The distinctive taste of Sichuan sauce-flavored sausage comes from an intricate microbial metabolism. The correlation between microbial composition and distinct flavor components has not been researched. The study used headspace solid-phase microextraction action with gas chromatography mass spectrometry to find flavor components and high-throughput sequencing of 16S rRNA to look at the diversity and succession of microbial communities. The correlation network model forecasted the connection between essential bacteria and the development of flavors. The study revealed that the primary flavor compounds in Sichuan sauce-flavored sausages were alcohols, aldehydes, and esters. The closely related microbes were Leuconostoc, Pseudomonas, Psychrobacter, Flavobacterium, and Algoriella. The microbes aided in the production of various flavor compounds, such as 1-octen-3-ol, benzeneacetaldehyde, hexanal, (R,R)-2,3-butanediol, and ethyl caprylate. This work has enhanced our comprehension of the diverse functions that bacteria serve in flavor development during the fermentation of Sichuan sauce-flavored sausage.

Plateau lakes (e.g., freshwater and saltwater lakes) are formed through intricate processes and harbor diverse microorganisms that mediate aquatic ecosystem functions. The adaptive mechanisms of lake microbiota to environmental changes and the ecological impacts of such changes on microbial community assembly are still poorly understood in plateau regions. This study investigated the structure and assembly of planktonic bacterial communities in 24 lakes across the Qinghai-Tibetan and Inner Mongolia Plateaus, with particular focus on habitat generalists, opportunists, and specialists. High-throughput sequencing of the 16S ribosomal RNA genes revealed that bacterial generalists had a lower species number (2196) but higher alpha diversity than the specialist and opportunist counterparts. Taxonomic dissimilarity and phylogenetic diversity analyses unraveled less pronounced difference in the community composition of bacterial generalists compared to the specialist and opportunist counterparts. Geographical scale (14.4 %) and water quality (12.6 %) emerged as major ecological variables structuring bacterial communities. Selection by water temperature and related variables, including mean annual temperature, elevation, longitude, and latitude, mainly shaped the assembly of bacterial generalists. Ecological drift coupled with selection by salt ions and related variables, including total phosphorus, chlorophyll a, and salinity, predominantly drove the assembly of bacterial specialists and opportunists. This study uncovers distinct bacterial responses to interacting ecological variables in diverse plateau lakes and the ecological processes structuring bacterial communities across various lake habitats under anthropogenic disturbance or climate change.

BACKGROUND: Crop diversification is considered as an imperative approach for synchronizing the plant nutrient demands and soil nutrient availability. Taking two or more crops from the same field in one year is considered as multiple cropping. It improves the diversity and abundance of soil microbes, thereby improving the growth and yield of crops. Therefore, the present study was conducted to explore the effects of different multiple winter cropping on soil microbial communities in paddy fields. In this study, eight rice cropping patterns from two multiple cropping systems with three different winter crops, including Chinese milk vetch (CMV), rape, and wheat were selected. The effects of different multiple winter cropping on soil microbial abundance, community structure, and diversity in paddy fields were studied by 16 S rRNA high-throughput sequencing and real-time fluorescence quantitative polymerase chain reaction (PCR).
RESULTS: The results showed that different multiple winter cropping increased the operational taxonomic units (OTUs), species richness, and community richness index of the bacterial community in 0 ~ 20 cm soil layer. Moreover, soil physical and chemical properties of different multiple cropping patterns also affected the diversity and abundance of microbial bacterial communities. The multiple cropping increased soil potassium and nitrogen content, which significantly affected the diversity and abundance of bacterial communities, and it also increased the overall paddy yield. Moreover, different winter cropping changed the population distribution of microorganisms, and Proteobacteria, Acidobacteria, Nitrospira, and Chloroflexi were identified as the most dominant groups. Multiple winter cropping, especially rape-early rice-late rice (TR) andChinese milk vetch- early rice-late rice (TC) enhanced the abundance of Proteobacteria, Acidobacteria, and Actinobacteria and decreased the relative abundance of Verrucomicrobia and Euryarchaeota.
CONCLUSIONS: In conclusion, winter cropping of Chinese milk vetch and rape were beneficial to improve the soil fertility, bacteria diversity, abundance and rice yield.

In aquatic ecosystems with low nutrient levels, organic aggregates (OAs) act as nutrient hotspots, hosting a diverse range of microbial species compared to those in the water column. Lake eutrophication, marked by intensified and prolonged cyanobacterial blooms, significantly impacts material and energy cycling processes, potentially altering the ecological traits of both free-living (FL) and particle-attached (PA) bacteria. However, the extent to which observed patterns of FL and PA bacterial diversity, community assembly, and stability extend to hypereutrophic lakes remains understudied. To address this gap, we investigated bacterial diversity, composition, assembly processes, and stability within hypereutrophic Lake Xingyun. Our results revealed that FL bacterial communities exhibited higher α-diversity than PA counterparts, coupled with discernible taxonomic compositions. Both bacterial communities showed distinct seasonality, influenced by cyanobacterial bloom intensity. Environmental factors accounted for 71.1% and 54.2% of the variation among FL and PA bacteria, respectively. The assembly of the PA bacterial community was predominantly stochastic, while FL assembly was more deterministic. The FL network demonstrated greater stability, complexity, and negative interactions, indicative of competitive relationships, while the PA network showed a prevalence of positive correlations, suggesting mutualistic interactions. Importantly, these findings differ from observations in oligotrophic, mesotrophic, and eutrophic lakes. Overall, this research provides valuable insights into the interplay among bacterial fractions, enhancing our understanding of nutrient status and cyanobacterial blooms in shaping bacterial communities.

Microbial fertilizers have the characteristics of high efficiency and environmental protection in improving saline soils, and the application of functional microbial fertilizers is of great significance for the green abatement of saline barriers and the improvement of soil quality in coastal areas. The experiment was based on moderately saline soil in the coastal area of Hebei Province, with corn as the indicator crop, on the basis of conventional chemical fertilizer application. Different microbial fertilizer treatments, namely, T1 （conventional chemical fertilizer 750 kg·hm-2 + compound microbial agent 75 kg·hm-2）, T2 （conventional chemical fertilizer 750 kg·hm-2 + Bacillus megaterium 300 kg·hm-2）, T3 （conventional chemical fertilizer 750 kg·hm-2 + B. mucilaginosus 300 kg·hm-2）, T4 （conventional chemical fertilizer 750 kg·hm-2 + organic silicon fertilizer 600 kg·hm-2）, T5 （conventional chemical fertilizer 750 kg·hm-2 + bio-organic fertilizer 600 kg·hm-2）, T6 （conventional fertilizer 750 kg·hm-2 + active microalgae 15 kg·hm-2）, and CK （only fertilizer 750 kg·hm-2）, were used for these seven treatments, to study the effects of different microbial fertilizers on soil nutrients, salinity, bacterial community, and corn yield and economic efficiency during two critical periods （V12 stage and maturity stage） of corn. The results showed that compared with that in CK, T1 significantly increased soil total nitrogen （TN） and available phosphorus （AP） contents during the whole growth period. Over the whole reproductive period, soil organic matter （OM） at maturity increased by 10.35% over the V12 stage compared to that in CK, but there was no significant difference between treatments. Compared with that in CK, T5 and T6 significantly reduced soil total salinity and Ca2+ content during the whole growth period by an average of 14.51%-18.48% and 24.25%-25.51%. T1 significantly increased the bacterial diversity index over the whole growth period by 45.16% compared to that in CK. The dominant soil phyla were Actinobacteria, Proteobacteria, Acidobacteria, and Chloroflexi, and the dominant genera were Bacillus and Geminicoccaceae. The most abundant functions of the bacterial community in the study area were chemoheterotrophy and aerobic chemoheterotrophy, with average relative abundances of 28.89% and 27.11%, and T3 and T6 significantly improved soil N cycling function. The results of redundancy analysis （RDA） indicated that Na+, SO42-, pH, and EC were important factors driving the structure of the bacterial community, and correlation heatmaps showed that Na+, SO42-, pH, and EC were significantly and positively correlated mainly with the phylum Planctomycetota, whereas soil OM and TN were significantly and positively correlated with Cyanobacteria. Compared with that in CK, T6 increased the relative abundance of Cyanobacteria and optimized the bacterial community structure during the whole growth period. Using recommended dosages of bacterial fertilizers T1 and T6 increased maize yield by 7.31%-24.83% and economic efficiency by 9.05%-23.23%, respectively. The preliminary results of soil chemical properties and yield correlation analysis revealed that EC, AP, HCO3-, and Mg2+ were the obstacle factors limiting soil productivity in coastal areas. In conclusion, the use of the compound bacterial agent （T1） and active microalgae （T6） at the recommended dosage can significantly enhance soil nutrients, reduce salinity, and improve the structural diversity of soil bacterial communities, which not only ensures the increase in maize yield and efficiency but also realizes the efficient use of microbial fertilizers and the improvement of soil quality.

Under a full straw returning system, the relationship between soil bacterial community diversity and straw decomposition, yield, and the combined application of slow-release nitrogen and urea remains unclear. To evaluate these effects and provide an effective strategy for sustainable agricultural production, a 2-year field positioning trial was conducted using maize as the research object. Six experimental treatments were set up: straw returning + no nitrogen fertilizer (S1N0), straw returning + slow-release nitrogen fertilizer:urea = 0:100% (S1N1), straw returning + slow-release nitrogen fertilizer:urea = 30%:70% (S1N2), straw returning + slow-release nitrogen fertilizer:urea = 60%:40% (S1N3), straw returning + slow-release nitrogen fertilizer:urea = 90%:10% (S1N4), and straw removal + slow-release nitrogen fertilizer:urea = 30%:70% (S0N2). Significant differences (p < 0.05) were observed between treatments for Proteobacteria, Acidobacteriota, Myxococcota, and Actinobacteriota at the jointing stage; Proteobacteria, Acidobacteriota, Myxococcota, Bacteroidota, and Gemmatimonadota at the tasseling stage; and Bacteroidota, Firmicutes, Myxococcota, Methylomirabilota, and Proteobacteria at the maturity stage. The alpha diversity analysis of the soil bacterial community showed that the number of operational taxonomic units (OTUs) and the Chao1 index were higher in S1N2, S1N3, and S1N4 compared with S0N2 at each growth stage. Additionally, the alpha diversity measures were higher in S1N3 and S1N4 compared with S1N2. The beta diversity analysis of the soil bacterial community showed that the bacterial communities in S1N3 and S1N4 were more similar or closely clustered together, while S0N2 was further from all treatments across the three growth stages. The cumulative straw decomposition rate was tested for each treatment, and data showed that S1N3 (90.58%) had the highest decomposition rate. At the phylum level, straw decomposition was positively correlated with Proteobacteria, Actinobacteriota, Myxococcota, and Bacteroidota but significantly negatively correlated with Acidobacteriota. PICRUSt2 function prediction results show that the relative abundance of bacteria in soil samples from each treatment differed significantly. The maize yield of S1N3 was 15597.85 ± 1477.17 kg/hm2, which was 12.80 and 4.18% higher than that of S1N1 and S0N2, respectively. In conclusion, a combination of slow-release nitrogen fertilizer and urea can enhance the straw decomposition rate and maize yield by improving the soil bacterial community and structure within a full straw returning system.

Bacterial diversity and its distribution characteristics in sediments are critical to understanding and revealing biogeochemical cycles in sediments. However, little is known about the relationship between biogeochemistry processes and vertical spatial distribution of bacterial communities in sandy sediments. In this study, we used fluorescence quantitative PCR, high-throughput sequencing technology and statistical analysis to explore the vertical distribution pattern of bacterial community diversity and its influencing factors in sandy sediments of the Yangtze River Basin. The aim is to enrich the understanding of the ecological characteristics and functions of bacteria in river ecosystems. The results showed that both sediment bacterial abundance and diversity showed a gradual decrease from surface to bottom in the vertical distribution. The main environmental factors that influenced the bacterial distribution pattern were pore water dissolved oxygen (DO), total nitrogen (TN) concentration and sediment nitrogen (N) content. The dominant bacterial species, Massilia and Flavobacterium, are suitable for growth and reproduction in high oxygen and nutrient-richer environments, while Limnobacter prefers low oxygen or anaerobic conditions. The vertical distribution pattern of bacteria and its influencing factors in river sandy sediment found in this study differ from the results in mud sediment, which may be related to the larger granular gap between sandy sediment and the lower content of organic matter. The findings of this study further our understanding of the distribution patterns and ecological preferences of microbial communities in river sediments, providing insights into how these communities may adapt to varying environmental conditions.

It is of great significance for the conservation of biodiversity in farmland ecosystems to study the diversity, structure, functions, and biogeographical distribution of soil microbes in farmland and their influencing factors. High-throughput sequencing technology was used to analyze the distribution characteristics of soil bacterial diversity, community structure, and metabolic function along elevation and their responses to soil physicochemical properties in farmland in the loess hilly areas of Ningxia. The results showed that:① The Alpha diversity index of soil bacterial was significantly negatively correlated with elevation (P < 0.05) and showed a trend of decreasing and then slightly increasing along the elevation. ② Seven phyla, including Proteobacteria, Actinobacteria, and Acidobacteria, were the dominant groups, and five of them showed highly significant differences between altitudes (P < 0.01). ③ At the secondary classification level, there were 36 metabolic functions of bacteria, including membrane transport, carbohydrate metabolism, and amino acid metabolism, of which 22 showed significant differences, and 12 showed extremely significant differences among different altitudes. ④ Pearson correlation analysis showed that soil water content, bulk density, pH, and carbon-nitrogen ratio had the most significant effects on bacterial Alpha diversity, whereas soil nutrients such as total organic carbon, total nitrogen, and total phosphorus had significant effects on bacterial Beta diversity. ⑤ Mantel test analysis showed that the soil water content, total organic carbon, and carbon-nitrogen ratio affected bacterial community structure at the phylum level, and soil pH, total organic carbon, total nitrogen, total phosphorus, and carbon-nitrogen ratio were significantly correlated with bacterial metabolic function. Variance partitioning analysis showed that soil water content had the highest explanation for the community structure of soil bacteria, whereas soil pH had the highest explanation for metabolic function. In conclusion, soil water content and pH were the main factors affecting the diversity, community composition, and metabolic function of soil bacteria in farmland in the loess hilly region of Ningxia.

Biochar amendment is acknowledged to favor plant resistance against soil-borne diseases. Although plant-beneficial bacteria enrichment in the rhizosphere is often proposed to be associated with this protection, the mechanism behind this stimulating effect remains unelucidated. Here, we tested whether biochar promotes plants to recruit beneficial bacteria to the rhizosphere, and thus develop a disease-suppressive rhizosphere microbiome. In a pot experiment, biochar amendment decreased tomato Fusarium wilt disease severity. Using a transplanting rhizosphere microbiome experiment, we showed that biochar enhanced the suppressiveness of tomato rhizosphere microbiome against Fusarium wilt disease. High-throughput sequencing of 16S ribosomal RNA gene and in vitro cultures further indicated that the recruited suppressive rhizosphere microbiome was associated with the increase of plant-beneficial bacteria, such as Pseudomonas sp. This amendment also enhanced the in vitro chemoattraction and biofilm promotion activity of tomato root exudates. Collectively, our results demonstrate that biochar amendment induces tomato seedlings to efficiently recruit a disease-suppressive rhizosphere microbiome against Fusarium wilt.

Tobacco (Nicotiana tabacum L.) is a major cash crop, and soil quality played a significant role in the yield and quality of tobacco. Most farmers cultivate tobacco in rotation with other crops to improve the soil characteristics. However, the effects of different previous crops on the soil\'s nutrient status and bacterial community for tobacco cultivation still need to be determined. Three treatments were assessed in this study, i.e., tobacco-planting soil without treatment (CK), soil with barley previously cultivated (T1), and soil with rapeseed previously cultivated (T2). The soil physical and chemical properties and the 16S rRNA gene sequence diversity of the bacterial community were analyzed. The effects of different crops on the physical and chemical properties of tobacco-planting soil and the diversity and richness of the bacterial community were comprehensively discussed. The results of this study showed that different previously cultivated crops altered the nutrient status of the soil, with changes in the ratio of NH4 +-N to NO3 --N having the most significant impact on tobacco. In CK, the ratio of NH4 +-N to NO3 --N was 1:24.2, T1-1:9.59, and T2-1:11.10. The composition of the bacterial community in tobacco-planting soil varied significantly depending on the previously cultivated crops. The richness and diversity of the bacterial community with different crops were considerably higher than without prior cultivation of different crops. The dominant bacteria in different treatments were Actinobacteriota, Proteobacteria, and Chloroflexi with their relative abundance differed. In conclusion, our study revealed significant differences in nutrient status, bacterial community diversity, and the richness of tobacco-planting soil after the preceding cultivation of different crops. Suitable crops should be selected to be previously cultivated in tobacco crop rotations in near future for sustainable agriculture.