Vietnam Academy of Science and Technology: Journals Online
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Optimization of L-asparaginase production from Escherichia coli using response surface methodology
Get PDFAmong the antitumor drugs, bacterial enzyme L-asparaginase has been employed as the most effective chemotherapeutic agent in pediatric oncotherapy especially for acute lymphoblastic leukemia. In previous study, the L-asparaginase from Erwinia chrysanthermy was expressed in Escherichia coli BL21(DE3). The recombinant L-asparaginase was produced from recombinant E.coli BL21(DE3) under different cultivation conditions (inducer concentration, inoculum concentration and KH2PO4 concentration). The optimized conditions by response surface methodology using face centered central composite design. The analysis of variance coupled with larger value of R2 (0.9) showed that the quadratic model used for the prediction was highly significant (p 0.05). Under the optimized conditions, the model produced L-asparaginase activity of 123.74 U/ml at 1.03 mM IPTG, 3% (v/v) inoculum and 0.5% (w/v) KH2PO4. Recombinant protein was purified by two step using gel filtration and DEAE chromatography. The purified L-asparaginase had a molecular mass of 37 kDa with specific activity of 462 U/mg and identified by MALDI-TOF mass spectrometry. Results of MALDI-TOF analysis confirmed that recombinant protein was L-asparaginase II. Recombinant L-asparaginase has antiproliferative activity with K562 cell line. In conclusion, this study has innovatively developed cultivation conditions for better production of recombinant L-asparaginase in shake flask culture
Optimization of culture conditions of Streptomyces antibioticus strain 1083 to improve the antimicrobial activity against Aeromonas hydrophila
Get PDFFish is a healthy, high protein and low fat food that encourages the health and growth of people, especially children. However, in fact fish is very sensitive to many diseases which affects the productivity and quality of fish. Therefore, identifying the cause of the diseases and finding preventive measures become an urgent task today. In the previous study, we isolated Streptomyces antibioticus strain 1083 that has the ability to antagonize Aeromonas hydrophila - a pathogenic bacterium in fish. Based on the obtained results, we continue to perform this study to determine optimal conditions for the culture of S. antibioticus strain 1083 in order to produce antimicrobial compounds against A. hydrophila. The production of antagonists by the strain 1083 was optimized by controlling the condition of different inoculations such as media, pH, temperature and incubation period. The results indicated that International Streptomyces Project 2 (ISP2) was the best medium for S. antibioticus strain 1083 to produce the highest antimicrobial activity against A. hydrophila with 32 mm in diameter of inhibited zone. The actinomycete strain 1083 could express the maximum antimicrobial activity when they were incubated in shaker incubator (200rpm) at 40oC with pH8 in 8 days. The ability of the actinomycete strain in antagonism against A. hydrophila was evaluated by adding different culture medium volume of S. antibioticus strain 1083. With adding 10% cultured solution volume of S. antibioticus strain 1083 into the culture medium of A. hydrophila, after 1 day of inoculation the number of pathogenic bacteria cells were completely eliminated
Screening and identification of actinomycetes having antimicrobial activity isolated from marine organisms and sediment samples in Ly Son island, Quang Ngai
No full textThe discovery of bioactive compounds from marine microorganisms for drug development has been currently widely studied. In which marine actinomycetes are highlighted as a potential source in finding antibiotics as well as substances with biological activity in general. The objective of this study is to isolate and screen the actinomycetes strains with antibacterial activity from the marine environment. Sixty one actinomycetes were isolated from 80 samples of marine organisms and sediments collected from Ly Son Island, Quang Ngai. The strains were fermented in the A1 medium and the culture broths were extracted by ethyl acetate and vacuum rotary evaporation to produce crude extracts. Antimicrobial activity of the extracts were carried out on 7 strains of tested microorganisms, including three strains of Gram-negative bacteria (Escherichia coli ATCC25922, Pseudomonas aeruginosa ATCC27853, Salmonella enterica ATCC13076), three Gram-positive strains (Enterococcus faecalis ATCC29212, Staphylococus aureus ATCC25923, Bacillus cereus ATCC 13245), and yeast Candida albicans ATCC10231. The screening results showed that three strains with the highest antimicrobial activity (G330, G336 and G361) were capable of inhibiting 5 of the 7 tested microorganisms with Minimum Inhibitory Concentration (MIC) values ranging from 4 to 256 μg/mL, depending on each tested strain. Specifically, all three strains inhibited C. albicans ATCC10231 and three Gram-positive strains (E. faecalis ATCC29212, S. aureus ATCC25923, B. cereus ATCC 13245). In addition, G330 and G336 also showed the inhibitory activity to Gram negative strain S. enterica ATCC13076 with value of 256 µg/mL, G361 has a good inhibitory ability for E. coli ATCC25922 with MIC value of 8 µg/mL. The strains were identified by morphological and the 16S rRNA gene sequences. The results showed that 16S rRNA sequences of the strains had over 99% similarity to the 16S rRNA sequences on the GeneBank database, strains G336 and G361 belonged to the genus Salinispora, whereas strain G330 belonged to the genus Streptomyces. These results showed that marine environment has a great potential in solation of actinomycetes strains for the search for antibacterial substances as well as other biologically active compounds
NUTRIENT RECOVERY AND POLLUTANT REMOVAL FROM PIGGERY WASTEWATER BY SPIRULINA CULTIVATION
Get PDFSpirulina is noticed for great applications on food supplements, animal feeds, pharmaceutical, cosmetics, biofuel, fertilizer, etc. Spirulina cultures in wastewaters could enhance the feasibility of commodities due to its ability to reduce the cost of biomass production and remove pollutants in wastewaters. This study investigates the effects of wastewater pretreatment using various aeration periods (i.e. from 3 to 7 days), the supplement of bicarbonate and N:P ratios on the growth of Spirulina sp. HH to produce protein-rich biomass. The work showed that Spirulina sp. had the ability to effectively remove ammonium, with the highest efficiencies up to 99.9 %. However, the high concentration of ammonium in wastewater, from 125 mg N/L upward, caused a decline in the growth rate of Spirulina. The growth and remediation potential of Spirulina sp. were in the best condition with the N:P ratio of the medium in the range of 19:1-22:1. This study suggested a procedure to cultivate Spirulina sp. in piggery wastewater and remove pollutants efficiently
Establishing an empirical equation for the relationship between total suspended solids and total phosphorus concentrations in the downstream Red river water
No full textRecently, the Asian rivers have faced the strong reduction of riverine total suspended solids (TSS) flux due to numerous dam/reservoir impoundment. The Red river system is a typical example of the Southeast Asian rivers that has been strongly impacted by reservoir impoundment in both China and Vietnam, especially in the recent period. It is known that the reduction in total suspended solids may lead to the decrease of some associated elements, including nutrients (N, P, Si) which may affect coastal ecosystems. In this paper, we establish the empirical relationship between total suspended solids and total phosphorus concentrations in water environment of the Red river in its downstream section from Hanoi city to the Ba Lat estuary based on the sampling campaigns conducted in the dry and wet seasons in 2017, 2018 and 2019. The results show a clear relationship with significant coefficient between total suspended solids and total phosphorus in the downstream Red river. It is expressed by a simple equation y = 0.0226x0.3867 where x and y stand for total suspended solids and total phosphorus concentrations (mg/l) respectively with the r2 value of 0.757. This equation enables a reasonable prediction of total phosphorus concentrations of the downstream Red river when the observed data of total suspended solids concentrations are available. Thus, this work opens up the way for further studies on the calculation of the total phosphorus over longer timescales using daily available total suspended solids values
Hydrophyte communities in the Tam Giang - Cau Hai lagoon
Get PDFThe Tam Giang - Cau Hai lagoon in Thua Thien-Hue province is the largest lagoon in South East Asia and also one of the places having the largest area of seagrass in Vietnam. The study results from 2009 to 2017 showed that 6 seagrasses species were identified (Halodule uninervis is a newly recorded species, however, Halophila minor is not recorded) and there were 8 freshwater grass species (with the exception of Potamogeton maackianus), with a total area of 2,840 ha. In particular, the area of seagrass has been recovering significantly from 1,000 hectares in 2009 to 2,037 hectares in 2017
Effect of mesh on CFD aerodynamic performances of a container ship
No full textIn this paper, a commercial CFD code, ANSYS-Fluent has been used to investigate the effect of mesh number generated in the computed domain on the CFD aerodynamic performances of a container ship. A full-scale model of the 1200TEU container ship has been chosen as a reference model in the computation. Five different mesh numbers for the same dimension domain have been used and the CFD aerodynamic performances of the above water surface hull of the ship have been shown. The obtained CFD results show a remarkable effect of mesh number on aerodynamic performances of the ship and the mesh convergence has been found. The study is an evidence to prove that the mesh number has affected the CFD results in general and the accuracy of the CFD aerodynamic performances in particular
Effects of stocking density on growth and survival of tilapia cultured in biofloc technology system in brackish water
Get PDFThis study examined the effect of stocking density on growth and survival of tilapia cultured in biofloc technology system. Three different stocking densities cultured in biofloc technology were 6 fish/m3, 8 fish/m3 and 10 fish/m3 for 86 days in triplicate for each treatment. The stocking density of the control lot was 3 fish/m3 cultured without biofloc technology. Initial stocking weight ranged from 2–3 g/fish. The water quality parameters were monitored and regulated in the suitable ranges for biofloc technology and for the growth and development of tilapia. The results showed that specific growth rate of fish cultured at a density of 6 fish/m3 was higher than that in the treatments of 8 fish/m3 and 10 fish/m3 with the average values of 5.72%; 5.62% and 5.43%, respectively, and the specific growth rate of fish in the control treatment was 5.71%. Daily growth rate of fish cultured at a density of 6 fish/m3 was higher than that cultured at densities of 8 fish/m3 and 10 fish/m3 with average values of 3.19 g/day, 2.98 g/day, and 2.55 g/day, respectively; and the daily growth rate of the control treatment was 3.27 g/day. Survival rate of tilapia cultured at densities of 6 fish/m3 and 8 fish/m3 was 100%, whereas survival rate of tilapia cultured at a density of 10 fish/m3 was 95.75%, and it was 88.9% for the control lot. The research results provide a scientific basis to propose tilapia culture technique in biofloc technology in brackish water, with the density of 6–8 fish/m3
Bacteria associated with soft coral from Mot island - Nha Trang bay and their antimicrobial activities
Get PDFMicrobial communities associated with invertebrates had been considered as a new source of bioactive compounds. The soft coral associated bacteria in Mot island, Nha Trang bay were isolated, extracted and assessed for antagonistic activity against human and coral pathogens, the strongly active strains were identified by 16S rRNA analysis. The soft coral associated bacterium SCN10 had abcd antibacterial pattern which was named for inhibition towards Bacillus subtilis (pattern a), Escherichia coli (pattern b), Salmonella typhimurium (pattern c) and Serratia marcescens (pattern d). It was the nearest strain to the well-known antibiotic producer Bacillus amyloliquefaciens with 99% sequence similarity. Whereas strain SCL19 had abde pattern which means inhibition of the growth of B. subtilis, E. coli, S. marcescens and Vibrio parahaemolyticus (pattern e). This strain SCL19 affiliated with Bacillus sp. strain A-3-23B with 99.8% identity. In addition to antimicrobial activity to the aforementioned tested bacteria, the isolate SCX15 also inhibited Vibrio alginolyticus (pattern f) and Candida albicans (pattern g), so this isolate possessed abcdefg antimicrobial pattern. The coral associated isolate SCX15 was identified as Bacillus velezensis with 99% sequence similarity. Among the 78 screened strains, 25 isolates possessed antibacterial activity against at least one of seven tested microorganisms and exhibited 12 different types of antimicrobial activities, suggesting that they can produce many different natural substances with antibacterial activity
AN EFFECTIVE REVERSIBLE DATA HIDING METHOD BASED ON PIXEL-VALUE-ORDERING
Get PDFThis paper presents a new effective reversible data hiding method based on pixel-value-ordering (iGePVO-K) which is improvement of a recent GePVO-K method that recently is considered as a PVO-used method having highest embedding capacity. In comparison with GePVO-K method, iGePVO-K has the following advantages. First, the embedding capacity of the new method is higher than that of GePVO-K method by using data embedding formulas reasonably and reducing the location map size. Second, for embedding data, in the new method, each pixel value is modified at most by one, while in GePVO-K method, each pixel value may be modified by two. In fact, in the GePVO-K method, the largest pixels are modified by two for embedding bits 1 and by one for bits 0. This is also true for the smallest pixels. Meanwhile, in the proposed method, the largest pixels are modified by one for embedding bits 1 and are unchanged if embedding bits 0. Therefore, the stego-image quality in proposed method is better than that in GePVO-K method. Theoretical analysis and experiment results show that the proposed method has higher embedding capacity and better stego image quality than GePVO-K method