Probiotic Bacillus as fermentation agents: Status, potential insights, and future perspectives.

Probiotic Bacillus strains can solve the problems of single flavor and long fermentation time of fermented products caused by the lack of certain functional genes and insufficient metabolism ability of fermenter strains (Lactobacillus and Bifidobacterium) at the present stage. There is a lack of systematic evaluation and review of probiotic Bacillus as food fermentation agents. In this paper, it is observed that probiotic Bacillus strains are involved to varying degrees in liquid-state, semi-solid state, and solid-state fermentation and are widely present in solid-state fermented foods. Probiotic Bacillus strains not only produce abundant proteases and lipases, but also effective antifungal lipopeptides and extracellular polymers, thus enhancing the flavor, nutritional value and safety of fermented foods. Bacillus with probiotic qualities is an underutilized group of probiotic food fermentation agents, which give a potential for the development of fermentation technology in the food business and the integration of ancient traditional fermentation techniques.

Characteristic substance analysis and rapid detection of bacteria spores in cooked meat products by surface enhanced Raman scattering based on Ag@AuNP array substrate.

BACKGROUND: Bacterial spores are the main potential hazard in medium- and high-temperature sterilized meat products, and their germination and subsequent reproduction and metabolism can lead to food spoilage. Moreover, the spores of some species pose a health and safety threat to consumers. The rapid detection, prevention, and control of bacterial spores has always been a scientific problem and a major challenge for the medium and high-temperature meat industry. Early and sensitive identification of spores in meat products is a decisive factor in contributing to consumer health and safety. RESULTS: In this study, we developed a novel and stable Ag@AuNP array substrate by using a two-step synthesis approach and a liquid-interface self-assembly method that can directly detect bacterial spores in actual meat product samples without the need for additional in vitro bacterial culture. The results indicate that the Ag@AuNP array substrate exhibits high reproducibility and Raman enhancement effects (1.35 × 105). The differentiation in the Surface enhanced Raman scattering (SERS) spectra of five bacterial spores primarily arises from proteins in the spore coat and inner membrane, peptidoglycan of cortex, and Ca2⁺-DPA within the spore core. The correct recognition rate of linear discriminant analysis for spores in the meat product matrix can reach 100 %. The average recovery accuracy of the SERS quantitative model was at around 101.77 %, and the limit of detection can reach below 10 CFU/mL. SIGNIFICANCE: It provides a promising technological strategy for the characteristic substance analysis and timely monitoring of spores in meat products.

Development of fluorescent GO-AgNPs-Eu3+ nanoparticles based paper visual sensor for foodborne spores detection.

Foodborne spores are ubiquitous with extremely strong resistance, and pose a serious threat to food safety and human health. Therefore, rapid, sensitive, and selective detection of spores are crucial. In this study, a fluorescent probe was developed based on lanthanide ion (Eu3+)-labeled nano-silver-modified graphene oxide (GO-AgNPs-Eu3+) for the detection of 2,6-dipicolinic acid (DPA), a biomarker unique to spores, to allow quantitative spores detection. The GO-AgNPs-Eu3+ nano-fluorescent probe was loaded onto a polyvinylidene fluoride microfiltration membrane, and a smartphone-assisted portable GO-AgNPs-Eu3+ nanoparticles-based paper visual sensor was designed for rapid on-site quantitative and real-time online detection of spores. The results indicated that the developed probe achieved equilibrium binding with DPA within 5 min, and enhanced fluorescence emission through antenna effect. The fluorescence detection presented a good linear relationship in the DPA concentration range of 0-45 µM, with a DPA detection limit of 4.62 nM and spore detection limit of 104 cfu/mL. The developed sensor showed a change in fluorescence from blue to red with increasing DPA concentration, and this color change was quantitatively detected through smartphone RGB variations, with a detection limit of 13.1 µM for DPA and 6.3 cfu/mL for Bacillus subtilis spores. Subsequently, the sensitivity and selectivity of the developed sensor were verified using actual milk and water samples spiked with B. subtilis spores. The results of this study provided objective technological support for rapid detection of spores, which is important for reducing the occurrence of foodborne diseases and improving food safety.