Obligate symbionts (or Primary symbionts) are essential for their hosts’ survival and reproduction. They tend to supplement the hosts’ diet with amino acids or vitamins that are rare or absent in the food source. –Source
There has been research to find Bacterial Obligate Symbionts in Insects, and there are also findings for Obligate symbionts in Fungi.
Meaning that there are some fungi that rely heavily on Bacteria to survive or reproduce.
The exact mechanism and interaction requires further study, and there exists practical applications for findings of such research.
There was mention within some seminars of some Molds relying on Bacterial Obligate Symbionts for reproduction. Therefore removing the Bacterial Obligate Symbiont would prevent the Mold from reproducing. Yet I am unable to source the specific study or case, therefore treat this as a hypothetical.
The applications for this knowledge may result in a fungicide that can effectively eliminate specific molds or contain specific molds by targeting the Bacterial Obligate Symbionts.
Additionally, in theory, Commercial farms could yield better or stronger harvests for gourmet fungi by nurturing their associated Bacterial Obligate Symbionts (as applicable).
There are some studies into Bacteria-Fungi relationships, yet further research is required. Some examples can be found on Wikipedia linking to articles as well.
To Recap,
Bacteria plays a large role in a lot of living things, that includes fungi too. Inside fungi and outside fungi, Bacteria exists. There are some that are helpful to Fungi and these hold the key in whether Fungi dies, survives, or thrives.
As a side note, Arbuscular Mycorrhizi are Obligate Symbionts for some Plants and Trees. There are Fungi Obligate Symbionts as well. It appears that the ecosystem is very much connected with mutualistic relationships and non-mutualistic relationships.
Which poses an even more interesting connection between all the relations above coupled with the chemical (and other) communication between each through Quorum sensing. Thus, from a mycoremediation standpoint, Fungi alone may not be the most optimal solution, it may require more partners such as the trees, plants, and bacteria as well.
Hopefully this article broadens the horizons on the interesting things and connectivity of Fungi and overall Nature for you.
