging to four major phyla. The relative abundances of the bacterial isolates in honeybee samples were phylum Proteobacteria (70.7%), Actinobacteria (10.7%), Firmicutes (10.3%), and Bacteroidetes (8.4%), respectively. Lactic acid bacteria comprised 18.95% with 10 groups including Bifidobacterium asteroides, B. indicum, Fructobacillus fructosus, Lactobacillus apinorum, L. apis, L. helsingborgensis, L. kimbladii, L. kullabergensis, and L. kunkeei. The presence of beneficial bacteria in the gut highlighted their role in the honeybee and suggested that they can be promising candidates for the development of probiotics for health improvement, infection control and disease management of honeybees.

The green alga Chlamydomonas reinhardtii is a model organism for studying mechanism of the body in response to changes in environmental conditions, photosynthesis as well as chloroplast biogenesis and can be modified to produce high value proteins. In this study, we present results on the selection of cultural conditions for the growth of cell wall - deficient mutant C. reinhardtii (503 strain- control) and recombinant 503-2 strain expressing VP28 protein of White Spot Syndrome Virus (WSSV) in 250 ml flasks. Suitable conditions for the growth of both control and recombinant strains were TAP medium, temperature of 25 C, pH = 7, light intensity of 2 klux, C source - Trisbase, N source - nitrate and salinity of 50 - 100 mM. In these conditions, maximum cell density of the control and recombinant strains was 3.20 ± 0.08 x 106 and 2.96 ± 0.17 x 106 cells/ mL after 3 and 7 days of cultivation, respectively. The presence of vp28 gene in the recombinant microalgal strain was stably maintained at all levels of culture. The results of this paper will be a scientific basis for culturing the recombinant C. reinhardtii to obtain algal biomass which had high expression of surface VP28 protein of WSSV’s envelope for edible vaccine production vaccine by feeding in order to prevent white spot disease of shrimp.

Biofilms are defined as community of microorganisms which are irreversibly or reversibly attached on solid surfaces. These microorganisms are embedded in a self-produced exopolysaccharide matrix, and exhibit different growth and bioactivity compared with planktonic cells. With their high biomass density, stability, and potential for biodegradation of recalcitrant compounds contained in oil contaminated wastewater such as aromatic hydrocarbons. Aromatic hydrocarbons are the main constituents of petroleum and its refined products. These compounds are also quantitatively the main environmental pollutants worldwide. In this report, cellulose material was used as a carrier for forming biofilm by microorganisms to remove of these components. Cellulose material is considered as inexpensive, available, sustainable, little waste production and can be recycled. As a result, the microorganisms were successful to adhere on cellulose material at 50 liter module with cell density of 4.3x108 CFU/ml after 7 day-incubation. Under the scanning electron microscope with the 1500 magnification, the microbial cells had a very high density, closely linked together and firm adhesion on the cellulose material. The mixture species biofilm attached on cellulose carrier at 50 liter module had the ability to degrade 80.1, 78.3, 60.0, 98.5 and 91.2% of anthracene, fluorene, naphthalene, phenol and pyrene after 7 days, respectively. The obtained results showed that biofilm formed by multiple bacterial strains attached on cellulose material may considerably increase the degrading efficiency of aromatic hydrocarbon compounds. The results also indicated that cellulose material is suitable carrier to choose in removal of aromatic hydrocarbon contaminated wastewater. These results are considered as new approach to apply microbial films on cellulose material to degrade oil polluted waste-water in the environment.

White spot syndrome virus (WSSV) is the leading cause of shrimp mortality in farms all over the world. In Vietnam, for the last five to ten years, WSSV has always been among the top causes of diseases and loss in our shrimp aquaculture. VP28 and VP26 are two capsid proteins of WSSV that commonly used as biomarkers for diagnosis and target antigens for vaccine against WSSV. Recombinant VP28 (rVP28) has been studied and expressed in various expression systems including E. coli, yeast and baculovirus. rVP28 expressed in these systems showed effective protection against WSSV in shrimps, though there remains limitation on expression efficiency and safety. Recently, green microalgae Chlamydomonas reinhardtii has been widely used to express pharmaceutical proteins and edible vaccines for aquaculture thanks to its advantages as a safe and efficient host. C. reinhardtii is also used as nutrious natural food for shrimps due to its benefits towards shrimp health and growth. In this study, the codons of vp28 gene was adapted and chemically synthesized, and transformed into the nucleus genome of C. reinhardtii using electroporation. The presence of a codon optimized vp28 gene in C. reinhardtii genome was confirmed by colony PCR and sequencing; and its expression level was examined by RT-PCR. These results proved our success in creating transgenic C. reinhardtiii expressing rVP28 and set the foundation for our future research on edible vaccine against WSSV for shrimp.

Chitinases (EC 3.2.1.14) are enzymes that degrade chitin. These enzymes are gaining importance for their wide-ranging applications including the preparation of pharmaceutically important chitooligosaccharides and N-acetyl D glucosamine, preparation of single-cell protein, isolation of protoplasts from fungi and yeast, control of pathogenic fungi, treatment of chitinous waste, mosquito control and morphogenesis and especially in agriculture fields to control pathogens. Previously, we have cloned chiA gene encoding chitinase for overexpresion in E. coli. Herein, we optimized the expression conditions for improvement of chitinase biosynthesis in recombinant E. coli strain using response surface method (RSM) based on Design-Expert 10.1 software (Stat-Ease, Inc., Minneapolis, USA. Fermentation conditions such as inducer concentrate, induction time and cell density at the time of induction and their effects on the chitinase biosynthesis were investigated. The RMS analysis suggested that the optimal conditions for production of recombinant ChiA are at lactose concentration of 6,15 mM, 8,12 hours after induction and cell density OD600nm = 0,87 with predicted enzyme activity of 7,49 U/ml. The model obtained was used for fermentation of recombinant strain and the real chitinase activity achieved 7,54 U/ml which is 1.32 times higher compared to that of the pre-optimization (5.71 U/ml). The RSM was found to be useful in optimizing and determining the interactions among process variables in ChiA enzyme production. Our data also indicated that using lactose as the inducer instead of ITPG for ChiA expression can also reduce product costs. Citation: Trinh Thi Thu Ha, Dong Van Quyen, Ngo Dinh Binh, 2018. Optimization and improvement of recombinant chitinase biosynthesis in E. coli using response surface method. Tap chi Sinh hoc, 40(1): x-xx. DOI: 10.15625/0866-7160/v40n1.10495. *Corresponding author: binh.gen@gmail.com Received 5 July 2017, accepted 20 December 2017

White Spot Syndrome Virus (WSSV) is a major cause of mortality in shrimp cultivation on farms all around the world. The serious monetary losses related with its occurrence in susceptible shrimps and the limitations of current methods used to treat WSSV disease in Vietnam, highlight the need for new methods to prevent and to manage the disease. The current study investigates the possibility of expressing the VP28 protein of WSSV from the nucleus of Chlamydomonas reinhardtii for WSSV control. The VP28 protein of WSSV was successfully expressed in C. reinhardtii as confirmed by Western blot analysis and RT-PCR. The immunological parameters analyzed in shrimp administered with 4 mg of dried algae (~ 6 × 107 cells)/1 g shrimp showed a high-level expression of lysosome (LSZ), anti-lipopolysaccharide factor (ALF), superoxide dismutase (SOD) and prophenoloxidase (proPO) compared to the control group. The result of oral administration experiments indicated that vaccinated shrimp survived up to 70% of the time as opposed to control group with 100% mortality. Taken together, the result indicated that recombinant C. reinhardtii expressing VP28 has a potential utility as an oral vaccine candidate against WSSV.

Syringomycin E (SRE) is a phytotoxin produced by Pseudomonas syringae pv syringae with high potential as a safe and effective therapy for the control of human fungal infections and as a preservative for the food industry. In this study, 27 strains of P. syringae pv syringae were isolated from plums, potatoes, apricots and peaches, of which P. syringae pv syringae 120 (PS120) showed the highest SRE production levels. Furthermore, random mutagenesis induced by ultraviolet (UV) radiation resulted in the generation of a P. syringae pv syringae mutant that produced 30% more SRE than the parental strain PS120. To elucidate molecular mechanism underlying the higher SRE production ability of the mutant strain, syrB1 and syrB2 genes, which are known to be involved in SRE production, were cloned and sequenced. The nucleotide and amino acid sequences analysis showed that UV radiation induced numerous mutations at the AMP binding site on adenylation domain of syrB1, while no mutation was detected in syrB2 gene. Real-time polymerase chain reaction (PCR) results showed that expression of syrB1 gene in mutant strain was six-fold higher than that of PS120 strain. Taken together, these results suggest that the mutations at AMP binding site and overexpression of syrB1 were responsible for increased biosynthesis of SRE in P. syringae pv syringae. Key words: Antifungal protein, syringomycin E, UV mutagenesis, Pseudomonas syringae pv syringae, syrB1.

We studied the prevalence and distribution of seven honey bee viruses, namely: acute bee paralysis virus (ABPV); cloudy wing virus (CWV); Israeli acute paralysis virus (IAPV); Kashmir bee virus (KBV); sacbrood virus (SBV); black queen cell virus (BQCV); and deformed wing virus (DWV), in healthy colonies from ten provinces in Vietnam. Colonies from each apiary were randomly selected to check viral infection. To confirm virus infection, samples were tested by Reverse Transcription Polymerase Chain Reaction using specific primer pairs. The positive products were sequenced and compared with the reference sequences using Basic Local Alignment Search Tool for molecular confirmation. In 360 Apis cerana samples, we found that the most prevalent virus was SBV (in 18.33% of samples), followed by BQCV (6.11%) and DWV (3.33%). The other four viruses, ABPV, CWV, IAPV, and KBV, were not detected in any sample. Infection rates were higher in adult bees than in larvae. The prevalences of SBV, BQCV, and DWV were 25.00, 10...

The isolation, identification and characterization of a novel huperzine A (HupA)-producing fungal strain Rsp5.2 isolated from Huperzia serrata (Thunb. ex Murray) Trev. in Vietnam. The fifty-eight endophytic fungi were recovered from roots of natural H. serrata in Lao Cai province of northern Vietnam and screened for HupA-producing by thin-layer chromatography (TLC). The only one of the 58 strains, Rsp5.2, could produce HupA. The amount of HupA produced by Rsp5.2 was quantified to be 19.45 µg g−1 dried mycelium by high-performance liquid chromatography (HPLC). Acetylcholine esterase (AchE) inhibition (IC50) of the crude HupA extract from Rsp5.2 fermentation broth was 2.849 ± 0.0026 µg mL−1. The fungus was identified as Fusarium sp. Rsp5.2 by morphological characteristics and Internal Transcribed Spacer (ITS) sequences. This is the first report of Fusarium sp. as a HupA-producing endophyte isolated from H. serrata.

Background Invasive meningococcal disease (IMD) persists in military units in Vietnam despite the availability of antibiotics and vaccines. A hindrance to reducing the incidence of IMD in Vietnam is a lack of molecular data from isolates of the causative agent, Neisseria meningitidis from this country. Here, we characterized key genetic and epidemiological features of an invasive N. meningitidis isolate from a military unit in Vietnam using whole-genome sequencing. Methods Neisseria meningitidis was isolated from a conscript admitted for meningitis and tested against seven antibiotics. DNA from the isolate was extracted and sequenced using the Illumina HiSeq platform. Denovo assembly and scaffolding were performed to construct a draft genome assembly, from which genes were predicted and functionally annotated. Genome analysis included epidemiological characterization, genomic composition and identification of antibiotic resistance genes. Results Susceptibility testing of the isolate showed high levels of resistance to chloramphenicol and diminished susceptibility to ampicillin and rifampicin. A draft genome of ~ 2.1 Mb was assembled, containing 2451 protein coding sequences, 49 tRNAs and 3 rRNAs. Fifteen coding sequences sharing ≥ 84% identity with known antibiotic resistance genes were identified. Genome analysis revealed abundant repetitive DNAs and two prophages. Epidemiological typing revealed newly described sequence type, antigenic finetype and Bexsero® Antigen Sequence Typing (BAST). The BAST profile showed no coverage by either Bexsero® or Trumenba®. Conclusions Our results present the first genome assembly of an invasive N. meningitidis isolate from a military unit in Vietnam. This study illustrates the usefulness of whole genome sequencing (WGS) analysis for epidemiological and antibiotic resistance studies and surveillance of IMD in Vietnam.