Tryptone Concentration Research Articles

Fermentation optimization and metabolomic analysis of a Bacillus subtilis co-culture system for fengycin production from mixed sugars

Fengycin is a cyclic lipopeptide with multiple effects, including cell membrane disruption, induction of systemic resistance in plants, and plant growth promotion. This study used a co-culture system to produce fengycin in a sugar mixture fermentation medium simulating lignocellulosic hydrolysate. First, we compared the fengycin production profiles of the pure cultures and co-culture of three Bacillus subtilis, 168DSABA1, BSP003, and BSJ0232, in a sugar mixture fermentation medium. The co-culture system was then optimized (relative inoculation ratio, ratio of glucose to xylose in the sugar mixture, fermentation time, total carbon source concentration and tryptone concentration) using response surface methodology (RSM) based on single-factor experiments, which increased the fengycin titer of the co-culture system from 241.7 ± 12.0–575.5 ± 5.8 mg/L. Finally, metabolomics was used to analyze the reasons for the increase of fengycin production and the deficiencies of the system: Based on this a co-culture system containing four Bacillus subtilis (4BS) and a co-culture system containing five Bacillus subtilis (5BS) were constructed, which further increased the titer of fengycin to 650.2 ± 9.6 mg/L and 2396 ± 42 mg/L, respectively. The present study provides a reference or improving the industrial production of fengycin and the utilization of lignocellulosic hydrolysates.

The effect of tryptone and tomato juice addition on the growth performance of strawberry (Fragaria ananassa) explant under in vitro condition

Strawberries are a fruit commodity that has high economic value. The obstacle in strawberry production is the lack of high-quality seed availability with disease-free properties. Tissue culture offers a promising solution to increase both the quantity and quality of strawberry seeds. This study aims to assess the effect of different concentrations of tomato juice and tryptone on the growth of strawberry explants under in vitro growing condition. The research was conducted at the Plant Breeding Laboratory, Faculty of Agriculture, Universitas Jenderal Soedirman, from December 2022 to May 2023. The study employed a Completely Randomized Design (CRD) with two factors. The first factor was tomato juice (Z), consisting of Z0 = 0 mL/L, Z1 = 50 mL/L, Z2 = 100 mL/L. The second factor was tryptone (T), consisting of T0 = 0 g/L, T1 = 1 g/L, T2 = 2 g/L, T3 = 3 g/L. The addition of 50 mL/L tomato juice solely (T0Z1) resulted in the highest plant height, number of leaves, number of branches, and leaf width. Meanwhile, the addition of2 g/L tryptone solely showed the highest germination rate.

Enhanced excretion of recombinant cyclodextrin glucanotransferase and cell stability of immobilized recombinant Escherichia coli by reducing tryptone concentration

AbstractBACKGROUNDRecombinant protein excretion has become a mainstream strategy in reducing downstream processing costs. However, recombinant protein excretion is often bottlenecked by cell lysis and plasmid stability. In the present study, recombinant Escherichia coli cell immobilization was performed on a hollow fiber membrane. Tryptone concentration in the expression medium (Super Optimal Broth), which was used as a nitrogen source, was varied between 5 and 20 g L−1 to enhance the excretion of recombinant cyclodextrin glucanotransferase (CGTase), plasmid stability, and resistance of cell lysis.RESULTSThe immobilized cells with 5 g L−1 concentration of tryptone improved the plasmid stability with 119% improvement and 69% reduction of cell lysis without remarkably altering the excretion of CGTase compared with the tryptone concentration of 20 g L−1. The immobilized cells showed a 2‐fold increase in excretion of CGTase, a 45% reduction in cell lysis, and a 172% gain in plasmid stability in comparison with the free cells. Moreover, the doubling time increased to 58 and 5 h for the immobilized and free cells, respectively. The immobilized cells recorded 2301.62 U mL−1 of cumulative CGTase activity through seven fermentation cycles using the untreated membrane, marking their excellent reusability.CONCLUSIONThis new technique of recombinant protein expression utilizing an immobilized cell system under low tryptone concentration is an outstanding approach to improve recombinant CGTase excretion and plasmid stability with low cell lysis. © 2023 Society of Chemical Industry (SCI).

Lipase from Fusarium solani: optimization of culture conditions, biochemical properties, and production

A Plackett-Burman factorial design with 15 experiments was conducted to evaluate the influence of seven factors on lipases production by Fusarium solani. The factors investigated were peptone, tryptone, yeast extract, calcium chloride, potassium phosphate, magnesium sulfate, and copper sulphate. Five fixed variables (cotton oil, pH, temperature, agitation, and time) were maintained and as a response to the enzymatic activity. The concentration of tryptone, calcium chloride, and magnesium sulphate had a significant effect (p < 0.10) on lipase production and was studied consecutively through a complete DCCR (central rotational compound design), to optimize lipase production of the fungi F. solani. After optimization using DCCR, maximum lipolytic activities of 24.84 U/ml were obtained with the use of 10 g.L-1 tryptone, 3.50 g.L-1 calcium chloride and 0.50 g.L-1 magnesium sulfate, 1 g.L-1 potassium phosphate and 1% soybean oil. The statistical model showed a correlation of 85.67% with the experimental data. The biochemical characterization of lipase showed that the enzyme has a better performance at pH 7 at a temperature of 40 °C, where the statistical model had a correlation of 94.15% with the experimental data. In this way, lipases produced by F. solani have potential for application and use in biodiesel production.

Optimization of a-Amylase Production from Bacillus Amyloliquefaciens using Taguchi method

α-amylase, an enzyme of industrial importance is used extensively in food, pharmaceutical, textile and detergent industries. Since, a substantial quantity of α-amylase isderived from microbial sources, manipulation of bacterial strain, fermentation conditions and media composition has a major effect on yield of enzyme. Bacillus amyloliqifaciens, obtained from MTCC culture collection was used to study the enhancement of α-amylase production using media concentration manipulation. Taguchi’s orthogonal array was designed for maximization of α-amylase output. The different media components selected as parameters to be optimized were calcium chloride, starch, tryptone, ammonium sulphate and glucose. The concentration of starch and tryptone demonstrated to have maximum effect on amylase production. The optimization strategy was successful in obtaining substantial increase in amylase production of about 2 folds as compared to the unoptimized medium.

Optimization of Polyunsaturated Fatty Acids (PUFAs) Production from Olive Cake by Pseudomonas fluorescens NBRC14160 using Response Surface Methodology and their Application in Kareish Cheese Manufacture

The aim of this study was to optimize the production of polyunsaturated fatty acids (PUFAs), using use the response surface methodology (RSM), to use the produced PUFAs in kareish cheese processing. Plackett Burman design (PBD) was employed to screen media components that affect PUFAs development (glucose, olive cake, yeast extract, tryptone, MgSO4, KH2PO4, NH4Cl, agitation speed, incubation time, and pH), and results showed that olive cake and yeast extract, with confidence level > 98%, had a positive effect on PUFAs production. The central composite design (CCD) of the response surface methodology was used to optimize the selected parameters levels where maximum PUFAs production (1790 mg/l) was observed near the mid-point (0) values (concentrations) of olive cake (15 g/l), tryptone (7.5 g/L) and KH2PO4 (1.25 g/l). Polyunsaturated fatty acids account for 47.83 % of the total fatty acid profile, according to gas chromatography analysis of the collected PUFAs. The produced PUFAs was encapsulated using whey protein concentrate and maltodextrin, freeze dried, grinded and incorporated in Kareish cheese manufacture. The average particle size of a 0.005% suspension of oil microcapsules was 671.4 nm with a poly dispersity index of 0.611 indicating a moderate stability of the emulsion. The negative zeta potential of the microcapsules particles was -37.6 mv, which is identical to the -42 mv value recorded in the literature for oil emulsions stabilized by whey protein, maltodextrin, and K-carrageenan. The addition of 0.5 % PUFAs-containing microcapsules to Kareish cheese increased antioxidative activity to 38.13 % compared to 30.14 % for the control, as well as Texture profile analysis (TPA) parameters including hardness, cohesiveness, gumminess, and chewiness. The elasticity of the Kareish cheese sample increased slightly by the addition of 0.5% microcapsules, but higher concentration tended to change the elasticity to a brittleness of the cheese structure.

Enhancing L-malate production of Aspergillus oryzae by nitrogen regulation strategy.

Regulating morphology engineering and fermentation of Aspergillus oryzae makes it possible to increase the titer of L-malate. However, the existing L-malate-producing strain has limited L-malate production capacity and the fermentation process is insufficiently mature, which cannot meet the needs of industrial L-malate production. To further increase the L-malate production capacity of A. oryzae, we screened out a mutant strain (FMME-S-38) that produced 79.8 g/L L-malate in 250-mL shake flasks, using a newly developed screening system based on colony morphology on the plate. We further compared the extracellular nitrogen (N1) and intracellular nitrogen (N2) contents of the control and mutant strain (FMME-S-38) to determine the relationship between the curve of nitrogen content (N1 and N2) and the L-malate titer. This correlation was then used to optimize the conditions for developing a novel nitrogen supply strategy (initial tryptone concentration of 6.5 g/L and feeding with 3 g/L tryptone at 24 h). Fermentation in a 7.5-L fermentor under the optimized conditions further increased the titer and productivity of L-malate to 143.3 g/L and 1.19 g/L/h, respectively, corresponding to 164.9 g/L and 1.14 g/L/h in a 30-L fermentor. This nitrogen regulation-based strategy cannot only enhance industrial-scale L-malate production but also has generalizability and the potential to increase the production of similar metabolites.Key Points• Construction of a new screening system based on colony morphology on the plate.• A novel nitrogen regulation strategy used to regulate the production of L-malate.• A nitrogen supply strategy used to maximize the production of L-malate.

Biotransformation of doxycycline by Brevundimonas naejangsanensis and Sphingobacterium mizutaii strains

The fate of doxycycline (DC), a second generation tetracycline antibiotic, in the environment has drawn increasing attention in recent years due to its wide usage. Little is known about the biodegradability of DC in the environment. The objective of this study was to characterize the biotransformation of DC by pure bacterial strains with respect to reaction kinetics under different environmental conditions and biotransformation products. Two bacterial strains, Brevundimonas naejangsanensis DD1 and Sphingobacterium mizutaii DD2, were isolated from chicken litter and characterized for their biotransformation capability of DC. Results show both strains rely on cometabolism to biotransform DC with tryptone as primary growth substrate. DD2 had higher biotransformation kinetics than DD1. The two strains prefer similar pHs (7 and 8) and temperature (30 °C), however, they exhibited opposite responses to increasing background tryptone concentration. While hydrolysis converted DC to its isomer or epimer, the two bacterial strains converted DC to various biotransformation products through a series of demethylation, dehydration, decarbonylation and deamination. Findings from the study can be used to better predict the fate of DC in the environment.

Effect of Tryptone Concentration on Cyclodextrin Glucanotranferase (CGTase) Excretion and Cell Lysis of Immobilized Recombinant Escherichia coli

The recombinant enzyme excretion into the culture medium provides significant advantages over cytoplasmic expression. Nevertheless, the problems encountered during the excretion of recombinant enzyme are the plasmid instability and occurrence of cell lysis. Various attempts have been made to improve the recombinant enzyme excretion and plasmid stability with the low occurrence of cell lysis. The approaches include the modification of the nitrogen sources in the medium such as tryptone, the use of cell immobilization system and lowering the induction temperature. In the present study, the effects of different tryptone concentrations (1, 5, 10, 20 and 30 g/L) as nitrogen source in super optimal broth (SOB) medium on CGTase excretion and plasmid stability as well as cell lysis of the immobilized cell were studied. The recombinant E. coli was immobilized on polyvinylidene fluoride polymer (PVDF) hollow fiber membrane. The immobilized cells were expressed using 0.011 mM IPTG at 25°C, 200 rpm of agitation rate and pH 8.8 for 24 h of post induction time. The use of low tryptone concentration (5 g/l) produced high CGTase excretion (758.64 U/ml) and increased the plasmid stability (86% increment) with reduction of cell lysis (90% reduction) in comparison with the initial tryptone concentration (20 g/l). Hence, low concentration of tryptone could reduce the cost for CGTase production due to low amount of tryptone used in the fermentation process.

Optimization Using 33 Full-Factorial Design for Crude Biosurfactant Activity from Bacillus pumilus IJ-1 in Submerged Fermentation

This study aimed to optimize the culture conditions to improve the crude biosurfactant activity of Bacillus pumilus IJ-1, using a 33 full-factorial design of response surface methodology (RSM). It was found that submerged fermentation of B. pumilus improved the activity of the crude biosurfactant. The factors selected for optimization were NaCl concentration, temperature, and tryptone concentration. Response surface analysis revealed that the fitted quadratic model was statistically significant and produced an adequate R2 value (0.9898) and a low probability value (<0.0001). The optimum level for each factor was found to be 0.567% (w/v) NaCl, 21.851℃ and 0.765% (w/v) tryptone, respectively. Crude biosurfactant activity was found to be most affected by tryptone concentration; then temperature, and finally NaCl concentration. Our results may potentially facilitate large-scale biosurfactant production from B. pumilus IJ-1.

CdSe QD Biosynthesis in Yeast Using Tryptone-Enriched Media and Their Conjugation with a Peptide Hecate for Bacterial Detection and Killing.

The physical and chemical synthesis methods of quantum dots (QDs) are generally unfavorable for biological applications. To overcome this limitation, the development of a novel “green” route to produce highly-fluorescent CdSe QDs constitutes a promising substitute approach. In the present work, CdSe QDs were biosynthesized in yeast Saccharomyces cerevisiae using a novel method, where we showed for the first time that the concentration of tryptone highly affects the synthesis process. The optimum concentration of tryptone was found to be 25 g/L for the highest yield. Different methods were used to optimize the QD extraction from yeast, and the best method was found to be by denaturation at 80 °C along with an ultrasound needle. Multiple physical characterizations including transmission electron microscopy (TEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDX), and spectrophotometry confirmed the optical features size and shape distribution of the QDs. We showed that the novel conjugate of the CdSe QDs and a cell-penetrating peptide (hecate) can detect bacterial cells very efficiently under a fluorescent microscope. The conjugate also showed strong antibacterial activity against vancomycin-resistant Staphylococcus aureus (VRSA), methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli, which may help us to cope with the problem of rising antibiotic resistance.

Effects of medium composition on the growth and lipid production of microplasmodia of Physarum polycephalum.

Physarum polycephalum is a plasmodial slime mold. One of the trophic stages in the life cycle of this organism is a plasmodium. In submerged culture, plasmodia are fragmented into microplasmodia. The latter both lack cell walls and are capable of rapid growth. There has been limited information on the effects of medium composition on the growth and lipid accumulation of microplasmodia. In this study, optimization of medium components by response surface methodology showed that tryptone and yeast extract concentrations had the most significant effects on lipid and biomass production; significant synergistic interactions between glucose and tryptone concentration on these responses were also recorded. The optimal medium was composed of 20 g/L of glucose, 6.59 g/L of tryptone, and 3.0 g/L of yeast extract. This medium yielded 13.86 g/L of dry biomass and 1.97 g/L of lipids. These amounts are threefold higher than those of the American Type Culture Collection (ATCC) medium. In addition, biomass and lipid production reached maximal values between only 4 and 5 days. Fatty acid compositions analysis by gas chromatography-mass spectrometer (GC-MS) revealed that P. polycephalum lipids consisted mainly of oleic acid (40.5%), linoleic acid (10%), and octadecynoic (15.8%). This is the first report on the fatty acid composition of P. polycephalum microplasmodia. These results suggest that the biomass of microplasmodia could be used as a source of material for direct conversion into biodiesel because of the absence of cell walls or it could also be used as a supplemental source of beneficial fatty acids for humans, albeit with some further evaluation needed.

Production of Vitamin D3 Enriched Biomass of Saccharomyces Cerevisiae as A Potential Food Supplement: Evaluation and Optimization of Culture Conditions Using Plackett-Burman and Response Surface Methodological Approaches.

Vitamin D deficiency causes osteoporosis, osteopenia, fractures, rickets, and more recently is linked with some chronic illnesses such as cancer. Because of the safety and probiotic properties of the yeast Saccharomyces cerevisiae, we hypothesized that yeast cells enriched with cholecalciferol (vitamin D3) could represent a solution for prevention or treatment of vitamin D deficiency. In this study S. cerevisiae was used as a vitamin D3 accumulator for the first time and the optimal conditions for enrichment of S. cerevisiae were determined. The Plackett-Burman screening studies were used for selection of the most important factors affecting cholecalciferol entrapment. Response surface methodology was employed for optimization of cholecalciferol accumulation in S. cerevisiae cells by using Box-Behnken design. A modified quadratic polynomial model fit the data appropriately. The optimal points of variables to maximize the response were cholecalciferol initial concentration of 358021.16 IU/mL, tryptone concentration of 1.82 g/L, sucrose concentration of 7.13 % (w/v), and shaking speed of 140.46 rpm. The maximum amount of cholecalciferol in dry cell weight of S. cerevisiae was 4428.11 IU/g. The cholecalciferol entrapment in yeast biomass increased about two-folds in optimized condition which indicates efficiency of optimization.

Optimization of Lipase Production in Solid-State Fermentation by Rhizopus Arrhizus in Nutrient Medium Containing Agroindustrial Wastes

Background: Rhizopus arrhizus is a potential microorganism for lipase production. Solid-state fermentation is used for microbial biosynthesis of enzymes, due to advantages, such as high productivity, utilization of abundant and low-cost raw materials, and production of enzymes with different catalytic properties. Objective: The objective of the research is optimization of the conditions for lipase production in solid-state fermentation by Rhizopus arrhizus in a nutrient medium, containing agroindustrial wastes. Method: Biosynthesis of lipase in solid-state fermentation by Rhizopus arrhizus was investigated. The effect of different solid substrates, additional carbon and nitrogen source, particles size and moisture content of the medium on enzyme production was studied. Response surface methodology was applied for determination of the optimal values of moisture content and tryptone concentration. A procedure for efficient lipase extraction from the fermented solids was developed. Results: Highest lipase activity was achieved when wheat bran was used as a solid substrate. The addition of 1% (w/w) glucose and 5% (w/w) tryptone to the solid medium significantly increased lipase activity. The structure of the solid medium including particles size and moisture content significantly influenced lipase production. A mathematical model for the effect of moisture content and tryptone concentration on lipase activity was developed. Highest enzyme activity was achieved at 66% moisture and 5% (w/w) tryptone. The addition of the non-ionic surfactant Disponyl NP 3070 in the eluent for enzyme extraction from the fermented solids increased lipase activity about three folds. Conclusion: After optimization of the solid-state fermentation the achieved 1021.80 U/g lipase activity from Rhizopus arrhizus was higher and comparable with the activity of lipases, produced by other fungal strains. The optimization of the conditions and the use of low cost components in solid-state fermentation makes the process economicaly effective for production of lipase from the investigated strain Rhizopus arrhizus.

Statistical Optimization of Medium Components by Response Surface Methodology to Enhance Menaquinone-7 (Vitamin K₂) Production by Bacillus subtilis.

Optimization of the culture medium to maximize menaquinone-7 (MK-7) production by Bacillus subtilis strain KCTC 12392BP in static culture was carried out using statistical experimental methods, including one factor at a time, fractional factorial design, and response surface methodology (RSM). Maltose (carbon source), tryptone (nitrogen source), and glycerol (activator) were identified as the key medium components for MK-7 synthesis by the fractional factorial design, and were selected for statistical optimization by RSM. The statistical analysis indicated that, in the range that was studied, maltose, tryptone, and glycerol were all critical factors having profound effects on the production of MK-7, with their coefficients for linear and quadratic all significant at the p < 0.05 level. The established model was efficient and feasible, with a determination coefficient (R²) of 0.9419. The predicted concentrations of maltose, tryptone, and glycerol in the optimal medium were determined as 36.78, 62.76, and 58.90 g/l, respectively. In this optimized medium, the maximum yield of MK-7 reached a remarkably high level of 71.95 ± 1.00 μg/ml after 9 days of static fermentation, which further verified the practicability of this optimized strategy.

Effect of the tryptone concentration on the calcium carbonate biomineralization mediated by Bacillus cereus

Se evaluaron cinco concentraciones de triptona (0.2%, 0.4%, 0.6%, 0.8% y 1.0%) en procesos de biomineralización de carbonato de calcio, utilizando acetato de calcio al 0.5%. Todos los ensayos se hicieron con una cepa de Bacillus cereus, aislada de los jardines de la Universidad Pontificia Bolivariana (Medellín, Antioquia, Colombia). Los experimentos fueron monitoreados con mediciones de pH y análisis mineralógicos de difracción de rayos X (XRD), espectroscopía de infrarrojo con transformada de Fourier (FTIR) y microscopía electrónica de barrido (SEM). La vaterita fue el polimorfo predominante en los precipitados después de 6 días de proceso. Sin embargo, una proporción considerable de calcita (por encima de 30%) apareció cuando la concentración de triptona fue de 0.4% y menor. Adicionalmente, los experimentos tuvieron una formación de precipitados similar (entre 3.2 y 3.6 g/L), menos el ensayo con 0.2% de triptona, que presentó una baja producción de carbonato de calcio (1.79 g/L), indicando que una concentración de triptona menor a 0.4% limitaría el metabolismo bacteriano y la formación de CO2, necesaria para la producción de carbonato de calcio.

Isolation, identification and characterisation of the nematophagous fungus Arthrobotrys thaumasia (Monacrosporium thaumasium) from China

ABSTRACTThe objective of this study is to select a native isolate of Arthrobotrys thaumasia (Monacrosporium thaumasium), a nematophagous fungus that shows potential for use in biocontrol programmes for ruminants. First, we looked for native isolates of A. thaumasia and characterised them using light microscopy and molecular markers. Then, we determined the effect of temperature, pH and nutrition on the growth rate and trap formation of a representative isolate. Of the 1532 samples of different types related to sheep and cattle, 11 isolates of A. thaumasia were isolated, and their occurrence frequency in the samples was 0.71% (11/1532). We sequenced the rDNA internal transcribed spacer of isolate NBS005, submitted it to GenBank (ID: KX640093) and then sequenced it using BLAST. The NBS005 could not grow at 37.5°C but could grow from 11°C to 35°C, and it exhibited its optimum growth at 30°C on 1% corn meal agar (CMA). Over 4 days, the fungus did not grow in the pH interval from 1 to 3 or from 13 to 14 but did grow in the pH interval from 4 to 12 and exhibited its optimum growth between pH 9 and 10 on 2% CMA. The factors responsible for the trap formation of NBS005 in liquid culture were identified. Trap formation was induced only by contact with L3 lysate. The concentrations of sucrose, ammonium chloride and tryptone of 0.4, 0.2 and 0.2%, respectively, promoted trap formation, and there were higher numbers of trapping nets in 2% wheat bran liquid medium containing L3 lysate.

Development of a semidefined growth medium for Pedobacter cryoconitis BG5 using statistical experimental design

ABSTRACTPedobacter cryoconitis BG5 are psychrophiles isolated from the cold environment and capable of proliferating and growing well at low temperature regime. Their cellular products have found a broad spectrum of applications, including in food, medicine, and bioremediation. Therefore, it is imperative to develop a high-cell density cultivation strategy coupled with optimized growth medium for P. cryoconitis BG5. To date, there has been no published report on the design and optimization of growth medium for P. cryoconitis, hence the objective of this research project. A preliminary screening of four commercially available media, namely tryptic soy broth, R2A, Luria Bertani broth, and nutrient broth, was conducted to formulate the basal medium. Based on the preliminary screening, tryptone, glucose, NaCl, and K2HPO4 along with three additional nutrients (yeast extract, MgSO4, and NH4Cl) were identified to form the basal medium which was further analyzed by Plackett–Burman experimental design. Central composite experimental design using response surface methodology was adopted to optimize tryptone, yeast extract, and NH4Cl concentrations in the formulated growth medium. Statistical data analysis showed a high regression factor of 0.84 with a predicted optimum optical (600 nm) cell density of 7.5 using 23.7 g/L of tryptone, 8.8 g/L of yeast extract, and 0.7 g/L of NH4Cl. The optimized medium for P. cryoconitis BG5 was tested, and the observed optical density was 7.8. The cost-effectiveness of the optimized medium was determined as 6.25 unit prices per gram of cell produced in a 250-ml Erlenmeyer flask.

The efficacy of EO waters on inactivating norovirus and hepatitis A virus in the presence of organic matter

The ability of acidic electrolyzed oxidizing water (AEO) and neutral electrolyzed oxidizing water (NEO) to inactivate the murine norovirus (MNV-1) surrogate for human norovirus and hepatitis A virus (HAV) in suspension and on stainless steel coupons in the presence of organic matter was investigated. Viruses containing tryptone (0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0%) were mixed with AEO and NEO for 1 min. In addition, stainless steel coupons containing MNV-1 with or without organic matter were treated with AEO or NEO for 3, 5, and 10 min. AEO was proven effective and generally killed more MNV-1 and HAV in suspension than NEO. Depending on the EO water generator, free chlorine concentrations are required to inactivate MNV-1 and HAV by 3-log PFU/mL or greater ranged from 30 mg/L to 40 mg/L after a 1 min contact time. The virucidal effect increased with increasing free chlorine concentration and decreased with increasing tryptone concentration in suspension. Both AEO and NEO at 70–100 mg/L of free chlorine concentration significantly reduced MNV-1 on coupons in the absence of organic matter. However, there was no significant difference between these two treatments in the presence of organic matter. In addition, the efficacy of these two EO waters on stainless steel coupons increased with the increasing treatment time. Results indicated that AEO and NEO can reduce MNV-1 and HAV in suspension. However, higher free chlorine concentrations and longer treatment times may be necessary to reduce viruses on contact surfaces or in the presence of organic matter.

전통 장류 유래 Bacillus subtilis SCJ4의 특성확인 및 통계학적 방법을 이용한 배양조건 최적화

strains isolated from Korean traditional fermented food in Sunchang and their investigated biochemical characterization and ability of biogenic amines non-producing. We selected the SCJ4 having various activity by measurement of extracellular enzyme, antioxidant and antimicrobial activities. Selected strain SCJ4 by 16S rRNA sequencing and biochemical characterization was named Bacillus subtilis SCJ4. And then, we investigated cell growth of SCJ4, and optimized of culture medium constituents using response surface methodology as statistically method. Response surface methodology used Plackett-Burman experimental design for screening of medium constituent. Tryptone, peptone and MgSO4 as medium constituent improving cell growth selected. In order to find out optimal concentration on each constituent, we carried out central composite design. Consequently, optimized concentrations of tryptone, peptone and MgSO4 were predicted to be 15.35 g/L, 12.235 g/L, and 3.5 g/L respectively. Through the model verification, we confirmed about 1.28-fold improvement of the dried cell weight from 0.8767 g/L to 1.1222 g/L when compared to basal medium.