Fungi interact with bacteria in specific environmental niches through microbial cell–cell interactions and carry out various ecological functions collectively. However, there are a number of known associations wherein some bacteria reside within the hyphae of fungi, leveraging their growth, development, distribution and secondary metabolism. These bacteria are referred to as endohyphal bacteria (EHB). The EHB have been found to regulate key components of host reproductive machinery, induce the production of phytohormones, and play a complementary protective role for the host fungus under stress conditions. In a unique endohyphal association of Burkholderia with Rhizopus sp., it was found that the phytotoxin which is essential for pathogenecity of the fungus, was produced by the endosymbiont rather than the host fungus causing the rice seedling blight. The EHB were also found to influence the ecology and diversity of endophytic fungi colonizing higher plants. In some cases, the EHB help in activation of genes involved in the recognition processes, transcription regulation, and synthesis of primary metabolism proteins. Although, methods have been developed to isolate EHB in axenic culture, this symbiotic association provides enormous opportunities for new discoveries and new insights into fungal biology. In this review article, we present a discussion on EHB, their significance, and diverse functions in nature as unraveled by the latest research to understand this unique microbial association.

真菌通过微生物细胞间的相互作用与特定环境中的细菌相互作用，并共同执行各种生态功能。但是，有许多已知的关联，其中某些细菌利用它们的生长，发育，分布和次级代谢而驻留在真菌的菌丝内。这些细菌被称为菌丝内细菌（EHB）。已发现EHB可以调节宿主生殖机械的关键成分，诱导植物激素的产生，并在胁迫条件下对宿主真菌起到补充保护作用。在伯克霍尔德氏菌与根霉的独特菌丝内结合中业已发现，对于真菌的致病性必不可少的植物毒素是由内共生体而不是引起水稻幼苗枯萎的宿主真菌产生的。还发现EHB影响定植于高等植物中的内生真菌的生态和多样性。在某些情况下，EHB有助于激活涉及识别过程，转录调控和初级代谢蛋白合成的基因。尽管已经开发出在无菌培养物中分离EHB的方法，但这种共生联系为真菌生物学的新发现和新见解提供了巨大的机会。在这篇综述文章中，我们讨论了有关EHB，其重要性以及自然界中各种功能的讨论，而最新研究并未对此进行阐述，以了解这种独特的微生物关联。