There is relatively little difference between the two in terms of wetting ability, and none, in my own experience, in effects on Beauveria/Metarhizium/Isaria spores.

Re surface decontamination of plant tissues: I do a lot of endophytism work in wheat. Many published protocols just do not eliminate all surface contamination. My own validated recipe is

(1) 30 secs in dilute detergent (e.g., Dawn(r) dish detergent, 1 drop per liter, or 0.1% Silwet L77 (which makes the Tweens look like "Model T Fords" Silwet L77 is truly superior wetting agent.);

(2) 3 minutes in 2% NaOCl (that's ~40% household bleach) that has been acidified to pH of 5.5 for good disinfection power;

(3) 30 sec. in 70% EtOH;

(4) two successive 30 sec rinses in sterile reverse osmosis water.

All steps with continuous agitation.

Unacidified bleach does not work. Bleach concentrations < 2% NaOCl for 3+ minutes do not work well. Regardless of method a key quality control check is to make leaf imprints of each sample, or (in the case of my wheat) stem internode rolls, on PDA. I have found that plating the last rinse water, as a number of recent papers describe, gives lots of false results. In validating my method I found regular instances where plating rinse water gave no colony forming units, but a stem roll gave a nice track of 10-20 Beauveria colonies on PDA. A single surviving Beauveria/Metarhizium spore on plant cuticle can result in an outgrowth that seems like the fungus was endophytic. I do this "QC" check on EVERY sample I explant. If the PDA is positive I discard the explant data for that tissue.

In relation to surface disinfection and isolation from bean plants. First make sure your plant material has no soil by washing them of at least 30 minutes in running water. Bundle your plants loosely and use a pipette washer can work well. Let the washed plants dry out and then take your plant parts of interested and submerge them in 10% bleach and let them soak for 4 minutes. Have pre prepared sterile distilled water use this to rinse for one minute drain and aerate under a sterile hood. A general sterile media such as potato dextrose agar can be used to isolate a wide range of diverse organisms which withstand the surface treatment are are known as endophytes.

Dear Teodora Cavazos

Pls. find the attached

Article Detergents: Triton X-100, Tween-20, and More

Article Effect of Tween 80 on exploratory behavior and locomotor act...

http://www.jpharmsci.org/article/S0022-3549(16)31777-4/abstract

Article Detergent tween 80 modifies the specific activity of PAI-1

https://www.researchgate.net/post/what_is_difference_between_Tween80_and_Tween201

https://www.researchgate.net/post/What_is_the_difference_between_tween_20_and_tween_80

Hoping this will be helpful to your project, good luck

Regards

Prof. Houda Kawas

There is relatively little difference between the two in terms of wetting ability, and none, in my own experience, in effects on Beauveria/Metarhizium/Isaria spores.

Re surface decontamination of plant tissues: I do a lot of endophytism work in wheat. Many published protocols just do not eliminate all surface contamination. My own validated recipe is

(1) 30 secs in dilute detergent (e.g., Dawn(r) dish detergent, 1 drop per liter, or 0.1% Silwet L77 (which makes the Tweens look like "Model T Fords" Silwet L77 is truly superior wetting agent.);

(2) 3 minutes in 2% NaOCl (that's ~40% household bleach) that has been acidified to pH of 5.5 for good disinfection power;

(3) 30 sec. in 70% EtOH;

(4) two successive 30 sec rinses in sterile reverse osmosis water.

All steps with continuous agitation.

Unacidified bleach does not work. Bleach concentrations < 2% NaOCl for 3+ minutes do not work well. Regardless of method a key quality control check is to make leaf imprints of each sample, or (in the case of my wheat) stem internode rolls, on PDA. I have found that plating the last rinse water, as a number of recent papers describe, gives lots of false results. In validating my method I found regular instances where plating rinse water gave no colony forming units, but a stem roll gave a nice track of 10-20 Beauveria colonies on PDA. A single surviving Beauveria/Metarhizium spore on plant cuticle can result in an outgrowth that seems like the fungus was endophytic. I do this "QC" check on EVERY sample I explant. If the PDA is positive I discard the explant data for that tissue.

Thanks to all of you! Thanks for all the tips ( it helped me a lot!)!!

Dear Stefan, how are you? and how is the retirement? I heard that you donate your isolates to a Portuguese researcher that I met her at Gordon Research Conference in NH as well as in the 11th International Mycological Congress in San Juan, Puerto Rico, this year.

What is the difference between Tween 80 and Tween 20, is it concentration? So T80 is more concentrated than T20? Because I only use Tween 80 I do not know the differences. Therefore, I can not answer your question.

Here everything is well and I am organizing again the third International Symposium on Fungal Stress - ISFUS https://isfus2019.wordpress.com/ that will be next year.

My best wishes'

Drauzio

Hi Drauzio! Retirement: I am still in USDA but only until Dec 19. Then I retire, but only from USDA. We have house in Virginia to where we will move in March 2019. Best of all I will have room for a 100-130 sq meter lab in my home so I can continue do some fun insect pathology research (I have my own phase contrast microscope, other equipment, etc., etc. !) and also consult on fungus development, mass production, formulation. I have my first client as a result of SIP meeting in Australia. Maybe a second project too. "MycoSystems LLC" Motto: "Have Microscope, Will Travel" This fall I have a scientist from Republic of Georgia in my lab for three months, investigating aspect of my endophytic fungi in wheat. I retire two weeks after she finishes and leaves! My culture collection I am steadily moving to ARSEF collection in Ithaca. Going to Ecuador on two week in October to consult mass production there. I see you are very busy and productive, despite all teh Brazilian politics and economic situation.

Stefan Jaronski

It feels bad to know that you retire but at the same time, it feels good to know that you will still be in touch with research and development. Other than that you can contribute in scientific writing.

Best regards

As Stefan said. Both are same. I find no literature differentiating them.

Hi Teodora

I add to you some useful references

1# Evaluation of Beauveria bassiana Spore

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=2ahUKEwizwezE64XhAhVM_qQKHRghBUgQFjAFegQICRAC&url=https%3A%2F%2Fwaset.org%2Fpublications%2F4655%2Fevaluation-of-beauveria-bassiana-spore-compatibility-with-surfactants&usg=AOvVaw3k5us0wLDnlYszk1n7W4Q0

2# Effect of surfactants and temperature

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=2ahUKEwizwezE64XhAhVM_qQKHRghBUgQFjAGegQIBBAC&url=https%3A%2F%2Fpdfs.semanticscholar.org%2F6fa8%2F41c2ca7c1bc8abb3721c1d7e6272115af058.pdf&usg=AOvVaw0QHlYiSnD3y8F8UxTc01Vo

3# Tween-20 or Tween80 non-ionic surfactants

https://books.google.com.my/books?id=CyBJuCcFNsQC&pg=PA101&lpg=PA101&dq=use+Tween+80+instead+of+Tween+20+when+inoculate+spores+of+Beauveria&source=bl&ots=Sm4oAWld4c&sig=ACfU3U212SlI6ZXmzievQYcfTn1MqD-uGQ&hl=en&sa=X&ved=2ahUKEwizwezE64XhAhVM_qQKHRghBUgQ6AEwCXoECAEQAQ

4# Effects of Tween 80 on Growth

Article Effects of Tween 80 on Growth and Biofilm Formation in Labor...

5 # Tween 80, Product Information

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&ved=2ahUKEwih48e074XhAhWB6aQKHT3dCUUQFjANegQICxAC&url=http%3A%2F%2Ffoodsafety.neogen.com%2Fpdf%2Facumedia_PI%2F7992_PI.pdf&usg=AOvVaw0dHrI5UgQIf0Q-M8nskr1O

6# Tween 80 and Tween 20 Biocompatible Surfactants

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=17&cad=rja&uact=8&ved=2ahUKEwih48e074XhAhWB6aQKHT3dCUUQFjAQegQIAhAB&url=https%3A%2F%2Fwww.cospheric.com%2FTween80_Surfactant_density_gradients.htm&usg=AOvVaw1-5320gfIfWzVRo_KrXLTf

7 # Tween 80 - an overview

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=20&cad=rja&uact=8&ved=2ahUKEwih48e074XhAhWB6aQKHT3dCUUQFjATegQIBRAB&url=https%3A%2F%2Fwww.sciencedirect.com%2Ftopics%2Fpharmacology-toxicology-and-pharmaceutical-science%2Ftween-80&usg=AOvVaw2Qc9BnBXjt7t5D9IECgQhn

8# Effect of Tween 80 on the Morphology and Physiology

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&cad=rja&uact=8&ved=2ahUKEwja0_qO8oXhAhVS3KQKHQIkDkU4ChAWMAF6BAgKEAE&url=http%3A%2F%2Fmic.microbiologyresearch.org%2Fcontent%2Fjournal%2Fmicro%2F10.1099%2F00221287-119-1-195%3Fcrawler%3Dtrue%26mimetype%3Dapplication%2Fpdf&usg=AOvVaw2EkDgIx3zy60YDeD3A_kgH

9# Performance of the Biocompatible Surfactant Tween 80

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&cad=rja&uact=8&ved=2ahUKEwja0_qO8oXhAhVS3KQKHQIkDkU4ChAWMAJ6BAgHEAE&url=https%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fjac%2F2013%2F930356%2F&usg=AOvVaw3-JXrs8t5VBrls0XxQ6udQ

10# Polyoxyethylene sorbitan monooleate (Tween-80)/sorbitan monooleate

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=18&cad=rja&uact=8&ved=2ahUKEwja0_qO8oXhAhVS3KQKHQIkDkU4ChAWMAd6BAgBEAE&url=https%3A%2F%2Fiom3.tandfonline.com%2Fdoi%2Fpdf%2F10.1163%2F156855511X615669&usg=AOvVaw1RzqDgX6WyuMFfeB0VMZ-V