Aug 14, 2024
SNA (Synthetic Nutrient Deficient) Agar for Identification fungi
- 1Oklahoma State University
Protocol Citation: Gabriela S Paredes 2024. SNA (Synthetic Nutrient Deficient) Agar for Identification fungi. protocols.io https://dx.doi.org/10.17504/protocols.io.261ge5jkjg47/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: August 14, 2024
Last Modified: August 14, 2024
Protocol Integer ID: 105230
Keywords: SNA, identification of fungi, fungal taxonomy
Funders Acknowledgements:
USDA
Grant ID: 2021-67013-33943
Disclaimer
This protocol is provided for educational and research purposes only. The procedures described herein should be conducted by trained personnel in a properly equipped laboratory, adhering to all relevant safety and ethical guidelines. The authors and publishers of this protocol are not responsible for any injuries, damages, or legal consequences that may result from the improper use of this protocol. The use of chemicals, reagents, and equipment should be done with caution, and users must ensure they are compliant with all local, national, and institutional regulations.
Users are responsible for ensuring that their work complies with applicable biosafety and bioethics standards, particularly when handling genetically modified organisms (GMOs), pathogens, or other hazardous materials. This protocol does not constitute medical, legal, or professional advice, and should not be used as a substitute for consultation with qualified professionals in those fields.
Abstract
SNA (Spezieller Nährstoffarmer Agar), or Synthetic Nutrient Deficient Agar, is a specialized culture medium designed for the identification and study of fungi such as Fusarium and Cylindrocarpon. This medium is nutrient-deficient, promoting specific morphological characteristics in these fungi that are critical for accurate identification. SNA is frequently used in mycological research and diagnostics, particularly in laboratories focused on plant pathology and fungal taxonomy. If the goal is to observe and document specific growth patterns, sporulation, or other morphological traits of these fungi under nutrient-limited conditions, SNA agar provides an optimal environment.
When Not to Use SNA Agar:
Isolation of Nutrient-Demanding Fungi:
- For fungi that require richer nutrient environments for growth, such as certain saprophytic or pathogenic fungi not belonging to Fusarium or Cylindrocarpon, SNA agar would not provide the necessary nutrients for their development.
Rapid Growth and Mass Production:
- If the objective is to rapidly grow and mass-produce fungal cultures for spore collection or other applications, a nutrient-rich medium such as Potato Dextrose Agar (PDA) or Sabouraud Dextrose Agar (SDA) would be more appropriate
Guidelines
- Aseptic Technique: Ensure that all steps, especially post-autoclaving, are conducted under aseptic conditions to prevent contamination.
- Homogeneous Mixing: Stir the medium well after dissolving the components and before autoclaving to ensure uniform distribution.
- Temperature Control: Allow the medium to cool to approximately 50°C before pouring to prevent the formation of condensation in Petri dishes and to maintain the sterility of the medium.
Materials
- 1.0 g of KH2PO4 (Potassium dihydrogen phosphate)
- 1.0 g of KNO3 (Potassium nitrate)
- 0.5 g of MgSO4·7H2O (Magnesium sulfate heptahydrate)
- 0.5 g of KCl (Potassium chloride)
- 0.2 g of Glucose
- 0.2 g of Sucrose
- 20 g of Agar
- Distilled water (1 liter)
- Sterile Petri dishes
Equipment
Adventurer™ Analytical Balances
NAME
Analytical balance
TYPE
Ohaus
BRAND
30100600
SKU
LINK
Equipment
8-Liter Autoclave
NAME
Portable Stainless Steel Pressure Steam Sterilizer
TYPE
China
BRAND
XFS-D-8L
SKU
LINK
Voltage: 220 V (AC)
Power: 1.2 kW
Working Medium: Steam
Design Pressure: 0.17 MPa
Working Temperature: 129 °C
Frequency: 50 Hz
Useful Life: 5 Years
Delivery Date: 3. Oct, 2019
SPECIFICATIONS
Equipment
Laminar Flow Hood
NAME
Benchtop workstation
TYPE
Envirco
BRAND
TT4830
SKU
Safety warnings
Chemical Handling:
- Handle all chemicals, especially potassium nitrate (KNO3) and magnesium sulfate heptahydrate (MgSO4·7H2O), with care. Wear appropriate personal protective equipment (PPE), including gloves, lab coats, and eye protection, to avoid skin contact, inhalation, or ingestion.
- Ensure that potassium nitrate, an oxidizing agent, is kept away from flammable materials and heat sources to prevent combustion or explosion risks.
Sterilization Safety:
- When using the autoclave, ensure that the lid is securely closed and that the pressure has fully released before attempting to open the autoclave to avoid burns from steam or hot liquids.
- Handle the sterilized medium with heat-resistant gloves to prevent burns.
Aseptic Technique:
- Maintain a sterile environment when handling the medium post-autoclaving to prevent contamination. Work under a laminar flow hood if possible and always sterilize tools and containers before use.
Temperature Control:
- Allow the medium to cool to around 50°C before handling or pouring it into Petri dishes. Pouring the medium while it's too hot can cause burns and may also result in condensation forming inside the Petri dishes, which can affect the medium's integrity.
Glassware Handling:
- When working with hot glassware, such as the Erlenmeyer flask after autoclaving, use heat-resistant gloves to avoid burns. Place hot glassware on a heat-resistant surface and avoid rapid temperature changes to prevent breakage.
Before start
Before starting the preparation of SNA medium, ensure that all necessary materials and equipment are available and properly sterilized. Measure out all the required chemical components accurately.
Dissolve SNA Components:
Dissolve SNA Components:
In a 1-liter Erlenmeyer flask, dissolve the following components in 1 liter of distilled water (dH2O):
- 1 g of KH2PO4 (Potassium dihydrogen phosphate)
- 1 g of KNO3 (Potassium nitrate)
- 0.5 g of MgSO4·7H2O (Magnesium sulfate heptahydrate)
- 0.5 g of KCl (Potassium chloride)
- 0.2 g of Glucose
- 0.2 µL of Sucrose
- 20 g of Agar
Sterilize:
Sterilize:
- Autoclave the solution at 121°C for 20 minutes to sterilize the medium.
- After autoclaving, allow the medium to cool to around 50°C before pouring it into Petri dishes.
Pour into Petri Dishes:
Pour into Petri Dishes:
- Work aseptically to pour the medium into sterile Petri dishes.
- Allow the agar to solidify at room temperature before use.
Protocol references
Leslie, J.F., & Summerell, B.A. (2006). The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA.