Identification, growth characteristics, and genomic potential analysis of indole-3-acetic acid producing strain D1 in the rhizosphere of ancient tea forests

Chryseobacterium is one of the important beneficial microorganisms groups for protecting plant health. It has the functions of promoting host plant growth, stress resistance, inducing systemic resistance, and resisting pathogens, playing an important role in reducing soil biological barriers, and has broad application prospects. Therefore, screening for IAA producing Chryseobacterium and quickly understanding its genomic potential is of great significance in agricultural production. The unique ecological environment of wild ancient tea forests nurtures rhizosphere microbial resources with unique properties. This study identified the high-yielding indole-3-acetic acid (IAA) producing strain D1 from the rhizosphere of ancient tea forests as a new species of the Chryseobacterium genus, which is closely related to Chryseobacterium aureum and is recommended to be named Chryseobacterium tea sp. nov. Strain D1 exhibits excellent fermentation performance in producing IAA, achieving a maximum IAA yield of 149.24 mg/L after 60 h of fermentation in tryptophan medium. The optimal growth temperature for strain D1 is 25 °C, the optimal growth pH is 6, and the tolerance concentration to sodium chloride is 30 g/L. The genome of strain D1 contains abundant genetic resources for carbohydrate active enzymes, heavy metal resistance, secondary metabolite synthesis gene clusters, and plant pathogen resistance. This study enhances our understanding of the cultivation and genomic function of Chryseobacterium tea sp. nov, as well as the understanding of rhizosphere microorganisms in wild ancient tea forests. It also provides a theoretical basis for the development of Chryseobacterium tea sp. nov as functional fertilizers for crops.