Resistance of Microbial Community of Artemisia annua L.to Pathogenic Fungi

[Objectives]This paper was to figure out whether the dominant bacterial community has the role and effect of bacterial community and its defense mechanism against potential pathogenic fungi in Artemisia annua,and thus establish a systematic model of bacteria-fungus-plant.[Methods]Fifty-eight strains of bacteria and one strain of pathogenic fungi,Globisporangium ultimatum,were used for the experiments.These 58 bacterial strains were assembled into a bacterial community,and the bacteria with abundance in the top 1%were reassembled into a dominant bacterial community as measured by 16S rDNA.[Results]The growth of A.annua seedlings inoculated with bacterial communities and pathogenic fungi or dominant bacterial communities and pathogenic fungi was significantly better than that of A.annua seedlings inoculated with pathogenic fungi during in vitro confrontation,which was evident in both enzymatic and non-enzymatic antioxidant assays.[Conclusions]The results suggest that the dominant bacterial community has a crucial role as a representative core microbial community of synthetic bacterial community,which can protect plants by interfering with the growth of phytopathogenic fungi mediated by chemical signals,and can be used as the main synthetic community of biocides to achieve the effect of biocontrol.

Stabilization of jiuyao quality for huangjiu brewing by fortifying functional strains based on core microbial community analysis

Jiuyao as a generally small saccharifying and spontaneously fermenting starter is indispensable for huangjiu brewing.However,jiuyao currently in use is facing a major challenge of standardized manufacturing because of its open operating environment and rather primitive operations.This study provided a stead manufacturing procedure for jiuyao by controlling the processing parameters.Saccharomycopsis fibuligera and Rhizopus microsporus were revealed as the core functional species related to starch-degrading enzyme activities with single-molecule real-time(SMRT)sequencing.Two strains with high starch-degrading abilities were successfully isolated and identified as Saccharomycopsis fibuligera CY2111 and Rhizopus microsporus SM4.Meanwhile,the environmental fermentation parameters of jiuyao were optimized to enhance enzyme activities.The glucoamylase andα-amylase activities of fortified jiuyao with strain CY2111 and SM4 were 3.07 and 3.15 times that of traditional jiuyao,respectively.Moreover,the alcohol content increased by approximately 7.5%when fortified jiuyao was used for huangjiu brewing.The flavor profiles determined by gas chromatography-mass spectrometry indicated there was no significant difference in the key aromas between the huangjiu fermented with fortified jiuyao and that of traditional jiuyao.Further,fortified jiuyao produced more pleasant esters in huangjiu such as ethyl isovalerate,isoamyl acetate,and ethyl caprylate.Combined with the sensory evaluation,huangjiu fermented with fortified jiuyao presented stronger fruity aroma.These results demonstrated that careful fermentation settings combined with biofortification technology were feasible to improve jiuyao quality,thus promoting huangjiu flavor.Taken together,it provided scientific guidance to improve traditional handcrafting and scale up the production of jiuyao under controllable fermentation.

Core activated sludge communities are influenced little by immigration:Case study of a membrane bioreactor plant

Microbial immigrants arriving with influent wastewater may influence activated sludge(AS)ecosystems.However,the extent to which immigration impacts AS communities is still debated.To explore the intensity of immigration impact,we used sequencing technology to track the raw wastewater and AS communities from a membrane bioreactor plant over a 12-month period.We first distinguished core populations from peripheral ones in both raw wastewater and AS based on their occurrence frequency and abundance.The results showed that core OTUs(≥80%occurrence frequency)made up a large fraction(>90%)of total sequences,while peripheral OTUs composed the majority of all detected OTUs but merely occupied a few sequences.A significant difference in core communities between the influent and AS was found,as well as between the compositions of core and peripheral populations.Additionally,the persistent functional bacteria of AS,although not numerically dominant,accounted for 96.24%of the total sequences related to nutrient turnover,suggesting the presence of a small number of longstanding and core functional bacteria in the AS ecosystem.Importantly,64%of the 5188 OTUs in AS,which accounted for 91.51%of the sequences,exhibited positive growth rates,which suggested that their apparent abundances were due to growth within the plant,not from immigration.Taken together,these results demonstrated that the impact of influent populations on core AS communities was limited.Overall,this work provides quantitative insights into the impact of immigration,which is expected to advance our understanding of the AS community assembly.

The structure and evolution of trade relations between countries along the Belt and Road

Trade facilitation is one of the five main agendas of the Belt and Road Initiative(BRI). Social network analysis has helped understand the complexity of trade networks, but existing studies tend to overlook the fact that not all bilateral trade relations are equally important to a country. To fill this gap in the literature, this paper focuses on the top 2 trade relations networks to illuminate the structure and evolution of B&R trade relations, the relative positions of different countries, and changes in the composition of trade communities(e.g., the community leaders) and the changing patterns of trade between them. We find rich dynamics over time both inter-and intra-communities. The overall international trade networks of B&R countries experienced a leadership change from Russia to China on one hand, some temporary communities experienced emergence, disappearance(e.g. the Kuwait-and Thailand-led communities) or reemergence(e.g. Poland-led community), and a community membership was generally consistent on the other hand. Since the future impacts of China's BRI will depend on the degree of integration of the connected regions, some countries with stable and high centrality indices(e.g. Russia, Singapore, Serbia, Greece, Turkey, Iran, Poland, Hungary and Romania) could be selected by China as strategic regional partners, and countries with a strategically important geographical position but weak trade links(e.g. Myanmar, Pakistan, and Belarus) should be prioritized.