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Antibiotic resistance and capacity for biofilm formation of Shigella flexnerirender previous prevention and control strategies minimally effective. Ferulic acid (FA) has been demonstrated to be useful due to its application in foods as an alternative natural preservative. However, information regarding the S. flexneriphenotype and molecular responses to FA exposure is limited. The present study investigated the effects of FA on S. flexneriplanktonic growth and biofilm formation. The results demonstrated that the cell membrane of S. flexneriin planktonic growth mode exhibited irreversible destruction after FA exposure, as characterized by decreased cell viability, leakage of cytoplasmic constituents, accelerated adenosine triphosphate (ATP) consumption, cell membrane depolarization, and cellular morphological changes. FA significantly inhibited S. flexneriadhesion and biofilm formation at a working concentration (1/8 MIC) that almost did not inhibit planktonic growth. Transcriptomics profiling showed that the exposure to a subinhibitory concentration of FA dramatically altered gene expression in the S. flexneribiofilm, as a total of 169 differentially expressed genes (DEGs) were upregulated and 533 DEGs were downregulated, compared to the intact biofilm. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the DEGs were mainly involved in pathways of ribosomes, ABC transporters, and the citrate cycle. Furthermore, we show that FA altered the transcription of S. flexnerigenes associated with adhesion, transcriptional regulation, and the synthesis and transport of extracellular polymeric substances that contribute to biofilm formation. These data provide novel insights into S. flexneribehavioral responses to FA exposure and suggest that FA could effectively constrain S. flexneriand its biofilm formation.

Nata de cocois a traditional fermented food, chemically known as bacterial cellulose (BC), widely used in the food industry, personal care, and biomaterial areas. In the nata de cocoindustry, microbiota-fermented coconut water (FCW) has been regarded as a highly efficient medium for improving BC synthesis by Komagataeibacterspp. However, its effects on the biological properties of BC producers and structural characteristics of BC remain unknown, resulting in unstable production and inconsistent quality of BC. This study aimed to find the commonality of biological behaviors between K. nataicolastrains and the peculiarity of BC structure under the effect of FCW. The results showed that FCW could increase the BC yield of K. nataicolaby 2.03–4.75 times, the uridine diphosphate glucose pyrophosphorylase activity by 10–45.3 times, and the hexokinase, phosphofructokinase, or pyruvate kinase activities by twofold. The extracellular metabolite profile of K. nataicolashowed that its glycolysis/gluconeogenesis pathway was significantly stimulated and the use of erythritol obviously increased. These phenomena might be attributed to the use of ethanol, lactate, xylitol, and mannitol in FCW by K. nataicola. In addition, the structural characteristics of BC produced in FCW included higher number of hydrogen bonds, thinner fibrils, a looser three-dimensional network, improved porosity, and greater mechanical strength. This study offered novel insights into the BC synthesis of K. nataicolaand the BC structural characteristics in FCW, providing valuable references for the efficient production and potential applications of both nata de cocoand BC.

There is increasing interest in the utilization of tartary buckwheat (TB) for making various fermented foods due to its unique starch structure and functional features. However, studies on Daqustarter produced with TB as a raw material are lacking. This study aimed to compare the differences between conventional low-temperature Daqu(NDQ; 65% barley and 35% pea) and Daqumade with TB (BDQ; 55% barley, 30% pea, and 15% TB) in physicochemical properties, microbial communities, and volatile and nonvolatile metabolites. Compared with NDQ, BDQ exhibited higher saccharifying power, liquefying power, acid protease activity, and lower pH value. High-throughput sequencing revealed that the microbial community structure of NDQ and BDQ had significant differences. NDQ were enriched in Kroppenstedtia, Bacillus, Saccharomycopsis, Issatchenkia, Cladosporium, and Aspergillus, while BDQ were dominated by Kroppenstedtia, Comamonas, Pseudomonas, Acinetobacter, Rhizopus, and Saccharomycopsis. There were notable distinctions in volatile and nonvolatile metabolomic profiles between NDQ and BDQ. The physicochemical differences between NDQ and BDQ were driven by their different microbiota, which also led to the inconsistency of their metabolite profiles. The bacterial community was significantly correlated with pH and acid protease activity, whereas the fungal community was only strongly correlated with saccharifying power. In addition, the correlation network demonstrated that the resident dominant microbes in Daquhad strong connections to numerous important volatile and nonvolatile compounds. This study provided a detailed insight into the microbiome characteristics that differ between the NDQ and BDQ, and it can be helpful to develop a TB-based starter applied in making traditional fermented foods.