My group has worked on a fungal exocellular beta-glucan over the last 25 years and details on our published works are available at: https://en.wikipedia.org/wiki/Botryosphaeran
I'd like to help you, but my research is about data mining. I've never been exposed to fungal extracellular dextran, so I don't have any literature on fungal extracellular dextran.