Hi: Its not appropriate  to use Hgcl2 in tissue culture, you can use fungicide to treated. what kind of fungi is it?  

useful paper:

https://naturalsciences.byuh.edu/sites/naturalsciences.byuh.edu/files/Okazaki%20Jason%20Winter%202008%20Poster_0.pdf

https://www.researchgate.net/publication/227293247_Miconazole_An_effective_antifungal_agent_for_plant_tissue_culture

Article Miconazole: An effective antifungal agent for plant tissue culture

http://www.openwetware.org/images/7/77/Troubleshopoting_Cell_Culture.pdf

Thanks for your answer and reference. I dont recognise the exact species but its showing cotton like colony. 

If you can have picture under microscopy showing the spore and mycelium of the fungus.