| Description | The bacterial viability / toxicity detection kit contains two fluorescent dyes. Nucgreen is a green nucleic acid dye that can stain live and dead bacteria; Ethd III is a red nucleic acid dye that only stains dead bacteria with damaged cell membranes. When nucgreen and ethd III are properly mixed, The bacterial viability / toxicity detection kit contains two fluorescent dyes. Nucgreen is a green nucleic acid dye that can stain live and dead bacteria; Ethd III is a red nucleic acid dye that only stains dead bacteria with damaged cell membranes. When nucgreen and ethd III are properly mixed, the bacteria with intact cell membrane appear green, while the bacteria with damaged cell membrane can appear green and red under different channels, respectively. A common criterion for bacterial viability is the ability to propagate in a suitable nutrient medium, known as a growth assay. This kit is generally in good agreement with the growth assay results in liquid or solid medium. However, under certain conditions, membrane damaged bacteria may recover and propagate in nutrient medium, and such bacteria will be identified as dead bacteria in this assay. On the contrary, some bacteria with intact membranes may not be able to propagate in nutrient medium, but will be recognized as viable bacteria in this assay. Therefore, if there is a large difference between the test results of this kit and the bacterial growth assay, the above possibilities should be considered. Component： Product parameters： NucGreen: Ex/Em = 503/530 nm (结合 DNA)；EthD-III: Ex/Em = 530/620 nm (结合 DNA)。Usage:1 Preparation of control samples for live and dead bacteria (optional)1. Cultivate 4 mL of bacteria in liquid medium until late logarithmic phase.2. Prepare two 1 mL bacterial solutions in an EP tube and centrifuge for 10-15 minutes under 5000-10000 g conditions.3. Remove the supernatant and add 0.3 mL of 0.85% NaCl resuspended bacteria to one of the EP tubes, and 1 mL of 0.85% NaCl resuspended bacteria to the other tube.4. Add 0.7 mL of isopropanol to a tube containing 0.3 mL of 0.85% NaCl, and mix thoroughly (with a final concentration of 70% isopropanol) to prepare a dead bacterial sample.5. Incubate the two samples at room temperature for 1 hour and mix every 15 minutes.6. Centrifuge the two samples at 5000-10000 g for 10-15 minutes.7. Remove the supernatant, add 1 mL of 0.85% NaCl to resuspend the bacteria in both samples, and centrifuge again as in step 6.8. Use a spectrophotometer to measure the absorbance values (OD670) of two bacterial suspensions at 670 nm.9. Adjust the density of the two bacterial suspensions (live and dead) to 108 bacteria/mL (OD670 ≈ 0.3), and then dilute with 0.85% NaCl at 1:100 to achieve a final density of 106 bacteria/mL.10. Mix two bacterial suspensions as shown in the table below to obtain the required live cell ratio: dead cell ratio.Table 1 Mix live and dead bacterial suspensions by a certain volume to achieve the required ratio of live and dead cellsLive cells: Dead cellsVolume of viable bacterial suspension（mL）Volume of dead bacterial suspension（mL）0:10001.010:900.10.920:800.20.830:700.30.750:500.50.5100:01.00II Staining methods for fluorescence microscopy observation1. Mix 1 volume of component A, NucGreen, and 2 volumes of component B, EthD-III, in a microcentrifuge tube. After thorough mixing, add 8 volumes of 0.85% NaCl solution to obtain a 100 x dye solution.2. Every 100 µ L bacterial suspension, add 1 µ 100 x dye solution of L.3. Mix thoroughly and incubate at room temperature in the dark for 15 minutes.4. Take 5 µ The bacterial suspension after L staining was dropped onto a glass slide with an 18 mm square cover glass.5. Observe under a fluorescence microscope. The fluorescence of live and dead bacteria can be observed simultaneously under any standard FITC long-acting filter. Alternatively, live (green fluorescent) and dead (red fluorescent) bacteria can be observed using FITC and Cy3 (or Texas Red) channels, respectively.Attention: (1) Before staining bacteria, attention must be paid to removing residues of growth media. Nucleic acid and other media components can bind to NucGreen and EthD-III dyes in some way, resulting in unacceptable staining changes. A simple washing step is usually sufficient to remove interfering media components from bacterial suspension. It is not recommended to use phosphate buffer solutions as they can reduce staining efficiency. (2) Before starting the formal experiment, the dye concentration should be adjusted to distinguish between NucGreen labeling live bacteria and EthD-III labeling dead bacteria. The optimal concentration may vary depending on the bacterial strain. It is generally best to use the lowest dye concentration that can provide sufficient signal. The above conditions have been optimized for staining live/dead cells of Escherichia coli.III Before starting the staining method experiment of flow cytometry, please read the precautions under the fluorescence microscope staining steps.According to Table 1, add 11 different proportions of live and dead bacteria to the EP tube. Each of the 11 samples has a volume of 1 mL.2. Add 12 µ The A component of L, NucGreen, and 24 µ The B component EthD-III of L was mixed in a microcentrifuge tube. Add 3 to each of the 11 samples µ Mix the mixed dyes of L thoroughly by blowing them up and down several times. (Note: Additional control bacterial samples need to be prepared for separate NucGreen and EthD-III staining)3. Incubate at room temperature in the dark for 15 minutes.4. Analyze each sample using a flow cytometer, detect NucGreen positive cells using FITC channels, and detect EthD-III positive cells using PI or PE channels.Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. if the orifice plate is used for detection, a small amount of bacterial liquid can be left for imaging after standing for 10 min, which can effectively reduce the background. 3. in order to be closer to the real results, it is recommended to keep the brightness of red fluorescence consistent with that of green fluorescence in merge pictures. 4. fluorescent dyes have quenching problems. Please try to avoid light during experimental operation to slow down fluorescence quenching. 5. for your safety and health, please wear experimental clothes and disposable gloves.Scope of application：Staining of dead and live bacteria... Read More | The content of this cell is too long for an XLSX file (more than 32767 characters). Please use the CSV format for this export | Inquire | Inquire | Product content Q665687Component100 TStorageQ665687AQuick T4 DNA Ligase (15 U/µL)100 µL-20℃. Avoid freeze/thaw cycle.Q665687B2×Quick Ligation Reaction Buffer5×200 µL-20℃. Avoid freeze/thaw cycle. Product IntroductionThe Quick Ligation Reaction Kit allows ligationProduct content Q665687Component100 TStorageQ665687AQuick T4 DNA Ligase (15 U/µL)100 µL-20℃. Avoid freeze/thaw cycle.Q665687B2×Quick Ligation Reaction Buffer5×200 µL-20℃. Avoid freeze/thaw cycle. Product IntroductionThe Quick Ligation Reaction Kit allows ligation of DNA sticky or flush ends in 5 minutes at room temperature (25°C). The kit contains Quick T4 DNA Ligase and 2×Quick Ligation Reaction Buffer optimized for fast and efficient DNA ligation.The ligation efficiency of Quick Ligation is equivalent to 1 hour of conventional ligation with T4 DNA Ligase. The Quick Ligation products can be used directly in routine bacterial transformation experiments.matters needing attention1. This kit enables most of the linkage reactions to reach the reaction endpoint within 5 minutes or less at 25°C. Increasing the reaction time will not enhance the reaction efficiency. If you use the rapid connection reaction after 1 hour, the conversion efficiency will be significantly reduced; if the rapid connection reaction at 25 ℃ overnight, the conversion efficiency will drop to 75%.2. 2×Quick Ligation Reaction Buffer contains ATP, which should be thawed on ice and mixed thoroughly before use. It is recommended to freeze the buffer in small tubes for the first time, so as to avoid repeated freezing and thawing, which will affect the efficiency of DNA ligation.3. Since T4 DNA Ligase contains glycerol, which is sticky and easy to hang on the wall, it is recommended to collect the liquid to the bottom of the tube by centrifugation for a short period of time before use, and the tip of the lance should not go too deep into the liquid surface when taking samples to avoid sticking to the tip of the lance and causing losses.4. If the quick ligation product is used for electrotransformation, the PEG in the quick ligation reaction system will affect the efficiency of electrotransformation, and it is recommended to use a centrifugal column to purify the ligation product from DNA before electrotransformation.Usage1. The reaction solution was prepared according to the following system:*The amount of Insert DNA used: the molar ratio of Vector DNA and Insert DNA is generally 1:3-1:8, and the appropriate molar ratio of Vector DNA and Insert DNA can be selected according to the experimental situation.Calculation of DNA molar number: DNA molar number (nmol)=DNA mass (ng)/( 660daltons x number of inserted DNA bases bp).2. mix gently and centrifuge briefly. react at 25°C for 5 minutes.Note: The reaction time should not exceed 15 minutes, otherwise the connection efficiency will be reduced.3. Do not perform heat inactivation reactions. Centrifuge instantly and collect the solution from the wall to the bottom of the tube.Note: Heat inactivation significantly reduces transformation efficiency due to the presence of PEG in the buffer.4. After the reaction, store the DNA ligation product at 0-4℃, and then carry out transformation experiments; you can also store the DNA ligation product at -20℃.Note: When transforming by chemical method, do not add more than 10% of the volume of the receptor cell for the ligation product.5. Heat shock the ligation product to transform 50 µl of receptor cells or take 1-2 µl of ligation product to electroshock transform 50 µl of receptor cells.Note: 1) When transforming by chemical method, do not add more than 10% of the volume of the receptor cell for the ligation product.(2) If the quick ligation product is used for electrotransformation, it is recommended to use a centrifugal column to purify the ligation product from DNA before electrotransformation because the PEG in the quick ligation reaction system will affect the efficiency of electrotransformation... Read More |