This study presents the effects of nanoscale zerovalent cobalt (NZVC) on the photosynthetic activity and expression of genes related to the photosynthetic apparatus as well as the activity of antioxidant enzymes in soybean (Glycine max L. Merr). Treatment of soybean seeds with NZVC solution (at concentrations of 0.17; 0.33 and 100 mg/kg seed) has increased the efficiency of light energy absorbed by photosystem II, improved photosynthetic efficiency, and maintained the function of photosynthetic apparatus when plant growth is reduced by enhancing the value of photosynthetic parameters (Fo, Fm, Fv/Fm, ETR, FPSII) compared with the control. The expression of genes involved in photosynthesis in soybean leaves was changed by growth time and NZVC treatment concentration. The psaA, Lhca, psbA, and psbB genes had increased expression levels at 17 and 32 days after sowing, then decreased at 70 days after sowing. The expression of the psbE, and Cyt b6f genes was greater than the control during the growth period. Treatment of soybean seeds with high concentrations of NZVC (0.33 and 100 mg/kg seed) did not negatively affect the photosynthetic function of soybean plants. The activity of nitrate and nitrite reductases and antioxidant enzymes including superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase of cobalt-treated plants were better than those of the control. This is a defense mechanism of plants to minimize the harmful effects of these stresses. This result has elucidated the mechanism of increasing the yield of soybean when its seeds were treated with NZVC.

Background: Haematococcus pluvialis, a green microalga, is a rich source of natural astaxanthin and a potent antioxidant with high commercial value. This study investigates the biological characteristics and potential of H. pluvialis HB isolated from Hoa Binh, Vietnam, for growth and astaxanthin accumulation using a two-phase culture method. Methods: H. pluvialis HB was cultured in a C/RM medium at 25 °C, and morphological characteristics were examined. NMR spectroscopy was used to determine the structure of the astaxanthin, which was extracted using the Soxhlet method. Results: After 22 days, the highest cell density (4.96 × 106 cells mL−1) was achieved under optimized light and ultraviolet conditions. Nutrient deprivation followed by bicarbonate supplementation resulted in a maximal astaxanthin accumulation of 48.8 mg g−1 dry cell weight within two days. The extracted astaxanthin demonstrated potent antioxidant activity (IC50: 3.74 mg mL−1) compared to ascorbic acid (IC50: 18.53 µg mL−1) and exhibited strong acetylcholinesterase inhibition (IC50: 297.99 µg mL−1). It also showed neuroprotective effects against H2O2 and amyloid beta-induced neurotoxicity in C6 cells. Conclusions: This study highlights H. pluvialis HB as a promising source for large-scale astaxanthin production with potential applications in neuroprotective health products.

Fucoxanthin extracted and purified from Vietnamese Sargassum oligocystum Montagne, 1845 exhibits various biological activities. In this study, the ability of fucoxanthin to inhibit acetylcholinesterase (AChE), the antioxidant activities, and the expression of antioxidant enzymes were investigated. Fucoxanthin isolated from Vietnamese S. oligocystum showed no cytotoxic effects; moreover, it exhibited AChE inhibitory activity (with an IC50 value of 130.12 ± 6.65 μg mL−1) and antioxidant activity (with an IC50 value of 3.42 ± 0.15 mg mL−1). At concentrations of 50 and 100 µg mL−1, fucoxanthin provided protection against amyloid β-protein fragment 25–35-induced neurotoxicity in a C6 neuronal cell line, and the survival of C6 cells was higher than 81.01% and 80.98%, respectively, compared to the control group (59%). Moreover, antioxidant enzyme activity and quantitative PCR analysis suggested that the neuroprotective effect of fucoxanthin resulted from regulation of the gene expression of antioxidant enzymes (CAT and GPx) and ER pathways (caspase-3 and Bax), as well as the promotion of expression of genes involved in PI3K/Akt signaling (GSK-3β), autophagy (p62 and ATG5), and the biosynthesis of ACh (VAChT and ChAT). Therefore, fucoxanthin extracted from the seaweed S. oligocystum in Vietnam is a potential feedstock source for the production of health foods that exert neuroprotective effects.

Fucoxanthin belonging to the carotenoid family has different bioactive properties as anti-oxidant, anti-obesity, anti-diabetic, and anti-cancer effects. This study presents the results of the extraction and purification of fucoxanthin from Sargassum olygocystum Montagne, 1845 using thin-layer chromatography, column chromatography, and high-performance liquid chromatography. Furthermore, this study demonstrated the antioxidant activities, expression of antioxidant enzymes, and inhibition of acetylcholinesterase (AChE) of fucoxanthin. The chemical structure, molecular formula (C 42 H 58 O 6 ), and molecular weight (658) of fucoxanthin were determined by nuclear magnetic resonance spectroscopy. Fucoxanthin isolated from S. olygocystum showed no cytotoxic effects, moreover, it showed potent antioxidant activity as assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method (with an IC 50 value of 3.42 ± 0.15 mg mL − 1 ), and AchE inhibitory activity (with an IC 50 value of 130.12 ± 6.65 µg mL − 1 ). At concentrations of 50 and 100 µg mL − 1 , fucoxanthin protected against amyloid β-protein fragment 25–35 - induced neurotoxicity on the C6 neuronal cell line with the survival of C6 cells higher than 81.01 and 80.98%, respectively, compared to the control group (59%). Moreover, antioxidant enzyme activity and quantitative PCR analysis revealed that the neuroprotective effect of fucoxanthin, was possibly due to not only regulation of gene expression of antioxidant enzyme (CAT and GPx), ER pathway (caspase-3 and Bax) but also promoting expression of genes involved in PI3K/Akt signaling (GSK-3β), autophagy (p62 and ATG5) and the biosynthesis of ACh (VAChT and ChAT). Therefore, fucoxanthin extracted from the Sargassum olygocystum is a potential feedstock source for the production of health foods with neuroprotective effects.

In this study, marine microalgal communities in 12 islands belonging to the sea water region of Truong Sa Islands (Spratly Islands), Vietnam in May-June and October-November 2021 was studied. There were 305 species of marine microalgae belonging to 7 phyla were identified in 12 islands in this sea water region of Truong Sa Islands (Spratly Islands) in 2021 in which with 39 dominant species, highest species number of 147 in Central (London) Reef (D1) and the lowest species number of 15 in Ambonya Cay (D4) were detected. Up to 2021, in the sea water region of the Truong Sa Islands (Spratly Islands), 14 genera of toxic harmful algae have appeared. The average value of biodiversity index (H') and the diversity value index (Dv) in all 12 studied islands in the Truong Sa Islands (Spratly Islands) in 2021 is 3.61±0.40 and 3.43±0.39, respectively, showing that the diversity of marine microalgae of this sea water region is rich and the quality of its sea water is generally good. It has been determined that two main factors NO3- and oil content, followed by DO, salinity, temperature and Hg content in seawater were affected the density of marine microalgal cells in the sea water of Truong Sa Islands (Spratly Islands) in 2021. In which, the marine microalgal cell density has a negative correlation with temperature, salinity, NO3- and Hg content of seawater and has a positive correlation with DO parameter was discovered.

Aurantiochytrium is a heterotrophic marine microalga that has potential industrial applications. The main objectives of this study were to isolate an Aurantiochytrium strain from Sand Cay (Son Ca) Island, Vietnam, optimize its culture conditions, determine its nutritional composition, extract polyunsaturated fatty acids (PUFAs) in the free (FFA) and the alkyl ester (FAAE) forms, and evaluate the antioxidation and neuroprotection properties of the PUFAs. Aurantiochytrium sp. SC145 can be grown stably under laboratory conditions. Its culture conditions were optimized for a dry cell weight (DCW) of 31.18 g/L, with total lipids comprising 25.29%, proteins 7.93%, carbohydrates 15.21%, and carotenoid at 143.67 µg/L of DCW. The FAAEs and FFAs extracted from Aurantiochytrium sp. SC145 were rich in omega 3–6–9 fatty acids (40.73% and 44.00% of total fatty acids, respectively). No acute or subchronic oral toxicity was determined in mice fed with the PUFAs in FFA or FAAE forms at different doses over 90 days. Furthermore, the PUFAs in the FFA or FAAE forms and their main constituents of EPA, DHA, and ALA showed antioxidant and AChE inhibitory properties and neuroprotective activities against damage caused by H2O2- and amyloid-ß protein fragment 25–35 (Aβ25-35)-induced C6 cells. These data suggest that PUFAs extracted from Aurantiochytrium sp. SC145 may be a potential therapeutic target for the treatment of neurodegenerative disorders.

Currently, nearly 36.5 million people live with Alzheimer’s disease worldwide, and acetylcholinesterase inhibition is considered the main treatment strategy against it. Seaweeds (or macroalgae) are a natural source of high-value bioactive compounds and have great potential in the production of health foods/foods, pharmaceuticals, cosmetics, animal feeds, biofertilizers, and biofuels. The most studied and applied seaweed species include red seaweed (Rhodophyta), green seaweed (Chlorophyta) and brown seaweed (Phaeophyta). This study aimed to evaluate the antioxidant and neuroprotective activities of extracts/substances isolated with solvents including ethanol 75o and 96o, water, n-hexane, ethyl acetate under normal and ultrasonic conditions (power 80W, frequency 4.7 kHz and for 1 hour) from 5 economically important seaweed species belonging to genera Caulerpa, Sargassum, Gracilaria, Ulva and Kappaphycus collected in Ninh Thuan and Khanh Hoa provinces, Vietnam. The results have shown that 05/30 extracts and substances (including SaE96S, SaH, SaHW, SaEA and fucosterol) isolated from five seaweed species exhibited high antioxidant activity through the free radical screening method using 2,2-diphenyl-1-picrylhydrazyl (DPPH) (with EC50 values < 5 mg/mL for extracts and EC50 value < 2 mM for substance) in comparison with positive control ascorbic acid (EC50 = 0.015 mg/mL); acetylcholinesterase inhibitory activity using acetylcholinesterase inhibitor screening KIT (with IC50 values of < 200 µg/mL for both extracts and substances), compared with positive control galantamine (with IC50 value of 52,8 µg/mL). The extracts/substances were able to protect the cell against cytotoxity in the C6 alzheimer’s disease cell model induced by amyloid beta-protein fragment (Aβ25-35). The results achieved from this research have proven that the extracts/substances isolated from seaweed species were a potential source of medicinal agents for the prevention and treatment of alzheimer’s disease.

Marine microalgae are an important source of raw materials for the extraction of highly bioactive substances for humans and domestic animals. In this study, the biological characteristics and the ability to grow biomass of green marine microalga of Dunaliella tertiolecta NY isolated from seawater of Namyit Island belonging to Spratly Islands, Vietnam (in May-June, 2021) was presented. Scientific name of the strain Dunaliella tertiolecta NY based on morphological characteristics and analysis of the sequence of rDNA ITS1-5.8S-ITS2 region was identified (with accession number of this gene region of this strain was supplied on the GenBank is OM 101011). At the best conditions for the growth (i.e. Walne medium, initial cell density of 2.0 x 106 cells/mL, growth temperature of 30oC, light intensity of 60 - 100 µmol/m2s, pH 7, salinity of 30-40‰), highest NY strain cell density of 8.63 x 106 cells/mL was obtained after 15 days of culture. The microalga D. tertiolecta NY was also successfully cultured on a pilot scale in the plastic bottles 10 L and closed photobioreactors 20 - 100 L resulting in a high biomass productivity of 285 mg/L/day and a biomass rich in polyunsaturated fatty acids such as gamma - linolenic acid (C18:3 ω-6; 5.07±0.59 % of total fatty acid - TFA), alpha - linolenic acid (ALA, C18:3 ω-3, 61.79±1.98 % of TFA) and stearidonic acid (SDA; C18: 4 ω-3, 1.59±0.65 % of TFA) qualified for the extraction of value bioactive compounds.

The application of nanotechnology in agriculture is a promising way to increase crop production and yield, reduce the amount of fertilizer, increase the storage time of the productions and protect the environmental sustainability. Soybean is one of the four important crops of Vietnam's agriculture and a source of food for humans and domestic animals. In this study, the effect of zerovalent cobalt nanoparticles with different concentrations (0; 0.17; 0.33 and 100 mg/kg seed) on chlorophyll a content and photosynthesis parameters of soybean plant Glycine max (L). Merr. DT96 which was planted in the autumn-winter crop in Xuan Hoa, Phuc Yen, Vinh Phuc were carried out. The obtained results showed that zerovalent cobalt nanoparticles had a positive effect on the photosynthetic parameters of soybean plants. At the used concentration of 0.33 mg cobalt/kg seed, the chlorophyll a content and photosynthetic parameters of soybean were the highest and there was a statistically significant difference compared with control. The chlorophyll a content tends to increase gradually and reaches the maximum value of 1.77 ± 0.05 mg/g fresh leaves after 40 days of sowing. The parameters related to chlorophyll fluorescence such as Fo (initial fluorescence), Fm (maximal fluorescence), Fv/Fm (maximal photochemical efficiency), effective quantum yield of photosystem II (FPSII), photosynthetic electron transport rate (ETR), Pn (net photosynthetic rate) of soybean seedlings which were treated by cobalt nanoparticles were higher than the control (except at the concentration of 100 mg/kg). The soybean seeds treated by cobalt nanoparticles had increased the chlorophyll a content of leaves and photosynthetic efficiency, leading to improve productivity of soybean.

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 Chlillnydomonas 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 (similar to 6 x 10(7) 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.

Thraustochytrium is a heterotrophic marine microalgae genus belonging to the Labyrinthula class, Thraustochytriaceae (Thraustochytrids) family. Recently, studied results have showed that some species/strains of Thraustochytrium genus are potential candidates to produce biomass rich in lipid containing high polyunsaturated fatty acid (PUFAs), especially docosahexaenoic (DHA C22: 6 ω-3), carotenoid, extracellular polysaccharides (EPSs) and enzymes which play a crucial role in human health. Therefore, throughout many decades, numerous studies have been conducted in exploiting bioactive compounds, especially PUFAs. Biomass and PUFAs yield of some strains Thraustochytrium spp. depend on environmental conditions. In this paper, the results on the effects of different culture conditions on the growth of Thraustochytrium aureum BT6 (isolated from coastal regions of Binh Thuan in 2010) in 500 mL erlenmeyer flask and 30 L fermentors is presented. Suitable conditions for the growth of strain BT6 were: Bajpai medium, 2% glucose, 0.5% yeast extract, temperature of 20−28 oC, salt concentration 0.5%; and initial algal cell concentration of 2 g/L. The dry biomass, lipid and DHA contents of strain BT6 in 500 mL erlenmeyer flasks and 30 L fermentor reached the highest levels of 8.56 ± 0.12 and 6.92 ± 0.27 g/L, 18.36 ± 1.15 and 5.50 ± 0.133% DCW, 2.00 ± 0.05 and 0.14 ± 0.01% DCW, respectively, after 4 days of cultivation. Carotenoid content in flask and 30L fermentor achieved 44.45 ± 1.4 and 28.84 ± 1.12 mg/kg DCW, respectively after 4 days of cultivation. Obtained results have indicated that the algae biomass met the requirements in orientation to exploit valuable bioactive compounds.

This study investigated the biomass production process from the laboratory to the pilot scale in order to use the nutrient-rich biomass of the diatom Thalassiosira weissflogii as live feed for white-leg shrimp ( Litopenaeus vannamei ) at larval stages (zoeal, mysis, and postlarval) and in commercial production in hatcheries in Vietnam. Our results showed that T . weissflogii was successfully cultured in 1–2 L Erlenmeyer flasks, 0.2–3.5 m 3 composite tanks, and 6.5 m 3 tubular photobioreactors, with the highest cell density of 1.6 × 10 6 cells mL −1 reached after 6 days of culture. Under optimal culture conditions, the protein, lipid, and carbohydrate contents in this algal biomass were 13.2%, 20.0%, and 10.0% of dry cell weight, respectively. The fatty acid composition contains high amount of palmitic acid (C16:0, 43.11% of total fatty acid), and polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA, C20:5ω-3), approximated 16.5% of total fatty acid. In a 50 L larval rearing tank, at the optimal stocking density of 125 nauplii L −1 , the survival percentage (75.55%), the total body length (from 5.376 ± 0.007 to 10.860 ± 0.030 mm), and weight (at from PL 1 to PL 12 stages) (from 0.145 ± 0.002 to 1.158 ± 0.005 g) of the white-leg shrimp larvae reached the highest values but the metamorphosis time (234 h) was shortest compared with the other stocking densities. Further, adding living T . weissflogii biomass to the diet of white-leg shrimp larvae at the nauplii 6 stage led to an increase in the body length, weight, and survival percentage of white-leg shrimp larvae of 21.17%, 35.7%, and 33% higher compared with those of larvae fed the control diet (without the addition of T . weissflogii ), respectively. At the same time, the metamorphosis time of larvae (from Z 1 to PL 1 ) decreased by 4 h compared to the control group. In intensive ponds (area of 6400 m 2 pond −1 ), using seed stocks at the postlarvae 12 stage that had been fed T . weissflogii , the final weight, yield, and survival percentage of the shrimp were increased by 7.3%, 14.2%, and 16.3%, respectively, compared with those of the control group. There were no statistically significant differences in the protein and carbohydrate contents in the shrimp flesh among the experimental and control group ( p > 0.05). The lipid, omega-3, omega-6, and omega-9 fatty acid contents of shrimp flesh in experiment formula (per 100 g shrimp) were 1.21 g, 72.9 mg, 114 mg, and 86.1 mg, 11%, 29%, 21.6%, and 17.7% higher than that those in control, respectively. The obtained results show the great potential of using T . weissflogii as live feed on white-leg shrimp farms in Vietnam.

Spirulina cyanobacteria have been widely cultivated to exploit products such as crude protein, vitamins, phycocyanin pigment... with high nutritional and pharmacological values. However, the commercialization of these products is still a challenging issue due to high biomass cost, which is mainly caused by expensive nutrients in the culture medium. In this study, from 11 freshwater S. platensis strains, by culture screening, we found 7 strains being capable of profitable growth on inexpensive seawater with salinity ranging from 5 - 30‰, and selected ST strain as the potential strain for further study. Natural seawater must be pretreated to remove ions that easily cause precipitation of nutrients in the culture medium such as Mg2+, Ca2+, SO42-… before using. The ST strain showed the best growth in the natural seawater medium with 30‰ salinity containing 3 g/L NaNO3, 0.5 g/L K2HPO4, 0.05 g/L FeSO4. This strain reached the highest biomass yield at 0.487 g/L and the specific growth rate (µ) of 0.12 x day-1; protein and phycocyanin contents reached 48.6% and 127 mg/g of dry biomass, respectively. There was no difference in the mentioned above values with biological statistical significance between this medium and SOT medium in distilled water. The ST strain biomass was qualified to be used for the production of functional foods. Results of this study provided scientific basis for the use of marine and brackish waters to produce biomass of this highly economic cyanobacterium.

Microalgae are known to be a nutrient-rich feed source for many aquatic animals. It is also an important raw material source to exploit high biological activity substances for humans. This is the first study on biological characteristics and algae biomass production from the green microalgae Nannochloris atomus being carried out in Vietnam. In this study, scientific name of the strain N. atomus NT12 based on morphological characteristics and 18S rRNA gene sequence (with accession number MW007766 on the GenBank) was identified. At the best conditions for the growth (i.e. Walne medium, 3 x 106 cells/mL initial cell density, 25 -30oC growth temperature, 60 - 100 µmol/m2s light intensity, pH 7, 30‰ salinity), highest NT12 strain cell density of 30 x 106 cells/mL was obtained after 30 days of culture. The microalgae N. atomus NT12 was also successfully cultured on a pilot scale in the plastic bottle 10 L and closed photobioreactors 20 – 50 L resulting in a high biomass productivity of 209 mg/L/day and a biomass rich in polyunsaturated fatty acids such as oleic acid (C18:1n-9), linoleic acid (C18:2n-6) and α-linolenic acid (C18:3n-3) qualified for the purpose of extraction of value bioactive compounds.

Astaxanthin (3,3′-dihydroxy-β,β-carotene-4,4-dione) is a known to be valuable carotenoid with strong antioxidant, which has been extensively used in various industries (such as aquaculture, nutraceutical, pharmaceutical, and food). There have been two major sources of astaxanthin: chemical (synthetic) and biological (natural) source. In nature, astaxanthin can be synthesized by plants, crustaceans by-product, bacteria, a few fungi, and green algae, in which microalga Haematococcus pluvialis is an appropriate source of natural astaxanthin exploitation that seems to be gaining potential in the market. Technology for natural astaxanthin production is an expensive process, depending on each producer, in each country. Therefore, continuous efforts were necessary to improve the different culture systems (photobioreactor (PBR) and open pond), culture models (heterotrophic and photoautotrophic), culture methods, harvesting, and astaxanthin extraction processes for enhanced production of astaxanthin-rich biomass and cost reduction in large-scale culture. In this chapter, we summarized about astaxanthin production and technology for its production in Vietnam and other Asian countries to get a more general view of this valuable product.

Green macroalgae have gained attention as promising renewable sources for biorefining. Despite the wide potential availability of green macroalgae, their utilization has been limited to ethanol production, hindering their further application. In this study, we report that a bacterium, Halomonas sp. strain BL6 (isolated from a mangrove forest in Bach Long, Nam Dinh Province, Vietnam), produces pyruvate from a saccharified solution of the green seaweed Ulva reticulata and secretes it into the medium. Pyruvate, an important α-oxocarboxylic acid, plays a central role in energy and carbon metabolism in living organisms and is used mainly for the synthesis of various chemicals and polymers or as an ingredient or additive in food, cosmetics, and pharmaceuticals. To investigate the possibility of using U. reticulata from the seashore of Vietnam as biomass feedstock, the chemical composition and saccharification yield of this seaweed were studied. Dry biomass of U. reticulata was found to contain 65.5% carbohydrate, 10.3% protein, 1.8% lipid, and 10.6% ash. Reducing sugar content reached 608.79 mg g−1 of biomass after pretreatment with diluted acid and 24 h of incubation with 50 IU g−1 Viscozyme L. The resulting sugars were fermented by Halomonas sp. strain BL6 to produce pyruvate, and the maximal pyruvate concentration reached 55.23 g L−1 after 72 h of cultivation. This study is the first to report the production of valuable compounds other than bioethanol products, such as pyruvate, from U. reticulata hydrolysate by a Halomonas strain.

In microalga culturing, one important topic is finding methods of increasing the productivity of algal biomass grown on a large scale. The cultured microalgal biomass must be inexpensive to produce, but rich in the bioactive substances, for use as raw materials for many different purposes, such as functional foods, drugs, pharmaceuticals, cosmetics, and biofuels. Here we present results about the effects of ferulic acid extracted from rice bran on the growth, photosynthetic activity, and valuable substance content of the eustigmatophyte Nannochloropsis oculata. The results showed that ferulic acid is a growth promoter that increases N. oculata biomass. Addition of 100 mg L−1 ferulic acid to the culture medium led to an increase in cell density and specific growth rate (μ; day−1) of N. oculata. These values were 2.52 and 2.02 times higher, respectively, than those in the control group (without the addition of ferulic acid). Moreover, photosynthetic parameters, lipid and carbohydrate contents, and intracellular pigment contents (such as chlorophyll a and carotenoids) in the treated algal biomass tended to be higher than those in the control treatment. This study provides an initial scientific basis for the improvement of algal biomass productivity and metabolite production in safe and sustainable ways with naturally derived substances.

Halophilic bacteria are receiving increasing attention for industrial chemical production processes due to their unique properties. Herein, an alkaliphilic and halophilic bacterium was isolated from a commercial Spirulina culture at Nghe An province in Vietnam and found to secrete pyruvate. Pyruvate is widely used as a starting material in the industrial biosynthesis of pharmaceuticals, and is employed for production of crop protection agents, polymers, cosmetics, and food additives. Phenotypic and chemotaxonomic characterization, and the 16S rRNA gene sequence homology with Halomonas hydrothermalis strain DSM 15,725 (99.2%) predicted that the strain belongs to the Halomonas genus, thus we named this strain as H. hydrothermalis strain C22. We investigated the biocharacteristics and capacity of strain C22 and determined the draft genome sequence comprising 3,934,166 bp with a G + C content of 60.2% encoding 3,668 proteins, 58 tRNAs, 9 rRNAs, and 1 tmRNA. Maximal pyruvate secretion reached 51.1 g/l after 84 h of cultivation. The results will facilitate future studies on the genetic and metabolic diversity of halophilic bacteria and expand our understanding of important bioprocesses in this microorganism.

Photosynthesis is an important physiological process in plants. It plays a crucial role in plant growth and development. In this study, we investigated the impact of zerovalent cobalt nanoparticles on the photosynthesis and expressing of gene involving in this process in leave of soybean Glycine max (L) Merr “DT26” at different growth stages. The results showed that treatment of zerovalent cobalt nanoparticles made in Vietnam and USA (with two doses of 0.17 and 16.67 mg/kg of soybean seed) enhanced the photosynthesis of soybean by increasing the content of chlorophyll a and the ratio of Fv/Fm compared with the control (without treatment of zerovalent cobalt nanoparticles). These values tended to increase and reached the maximum value at 40 days and then decreased in at 70 days. The expression level of photosynthesis-related genes of soybean leaves also changed depending on the soybean’s growth stage and concentration of zerovalent cobalt nanoparticles being treated. The genes psaA, Lhca, psaB, Cytb6f (belonging to photosystem I) and psbA, psbB, psbC, psbD, psbE (belonging to photosystem II) in the experimental fomulas were higher expressed than that in control group at 20 and 70 days. However, at 40 days, the expression levels of these genes were significantly different. Obtained results supplied the basis for understanding the active mechanism of the above genes to control/regulates photosynthetic activity of plants with and without the presence of zerovalent cobalt nanoparticles as well as under stress conditions.

Photosynthesis is an important physiological process in plants. It plays a crucial role in plant growth and development. In this study, we investigated the impact of zerovalent cobalt nanoparticles on the photosynthesis and expressing of gene involving in this process in leave of soybean Glycine max (L.) Merr “DT26” at different growth stages. The results showed that treatment of zerovalent cobalt nanoparticles made in Vietnam and USA (with two doses of 0.17 and 16.67 mg/kg of soybean seed) enhanced the photosynthesis of soybean by increasing the content of chlorophyll a and the ratio of Fv/Fm compared with the control (without treatment of zerovalent cobalt nanoparticles). These values tended to increase and reached the maximum value at 40 days and then decreased in at 70 days. The expression level of photosynthesis-related genes of soybean leaves also changed depending on the soybean‟s growth stage and concentration of zerovalent cobalt nanoparticles being treated. The genes psaA, Lhca, psaB, Cytb6f (belonging to photosystem I) and psbA, psbB, psbC, psbD, psbE (belonging to photosystem II) in the experimental fomulas were higher expressed than that in control group at 20 and 70 days. However, at 40 days, the expression levels of these genes were significantly different. Obtained results supplied the basis for understanding the active mechanism of the above genes to control/regulates photosynthetic activity of plants with and without the presence of zerovalent cobalt nanoparticles as well as under stress conditions.