Department of Agricultural and Food Sciences, University of Bologna, Bologna, Italy.
Department of Life, Health and Environmental Science, University of L'Aquila, L'Aquila, Italy.
Environ Microbiol Rep. 2024 Jun;16(3):e13271. doi: 10.1111/1758-2229.13271.
Tuber magnatum is the most expensive truffle, but its large-scale cultivation is still a challenge compared to other valuable Tuber species. T. magnatum mycelium has never been grown profitably until now, which has led to difficulties to studying it in vitro. This study describes beneficial interactions between T. magnatum mycelium and never before described bradyrhizobia, which allows the in vitro growth of T. magnatum mycelium. Three T. magnatum strains were co-isolated on modified Woody Plant Medium (mWPM) with aerobic bacteria and characterised through microscopic observations. The difficulties of growing alone both partners, bacteria and T. magnatum mycelium, on mWPM demonstrated the reciprocal dependency. Three bacterial isolates for each T. magnatum strain were obtained and molecularly characterised by sequencing the 16S rRNA, glnII, recA and nifH genes. Phylogenetic analyses showed that all nine bacterial strains were distributed among five subclades included in a new monophyletic lineage belonging to the Bradyrhizobium genus within the Bradyrhizobium jicamae supergroup. The nifH genes were detected in all bacterial isolates, suggesting nitrogen-fixing capacities. This is the first report of consistent T. magnatum mycelium growth in vitro conditions. It has important implications for the development of new technologies in white truffle cultivation and for further studies on T. magnatum biology and genetics.
块菌是最昂贵的块菌，但与其他有价值的块菌物种相比，其大规模种植仍然是一个挑战。到目前为止，块菌菌丝体从未盈利性地生长过，这导致了在体外研究它的困难。本研究描述了块菌菌丝体与从未描述过的慢生根瘤菌之间的有益相互作用，这使得块菌菌丝体的体外生长成为可能。三种块菌菌株与好氧细菌一起在改良的木本植物培养基（mWPM）上共分离，并通过显微镜观察进行了特征描述。仅在 mWPM 上培养两种单独的合作伙伴，细菌和块菌菌丝体，都存在困难，这证明了它们的相互依存关系。从每个块菌菌株中获得了三个细菌分离株，并通过测序 16S rRNA、glnII、recA 和 nifH 基因对其进行了分子特征描述。系统发育分析表明，所有 9 株细菌菌株均分布在 5 个亚群中，这些亚群属于根瘤菌属内的 Bradyrhizobium jicamae 超群中的一个新的单系谱系。所有细菌分离株中均检测到了 nifH 基因，表明它们具有固氮能力。这是首次报道块菌菌丝体在体外条件下持续生长。这对开发白块菌栽培新技术以及进一步研究块菌生物学和遗传学具有重要意义。
