The family of Wenzhouxiangellaceae belongs to the order Chromatiales within the class Gammaproteobacteria, was initially proposed by Wang et al. (2015). At present, there are three validly published genera in this family, which are mainly distributed in intertidal sediment, marine sediment and the culture broth of a marine microalga (Zhang et al., 2024; Zhang et al., 2023; Wang et al., 2015). Wenzhouxiangella is the type genus of the family Wenzhouxiangellaceae, which was first discovered in marine algae cultures, and then also isolated from the coastal sediment and the saline lake (Guo et al., 2016; Zhang et al., 2020). At the writing time, the genus comprises four species and three of them had been validly published (https://lpsn.dsmz.de/genus/wenzhouxiangella). The cells display features typical of Gram-stain negative, non-spore-forming, non-motile, and do not participate in phototrophic processes. These organisms are characterized as moderately halophilic obligate aerobes, relying on chemoheterotrophic metabolism. The major fatty acids of this genus are isoC16:0 and isoC15:0. The predominant respiratory quinone identified is Q-8. Analysis of the polar lipid composition reveals the presence of diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol, along with an unidentified phospholipid.

Indoleacetic acid (IAA), a prominent member of the auxin class of plant hormones, plays a vital role in the growth and development of various plants, including algae (Chung et al., 2018; Labeeuw et al., 2016). Besides the plant itself, certain bacteria and fungi can secrete the phytohormone indole-3-acetic acid (IAA) to directly stimulate plant growth and development (Jaiswal et al., 2021; Khan et al., 2016). Research on indole-3-acetic acid (IAA)-producing microorganisms has predominantly centered on rhizosphere microorganisms, with limited studies focusing on those in aquatic environments. However, recent investigations have begun to explore the roles of IAA in aquatic ecosystems, revealing significant interactions between IAA-producing bacteria and aquatic plants (Popržen et al., 2023). At present, six IAA synthesis pathways have been discovered, and the TAM (tryptamine) pathway was first reported in plants (Phelps and Sequeira, 1967). However, the exploration of this pathway in microorganisms is limited, and further research is needed to elucidate the distribution and evolutionary relationships of this synthetic pathway among microorganisms.

Barkol lake, located 18 km northwest of Barkol County in Xinjiang, is the fourth largest saline lake in China, covering an area of 112.15 km2 and situated at an altitude of 1585 m (Lu et al., 2015). As a typical sulfate-type saline lake, it presents an extreme environment characterized by oligotrophic oxytrophication, high salinity, and elevated pH levels. These harsh conditions create a unique habitat where functional strains can adapt well and thereby enhance their potential utilization. In a study aimed at exploring the cultivable microbial diversity of saline lake sediments with varying nutrient supplements, two novel isolates, designated EGI_FJ10305T and EGI_FJ10409T, were successfully obtained from an enrichment culture using brine shrimp as substrates. These novel isolates exhibit significant phenotypic, chemotaxonomic, and molecular differences from other species within the genus Wenzhouxiangella, suggesting that strains EGI_FJ10305T and EGI_FJ10409T may represent two novel species within this genus. Three MAGs were recovered from enrichment systems adding same sediment with different nutrient resources, then a novel genus of the family Wenzhouxiangellaceae was subsequently proposed. To comprehensively explore IAA-producing bacteria in this underexplored extreme saline habitat, we employed both traditional cultivation techniques and metagenomic analysis. This integrated strategy aimed not only to isolate and characterize novel strains but also to recover genomes of uncultivated taxa potentially contributing to IAA production, while subsequently investigating their global distribution patterns.