Traditional fermented foods are widely consumed and valued for their distinctive sensory properties and potential health benefits. These foods contain complex microbiota whose interactions and metabolic activities shape biochemical transformations relevant to product quality, safety, and functionality. Metatranscriptomics provides a culture-independent means of profiling community RNA and examining changes in microbial gene expression during fermentation. However, most fermented-food microbiome studies continue to infer function from community composition or genomic potential rather than from in situ gene expression. Existing metatranscriptomic applications also differ substantially in sampling, RNA processing, sequencing, and data analysis, limiting comparisons across food systems. This review examines the metatranscriptomic workflows applied to fermented foods, including sample preparation, sequencing strategies, and bioinformatic analysis. It identifies practical requirements for reproducible RNA-based studies in complex food matrices and compares transcriptionally represented taxa and pathways across fermentation systems. The review also distinguishes gene expression from realized metabolic activity, an important boundary when interpreting transcript annotations and reconstructed pathways. We further assess the strengths and limitations of metatranscriptomics, both alone and in combination with complementary omics, for resolving microbiota structure-function relationships. Key challenges include data integration, evidence interpretation, and the recovery of biologically meaningful information from complex transcriptomic datasets. When combined with complementary omics and experimental validation, metatranscriptomics can help relate expressed genes and pathways to fermentation phenotypes. These insights may guide the experimental evaluation of starter cultures and the development of more precise fermentation-control strategies.
Macadamia protein isolate (MPI) was phosphorylated using sodium tripolyphosphate (STPP) and sodium trimetaphosphate (STMP), and the effects of phosphorylation on its solubility, structure, and high internal phase emulsion (HIPE) stabilization of MPI were investigated. Both STPP and STMP reached the highest phosphorylation degree at 5% addition, with phosphorus contents of 3.95 ± 0.05 and 3.22 ± 0.02 mg/g, respectively. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the successful introduction of phosphate groups into MPI through the formation of phosphorus-containing bonds. Phosphorylation markedly altered the aggregation state and molecular conformation of MPI. In particular, STMP-treated MPI exhibited its highest solubility at 4% addition, whereas 5% STPP-treated MPI showed the best overall performance, with particle size decreasing from 197.9 ± 0.99 to 165.2 ± 0.57 nm, absolute zeta potential increasing from 25.77 ± 0.06 to 70.67 ± 0.41 mV, and solubility increasing from 14.01% ± 0.72% to 96.78% ± 0.24%. In addition, phosphorylation increased surface hydrophobicity and free sulfhydryl content, and promoted the transformation of β-sheet and β-turn structures into α-helix and random coil, suggesting pronounced conformational rearrangement of MPI. These changes improved the aqueous dispersion and interfacial adsorption behavior of MPI. Accordingly, 5% STPP-treated MPI exhibited superior ability to stabilize HIPEs, producing smaller droplet sizes, a more uniform and compact microstructure, while native MPI failed to stabilize HIPEs at an internal phase fraction of 80%. Overall, phosphorylation is an effective strategy for improving MPI functionality and broadening its application in HIPE-based food systems.
To address the severe threat posed by Bacillus cereus (B. cereus) and its spores to food safety, this study isolated and characterized a novel lytic phage, WAH2, using a multidrug-resistant B. cereus strain as the host. Morphological observation showed that WAH2 had an icosahedral head and a contractile tail. The phage lysed 7 of 51 (13.7%) B. cereus strains covering 3 sequence types. Biological characterization showed that the optimal multiplicity of infection of WAH2 was 0.0001. It remained stable at 4–45 °C, pH 5–11, and 2%–10% NaCl. Its latent period was 30 min, and the burst size was 208 PFU/cell. Genome analysis showed that WAH2 possesses a linear double-stranded DNA genome of 158991 bp with a GC content of 37.96%. It encodes 284 open reading frames and 6 tRNA genes. No antibiotic resistance genes, virulence factors, or lysogeny-related elements were detected. WAH2 was classified as a novel species within the genus Bastillevirus, family Herelleviridae. In vitro assays showed that WAH2 strongly inhibited host bacterial growth (no regrowth within 36 h), significantly reduced biofilm formation and disrupted mature biofilms, and effectively inhibited the outgrowth of germinated spores. Importantly, in food matrices such as milk, rice, and pork, WAH2 significantly reduced or completely eliminated B. cereus in a dose- and time-dependent manner at both 25 and 4 °C, with no regrowth observed. In TSB and milk, WAH2 persisted for 120 h without detectable resistant survivors. In summary, WAH2 is a safe, efficient, and promising phage that can serve as a biocontrol candidate against B. cereus in food.
