Protected areas are widely considered an essential strategy for biodiversity conservation. Dictyostelids are unique protists known to have important ecological functions in promoting soil and plant health through their top-down regulation of ecosystem processes, such as decomposition, that involve bacterial populations. But the relationship between dictyostelid diversity within protected areas remains poorly understood, especially on a large scale. Herein, we report data on the distribution of dictyostelids, identified with ITS + SSU rRNA molecular and morphology-based taxonomy, from soil samples collected in the Fanjing Mountain protected area of Guizhou Province, Southwest China. We compared the biodiversity data of dictyostelids in Fanjing Mountain with similar data from previously sampled sites in four other protected areas, including Changbai Mountain (CB), Gushan Mountain (GS), Baiyun Mountain (BY), and Qinghai–Tibet Plateau (QT) in China. We identified four species of dictyostelids belonging to three genera (Dictyostelium, Heterostelium, and Polysphondylium) and herein provide information on the taxonomy of these species. Two species (Heterostelium pallidum and Dictyostelium purpureum) are common and widely distributed throughout the world, but one species (Polysphondylium fuscans) was new to China. Our data indicate that there is no distinguishable significant correlation between the dictyostelid species studied and environmental factors. Overall, the similarity index between Baiyun Mountain in Henan Province and Fanjing Mountain in Guizhou Province, located at approximately the same longitude, is the highest, and the Jaccard similarity coefficients (Jaccard index) of family, genus, and species are 100%, 100%, and 12.5%, respectively. From a species perspective, species in the same climate zone are not closely related, but obvious geographical distributions are evident in different climate zones. This preliminary study provided evidence of the ecological adaptation of dictyostelids to different biological niches.

Species of Sanghuangporus produce abundant bioactive compounds, including flavonoids, polysaccharides, and triterpenoids, among which flavonoids exhibit prominent antioxidant activity and great development potential. Taking the peak extracellular flavonoid (EF) concentration in fermentation broth as the index, we optimized the liquid fermentation media and conditions for three Sanghuangporus strains (wild S. vaninii Z-0090, cultivar S. vaninii Z-0119, and cultivar S. baumii Z-0118) via single-factor experiments and the Box–Behnken response surface methodology. We further evaluated the antioxidant activity of the fermentation broth and analyzed its correlation with EF concentration using Pearson correlation analysis. After optimization, the EF concentrations of strains Z-0090, Z-0119 and Z-0118 were increased by 22.82%, 13.47% and 16.66%, respectively, compared with the control group. Antioxidant assays showed that strain Z-0090 had the highest hydroxyl radical scavenging rate (88.63%), strain Z-0119 presented balanced performance across all antioxidant indicators, and strain Z-0118 exhibited the strongest ABTS radical scavenging capacity (184.96 μg Trolox equivalents/mL), which was highly correlated with its EF concentration. This study provides a theoretical basis for the application of Sanghuangporus EFs in food, medicine, and industrial flavonoid production.

Dictyostelids represent a crucial element in the protist community, and their abundant presence in Jilin Province underscores their indispensable role in biodiversity conservation. In the present study, a resource survey of dictyostelids used random sampling to collect 28 soil samples from five localities in Changbai Korean Autonomous County, Jilin Province. In addition, a compilation of dictyostelid species reported from Jilin Province was developed, based on a thorough review of the literature. The survey yielded fifteen isolates of dictyostelids, comprising six species from four genera. Notably, two new species (Dictyostelium longigracilis sp. nov. and Dictyostelium macrosoriobrevipes sp. nov.) were described using morphological characteristics and SSU gene-based phylogenetic analyses. One other species (Polysphondylium patagonicum) was recorded as new for China, while another (Cavenderia aureostipes) was recorded as a new record for Jilin Province. The dictyostelid assemblage in Jilin Province is dominated by the genus Dictyostelium (51.4%), with a total of 35 species, which represent 59.3% of the current total known for all of China. These findings provide a scientific basis for the protection of species diversity and resource utilization of dictyostelids in Jilin Province.

China’s northeastern black soil region, a global black soil hotspot, is vital for supporting national food security with its fertile and agricultural-friendly soil. The dictyostelids are well-known eukaryotic microorganisms with an unusual multicellular stage in their life cycle, and they inhabit surface soils worldwide. Although numerous species have been isolated from forest ecosystems and their remarkable biological activities have been reported, species of plant-associated dictyostelids of agroecosystems remain surprisingly understudied, especially in the agroecosystems of the black soil region of Jilin Province. In this study, the diversity of this group was evaluated based on corn, cabbage, and soybean soil samples from black soil land, including mollisol and chernozem soil types in Jilin Province of China. Morphological characterization and molecular analyses of the nuclear small subunit (18S) were used for species delineation. A total of 20 strains of dictyostelids were isolated from four localities, and on the basis of morphological examination and molecular phylogenetic analyses, five species of dictyostelids are described as new to science. These are Coremiostelium viridiflava , Raperostelium macrosorus , Dictyostelium torta , Cavenderia densissima , and Polysphondylium sparsiramus . These new species are described in detail, with morphological and molecular distinctions from their closest relatives explicitly discussed. This study not only revealed the diversity of dictyostelids in agroecosystems but also provided more research data for further studies in black soil land microbe protection in China. IMPORTANCE: Despite the recognition of the presence of dictyostelids in various ecosystems, only limited information is available on their diversity and characteristics, particularly in the agroecosystems of China’s northeastern black soil region. These eukaryotic microorganisms are known for their multicellular life cycle stages and widespread occurrence in surface soils. However, the species of dictyostelid in the black soil region of Jilin Province remain largely unexplored. In this study, a total of 20 dictyostelid strains, including five newly described species, were isolated and characterized from soil samples. Morphological examination and molecular phylogenetic analysis were conducted to document these new species. This research not only revealed the diversity of dictyostelid species in this important agroecosystem but also provided valuable data for future studies on microbe protection in China’s black soil land. The discovery and detailed analysis of these new species contribute to our understanding of dictyostelid ecology, biology, and potential roles in agroecosystems.