Jianqiu Sun

A new species of Talaromyces sect. Subinflati isolated from soil in China is proposed based on polyphasic taxonomy, namely, T. bawangicus . Morphologically, this new taxon is characterized by limited growth on culturing media Czapek yeast autolysate agar (CYA), yeast extract sucrose agar (YES), Czapek solution agar (Cz) and oatmeal agar (OA), with sparse sporulation on CYA, Cz, OA, while abundant sporulation on YES, and moderate growth and sporulation on 5% malt extract agar (MEA), producing apically vesiculate stipes, loose biverticillate penicilli with metulae and phialides unequal in length, bearing ampuliform phialides and smooth-walled, ovoid, ellipsoidal to fusiform conidia. The proposed taxonomic novelty is supported by the phylogenetic analysis of the concatenated BenA-CaM-Rpb2- ITS sequence matrix. The new species is in the clade including Talaromyces guizhouensis , Talaromyces jiangxiensis , Talaromyces sinensis , Talaromyces subinflatus and Talaromyces tzapotlensis , closely related to T. jiangxiensis .

The influence of lactic acid bacteria (LAB) strains of various species isolated from Chinese traditional sourdough on the properties of rice sourdough and the textural and flavor qualities of steamed rice bread (SRB) was investigated. Lactiplantibacillus plantarum-fermented rice sourdough had a higher total titratable acidity (13.10 mL) than the other groups. Strains Lacticaseibacillus paracasei PC1 (LPC), Lactobacillus helveticus H1 (LH), Lactobacillus crustorum C1 (LC), Lactobacillus paralimentarius PA1 (LPA), and Lactiplantibacillus plantarum P1 (LP) showed marked protein hydrolysis during rice sourdough fermentation and increased free amino acid levels in rice sourdoughs relative to the control. The Fourier Transform Infrared Spectroscopy results indicated that LAB fermentation could promote the strengthening of inter-intramolecular hydrogen bonds and cause modifications in protein structures; however, these effects varied among the different strains. The LC and LPC strains had the most significant effect on improving the specific volume and textural properties of SRBs. Gas chromatography-mass spectrometry (GC-MS) and GC-ion mobility spectrometry (IMS) identified 33 and 35 volatile compounds, respectively, in the LAB-fermented SRBs, and differentiation was observed in the volatile profiles of SRBs made using different LAB strains. The differential impacts of LAB strains during rice sourdough fermentation can assist in the selection of candidate microorganisms for the production of high-quality gluten-free rice products.

Fructilactobacillus sanfranciscensis, the dominant species of lactic acid bacteria in sourdoughs, impacts the microstructure and flavor of steamed bread through exopolysaccharide production, acidification, proteolysis, and volatile compound generation. The aim of this study is to investigate the phenotypic diversity and technological traits of 28 F. sanfranciscensis strains of different genotypes isolated from Chinese traditional sourdoughs. The results showed that F. sanfranciscensis strains exhibited substantial variation in proteinase and peptidase activities and the amount of acidification and volatiles in fermented sourdoughs. However, we observed no significant differences in exopolysaccharide production among the strains. The strains Sx14 and Ts1 were further chosen for transcriptomics to gain a deep insight into their intraspecies diversity in sourdough fermentation. Significant transcriptome differentiations between these two strains after 12 h fermentation in sourdoughs were revealed. According to the results, the strain Sx14 possessed higher dipeptidase and aminopeptidase activities, galactose utilization, and lactic and acetic acid production abilities, whereas Ts1 showed higher transmembrane transport of substrates and fructose utilization.

Summary: The wheat Qu and Lin‐fan yeast starter are two vital components of Huangjiu brewing, the microbiome composition of which can have a major impact on the end product's quality. This investigation aimed to investigate and compare the fungal diversity of eight starters, including four wheat Qus and four Lin‐fan yeast starters collected from different manufacturers of Shaoxing Huangjiu using high‐throughput sequencing (HTS) technology. Significant variation was observed in the fungal community composition among different starter samples. Fusarium, Epicoccum, Aspergillus and Alternaria were the most predominant fungal genera in wheat Qus. In contrast, Lin‐fan yeast starters possessed relatively simple fungal communities and were predominated by Saccharomyces and Saccharomycopsis. LEfSe analysis showed that nine genus‐level fungal taxa could be retrieved to differentiate the two starter types. Furthermore, the complicated association among the dominant fungi in traditional starters was revealed by utilising Spearman's correlation‐based network analysis. A total of 42 positive and 28 negative correlations were identified respectively. Ultimately, this investigation described the fungal communities in wheat Qus and Lin‐fan yeast starters and will aid in screening fermentation strains, which can remarkably enhance the quality of Shaoxing Huangjiu.

In order to collect basic data for the analysis of metabolic mechanism, the composition and distribution patterns of yeasts at different fermentation stages for Maotai-flavor Chinese liquor production. By using plate screening techniques, a large number of yeast cultures were obtained from fermenting grains. Based on 26S rDNA D1/D2 region sequencing, the yeasts were identified. According to quantitative change, species composition, relative frequency, diversity indices and similarity coefficients, the composition and distribution patterns of yeasts were studied. The numbers of yeasts in fermenting grains showed a rule of "higher-lower-higher-lower". A total of 13 species, 8 genera of the yeasts were identified. The whole diversity index of the yeasts was comparatively high. That the similarity coefficient in most cases was significantly higher than 0.5 showed that the species composition and distribution of yeasts were relatively stable. Issatchenkia orientalis, Pichia kudriavzevii and Saccharomyces cerevisiae play a very important role in the process of liquor fermentation. There were abundant yeast resources in fermenting grains of maotai-flavor liquor.