Fungal-Bacterial Mutualism: Species and Strain-Dependent Simultaneous Modulation of Branched-Chain Esters and Indole Derivatives in Fermented Sausages through Metabolite Cross-Feeding.

The precise impact of species and strain diversity on fungal-bacterial interactions and the overall community functioning has remained unclear. First, our study revealed how Debaryomyces hansenii influences diverse bacteria to accumulate key metabolites in a simulated fermented food system. For flavor, D. hansenii promoted the accumulation of branched-chain esters in Staphylococcus xylosus by promoting growth and facilitating the precursor branched-chain acids transformations but hindered the accumulation of Staphylococcus equorum. Furthermore, fungal-bacterial interactions displayed diversity among S. equorum strains. For bioactive compounds, species and strain diversity of lactic acid bacteria (LAB) also influences the production of indole derivatives. Then, we investigated specific metabolic exchanges under reciprocal interaction. Amino acids, rather than vitamins, were identified as the primary drivers of the bacterial growth promotion. Moreover, precursor transformations by D. hansenii played a significant role in branched-chain esters production. Finally, a synthetic community capable of producing high concentrations of branched-chain esters and indole derivatives was successfully constructed. These results provide valuable insights into understanding and designing synthetic communities for fermented sausages.

The effective of bacterial community dynamics driven by different starter cultures on the flavor development of Chinese fermented sausages.

This study aimed to understand the community successions driven by different starters and their effects on the flavor development of Chinese fermented sausages. The results showed that the bacterial genus (67.6%) and pH (32.4%) were the key factors influencing the volatile profile. Inoculated the starters composed of Pediococcus and staphylococci maintained the stable community succession patterns dominated by staphylococci (samples T and S). Although the highly acidic environment (pH < 5.2) caused the community to exhibit a fluctuation in succession pattern, the inoculation of Latilactobacillus paracasei (sample Y) maintained microbial diversity and was conducive to the accumulation of aldehydes and esters. In sample P, inoculated the starter with Latilactobacillus and Staphylococcus also maintained microbial diversity, the moderately acidic environment (pH > 5.4) resulted in a stable succession pattern of the microbial community, and it was not conducive to the accumulation of aldehydes, alcohols and esters.

Metabolic cross-feeding enhances branched-chain aldehydes production in a synthetic community of fermented sausages.

Microbial interactions play an important role in regulating the metabolic function of fermented food communities, especially the production of key flavor compounds. However, little is known about specific molecular mechanisms that regulate the production of key flavor compounds through microbial interactions. Here, we designed a synthetic consortium containing Debaryomyces hansenii D1, Staphylococcus xylosus S1, and Pediococcus pentosaceus PP1 to explore the mechanism of the microbial interactions underlying the branched-chain aldehydes production. In this consortium, firstly, D. hansenii secreted amino acids that promoted the growth of P. pentosaceus and S. xylosus. Specifically, D. hansenii D1 secreted alanine, aspartate, glutamate, glutamine, glycine, phenylalanine, serine, and threonine, which were the primary nutrients for bacterial growth. P. pentosaceus PP1 utilized all these eight amino acids through cross-feeding, whereas S. xylosus S1 did not utilize aspartate and serine. Furthermore, D. hansenii D1 promoted the production of branched-chain aldehydes from S. xylosus and P. pentosaceus through cross-feeding of α-keto acids (intermediate metabolites). Thus, the accumulation of 2-methyl-butanal was promoted in all co-culture. Overall, this work revealed the mechanism by which D. hansenii and bacteria cross-feed to produce branched-chain aldehydes in fermented sausages.

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.

Soybean polysaccharide fermentation products regulate the air-liquid interface in co-cultured Caco-2 cells by increasing short chain fatty acids transport.

Soybean polysaccharides have a large molecular weight and complex structure, which is not conducive to body absorption and exerting their biological activities. After the in vitro hydrolysate digestion of soybean polysaccharides, their interactions with intestinal epithelial cell monolayers during soybean polysaccharide-derived short chain fatty acids (SCFAs) uptake and transport were determined by co-culturing soybean polysaccharide hydrolysate products with Caco-2 cells. Based on prepared soybean polysaccharide hydrolysates, physicochemical indices and hydrolysate components were explored and the interface characteristics between SCFAs and Caco-2 cells were characterized using interfacial rheology methods for the first time. Transwell chambers were used to explore relationships between SCFAs transport and the air-liquid interface in Caco-2 cells. We showed that physicochemical properties, cell proliferation rates, and the interfacial tension of soybean polysaccharide hydrolysis products were related to fermentation times, with differences observed between the two hydrolyzed soybean polysaccharides (microwave ammonium oxalate soy hull polysaccharides (MASP) and soluble soy polysaccharides (SSP)). MASP outperformed SSP in terms of total sugar utilization and added cellular value by intestinal flora. Hydrolyzed soybean polysaccharides decreased interfacial tension with increasing hydrolysis times when modulating the interfacial properties of a Caco-2 cell co-culture system. SCFAs translocation rates increased with fermentation time, from 0 h to 24 h. Also, a negative correlation was observed between SCFAs translocation rates and interfacial tension. Our data provide a foundation for the intestinal absorption of soybean polysaccharides and at the same time bring new insights into the interactions between polysaccharides and food in the future, promoting the application of polysaccharides in food processing and even medicine.

Enhancing the bioaccessibility of puerarin through the collaboration of high internal phase Pickering emulsions with ß-carotene.

Puerarin, a bioactive flavonoid found in the root of Pueraria lobata, is claimed to possess various medicinal properties. However, application of puerarin in functional foods is currently limited by its poor bioaccessibility. Existing delivery systems that guarantee puerarin bioaccessibility involve complex preparation steps and safety issues. Therefore, this study aimed to use meat protein and olive oil to efficiently and economically fabricate a food grade high internal phase Pickering emulsion (HIPPE) with co-encapsulated puerarin and ß-carotene to improve the bioaccessibility of puerarin. Moreover, the impact on lipid digestibility and puerarin bioaccessibility was verified using a simulated in vitro gastrointestinal tract. Co-encapsulating puerarin and ß-carotene in HIPPE increased puerarin bioaccessibility (85.17%) compared to that achieved with only puerarin in HIPPE (62.66%). This increased bioaccessibility may have been due to the personalized formulation and the exceptional structure of the HIPPE, which slowed down lipid digestion and inhibited puerarin degradation. A synergistic interaction occurred between ß-carotene and HIPPE to improve puerarin bioaccessibility. Our results have important implications for the design of effective delivery systems for encapsulation of puerarin and other bioactive components.

Na+/Ca2+ induced the migration of soy hull polysaccharides in the mucus layer in vitro.

This study aimed to investigate the mechanism of Na+/Ca2+-induced soy hull polysaccharide (SHP) migration in the mucus layer. The viscosity, potential, microstructure, SHP migration, and metabolite migration were analyzed. The results showed that Na+ had little effect on the viscosity of polysaccharides, while Ca2+ increased the viscosity of polysaccharides. Na+ and Ca2+ promoted the migration of SHP particles by reducing the zeta potential, while they decreased the migration of SHP chyle particles by increasing the aggregation. SHP was fermented by gut microbiota to produce a large number of short-chain fatty acids (SCFAs). Compared with Ca2+, Na+ increased the migration of total SCFAs in the mucus layer. The high-Na+/Ca2+ mucus internal environment had a specific effect on the transport of nutrients in the intestine.

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.

Method for extraction of airborne LiDAR point cloud buildings based on segmentation.

The LiDAR technology is a means of urban 3D modeling in recent years, and the extraction of buildings is a key step in urban 3D modeling. In view of the complexity of most airborne LiDAR building point cloud extraction algorithms that need to combine multiple feature parameters, this study proposes a building point cloud extraction method based on the combination of the Point Cloud Library (PCL) region growth segmentation and the histogram. The filtered LiDAR point cloud is segmented by using the PCL region growth method, and then the local normal vector and direction cosine are calculated for each cluster after segmentation. Finally, the histogram is generated to effectively separate the building point cloud from the non-building.Two sets of airborne LiDAR data in the south and west parts of Tokushima, Japan, are used to test the feasibility of the proposed method. The results are compared with those of the commercial software TerraSolid and the K-means algorithm. Results show that the proposed extraction algorithm has lower type I and II errors and better extraction effect than that of the TerraSolid and the K-means algorithm.

Can more carbon be captured by grasslands? A case study of Inner Mongolia, China.

Grasslands cover a large part of the Earth's surface and play an important role in the global carbon cycle. Previous studies have indicated that nearly half of the grassland vegetation cover has experienced degradation on a global scale; if this degradation is reversed, grasslands can act as potential carbon sinks. However, the question of how much more carbon (carbon gap) could be sequestrated by grassland vegetation by regulating human activities remains unanswered. Here, we present an innovative approach to assess the achievable carbon gap through focal analysis of long-term Moderate Resolution Imaging Spectroradiometer (MODIS) Net Primary Production (NPP) dataset or observed NPP (ONPP). In focal analysis, region segmentation was done to produce spatially homogeneous patches of the same types of soil, topography, and vegetation, referred to as S-T-V units, to minimize the variation in environmental conditions and their impacts on the NPP. Then, the ONPP within each S-T-V unit was rectified by offsetting the variations in potential NPP determined by the climate-oriented Miami NPP model. Hence, spatial variations in the climate-rectified ONPP (ONPPCR) in an S-T-V unit were solely determined by different human activities across locations. In a case study of the Inner Mongolia grassland of China, three focal statistics, namely mean (Mean), 95% percentile threshold (95%PCT), and maximum (Max) within each S-T-V unit were computed for ONPPCR for each year from 2000 to 2014 to assess the annual carbon uptake that was achievable by updating grassland management practices. The carbon gaps were assessed to be 11.8, 58.9, and 74.6 gC/m2 per year based on Mean, 95%PCT, and Max, respectively, compared to 65.0 gC/m2 per year based on the traditional pixel-based approach. We conclude that the carbon gap patterns identified from focal analysis are practically achievable and are more valuable in formulating policy-related decisions for grassland management. Implementing sustainable management practices that are currently being practiced at locations with high ONPPCR in neighboring degraded areas is expected to increase the carbon sequestration by grassland vegetation by one-third.

High Homogenization Speeds for Preparing Unstable Myofibrillar Protein-Olive Oil Emulsions.

Natural protein-based oil-in-water emulsions have recently attracted a lot of attention because of their potential as a synthetic emulsifier replacer. It is, however, unclear how the emulsification process and protein concentration may affect the stability of such emulsions. Therefore, this study investigated the effects of homogenization speeds (4,000, 8,000, 12,000, and 16,000 rpm/min) and myofibrillar protein (MP) concentrations (10, 20, 30, 40, and 50 mg/mL) on the stability of MP-olive oil emulsion. The emulsifying creaming index, emulsifying activity index (EAI), droplet size, microstructure, free sulfhydryl content, and zeta potential of the emulsion were measured. The results showed that with the condition of sufficient emulsifier (at least 20 mg/mL), the EAI increased, and the droplet size and zeta potential of emulsions decreased with the increase of homogenization speed. Emulsions were stable at 4,000 and 8,000 rpm/min (20, 30, 40, and 50 mg/mL) within 48 hr, and they were unstable at 12,000 and 16,000 rpm/min (20, 30, 40, and 50 mg/mL) within 48 hr. This result is mainly attributed to the fact that sulfhydryl-disulfide interchange leads the excessive aggregate of MP at the oil-water interface. PRACTICAL APPLICATION: Myofibrillar protein-olive oil emulsions (oil-in-water) may be used to deliver nutrients into food products. In this study, myofibrillar protein-olive oil emulsions stabilized with the optimizing emulsification conditions. This study may have important implications to produce food-grade myofibrillar protein-olive oil emulsions to deliver nutrients.

Low-field NMR determination of water distribution in meat batters with NaCl and polyphosphate addition.

The objective was to elucidate the influence of NaCl and polyphosphates in the stage of protein swelling on the water-holding capacity (WHC) of meat batter. The meat batters were formulated with salt in different ways by adding established amounts of only NaCl, only polyphosphates, jointly adding NaCl and polyphosphates, and a control without any salt. An increase (p<0.05) in water retention was found when a combination of NaCl and polyphosphates was used. A high textural parameter was observed in the two treatments with NaCl, but not in the group with only polyphosphate. For the polyphosphate group, T22 was lower (p<0.05) than in the other three before heating; however, after heating, T21 and T22 were both significantly decreased, and a new component emerged, T23, which was significantly lower than the others. For the NaCl treatment, heated or not, T22 was always the highest. It was revealed that NaCl had affected the WHC by increasing the mobility and distribution of water, particularly with polyphosphate, but polyphosphate could not be an equal substitute for NaCl given its resulting lowest textural properties and poor microstructure. By presenting different hydration states in the protein swelling stage, the meat batter qualities were differentiated.

Nutritional Characteristics and Active Components in Liver from Wagyu×Qinchuan Cattle.

We investigated nutritional characteristics and active components in the liver of Wagyu×Qinchuan cattle and Qinchuan cattle produced in Shaanxi (China). We observed significant differences (p<0.05) in the proximate composition of protein, fat, carbohydrate, total energy, and glycogen. Wagyu×Qinchuan cattle liver showed higher (p<0.05) sodium, iron, zinc, and selenium concentrations than Qinchuan cattle liver. The amino acid composition of Wagyu×Qinchuan cattle liver was richer (p<0.05) in 13 types of amino acids, with the exception of Asp (10.06%), Val (5.86%), and Met (1.72%). Total essential amino acids accounted for almost half the composition (39.69%) in Wagyu×Qinchuan cattle liver. Wagyu×Qinchuan cattle liver had lower (p<0.05) levels of monounsaturated fatty acids (18.2%), but higher (p<0.05) levels of polyunsaturated fatty acids (35.11%), compared with Qinchuan cattle liver (23.29% and 28.11%, respectively). The thrombogenic index was higher in Qinchuan cattle liver (0.86) than in Wagyu×Qinchuan cattle liver (0.70), and the glutathione (38.0 mg/100g) and L-carnitine (2.12 µM/g) content was higher (p<0.05) in Wagyu×Qinchuan cattle liver than in Qinchuan cattle liver (29.8 mg/100g and 1.41 µM/g, respectively). According to the results obtained, the liver of Wagyu×Qinchuan cattle, which is insufficiently used, should be increasingly utilized to improve its commercial value.