Shaker Speed Research Articles

Increased Extracellular Saponin Production after the Addition of Rutin in Truffle Liquid Fermentation and Its Antioxidant Activities

Saponins possess a variety of pharmacological effects and exhibit great potential in the food industry as bioactive substances. In this study, extracellular saponin production via the liquid fermentation of Tuber melanosporum occurred with the addition of rutin. For this purpose, medium composition and culture conditions were optimized using single-factor experiments and an orthogonal experiment design. The optimal medium consisted of glucose (43.5 g/L), peptone (6 g/L), KH2PO4 (1.15 g/L), NaCl (0.2 g/L), vitamin B2 (0.082 g/L), vitamin B6 (0.1 g/L), vitamin C (0.02 g/L), and rutin (4.8 g/L). The culture conditions were as follows: 12.5% (v/v) inoculation, medium volume of 50 mL/250 mL flask, culture temperature of 24 °C, shaker speed of 190 rpm, initial pH of 5.7, and culture time of 96 h. Finally, a maximal extracellular saponin content of 0.413 g/L was obtained, which was 134.7% higher than that in the base medium. Rutin proved to be an excellent promoter, because the saponin production was increased by 50.2% compared to that in the optimized medium without rutin. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, hydroxyl radical scavenging activity, and ferric reducing antioxidant power of truffle saponins reached 94.13%, 79.26%, and 42.22 mM, respectively. This study provides a useful strategy for fungal bioactive saponin production by liquid fermentation with the addition of flavonoid compounds.

Effect of process route on powder three-dimensional-printing of metal powders

Purpose The purpose of this study is to investigate the effect of two unique processing routes (solvent jetting (SJ) and binder jetting (BJ)), on the green density of printed stainless steel 316L (SS316L) and Nickel (Ni) powders. Design/methodology/approach In the SJ processing route, a solvent is jetted unto the powder/binder mixture to selectively activate the binder, layer by layer. In the BJ processing route, a solution of the binder mixture is jetted onto the powder bed to selectively bind powder particles. The effects of printing parameters such as layer height, roller speed, shaker speed and nozzle temperature on the green density of printed components are investigated and compared for both processing routes. Findings Results show that layer height and nozzle temperature affect the relative density of the printed compact for both processing routes. Slightly higher relative densities were achieved via the SJ route, with the overall highest relative density being 42.7% at 100 µm layer height and 70% nozzle temperature for the SS316L components and 43.7% at 150 µm layer height and 90% nozzle temperature for the Ni components, respectively. Results also show an increase in the final sintered relative density with an increase in green (printed) relative density of the solvent jetted SS316L components, with the highest relative density being 87.2%. Originality/value The paper studies the influence of printing parameters on the green density of printed SS316L and Ni samples in an unprecedented effort to provide a comparative understanding of the process-property relationships in BJ and SJ of SS316L and Ni components to the additive manufacturing research community.

Effectiveness of Fe, Mn, UV254 and Colour Removal from Pre-ozonated Groundwater Using Anthracite Coal

This paper investigates the potential use of anthracite coal to remove Fe, Mn, UV254, and colour from pre-ozonated groundwater using batch experiment studies. Pre-ozonated groundwater samples were prepared in a laboratory to present the actual characteristics of groundwater samples. General characteristics for anthracite, as well as for groundwater samples, were examined. The influences of anthracite dosage, pH, agitation speed, and contact time on the reduction of tested parameters were discussed. Also, three adsorption isotherms (Langmuir, Freundlich, and Temkin), as well as kinetics models, were evaluated. Results demonstrated that the maximum removal of Fe (67%) occurred at 100 g of anthracite dosage, and no significant removal of Mn was observed. In addition, anthracite was capable of removing UV254 and colour using a dosage of 100 g. However, the maximum removal efficiency of colour was 76% using the same anthracite dosage of 100 g. The optimum shaking speed of 300 rpm resulted in the maximum removal efficiency of all parameters. The optimum pH was 7, which resulted in the maximum removal efficiency of Fe (40%), Mn (7%), UV254 (43%), and colour (50%). The optimum contact time was 90 min for all parameters with a dosage of 100 g which resulted in the removal efficiency of 54%, 52%, and 70% for Fe, Mn, UV254, and colour. The adsorption and kinetics models were well fitted with the experimental results. Overall, this study demonstrated that anthracite could be a good practical option for groundwater treatment. The strong iron (Fe) and manganese (Mn) concentrations; is one of the big groundwater issues, causing reddish and blackish in the groundwater. Batch experimental works have been undertaken to investigate the applicability of anthracite as an alternative adsorbent to remove Fe, Mn, UV254, and colour from pre-ozonated groundwater. The application of ozone alone was less effective to remove these pollutants. At the optimum pH value of 7 and 90 minutes of contact time, the adsorption and kinetics models were fit well with the experimental results. The study demonstrated that ozonation with anthracite could be a good practical option for groundwater treatment.

Statistical design and optimization of nutritional value production by an oleaginous yeast Yarrowia lipolytica cultured in industrial – waste molasses

Abundant by-products from sugar mills as industrial-waste molasses can be used as a carbon source in yeast culture media. Yarrowia lipolytica is an interesting yeast used as a candidate for cultivation in molasses medium. Here, we used response surface methodology to derive a statistical model for the individual and interactive effects of pH, temperature, and shaking speeds on the production of yeast cells. Cultivation conditions of yeast were optimized using Design Expert based on a 23 factorial central composite design (CCD) for maximum yeast cell production. Optimal conditions for maximum Y. lipolytica 5151 cell masses were as follows: pH, 6.45; temperature, 30°C; Shaking speed, 165 rpm. The Design Expert represented the maximal numerical solution with a predicted cell mass production level at 8.96 g/L. The experimental production of Y. lipolytica 5151 cell mass yielded 8.27 g/L that is 7.67% deviated from the model. Whereas, the model of TISTR 5621 was not adequate for prediction. Yeasts cultured under statistic prediction provide 55.94% and 51.25% of total protein. Amino acid content and vitamin B1 (1.06 mg and 1.47 mg per 100 g of dried Y. lipolytica 5151 and 5621, respectively) provided the relevant information for an alternative supplement in aquatic feed.

Optimization of alkali-treated poplar fiber saccharification using metal ions and surfactants

ABSTRACT In this study, contrary to untreated poplar fiber, processing of alkali-treated poplar fiber was optimized for the enzymatic saccharification. Considering reducing sugar content as the evaluation index, pH, temperature, time, amount of enzyme, and rotational speed of shaker were standardized to optimize the sugar production by enzymatic hydrolysis. Using response surface methodology, the optimum technological condition of enzymatic hydrolysis was found to be utilizing 43 mg cellulase at 46 °C for 50 h. At this, the sugar conversion amount of NaOH or H2O2-NaOH pretreated poplar was 164.62 mg/g and 218.82 mg/g respectively. It was a corresponding increase of 446.73% or 626.75% than that of poplar fiber without a pretreatment. At a low concentration, metal ions and surfactants promoted the conversion of reducing sugar. Especially, 0.01 g/L Mn2+ and 0.50 g/L hexadecyl trimethyl ammonium bromide (CTAB) produced the best effect and increased the conversion rate of reducing sugar by 23.62% and 21.44% respectively. Also, the effect of the combination of metal ions and surfactants was better than that of a single accelerator. By improving the enzymatic process, these findings could enhance the utilization of poplar fiber for the production of reducing sugar.

Identification and Characterization of a Highly Efficient and Resistant Aniline-Degrading Strain AD4

Environmental friendly and effective bio-augmentation is a very promising technology in the aniline wastewater treatment field. In this study, an aniline degradation bacterial strain was isolated from activated sludge, designated AD4. It was proved to be capable of removing aniline effectively in the concentration range between 200 and 800 mg/L within 72 h and could tolerate 1,400 mg/L of aniline, which was identified as Delftia tsuruhatensis. The influence of environmental factors containing initial aniline concentration, initial pH, temperature, shaker speed, salinity, and inoculum amount on the growth and degradation of strain AD4 were investigated. The results showed that AD4 had a wide range of suitable pH (5–8) and higher efficiency in a weak acidic environment than in weak base. The aniline concentration, pH, and temperature were used as independent parameters to optimize the aniline degradation by strain AD4, and a statistically significant (R2 = 0.9817, p < 0.001) quadratic polynomial mathematical model was built. Meanwhile, a simulated reactor was designed to test the aniline-degradation ability of strain AD4 during the aeration stage. The degradation rate in 600 mg/L of aniline solution reached 51.5% after 8 h.

Screening of Laccase Producing Fungi Using Agro-Wastes under Different Cultural Conditions

This study evaluated the potential of fungal isolates for laccase production. Fungi cultures were screened for laccase production on plate assay using 2’ 2’ – azinobis-(-3-ethyl benzthiazoline -6- suphonate) (ABTS), and by submerged fermentation. Result obtained from the plate assay showed the formation of green halo after 2-4 days of incubation due to oxidation of 2’ 2’ – azinobis-(-3-ethyl benzthiazoline -6- suphonate) (ABTS) which is as a result of lignolytic enzymes production Utilization of selected agro-wastes residues (sawdust, plantain and banana peels) for laccase production was evaluated. Fungal isolates were identified based on their cultural characteristics according to standard mycology methods. Light microscopy was performed on cultures and the fungal isolates were identified by their different morphological and colonial characteristics after which they were confirmed using fungal atlas. Total protein content was also determined using the Bradford method Five out of twelve isolates were positive for oxidation of 2’ 2’ – azinobis-(-3-ethyl benzthiazoline -6- suphonate) (ABTS) which signifies laccase enzyme activity and identified as Geotrichum spp, Cephalosporium spp, Trichoderma spp, Trametes spp and Fusarium sppThe highest enzyme activity was observed using Trichoderma spp at 57.1U/l, Trametes spp 51.99 U/l, Fusarium spp had 29.2 U/l. Geotrichum spp and Cephalosporium spp were least at 28.04 U/l and 9.72 U/l respectively. Trichoderma spp was used for further studies. Effect of carbon sources, inoculum size, pH, total protein and shaker speed on laccase production was evaluated. Sawdust gave the highest yield of laccase enzyme 151.17U /l, followed by plantain peel with 62.49U/l of enzyme, banana peel recorded the least of laccase enzyme 54.94 U /l. Protein content obtained from sawdust medium was 45.8mg/ml, plantain peel medium had 29.2 mg/ml while banana peel was the lowest with 16.8mg/ml all at the sixth day of the fermentation process. Optimum pH for sawdust, banana peel and plantain peel was 5.95, 5.94, and 5.83 respectively. Using shaker incubator (150 rpm) with sawdust as carbon source, laccase yield of (310.45U/l) was obtained at pH 6, temperature 25°C and inoculum size of 105 spores per ml. Thus, sawdust can be categorically stated to be safe, cheap and could be suggested for prospective application of higher production of laccase enzyme in various industries.

Adsorption of toxic Pb(II) on activated carbon derived from agriculture waste (Mahogany fruit shell): isotherm, kinetic and thermodynamic study

ABSTRACT An adsorbent, mahogany fruit shell activated carbon(MFSAC), was derived from environmental friendly raw material, i.e. agriculture waste and explored for bench scale adsorption of toxic Pb(II). A facile MFSAC material was synthesised using a chemical activation method using concentrated sulphuric acid as an impregnating (activating) reagent. So derived adsorbent material was characterised by FTIR, XRD, BET, SEM, EDAX, TGA and XPS techniques to know the properties and plausible adsorption mechanism. Bench scale adsorption of toxic Pb(II) and maximum adsorption capacity of MFSAC were exhibited through batch adsorption experiments. The effect of physico-chemical parameters such as pH (1–7), MFSAC amount (0.5–5.0 g L−1), Pb(II) concentration (200–1000 mgL−1), contact period (60–600 min) and orbital shaking speed (60–200 rpm) was studied for maximum removal of Pb(II) upto 99.70 ± 0.17%. The experimental data follow the Langmuir adsorption isotherm with a maximum monolayer adsorption capacity 322.28 mg g−1and pseudo-second-order kinetic uptake rate. The thermodynamic and temperature study revealed that the adsorption process was spontaneous and endothermic in nature (ΔHo = 43.37 kJ mole−1, ΔSo = 158.02 J mol−1K−1). Most importantly, the MFSAC adsorbent was successfully regenerated and reused with conspicuous performance up to five consecutive cycles. The bench-scale adsorption with simple synthesis route, good stability and remarkable regeneration capability makes the MFSAC as an encouraging adsorbent for wastewater treatment.

Preparation and characterization of MnO2-based nanoparticles at different annealing temperatures and their application in dye removal from water

In this research, manganese oxides (MnO2) nanoparticles were prepared by hydrothermal method using KMnO4 as a precursor. The final brown–black precipitate MnO2 nanoparticles as prepared, and annealed at different temperatures (250, 450, and 750 °C) were characterized. The nanoparticles prepared were tested for removal of methylene blue (MB), used as a model dye from water. In order to determine the structure and the chemical nature of the MnO2 nanoparticles prepared, the characterization was carried out by X-ray diffraction. For the surface morphological studies of nanoparticles, field emission scanning electron microscopy was used. In order to study the surface roughness atomic force microscopy was used for determination of the imaging surface structures in the nm scale. Fourier transform infrared spectrometry was used to investigate the vibrations of functional groups in MnO2. The tests for dye removal from water using MnO2 nanoparticles have been carried out for MnO2 nanoparticles as prepared and annealed at different temperatures. The process parameters such as speed of shaking, reaction time, and MB concentration were studied at 25 °C temperature to determine the best removal efficiency of methylene blue from water. UV/Visible spectrophotometer was used to follow the MB removal. MnO2 annealed at 750 °C exhibited the highest MB removal efficiency, 89%, as compared with MnO2 nanoparticles as prepared and annealed at 250 and 450 °C.

Preliminary study on protein isolation process of walnut dregs by single factor experiments and response surface method

The production of protein by alkali-solution and acid-isolation method will lead to the increase of salt in the feed liquid and affect its quality. In order to simplify the production of protein by the alkali acid precipitation process and obtain protein with high content and quality, the cation exchange resin was used to separate the walnut dreg protein. The desalination rate, protein content and recovery rate were used as indicators. Single factor experiments and response surface method were used to optimize the time used to isolate the protein from the cation exchange resin, the speed and temperature of the water bath shaker. Our results showed that the optimal time was determined at 62 min; the optimal speed of the water bath shaker was 120 rpm, and the optimal temperature was 49 °C. Under these conditions, the optimal protein recovery was 95.22% and the optimal protein content was 78.12%.

Improving Robustness of Pharmaceutical Dosage form Sample Preparation Using Experimental Design and Process Understanding Tools

As a result of the excipient materials added to the drug substance to create a formulated pharmaceutical product, the preparation of drug product samples for chromatographic or other quantitative analysis can be manually intensive and time-consuming. It is therefore important that enough focus is placed on this aspect of method development to ensure accurate and reproducible results are obtainable across different laboratories. This paper outlines some of the challenges encountered when developing quantitative assay methods which are attributable to sample preparation procedures for solid-oral dosage forms (i.e. tablets and capsules). Approaches utilising experimental design, data visualisation and process understanding tools are described to highlight the importance of common sample preparation factors on drug recovery in product formulations. For a tablet formulation, experimental design highlighted that the percentage of organic in the sample diluent and the orbital shaker speed were statistically significant and could impact accuracy of assay result. For the second formulation, a gelatin capsule, the use of experimental design and the Britest process understanding tools highlighted the initial volumetric flask fill volume required close control to ensure reproducible assay results while the stand time (time sample left to stand post-shaking to aid analyte solubilisation) and capsule storage conditions were also significant.

Production of 7-methylxanthine from Theobromine by Metabolically Engineered E. coli

In this work, a novel biocatalytic process for the production of 7-methylxanthines from theobromine, an economic feedstock has been developed. Bench scale production of 7-methlxanthine has been demonstrated. The biocatalytic process used in this work operates at 30 OC and atmospheric pressure, and is environmentally friendly. The biocatalyst was E. coli BL21(DE3) engineered with ndmB/D genes combinations. These modifications enabled specific N7- demethylation of theobromine to 7-methylxanthine. This production process consists of uniform fermentation conditions with a specific metabolically engineered strain, uniform induction of specific enzymes for 7-methylxanthine production, uniform recovery and preparation of biocatalyst for reaction and uniform recovery of pure 7-methylxanthine.&#x0D; Many E. coli BL21(DE3) strains metabolically engineered with single and/or multiple ndmB/D genes were tested for catalytic activity, and the best strains which had the higher activity were chosen to carry out the N-demethylation reaction of theobromine. Strain pBD2dDB had the highest activity for the production of 7-methylxanthine from theobromine. That strain was used to find the optimum amount of cells required to achieve complete conversion of theobromine to 7-methylxanthine within two hours. It was found that the optimum concentration of pBD2dDB strain to achieve 100% conversion of 0.5 mM theobromine to 7-methylxanthine was 5 mg/mL. The cell growth of pBD2dDB strain was studied using two different growth media, (Luria-Bertani Broth and Super Broth). Super broth was found to be the best medium to produce the highest amount of cell paste (1.5 g). Subsequently, the process was scaled up in which 2 L reaction volume was used to produce 7-methylxanthine (100% conversion) from 0.5 mM theobromine catalyzed by pBD2dDB strain. The reactions was carried out at 30 oC and 250 rpm shaker speed, and the reaction medium was 50 mM potassium phosphate buffer (pH=7). 7-methylxanthines was separated by preparative chromatography with high recovery, and the product solution was collected, purified by drying at 120-140 oC for 4 hours and, recovered (127 mg). Purity of the isolated 7-methylxanthine was comparable to authentic standards with no contaminant peaks, as observed by HPLC, LC-MS, and NMR.

Statistical optimization of the extraction of citric acid from the solid fermented substrate of empty fruit bunches

AbstractOptimization of the process parameters for the extraction of a product from a solid substrate after bioconversion is essentially important to maximize the yield. The extraction of citric acid from the solid substrate of oil palm empty fruit bunches (EFB) after bioconversion was initially optimized by following single factor variation. Following this, the extraction parameters were optimized statistically with the help of experimental design by Box‐Behnken Design under Response Surface Methodology through the development of a second order regression model. The statistical analysis of the result showed that in the range studied all three factors, that is, shaking speed, solvent ratio, and shaking time, had a significant influence on the citric acid extraction. The highest amount of citric acid extracted was 337.34 ± 1.1 g/kg‐dry EFB, for which the extraction parameters were a shaking speed of 125 rpm, a shaking time of 58.5 minutes, and a solvent ratio of 10.70. The coefficient of determination observed (R2) from the analysis was .9921, indicating a satisfactory fit of the model with the response. The analysis showed that all the terms of the model were highly significant with the P‐value &lt;.05.

Homogenization of initial cell distribution by secondary flow of medium improves cell culture efficiency

Homogenization of the initial cell distribution is essential for effective cell development. However, there are few previous reports on efficient cell seeding methods, even though the initial cell distribution has a large effect on cell proliferation. Dense cell regions have an inverse impact on cell development, known as contact inhibition. In this study, we developed a method to homogenize the cell seeding density using secondary flow, or Ekman transportation, induced by orbital movement of the culture dish. We developed an orbital shaker device that can stir the medium in a 35-mm culture dish by shaking the dish along a circular orbit with 2 mm of eccentricity. The distribution of cells in the culture dish can be controlled by the rotational speed of the orbital shaker, enabling dispersion of the initial cell distribution. The experimental results indicated that the cell density became most homogeneous at 61 rpm. We further evaluated the cell proliferation after homogenization of the initial cell density at 61 rpm. The results revealed 36% higher proliferation for the stirred samples compared with the non-stirred control samples. The present findings indicate that homogenization of the initial cell density by Ekman transportation contributes to the achievement of higher cell proliferation.

Optimization of Cadmium and Zinc Removal from Contaminated Soil by Surfactants Using Mixture Design and Central Composite Rotatable Design

Surfactants are substances applicable in the removal of heavy metals from contaminated soil. This study aims to investigate the effects of surfactant mixtures, composed of nonionic, anionic, and cationic surfactants, on the removal efficiency of Cd and Zn by mixture design (MD). Central composite rotatable design (CCRD) was integrated to optimize the conditions of contaminated soil washing. However, as representatives of each type of surfactant, a single surfactant with the most effective Cd removal was selected for each type before MD and CCRD studies. Sodium dodecyl sulfate (SDS) and sodium laureth sulfate (SLES) were the most effective anionic surfactants, while dodecyl trimethyl ammonium bromide (DTAB) and polysorbate 80 (Tween 80) were chosen to represent cationic surfactants and nonionic surfactants, respectively. Two systems of SDS-DTAB-Tween 80 and SLES-DTAB-Tween 80 were studied to examine their roles in Cd and Zn removal by MD. The results indicate insignificant enhancement in mixed surfactant systems for Cd and Zn removal. DTAB was identified as an ineffective surfactant, but at present, the presence of Tween 80 in both systems compensated for the use of SDS and SLES. The system containing SLES was selected to study CCRD because of its low cost and biodegradation. Cd and Zn removal efficiencies were 45.2% and 47.7%, respectively, at 40 mmol/L of 5-mL SLES solution per gram of soil with a 200-rpm shaker speed for 8 h. The Cd concentration of treated soil met Thailand’s agricultural soil standard. However, the further increase in removal efficiency should be considered.

Production and optimization of polyhydroxybutyrate (PHB) from Bacillus megaterium as biodegradable plastic

Among biodegradable plastics polyhydroxy alkanate and its polymers have received more attention than other biodegradable polymers because of their complete degradability, flexibility, water resistance and also the ease of production process. Polyhydroxybutyrate is one of the types of polyhydroxy alkanates that is seen as a storage granule in many microorganisms. In this study, Bacillus megaterium was prepared from Iranian microbial collection. Glucose and yeast extract were used as the main components of the medium in seed media 9 and 2.5 g/l and in fermentation medium 30 and 7.5 g/l respectively. GC-MASS and FTIR were used to identify the PHB produced. The results showed that the highest amount of biomass (0.221 g/l) and PHB (0.080 g/l) were obtained with glucose at 37°C and shaker speed of 150 rpm for 72 h incubation. The results of GC MASS and FTIR showed the production of PHB by Bacillus under investigation. Based on the mean of data on total cell growth conditions, the rate of cell biomass and PHB production in B. megaterium were 0.0869 and 0.0171 respectively. According to the results of the experiments, temperature had the greatest effect on biomass production and PHB production. The bioplastics produced by microbes are also highly degradable in the environment, and due to their specific chemical structure, they have been widely used in various fields of the food, pharmaceutical and chemical industries and are likely to replace today's plastics in the near future. DOI: http://dx.doi.org/10.5281/zenodo.3711400

Dental resin as controlled release layer for the development of an innovative long-acting intra-oral delivery system

The objective of the present study was to develop a novel long-acting intra-oral delivery system (LIDS) to overcome the frequent administration by the nonparenteral route with Huperzine A (HupA) as a model drug. HupA-LIDS was prepared using a magnetic drug delivery with dental resin as release controlling layer for long-term release of HupA. The factors that influenced the drug release comprised of the type and amount of pore formers, the speed of shaker, resin layer weight and drug loading. These factors were evaluated and optimized. The in-vitro release studies showed that the system was able to deliver HupA in an approximately zero-order kinetic. The SEM study showed that the multiple orifices on the surface of a resin layer formed due to presence of pore formers, which contributed to the HupA release. The pharmacokinetic study in rabbits demonstrated the HupA-LIDS could be released in vivo for more than 8 days with prolonged Tmax and significantly reduced Cmax in comparison with commercial tablets. This study provided some pioneering ideas for developing intra-oral extended release drug delivery system using dental resin as release controlling materials. The optimized HupA-LIDS can make excellent sustained release and have the potential for the long-acting product in the therapy of Alzheimer's disease.

Screening and identification of a Penicillium brevicompactum strain isolated from the fruiting body of Inonotus obliquus and the fermentation production of mycophenolic acid

Mycophenolic acid (MPA) is a fungal metabolite with a variety of biological activities and widely applied in clinical practices. We herein aimed to isolate a new Penicillium brevicompactum strain from the fruiting body of Inonotus obliquus to improve the production of MPA. The fruiting body of Inonotus obliquus was used to isolate P. brevicompactum strains. Identification of the P. brevicompactum strain was performed by sequencing and phylogenetic tree analysis. HPLC assay was conducted to identify the production of MPA. Submerged liquid fermentation and bi-directional fermentation were applied to improve the yield of MPA. The candidates of the P. brevicompactum strain were isolated and screened from the fruiting body of Inonotus obliquus collected from Changbai mountains in China. Based on sequencing and phylogenetic tree analysis of 18S rDNA-ITS, the strain MC-4 was finally identified as P. brevicompactum. And HPLC assay indicated that the isolated P. brevicompactum strain could produce MPA in metabolic products. The optimized conditions of submerged liquid fermentation were as follows: 100 g/L Chinese yam in a liquid PDB medium, pH 6, fermentation temperature of 24 °C, shaker speed of 130 r/min, and fermentation time of 6 days. The maximum value of MPA production was 1.415 g/L after submerged liquid fermentation. Furthermore, the yield of MPA could be significantly increased to 1.537 g/L after bi-directional fermentation with the extractive from fructus Swietenia macrophylla (FSM). We demonstrated that a Penicillium brevicompactum strain isolated from the fruiting body of Inonotus obliquus can be used to improve the production of MPA by submerged liquid fermentation and bi-directional fermentation. This would provide a novel approach for more efficient and safer production of MPA.

Ultrasound assisted combined molecularly imprinted polymer for the selective micro-solid phase extraction and determination of aflatoxins in fish feed using liquid chromatography-tandem mass spectrometry

A combined procedure based on using ultrasounds for target isolation followed by porous membrane-protected micro solid phase extraction using a molecularly imprinted polymer as an adsorbent has been developed as a highly selective extraction and clean-up procedure for isolating aflatoxins B1, B2, G1, and G2 from fish feed before ultra-high-performance liquid chromatography tandem mass spectrometry determination. Polymeric adsorbent beads have been synthesized by the precipitation polymerization method which guarantees a homogeneous particles size distribution and the integrity of the generated imprinted cavities. In addition, polymerization was performed using a higher proportion of organic solvent (toluene) in the porogen mixture, which generates MIP particles adequate for interacting with targets dissolved in organic (hydro-organic) mixtures (extracts from fish feed). These approaches led to a selective and high efficient pre-concentration method for AFs. Ultrasound-assisted extraction (10 mL of 60:40 acetonitrile/0.1 M KH2PO4 pH 6.0, 40% amplitude, continuous sonication for 7.0 min) allowed an efficient aflatoxins isolation from fish feed. In addition, the resulting pH of the extract (pH 7.0) has been found to be the optimum for performing clean-up/pre-concentration (enrichment factor of 33.3) by molecularly imprinted polymer based micro-solid phase extraction (orbital horizontal shaking speed at 150 rpm for 10 min for loading, and 5 mL of 95:5 acetonitrile/formic acid as eluting solution using ultrasounds 35 kHz for 15 min). The current proposal was shown to be an accurate and precise method through relative standard deviation of intraday and inter-day tests below 20% and analytical recoveries in the range of 80–100%. The limits of detection were within the 0.42–1.15 μg kg−1 range, quite lower than those established by European Commission guidelines for aflatoxins in animal feeds.

Effect of media and fermentation conditions on surfactin and iturin homologues produced by Bacillus natto NT-6: LC\u2013MS analysis

Lipopeptides possess excellent broad spectrum antimicrobial activity. Different lipopeptides have their own unique chemical structures, properties and biological activities. Quantitative analysis of the lipopeptides iturin and surfactin and their homologues produced by Bacillus natto NT–6 subjected to different culture media, shaking speed of rotary shaker, and liquid and solid fermentation methods was conducted using LC–MS. For iturins, liquid-state fermentation in Landy medium at a shaking speed of 160 r min−1 was the most suitable for maximal homologue production. Addition of 0.4% attapulgite powder increased production by 1.92-fold; activated carbon significantly reduced production. For surfactin homologues, solid-state fermentation in potato dextrose broth medium at shaking speed > 160 r min−1 was the best. Addition of 0.4% attapulgite powder increased production by 1.96-fold; activated carbon had no effect. Thus it is clear that fermentation conditions can be manipulated to maximize iturin and surfactin production.