1-Aminocyclopropane-1-Carboxylate Deaminase-Producing Bacteria Associated with Phlebopus portentosus Using Culture-Independent and -Dependent Methods

Abstract

The diversity of ACC deaminase-producing bacteria in the casing soil of Phlebopus portentosus and their roles in fruiting body development were investigated in this study. The dynamic succession of the functional microbial community in casing soil at different developmental stages, including the original casing soil (FT), mycelial stage (JS), pinhead stage (EJ), primordium stage (YJ), and harvest stage (CS), was analyzed by acdS gene high-throughput sequencing, enrichment isolation, and co-culture assays. The results showed that the richness and diversity of the acdS gene community were highest in the JS samples, and then decreased significantly at the EJ and CS stages. Proteobacteria became the dominant phylum after fruiting body formation, and its relative abundance reached 99%. In contrast, the relative abundance of Actinobacteria decreased significantly. At the genus level, Burkholderia and Paraburkholderia were dominant across all developmental stages. A total of 177 ACC deaminase-producing bacterial strains were isolated through enrichment cultivation, all of which belonged to the genus Burkholderia. Co-culture assays showed that 10 representatives of these strains significantly promoted mycelial growth, primordium formation, and fruiting body yield. The maximum yield increase reached 54%. This study is the first to systematically reveal the succession pattern of ACC deaminase-producing bacteria in the casing soil of P. portentosus. It provides an important basis for elucidating the molecular mechanism by which casing soil microbiota promotes fruiting body development.