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    CTAB DNA extraction protocol for fungi

    Erin Carr

    Published: 2022-10-12 DOI: 10.17504/protocols.io.n92ldp9qol5b/v1
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    Abstract

    CTAB Fungal DNA Extraction Protocol Erin Carr- University of Nebraska-Lincoln*Adapted from Cubero et al., 1999 and Lagonigro et al., 2004 February 2020; Updated August 15th, 2022

    Attachments

    2022-05-20_CTAB_Fungal_DNA_Extraction_Protocol.docx

    Steps

    Preparing Yeast from liquid culture for DNA extraction

    1.

    Grow fungi in preferred media type till fungi are in mid-exponential phase

    2.

    Centrifuge fungal samples at 10,000x g for 1 minute and wash with water 3 times, centrifuging in between, then obtain as tight of a fungal pellet as possible and remove all liquid from the tube.

    3.

    Place tube of cell pellet in liquid nitrogen to freeze cells, then keep tube in -80 freezer until you are ready to perform the DNA extraction.

    Preparing Yeast from solid culture for DNA extraction

    4.

    Grow fungi on preferred media type till fungi grows to its maximum on the plate

    5.

    Place 800µL of water in a 1.5mL tube and weigh recording the weight

    6.

    Scrape 0.03g of fungus off the plate and place into the tube, avoiding agar

    7.

    Centrifuge at 10,000x for 1 minute to obtain a fungal pellet and remove all water

    8.

    Place tube in liquid nitrogen to flash freeze, and place frozen tube in -80 freezer until you are ready to do the DNA extraction

    Lysing Filamentous fungi

    9.

    Grab as many mortar and pestles as necessary for the number of samples you have (or wash one out thoroughly with 70% ethanol between samples)

    10.

    Obtain liquid nitrogen placed in Dewar

    11.

    Place tubes with processed fungi in a small container and pour liquid nitrogen over the tubes until the fungi pellets are frozen completely

    12.

    With tube lids closed, tap the lids against the table to dislodge the pellet from the tube

    13.

    Put the frozen fungal pellet into the mortar and pour additional sterile Liquid nitrogen over the pellet

    14.

    Carefully grind the fungus being sure not to launch it out of the mortar, grind till the fungus is a powder, adding more liquid nitrogen if the fungus gets too liquidy

    15.

    Scrape ground up fungus out of the mortar and place in a fresh 1.5mL tube, place sample in -80° C freezer until ready for DNA extraction.

    DNA extraction Protocol (from cell growth to final DNA product):

    16.

    Grow fungi in preferred media type till fungi are in mid-exponential phase (3-7 days)

    17.

    Pipette 1 mL of fungus into a 1.5 mL tube

    18.

    Centrifuge fungal samples at 10,000x g for 1 minute

    19.

    Wash with 1 mL of ddH2O 3 times, centrifuging in between, then obtain as tight of a fungal pellet as possible and remove all liquid from the tube

    20.

    Take your 1.5 mL tube of washed cell pellet and place in liquid nitrogen to flash freeze and place tubes in -80 freezer till you’re ready to extract DNA

    21.

    START OF DNA EXTRACTION

    22.

    Turn on water bath/heat block to 70° C

    23.

    Determine the number of samples you will be processing, multiply that number by 750 µL to determine the amount of CTAB Extraction buffer you will need (700 µL per sample) and aliquot that out into a 15 mL centrifuge tube

    24.

    Add 1% w/v PVP (.01g/mL) and 1% v/v 20mg/mL Proteinase K (5µL/500µL) to your aliquoted CTAB Extraction buffer

    25.

    Grab as many bead beating tubes as you have samples

    26.

    Pour ~300uL of glass beads into tubes and label tubes accordingly

    27.

    Remove tubes of frozen fungus from the freezer

    28.

    Dislodge pellet from bottom of tube by pipetting 700 µL of the complete CTAB Extraction buffer into each frozen sample tube

    29.

    Transfer sample in CTAB Extraction buffer to Bead beating tube

    30.

    Put tubes in 70 °C water bath or heat block for 5 minutes, then bead beat for 5 minutes; repeat 2 more times (30 mins total) (change temperature of heat block/water bath to 37° C after this step, unless you have a 37° C incubator)

    31.

    Confirm cells have lysed via microscopy, 5 µL of sample onto a microscope slide. If cells have not lysed, bead beat for additional 2-5 minutes.

    32.

    Remove tubes from the water bath/heat block and transfer as much liquid as possible into a new 2 mL microcentrifuge tube, avoiding the glass beads

    33.

    Add 1x the volume of 24:1 Chloroform: Isoamyl to the tubes, invert tubes to mix and then centrifuge tubes at 10,000x g for 5 minutes

    34.

    Carefully remove tubes from centrifuge, collect upper layer only, and transfer the upper layer into a new 2 mL microcentrifuge tube

    35.

    Add 2 volumes of CTAB Precipitation buffer to the tubes and mix by inverting for 2 minutes

    36.

    Centrifuge tubes at 13,000x g for 15 minutes

    37.

    Remove supernatant, being sure to leave the pellet behind in the tube

    38.

    Re-suspend pellet in 350 µL of 5M NaCl

    39.

    Add 2µL of 10 mg/mL RNase A to tubes and place tubes at 37° C for 30 minutes

    40.

    Remove tubes from 37° C and add one volume of 24:1 Chloroform: Isoamyl; mix thoroughly by inverting

    41.

    Centrifuge tubes at 10,000x g for 5 minutes

    42.

    Remove upper phase and transfer to a new 1.5 mL tube

    43.
    1. Add 6 volumes of ice cold isopropanol and mix by inverting
    44.

    (PAUSE POINT) Place tubes in -20 °C freezer for 15 minutes OR OVERNIGHT/FOR MULTIPLE DAYS

    45.

    Centrifuge tubes in 4 °C at 13,000x g for 20 mins

    46.

    Remove all liquid and let air dry for 30 mins to over night, until it’s dry to remove excess alcohol

    47.

    Resuspend pellet in 30-50 µL of UltraPure water or TE buffer

    DNA clean-up

    48.

    Add 0.1 volumes of 3M Sodium Acetate and 3 volumes of ice cold 100% Ethanol to your DNA samples, mix by inverting.

    49.

    Freeze samples at -80° C for 20mins or at -20° C overnight.

    50.

    Centrifuge tubes at 4° C at max speed for 30 minutes

    51.

    Remove supernatant and resuspend pellet in 1mL of ice cold 70% Ethanol, being sure the DNA pellet becomes loose from the tube and floats freely in the liquid.

    52.

    Centrifuge at 4° C  at max speed for 10 minutes

    53.

    Remove Ethanol and let tubes dry completely with no ethanol left in the tubes. Overnight with running air over the open tubes works best.

    54.

    Pre-heat elution buffer (TE or water) at 65° C, then re-suspend DNA in 30-50µL of warmed elution buffer

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