Three yeast strains belonging to the ascomycetous yeast genus Pichia were isolated from two soil samples from Yunnan and Guizhou provinces and a marine water sample from Liaoning province, PR China. Phylogenetic analyses based on the sequences of the D1/D2 domains of the large subunit(LSU) rRNA gene and the internal transcribed spacer (ITS) region indicate that these three strains, together with 12 additional strains isolated from various substrates collected in different regions or countries of the world, represent a novel species of the genus Pichia, for which the name Pichia kurtzmaniana sp. nov. (holotype: strain CGMCC 2.7213) is proposed. The novel species differs from its close relatives Candida californica by eight (1.5 %) and 26 (11.1 %) mismatches in the D1/D2 domains and the ITS region, respectively; and from Pichia chibodasensis by 11 (2.1 %) and 20 (8.7 %) mismatches in the D1/D2 domains and the ITS region, respectively. In addition, eight Candida species which belong to the Pichia clade are transferred to the genus Pichia, resulting in the proposal of the following new combinations: Pichia cabralensis comb. nov., Pichia californica comb. nov., Pichia ethanolica comb. nov., Pichia inconspicua comb. nov., Pichia phayaonensis comb. nov., Pichia pseudolambica comb. nov., Pichia rugopelliculosa comb. nov., and Pichia thaimueangensis comb. nov.

Plant rhizosphere soil contains a large number of plant-growth promoting rhizobacteria, which can not only resist the invasion of pathogenic microorganisms and protect plants from damage, but also promote the growth and development of plants. In this study, Pseudomonas aeruginosa strain YY322, isolated and screened from the rhizosphere soil of saffron (Crocus sativus L.), was found through a plate confrontation experiment to show highly effectual and obvious antagonistic activity against the pathogens of saffron, including Fusarium oxysporum, Fusarium solani, Penicillium citreosulfuratum, Penicillium citrinum and Stromatinia gladioli. In addition, the volatile organic compounds of strain YY322 had great antagonistic activity against these pathogens. Observation under a scanning electron microscope and transmission electron microscope reflected that strain YY322 had a significant effect on the hyphae and conidia of F. oxysporum and F. solani. Through the detection of degrading enzymes, it was found that P. aeruginosa can secrete protease and glucanase. The plant growth promoting performance was evaluated, finding that strain YY322 had the functions of dissolving phosphorus, fixing nitrogen, producing siderophore and producing NH₃. In addition, whole genome sequencing analysis indicated that the YY322 genome is comprised of a 6,382,345-bp circular chromosome, containing 5809 protein-coding genes and 151 RNA genes. The P. aeruginosa YY322 genome encodes genes related to phenazine (phzABDEFGIMRS), hydrogen cyanide(HCN) (hcnABC), surfactin (srfAA), salicylate (pchA), biofilm formation (flgBCDEFGHIJKL, motAB, efp, hfq), and colonization (minCDE, yjbB, lysC). These results collectively indicated the role of P. aeruginosa YY322 in plant growth enhancement and biocontrol mechanisms. All in all, this study provides a theoretical basis for P. aeruginosa as the PGPR of saffron, paving the way for the subsequent development and utilization of microbial fertilizer.

Fermented foods have been produced by humans since prehistoric times and are consumed worldwide today due to their enhanced nutritional value, taste and flavor, and benefits for human health. Various microorganisms are essential agents responsible for food fermentation and have been extensively studied using both culture-dependent and -independent methods. However, previous research has mainly focused on fermented foods produced on a large scale in urbanized areas. In this study, we collected 255 samples of diverse traditional fermented foods—including alcoholic beverages, amylolytic starters, fruit vinegar, and fermented products of milk, vegetables, cereals, legumes, fish, meat, and other materials—from ethnic minority areas of China through a citizen science initiative for the study of yeast diversity. A total of 516 yeast strains were isolated, and 81 yeast species, including four new species, were identified based on sequence analyses of the D1/D2 domain of the large subunit rRNA gene and the internal transcribed spacer region. The proposals of the new species were further supported by whole-genome average nucleotide identity (ANI) analysis. The dominant species isolated were Saccharomyces cerevisiae, Pichia kudriavzevii, Wickerhamomyces anomalus, Saccharomycopsis fibuligera, and Clavispora lusitaniae. The new species are described as Blastobotrys guizhouensissp. nov., Wickerhamiella shiruiisp. nov., Trichosporon jiuqusp. nov., and Parajaminaea albasp. nov. This study demonstrates the high yeast diversity in traditional fermented foods of ethnic minorities in China. These yeast resources are of special value for both basic and applied research in the future.

The genus Pichia belonging to the family Pichiaceae is widely distributed worldwide and has garnered significant attention due to its importance in various industries and its potential role in human infections. During our investigation of yeast diversity in China, several strains representing undescribed taxa were isolated from forests in Hainan province, Hubei province, Beijing city and a mudflat in Guangdong province. Based on phylogenetic analyses of the internal transcribed spacer (ITS) region and the D1/D2 domain of the large subunit (LSU) rRNA, these strains were identified as four new species: Pichia kregerianasp. nov. (holotype strain CGMCC 2.7383^T), P. phaffiisp. nov. (holotype strain CGMCC 2.8239^T), P. ureolyticasp. nov. (holotype strain CGMCC 2.6825^T) and P. wuzhishanensis f.a. sp. nov. (holotype strain CGMCC 2.7381^T). The six strains of P. ureolytica were identified as positive for urease production. This phenomenon is extremely rare in the genus Pichia, as only P. bovicola is reported to exhibit weak urease activity.

A study on yeast species from the genera Geotrichum and Magnusiomyces in southwest and central China was conducted based on morphological and molecular phylogenetic analyses using the ITS region and the D1/D2 domain of the LSU rRNA gene. The research identified two new yeast species: Geotrichum hubeiense and Magnusiomyces pitmudophilus. The study contributed to understanding arthroconidial yeast diversity in fermentation and natural environments and paved the way for future taxonomic and ecological studies. Descriptions, illustrations, and phylogenetic analysis results of the two new taxa are provided.

A yeast strain (CGMCC 2.6937^T) belonging to the ascomycetous yeast genus Saturnispora was recently isolated from soil collected in Xinghuacun, Shanxi Province, PR China. The strain produces one or two ellipsoid or spherical ascospores in asci formed by the conjugation between a cell and its bud. Phylogenetic analyses of the internal transcribed spacer (ITS) region and the D1/D2 domain of the large subunit rRNA gene suggest that this strain is conspecific with strains NYNU 14639 isolated from rotten wood collected in Funiu Mountain, Henan province and ES13S05 from soil collected in Nantou County, Taiwan. The CGMCC 2.6937^T group is most closely related to Saturnispora dispora and Saturnispora zaruensis. However, strain CGMCC 2.6937^T differs from S. dispora by 17 (3.2 %, 13 substitutions and four gaps) and 77 (18.8 %, 52 substitutions and 25 gaps) mismatches, and from S. zaruensis by 15 (2.9 %, 12 substitutions and three gaps) and 64 (15.6 %, 44 substitutions and 20 gaps) mismatches, in the D1/D2 domain and ITS region, respectively. The results suggest that the CGMCC 2.6937^T group represents an undescribed species in the genus Saturnispora, for which the name Saturnispora sinensis sp. nov. is proposed. The holotype strain is CGMCC 2.6937^T.