Simpson Hunter J, Schilling Jonathan S
Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota, USA.
Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA.
Environ Microbiol. 2025 Jun;27(6):e70132. doi: 10.1111/1462-2920.70132.
Neurospora crassa is a popular model organism for laboratory research, yet its natural ecology remains mysterious. Its proliferation on charred plant biomass (wood and grasses) in fire-affected environments is often linked to the heat tolerance or heat-/chemical-induced germination of N. crassa spores; however, this link is not consistent across ecosystems or substrate types. Another possible, yet unvalidated, explanation is that N. crassa has an enhanced capacity for degrading charred (i.e., pyrolyzed) plant biomass. We assessed this adaptation for N. crassa by quantifying the decay of wood and grasses that were pyrolyzed to relevant extents (untreated, heated at 225°C or 350°C for 20 min) and by comparing this decay with non-fire-associated fungi. Neurospora crassa did not have an enhanced ability to degrade pyrolyzed substrates. Additionally, N. crassa struggled to degrade any wood substrate (< 6% mass loss) but did degrade untreated grasses (> 20% mass loss). These results, paired with chemical analyses of substrates pre- and post-decay, support a fire-response strategy for N. crassa, rather than a fire-adaptive ability to degrade charred substrates. This fungus likely proliferates on charred biomass by rapidly colonising heat-sterilised substrates after heat- or smoke-induced spore germination and then consuming unpyrolyzed lignocellulose beneath a charred exterior.
粗糙脉孢菌是实验室研究中常用的模式生物，但其自然生态仍然神秘。它在受火灾影响的环境中于烧焦的植物生物质（木材和草类）上繁殖，通常与粗糙脉孢菌孢子的耐热性或热/化学诱导萌发有关；然而，这种联系在不同生态系统或底物类型中并不一致。另一种可能但未经证实的解释是，粗糙脉孢菌具有增强的降解烧焦（即热解）植物生物质的能力。我们通过量化热解至相关程度（未处理、在225°C或350°C加热20分钟）的木材和草类的腐烂情况，并将这种腐烂情况与非火灾相关真菌进行比较，来评估粗糙脉孢菌的这种适应性。粗糙脉孢菌没有增强的降解热解底物的能力。此外，粗糙脉孢菌难以降解任何木材底物（质量损失<6%），但确实能降解未处理的草类（质量损失>20%）。这些结果，再加上对腐烂前后底物的化学分析，支持了粗糙脉孢菌的火灾响应策略，而不是降解烧焦底物的火灾适应能力。这种真菌可能通过在热或烟雾诱导孢子萌发后迅速定殖于热灭菌的底物上，然后消耗烧焦外表下未热解的木质纤维素，从而在烧焦的生物质上繁殖。
