Improving the aroma profile of inoculated fermented sausages by constructing a synthetic core microbial community.

Commercial starter cultures play a critical role in the industrial production of fermented sausages. However, commercial starter cultures could not reproduce the metabolic actions of diverse microorganisms and the aroma profile of the traditional spontaneously fermented sausages. Identifying the core microbial community in spontaneously fermented sausages will facilitate the construction of a synthetic microbial community for reproducing metabolic actions and flavor compounds in spontaneously fermented sausages. This study aimed to reveal the core microbial community of spontaneously fermented sausages based on their relative abundance, flavor-producing ability, and co-occurrence performance. We identified five promising genera to construct the synthetic core microbial community, these were Lactobacillus, Staphylococcus, Macrococcus, Streptococcus, and Pediococcus. Sausages inoculated with a synthetic core microbial community presented higher quality of aroma profile than the fermented sausages inoculated with a commercial starter culture. Some important volatile flavor compounds of spontaneously fermented sausage, such as (-)-ß-pinene, ß-caryophyllene, 3-methyl-1-butanol, α-terpineol, ethyl 2-methylpropanoate, and ethyl 3-methylbutanoate which are associated with floral, fruity, sweet, and fresh aromas, were also detected in fermented sausage inoculated with synthetic microbial community. This indicated that the synthetic core microbial community efficiently reproduced flavor metabolism. Overall, this study provides a practical strategy to design a synthetic microbial community applicable to different scientific fields.

[Effects of shading and drought on light-induced stomatal dynamics in Betula platyphylla seedlings]. / é®é˜´å’Œå¹²æ—±å¯¹ç™½æ¡¦å¹¼è‹—å ‰è¯±å¯¼çš„æ°”å­”åŠ¨åŠ›å­¦å½±å“.

Two factors-two levels experiment (full light and shading, the irradiance in the shading was 30% of the full light; normal water and drought, where soil moisture was maintained at 75%-80% and 40%-45% of field capacity, respectively) was conducted to study the variation of light-induced stomatal dynamics, stomatal traits, whole plant growth and water use under shading and drought for the early succession stage species Betula platyphylla seedlings in the hilly area of the Loess Plateau. Results showed that shading significantly increased lag and response time by 0.8 and 1.8 times during stomatal opening, decreased response speed significantly by 82.2% and 65.0%, and response amplitude by 43.3% and 56.9% during stomatal opening and closing, respectively. Drought significantly reduced response amplitude by 43.9% during stomatal opening and response speed by 33.0% during stomatal closing. The interaction of shading and drought only affected lag time during stomatal opening. The response speed during stomatal closing was significantly positively correlated with stomatal density and stomatal index. There was no significant correlation between other stomatal dynamic parameters and stomatal anatomical structure. Response speed during stomatal closing was positively correlated with whole plant biomass and water consumption, and there was no correlation between stomatal dynamics parameters and water use efficiency. The results showed that the effects of shading and drought on light-induced stomatal dynamics were partly attributed to the alteration of stomata anatomical structure, and that the light-induced stomatal dynamic parameters could partly explain the alterations of B. platyphylla growth under different habitats.

Metagenomic and metabolomic profiling reveals the correlation between the microbiota and flavor compounds and nutrients in fermented sausages.

Understanding the interrelationships between the differentially abundant microorganisms and metabolites of traditional "Fuet" fermented sausages (FSs) and inoculated fermented sausages (IFSs) can help us identify key species that are missing from commercial starter cultures to reproduce the flavor compounds and nutrients of traditional Fuet FSs. IFSs, inoculated with P. pentosaceus, P. acidilactici, S. xylosus, S. carnosus (SBM-52) or P. pentosaceus, and S. xylosus (THM-17), were deficient in reproducing the volatilome profile (in particular esters, methyl aldehydes, and methyl ketones) of traditional Fuet FSs because of the lack of diverse Staphylococci (S. carnosus, S. xylosus, S. equorum, and S. saprophyticus). Moreover, the combination of Pediococcus and Staphylococcus were positively associated with amino acid, fatty acid, l-anserine, and l-carnosine levels. Pyridoxal and indolelactic acid levels were significantly increased in IFSs with the addition of P. acidilactici and S. carnosus, which were positively associated with vitamin B6 and tryptophan metabolic pathways.

Proteomics reveals intersexual differences in the rat brain hippocampus.

It is widely accepted that intersexual differences occur in cognitive domains, e.g., in spatial learning and memory. The hippocampus plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. However, it still remains unknown whether the hippocampal proteomic profiling differs between males and females. In this study, we investigated the intersexual differences in protein expression of hippocampi using the two-dimensional electrophoresis analysis. In all, 33 differentially expressed proteins were characterized by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry and validated by Western-blotting analysis. In line with Western-blotting validation, the proteomic identification revealed the overexpression of glial fibrillary acidic protein in female rats' hippocampi, and the overexpression of both creatine kinase B-type and DRP-2 in male rats' hippocampi. The intersexual differences in hippocampal proteomic profiling are probably closely related to those in spatial learning and memory abilities.

Application of cell penetrating peptide in magnetic resonance imaging of bone marrow mesenchymal stem cells.

Tracking the distribution and differentiation of stem cells by high-resolution imaging techniques would have significant clinical and research implications. In this study, a model cell-penetrating peptide was used to carry gadolinium particles for magnetic resonance imaging (MRI) of mesenchymal stem cells (MSCs). MSCs were isolated from rat bone marrow and identified by osteogenic differentiation in vitro. The cell-penetrating peptide labeled with fluorescein-5-isothiocyanate (FITC) and gadolinium was synthesized by a solid-phase peptide synthesis method. Fluorescein imaging analysis confirmed that this new peptide could internalize into the cytoplasm and nucleus at room temperature, 4 degrees and 37 degrees . Gadolinium were efficiently internalized into mesenchymal stem cells by the peptide in a time or concentration-dependent manner, resulting in intercellular shortening of longitudinal relaxation enhancements, which were obviously detected by 1.5 Tesla Magnetic Resonance Imaging. Cytotoxicity assay and flow cytometric analysis showed that the intercellular contrast medium incorporation did not affect cell viability at the tested concentrations. The in vitro experiment results suggested that the new constructed peptides could be a vector for tracking MSCs.