Lili Zhao

This study aimed to evaluate the impact of four strains, Bifidobacterium longum BL11, Streptococcus thermophilus LB42, Lacticaseibacillus casei LC15, and Lactiplantibacillus plantarum XJ25, on the antioxidant activity, flavor components and metabolic characteristics of fermented coffee pulp beverage (CPB). Results indicated that the antioxidant activities were remarkably enhanced in the fermented CPB samples (p < 0.05). A total of 103 volatile compounds (VOCs) were detected by HS-SPME-GC-MS and GC-IMS, with 37 types of VOCs newly generated after fermentation, including esters, alcohols and ketones, thereby enhancing the flavor quality of CPB. In addition, a total of 334 differential non-volatile metabolites covering 20 subclasses were obtained in all CPB samples, such as D-tagatose, glyceraldehyde, isorhynchophylline and pyruvic acid, which showed remarkably increased levels after fermentation (p < 0.05). Organic acids, amino acids and derivatives were the two major classes of differential metabolites. The CPB samples had a different flavor profile after fermentation, while the group of Lactiplantibacillus plantarum showed the highest overall acceptability. These findings provide a systematic comparison of single-strain fermentation effects on VOCs and non-volatile metabolites in CPB samples, promoting its high-value utilization in innovative food applications.

Elemental migration and enrichment are important processes influencing tea plant growth and the assembly of rhizosphere bacterial communities within the rock–soil–plant continuum. This study explores how soil parent materials (granite, quartz schist, and sericite schist) are potentially associated with these processes and their observed associations with the elemental composition of tea leaves. Exploratory statistical analyses revealed distinct, lithology-specific biogeochemical patterns that serve as a foundation for hypothesis generation. In granite soils, chlorite correlated with the mobility of Cr, Pb, Cu, Ni, Mg, and Na, coinciding with shifts in the relative abundances of Verrucomicrobia, Armatimonadetes, and Chloroflexi. In quartz schist, kaolinite exhibited notable correlations with the dynamics of Pb, Cr, Ni, Zn, and As, which were statistically linked to Planctomycetes, Proteobacteria, and Acidobacteria. Complex mineral–microbe interactions were observed in sericite schist soils, where clay minerals (e.g., chlorite, illite) were closely associated with the migration of multiple elements (Pb, K, Ca, Cd, As, Al, Fe, Zn), paralleling structural variations in communities of Actinobacteria, Planctomycetes, Chloroflexi, and Proteobacteria. Potassium (K), calcium (Ca), and manganese (Mn) showed bioaccumulation tendencies in tea leaves across all lithologies, with an enrichment capacity order of Ca > K > Mn > Mg > Na > Al. Exploratory Classification and Regression Tree (CART) analysis suggested that the migration of K, Ca, Cu, Zn, and Hg corresponded most closely with their soil concentrations. Manganese (Mn) exhibited a mineral-associated trend, with kaolinite content as a potential correlate, while cadmium (Cd) migration was statistically linked to the relative abundance of Armatimonadetes. These findings highlight potential candidate relationships between mineralogy, microbes, and elemental mobility rather than confirming causal mechanisms, emphasizing the need for further validation in larger or experimental datasets.

Introduction: Owing to its remarkable capacity to modify the aroma profile of wine, Lactiplantibacillus plantarum ( L. plantarum ) derived from wine has emerged as a potential starter for malolactic fermentation. However, the inadequate acid resistance of this bacterium severely restricts its application. In some bacterial species, GlnR is considered a universal transcriptional regulator in response to acid stress. Methods: In this study, we determined the function of GlnR in the acid resistance of L. plantarum for the first time. RT-qPCR and yeast one-hybrid assays revealed a direct regulatory correlation between GlnR and genes associated with the glutamate metabolic pathway. Metabolomics analysis via liquid chromatography-mass spectrometry and fermentation studies confirmed that GlnR affected γ-aminobutyric acid (GABA) production. Results: The growth and survival rate of the knockout strain XJ25-Δ glnR were significantly lower than those of the wild-type strain XJ25. GlnR can directly bind to the promotor regions of the genes glnA , gadB , and glms1 , thereby upregulating gadB transcription while downregulating glnA and glms1 transcription, directing the increased metabolic flux toward GABA synthesis. Discussion: We present evidence that GlnR plays a vital role in the glutamate metabolic pathway and is a positive transcriptional regulator that can control the acid resistance of L. plantarum XJ25. Although GlnR interacts with glnA , gadB , and glms1 , additional studies are warranted to determine how this interaction affects its acid resistance.

Microorganism employs sophisticated strategies to adapt to acidic environments, with transcription factors occupying pivotal nodes within their hierarchical regulatory networks. In this study, we performed functional characterization of the AraR transcription factor LP_RS14895 via integrated multiomics approaches. RNA sequencing revealed 40 acid-responsive targets that were enriched in pathways related to pentose/glucuronate interconversions and amino sugar and nucleotide sugar metabolism. A genome-wide binding analysis via DAP-seq identified 1279 interaction sites and the most significantly enriched motif is “ARCCMATMAHC”. The results revealed that AraR plays a crucial role in regulating acid tolerance and metabolizable sugar (including arabinose, glucose, fructose, ribose, mannose, and trehalose). Overall, these findings offer mechanistic insights into microbial stress responses and provide a valuable method for addressing inhibitory processes of carbohydrate metabolizability under high-acid conditions.

Microorganism employs sophisticated strategies to adapt to acidic environments, with transcription factors occupying pivotal nodes within their hierarchical regulatory networks. In this study, we performed functional characterization of the AraR transcription factor LP_RS14895 via integrated multiomics approaches. The results revealed the pivotal role of AraR in acid tolerance and carbohydrate utilization (including arabinose, glucose, fructose, ribose, mannose, and trehalose). RNA sequencing revealed 40 acid-responsive targets that were enriched in pathways related to pentose/glucuronate interconversions and amino sugar and nucleotide sugar metabolism. A genome-wide binding analysis via DAP-seq identified 1,279 interaction sites; the results highlighted the most significantly enriched motif, “ARCCMATMAHC”. These findings suggest that AraR plays a crucial role in regulating sugar metabolism and acid adaptation, offering mechanistic insights into microbial stress responses and providing a valuable method for addressing inhibitory processes of carbohydrate utilization under high-acid conditions.

This study used litchi (Heiye) wine and distilled spirit as raw experimental materials to analyze the volatile aroma compounds. Qualitative and quantitative determination of aromatic components was studied using stir bar sportive extraction (SBSE) and gas chromatography coupled to mass spectrometry (GC/MS). Results indicated that a total of 128 different types of aroma compounds were observed, which belonged to six chemical groups, including 39 esters, 16 alcohols, 16 acids, 22 terpenes, 17 aldehydes and ketones, and 18 other compounds. In particular, esters were the highest among all six categories and represented approximately 52% of the total flavor component content in litchi distilled spirit. The odor activity values (OAVs) revealed 22 types of aroma compounds with OAVs >1 in this test. It is possible that the produced litchi distilled spirit had a stronger varietal character due to the increased concentrations and OAVs of β‐damascenone, linalool, ethyl butyrate, ethyl isovalerate, ethyl caproate, trans‐rose oxide, and cis‐rose oxide. Taking the OAVs into account, we evaluated the characteristic aromas for litchi wine and litchi distilled spirit.

Summary: This study assessed the effect of ferulic acid on the accumulation of histamine in traditional Xinjiang smoked horsemeat sausage. The dynamics of histamine‐producing microorganisms were monitored by PCR‐denaturing gradient gel electrophoresis (DGGE) with specific primer pairs, and histidine and histamine levels were measured by high‐performance liquid chromatography (HPLC). Relative parameters including microbiological growth, pH and moisture content were also evaluated. PCR‐DGGE provided a rapid and convenient method for detecting and identifying histamine‐producing bacteria. The results showed that ferulic acid reduced the histamine concentration and inhibited the growth of histamine‐producing bacteria during fermentation and ripening. Additionally, the inhibitory effect of ferulic acid was stronger than that of the starter culture. Therefore, ferulic acid appears to be a useful additive for manufacturing fermented sausages.