Institute of Food Chemistry and Food Biotechnology, Justus-Liebig-University Giessen, 35292 Giessen, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Bioresources, 35392 Giessen, Germany.
Institute of Food Chemistry and Food Biotechnology, Justus-Liebig-University Giessen, 35292 Giessen, Germany.
Microbiol Res. 2023 Jan;266:127250. doi: 10.1016/j.micres.2022.127250. Epub 2022 Nov 1.
Bacteria play an important role in the life cycle of fungi by influencing positively or negatively morphological features, mycelial growth and/or fruiting body induction. However, little is known about the underlying mechanisms and their species-dependence, especially among fungi of the phylum Basidiomycota. Hence, we analyzed the effects of seven bacterial isolates, that were previously obtained from Pleurotus ostreatus HK35, on the mycelial growth of P. ostreatus HK35, Pleurotus eryngii DSMZ 8264, Pleurotus sapidus DSMZ 8266, Pleurotus citrinopileatus DSMZ 5341, Cyclocybe aegerita AAE-3, Lentinula edodes CBS 389.89 and Kuehneromyces mutabilis DSMZ 1013 during eight days. Notably, the bacterial isolates only showed significant mycelial growth-promoting effects when co-cultivated on Petri dishes with Pleurotus species, except for P. citrinopileatus. In particular, Paenibacillus peoriae strain M48F induced remarkably the mycelial growth in P. ostreatus (∼47 %), P. eryngii (∼32 %) and P. sapidus (∼27 %) during the early cultivation stages, but with ongoing cultivation this strain inhibited the growth of all fungi. To investigate the impact of bacterial volatile organic compounds (VOCs) on the mycelial growth, P. ostreatus and P. eryngii were co-cultivated with the bacteria on bi-plates. No growth inhibition on bi-plates was observed while bacterial isolates and mycelia were separated by a physical barrier, assuring that late mycelial growth inhibition was not caused by bacterial volatile compounds. VOCs from strain M48F induced the strongest growth of P. ostreatus (∼50 %) and P. eryngii (∼20 %) mycelia compared to controls. Furthermore, we analyzed the VOCs of strain M48F alone and in combination with P. ostreatus, P. eryngii, P. sapidus and L. edodes using bi-plates and SPME-GC-MS. Strain M48F triggered the formation of β-bisabolene when co-cultivated with P. ostreatus or P. eryngii, which may indicate a fungal defense reaction. Additionally, 2,5-diisopropylpyrazine dominated the volatilome of strain M48F on all eight sampling days. In samples of strain M48F, alone and co-cultivated with L. edodes, the amount of 2,5-diisopropylpyrazine remained quite constant. In contrast, the quantity of this substance declined substantially in co-cultures with P. ostreatus. Interestingly, 2,5-diisopropylpyrazine enhanced P. ostreatus mycelial growth significantly although the growth-promoting effect was not as pronounced as during co-cultivation with strain M48F. Our results show that the mycelial growth-promoting effects of bacteria are remarkably species-dependent, and that bacterial VOCs such as 2,5-diisopropylpyrazine can enhance mycelial growth.
细菌通过影响真菌的形态特征、菌丝生长和/或子实体诱导，在真菌的生命周期中发挥着重要作用。然而，人们对潜在机制及其物种依赖性知之甚少，尤其是在担子菌门的真菌中。因此，我们分析了之前从糙皮侧耳 HK35 中获得的 7 种细菌分离株对糙皮侧耳 HK35、杏鲍菇 DSMZ 8264、美味牛肝菌 DSMZ 8266、金顶侧耳 DSMZ 5341、环柄香菇 AAE-3、香菇 CBS 389.89 和滑菇 DSMZ 1013 的菌丝生长的影响，共 8 天。值得注意的是，只有当与糙皮侧耳属的物种在培养皿上共培养时，细菌分离株才表现出显著的菌丝生长促进作用，除了金顶侧耳属外。特别是佩诺氏芽孢杆菌 M48F 在早期培养阶段显著诱导糙皮侧耳（约 47%）、杏鲍菇（约 32%）和美味牛肝菌（约 27%）的菌丝生长，但随着培养的进行，该菌株抑制了所有真菌的生长。为了研究细菌挥发性有机化合物（VOCs）对菌丝生长的影响，将糙皮侧耳和杏鲍菇与细菌在双板上共培养。当细菌分离株和菌丝体通过物理屏障分离时，在双板上没有观察到生长抑制，这确保了后期的菌丝体生长抑制不是由细菌的挥发性化合物引起的。与对照相比，M48F 菌株的 VOC 诱导糙皮侧耳（约 50%）和杏鲍菇（约 20%）菌丝生长的效果最强。此外，我们使用双板和 SPME-GC-MS 分析了 M48F 菌株单独和与糙皮侧耳、杏鲍菇、美味牛肝菌和香菇共培养时的 VOC。当与糙皮侧耳或杏鲍菇共培养时，M48F 菌株触发了 β-毕圆烯的形成，这可能表明是真菌的防御反应。此外，2,5-二异丙基吡嗪在所有 8 个采样日都主导着 M48F 的挥发组。在 M48F 菌株的样本中，单独培养和与香菇共培养时，2,5-二异丙基吡嗪的含量保持相当稳定。相比之下，在与糙皮侧耳共培养时，这种物质的数量大幅下降。有趣的是，尽管 2,5-二异丙基吡嗪与 M48F 菌株共培养时的促生长作用没有那么明显，但它显著促进了糙皮侧耳的菌丝生长。我们的结果表明，细菌的菌丝生长促进作用具有显著的物种依赖性，并且细菌 VOC，如 2,5-二异丙基吡嗪，可以促进菌丝生长。
