Aspergillus nidulans biofilm formation modifies cellular architecture and enables light-activated autophagy
Mol Biol Cell. 2021 Apr 7:mbcE20110734. doi: 10.1091/mbc.E20-11-0734. Online ahead of print.
After growing on surfaces, including those of medical and industrial importance, fungal biofilms self-generate internal microenvironments. We previously reported that gaseous microenvironments around founder Aspergillus nidulans cells change during biofilm formation causing microtubules (MTs) to disassemble under control of the hypoxic transcription factor SrbA. Here we investigate if biofilm formation might also promote changes to structures involved in exocytosis and endocytosis. During biofilm formation the ER remained intact but ER exit sites and the Golgi apparatus were modified as were endocytic actin patches. The biofilm driven changes required the SrbA hypoxic transcription factor and could be triggered by nitric oxide, further implicating gaseous regulation of biofilm cellular architecture. By tracking GFP-Atg8 dynamics, biofilm founder cells were also observed to undergo autophagy. Most notably, biofilm cells that had undergone autophagy were triggered into further autophagy by spinning disc confocal light. Our findings indicate that fungal biofilm formation modifies the secretory and endocytic apparatus and show biofilm cells can also undergo autophagy that is reactivated by light. The findings provide new insights into the changes occurring in fungal biofilm cell biology that potentially impact their unique characteristics, including antifungal drug resistance. [Media: see text].