Comparative analysis of phycospheric microbial diversity and metabolome between vegetative and matured conchocelis of Pyropia haitanensis

Pyropia haitanensis, relies heavily on conchocelis maturation for its production. However, the prolonged conchocelis development time limits the factory breeding of P. haitanensis. The development of algae is closely concerned in phycospheric microbial communities, yet little is known about the variations in these microbial communities across different conchocelis life stages. This study employed 16S rRNA, ITS gene sequencing and untargeted metabolomics to compare and analyze the phycospheric microbial communities and metabolites between filamentous conchocelis and sporangia branchlet stages. We identified 19 microorganisms with significantly different abundances and established a significant positive correlation with 10 key metabolites. These findings suggested that phycospheric microorganisms actively participated in metabolite synthesis during conchocelis maturation, influencing development, defense response, hormone levels, sulfur metabolism, protein and photosynthetic pigment synthesis. The differential microorganisms between filamentous conchocelis and sporangia branchlet stages were a vital factor in metabolite accumulation, highlighting the interconnectedness between phycospheric microorganisms and metabolites. Our research provided theoretical guidance for utilizing beneficial microorganisms to facilitate conchocelis maturation.