Effect of soil management systems on the rhizosphere bacterial community structure of tobacco: Continuous cropping vs. paddy-upland rotation.

Rhizosphere bacteria play important role in soil nutrient cycling and plant growth, and their richness and diversity are influenced by soil management systems. However, the specific changes in tobacco rhizosphere bacterial community structure in continuous and tobacco-rice rotation cropping systems remain uninvestigated. In this study, soil properties and the composition of the rhizosphere bacterial community in tobacco monocropping and tobacco-rice rotation cropping systems were analyzed. Moreover, the comparison of rhizosphere bacterial community structure between tobacco continuous and tobacco-rice rotation cropping systems was performed via high-throughput sequencing. The changes in the composition of the rhizosphere bacterial community were investigated at different tobacco growth stages. The results showed that continuous tobacco cropping increased the soil soluble organic carbon (SOC), total nitrogen (TN), and the content of other nutrients (e.g., available phosphorus and available potassium) compared to tobacco-rice rotation cropping. However, monocropping decreased bacterial alpha-diversity and altered the community composition when compared to the rotation cropping system. At the phylum level, the relative abundance of Proteobacteria, Gemmatimonadetes, and Bacteroidetes increased in the continuous cropping soil, while that of Acidobacteria, Firmicutes, and Actinobacteria decreased. At the genera level, the average abundance of the dominant genus Bacillus varied from 12.96% in continuous cropping libraries to 6.33% in the rotation cropping libraries (p < 0.05). Additionally, several other taxa, such as o_Acidobacteriales and Candidatus_Solibacter decreased from 7.63 to 6.62% (p < 0.05) and 4.52 to 2.91% (p < 0.05), respectively. However, the relative abundance of f_Gemmatimonadaceae and c_Subgroup_6 showed an increase of 1.46% (p < 0.05) and 1.63% (p < 0.05) in the tobacco-rice rotation cropping system, respectively. The results of NMDS indicated that the rhizobacteria community structure differed in the two cropping systems. In tobacco, the rhizosphere bacterial community structure showed no significant changes in the prosperous long-term stage and topping stage, but the composition changed significantly in the mature stage.

Organic materials with high C/N ratio: more beneficial to soil improvement and soil health.

In order to figure out the effect of organic fertilizers with different carbon-nitrogen (C/N) ratios on the soil improvement and the healthy cultivation, the pot experiment method was used to study effects on the physical and chemical properties and the bacterial community structure of sandy loam soil using five treatments of chemical fertilizer application with the C/N ratios of 15 (CN15), 20 (CN20), 25 (CN25), 30 (CN30) and the control (CK) respectively. Results show that the organic materials with different C/N ratios significantly improve the soil porosity and water content, which all show a linear change rule with the C/N ratio. It can also significantly increase the soil total carbon, total nitrogen, soil C/N ratio, soil microbial biomass carbon, microbial biomass nitrogen and microbial biomass C/N ratio. Among them, CN30 significantly increases the soil total carbon and C/N ratio, which are 5.34-24.13% and 8.87-30.15% respectively compared with other treatments. It can be also found that the dominant flora (at the phylum level) of each treatment are Actinobacteria, Proteobacteria and Chlorobi. The CN30 treatment presents the most obvious improvement in the diversity and richness of the soil bacterial community and is more conducive to the growth and reproduction of Proteobacteria and Firmicutes. The correlation analysis shows that Ctotal/Ntotal and Cmic/Nmic are the most important environmental factors affecting the soil physical and chemical properties and their correlation with the bacterial communities. The higher C/N ratio of organic materials results in a more significant improvement of the soil physical and chemical properties. This study provides a new theoretical basis for the soil health cultivation technology.

Exogenous application and interaction of biochar with environmental factors for improving functional diversity of rhizosphere's microbial community and health.

The usage of fertilizer with high nitrogen content in many countries, as well as its enormous surplus, has a negative impact on the soil ecological environment in agricultural system. This consumption of nitrogen fertilizer can be minimized by applying biochar to maintain the sufficient supply of nitrogen as nutrient to the near-root zone. This study investigated the effects of various amounts of biochar application (450, 900, 1350, and 1800 kg/hm2) and reduction of nitrogen fertilizer amount (10, 15, 20, and 25%) on the nutrients and microorganism community structure in rhizosphere growing tobacco plant. The microorganism community was found essential in improving nitrogen retention. Compared with conventional treatment, an application of biochar in rhizosphere soil increased the content of soil available phosphorus, organic matter and total nitrogen by 21.47%, 26.34%, and 9.52%, respectively. It also increased the abundance of microorganisms that are capable of degrading and utilizing organic matter and cellulose, such as Actinobacteria and Acidobacteria. The relative abundance of Chloroflexi was also increased by 49.67-78.61%, and the Acidobacteria increased by 14.79-39.13%. Overall, the application of biochar with reduced nitrogen fertilizer amount can regulate the rhizosphere microecological environment of tobacco plants and their microbial population structure, thereby promoting soil health for tobacco plant growth while reducing soil acidification and environmental pollution caused by excessive nitrogen fertilizer.

Soil carbon supplementation: Improvement of root-surrounding soil bacterial communities, sugar and starch content in tobacco (N. tabacum).

Soil carbon supplementation is known to stimulate plant growth by improving soil fertility and plant nutrient uptake. However, the underlying process and chemical mechanism that could explain the interrelationship between soil carbon supplementation, soil micro-ecology, and the growth and quality of plant remain unclear. In this study, we investigated the influence and mechanism of soil carbon supplementation on the bacterial community, chemical cycling, mineral nutrition absorption, growth and properties of tobacco leaves. The soil carbon supplementation increased amino acid, carbohydrates, chemical energy metabolism, and bacterial richness in the soil. This led to increased content of sugar (23.75%), starch (13.25%), and chlorophyll (10.56%) in tobacco leaves. Linear discriminant analysis revealed 49 key phylotypes and significant increment of some of the Plant Growth-Promoting Rhizobacteria (PGPR) genera (Bacillus, Novosphingobium, Pseudomonas, Sphingomonas) in the rhizosphere, which can influence the tobacco growth. Partial Least Squares Path Modeling (PLS-PM) showed that soil carbon supplementation positively affected the sugar and starch contents in tobacco leaves by possibly altering the photosynthesis pathway towards increasing the aroma of the leaves, thus contributing to enhanced tobacco flavor. These findings are useful for understanding the influence of soil carbon supplementation on bacterial community for improving the yields and quality of tobacco in industrial plantation.

Improvement of Nicotine Removal and Ethanol Fermentability From Tobacco Stalk by Integration of Dilute Sulfuric Acid Presoak and Instant Catapult Steam Explosion Pretreatment.

The nicotine from tobacco stalk showed obvious inhibitory effect on the activity of cellulase and fermentability of microorganisms, which seriously hinders the utilization of tobacco stalk. Dilute sulfuric acid presoak of tobacco stalk was used to enhance the performance of instant catapult steam explosion (ICSE) for tobacco stalk pretreatment. The presoak was beneficial to break the recalcitrant structure of tobacco stalk, reduce nicotine content to relieve the inhibition on the activity of cellulase and metabolism of microorganisms, and promote the performance of enzymatic hydrolysis and ethanol fermentation. The optimized 0.8% sulfuric acid (w/w) presoak-integrated ICSE pretreatment resulted in 85.54% nicotine removal from tobacco stalk; meanwhile, the total sugar concentration from enzymatic hydrolysis of pretreated tobacco stalk increased from 33.40 to 53.81 g/L (the ratio of dry tobacco stalk to water was 1:8, w/w), ethanol concentration increased 103.36% from 5.95 to 12.10 g/L in flask, compared with separate ICSE pretreatment. Finally, the ethanol concentration achieved the highest 23.53 g/L in a 5-L fermenter with the ethanol yield from the glucose of tobacco stalk hydrolysate achieving 71.40% by increasing the solid loading of the tobacco stalk in the enzymatic hydrolysis process (the ratio of dry tobacco stalk to water was 1:4, w/w). These results achieved the expected purpose of efficient utilization of discarded tobacco stalk.

Biochar increases tobacco yield by promoting root growth based on a three-year field application.

In order to explore the effects of biochar on root system and growth characteristics of flue-tobacco, three years of field experiments were conducted to study the influence of different biochar application levels [600 (T1), 1200 (T2), 1800(T3), 2400 (T4), 3000 (T5) kg/ha] and no fertilizer (CK) on the root physiological indexes and growth index of tobacco. Compared with local conventional fertilization, the application rate of N fertilizer in each treatment (except for control) was reduced by 40% to analyze the effects of different amount of biochar on the physiological indexes of tobacco roots and leaf photosynthesis during flourishing. The results showed that tobacco plants' root development status in the flourishing period was consistent with the photosynthetic physiological indexes, chlorophyll content, and leaf-area coefficient. Compared with the control, the application of biochar could increase the root vigor by 177.8%. Biochar improved the roots, increasing the total root area by 91.35% and the number of root tips by 100.9%. Meanwhile, biochar increased the net photosynthetic rate of tobacco leaves by 77.3% and the total tobacco biomass by 72.5%. Studies have shown that biochar can promote the development of tobacco roots, and then enhance the photosynthesis of leaves, so that tobacco plants can grow healthily, which is conducive to the tobacco production and the cultivation of soil.

Biochar for cadmium pollution mitigation and stress resistance in tobacco growth.

Pot experiments were conducted to investigate the influence of biochar addition and the mechanisms that alleviate Cd stress in the growth of tobacco plant. Cadmium showed an inhibitory effect on tobacco growth at different post-transplantation times, and this increased with the increase in soil Cd concentration. The growth index decreased by more than 10%, and the photosynthetic pigment and photosynthetic characteristics of the tobacco leaf were significantly reduced, and the antioxidant enzyme activity was enhanced. Application of biochar effectively alleviated the inhibitory effect of Cd on tobacco growth, and the alleviation effect of treatments is more significant to the plants with a higher Cd concentration. The contents of chlorophyll a, chlorophyll b, and carotenoids in the leaves of tobacco plants treated with biochar increased by 9.99%, 12.58%, and 10.32%, respectively, after 60 days of transplantation. The photosynthetic characteristics index of the net photosynthetic rate increased by 11.48%, stomatal conductance increased by 11.44%, and intercellular carbon dioxide concentration decreased to 0.92. Based on the treatments, during the growth period, the antioxidant enzyme activities of tobacco leaves comprising catalase, peroxidase, superoxide dismutase, and malondialdehyde increased by 7.62%, 10.41%, 10.58%, and 12.57%, respectively, after the application of biochar. Our results show that biochar containing functional groups can effectively reduce the effect of Cd stress by intensifying the adsorption or passivation of Cd in the soil, thereby, significantly reducing the Cd content in plant leaves, and providing a theoretical basis and method to alleviate soil Cd pollution and effect soil remediation.

Soil type regulates carbon and nitrogen stoichiometry and mineralization following biochar or nitrogen addition.

Most studies on the effects of biochar and fertilizer on soil carbon (C) and nitrogen (N) mineralization, and microbial C and N content, are restricted to a single soil type, limiting our understanding of the interactions between these factors and microbial functions. To address this paucity in knowledge, we undertook a 3-year experiment using four contrasting soils to assess the role of peanut shell biochar and fertilizer on C and N mineralization, microbial C and N, and N stoichiometry. Across all four soils, biochar significantly (P < 0.05) increased soil carbon mineralization (Cmin) and nitrogen mineralization (Nmin) over three years compared to fertilizer and the control. Biochar also increased total C (Csoil) across the four soils in year 1, with the Fluvisol recording greater total C in year 2 and Phaeozem having greater total C in year 3. Biochar resulted in a higher microbial biomass C (Cmic), total N (Nsoil) and microbial biomass N (Nmic); the degree of change was closely related to Csoil and Nsoil. There was a positive correlation between Cmic:Nmic and Csoil:Nsoil; while Csoil and Cmic increased following amendment with biochar, which reduced the soil C and N stoichiometric imbalance (Nimb) caused by the increase in the C to N ratio. However, fertilizer exacerbated the imbalance of soil C and N stoichiometry. Fertilizer also reduced the Csoil:Nsoil and Cmic:Nmic ratios. Soil pH had a positive correlation with Csoil, Cmic, Nmic, Cmin, Nmin, Csoil:Nsoil, Cmic:Nmic, and biochar increases this correlation. The soil pH was negatively correlated with Cimb:Nimb and Nsoil. Fertilizer was positively correlated Cimb:Nimb and Nsoil. In contrast, fertilizer N application lowered microbial biomass C:N. We conclude that biochar reduces the imbalance of soil C and N stoichiometry, whereas fertilizer increased this imbalance. Biochar had a greater impact on C and N in soils with a lower pH.

[Effect of Biochar on Soil Enzyme Activity & the Bacterial Community and Its Mechanism].

Biochar-based fertilizers can improve the mineralization of carbon and nitrogen in soil and enhance the soil micro-ecological environment due to particular physical and chemical properties. It is of great significance to explore the underlying mechanism of biochar-based fertilizer in the regulation of soil microorganisms and soil enzyme activity to improve soil quality. Field experiments were conducted to investigate the effects of different biochar-based fertilizer rates[0 (CK2), 0.6 (T1), 0.9 (T2), 1.2 (T3), and 1.5 (T4) t·hm-2]on soil nutrients, soil enzyme activity, and bacterial community structure. The results showed that with the application of biochar-based fertilizer, soil bulk density decreased, while the pH value, available P, available K, organic matter content, and the C/N ratio increased by 0.32%-5.83%, 14.09%-23.16%, 0%-38.70%, 7.49%-14.16%, and 4.06%-10.13%, respectively, compared to that of the CK2 treatment. With increasing rates of biochar-based fertilizer, the enzyme activity first increased and then decreased. Invertase (INV), urease (URE), catalase (CAT), and neutral phosphatase (NPH) activity under the application of biochar-based fertilizer were 63.73%-166.37%, 117.52%-174.03%, 12.98%-23.59%, and 60.84%-119.71% higher than that of CK2, respectively. The corresponding bacterial diversity was significantly improved, especially with regard to the increase in the abundance of growth promoting bacteria, such as Gemmatimonadetes and Proteobacteria, and decreased the abundance of Acidobacteria and Actinobacteria. The correlation analysis showed that soil C/N ratio was the key factor affecting soil enzyme activity, and there was a significant positive correlation between soil enzyme activity and bacterial diversity. There were significantly positive correlations among the activities of the above four soil enzymes and the relative abundance of Gemmatimonadetes (P<0.01), with CAT being the key factor affecting the bacterial community structure. This study revealed a relationship between soil enzyme activity and microbial colonies, which provides a theoretical basis and mechanism for applying biochar to regulate the soil enzyme and micro-ecological environment.

Soil amendment in plastic greenhouse using modified biochar: soil bacterial diversity responses and microbial biomass carbon and nitrogen.

Excessive application of chemical fertilizer and continuous cropping in plastic greenhouse resulted in soil quality decline. The decrease of soil C/N ratio and the imbalance of soil carbon pool structure have brought new challenges to soil health, crop yield and sustainable agricultural development. OBJECTIVES: The experiment was set up to explore the effect of modified biochar on soil bacterial community structure, and the correlation between soil environmental factors and bacterial community structure changes. Based on the plot experiment in the field, the effect of modified biochar was studied via high-throughput MiSeq sequencing. RESULTS: Compared with the control (CK), the modified biochar (T) significantly increased soil water content, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) content and the ratio of MBC and MBN by 7.92%, 24.58%, 2.07% and 18.95%. Diversity index analysis showed that the application of modified biochar significantly increased the Shannon index, ACE index and Chao1 index of the bacterial community by 3.05%, 5.07% and 5.24%. Compared with the control, the modified biochar decreased the relative abundance of Actinobacteriota and Chloroflex by 6.81% and 2.19%, and increased the relative abundance of Proteobacteria and Acidobacteriota by 7.34% and 12.52%. Correlation analysis shows that soil bulk density and water content may be important related factors that affect bacterial community structure. CONCLUSIONS: This study provides a theoretical basis for the directional control of modified biochar in the soil microecological environment in plastic greenhouse, which is conducive to healthy and sustainable farming.

Novel environmental factors affecting microbial responses and physicochemical properties by sequentially applied biochar in black soil.

Biochar was increasingly used in agriculture soil amendment and has received widespread attention due to its potential to improve soil micro-ecological environment and crop growth. The raw material of the biochar used in this study is peanut shell, which is mixed with other organics and minerals to become a mineral-enhanced biochar under heating conditions (220 °C). When the third season crop is finished, we evaluated black soil physicochemical properties, microbial communities, and crop growth in long-term agricultural trials. Four treatments were set up: no amendment (control CK), nitrogen fertilizer only (70 kg ha-1 N), enhanced biochar only (5 t ha-1 B), and nitrogen fertilizer (70 kg ha-1) + enhanced biochar (5 t ha-1) (NB). The enhanced biochar promotes crop growth and increased the richness of the bacterial community, while reducing the richness of the fungal community. Nitrogen fertilizer + enhanced biochar increased soil microbial biomass carbon, nitrate nitrogen, and ammonium nitrogen by 43.75, 7.25, and 19.28%. In addition, we found changes in bacterial community were closely related to soil organic carbon, while changes in fungal community structure were closely related to soil carbon to nitrogen ratio. And the soil organic carbon and soil carbon to nitrogen ratio of biochar treatment were increased by 5.64 and 6.25% compared with fertilizer treatment, respectively. We concluded that enhanced biochar improved the soil more effectively and made the soil more conducive to crop growth. Regulating the microbial community by improving the physicochemical properties of soil was an important way to improve the stability and condition of the soil system with biochar. An enhanced biochar was of great significance for circular development of agriculture and soil improvement in Northeast China.

Study on the preparation of geranyl acetone and ß-cyclodextrin inclusion complex and its application in cigarette flavoring.

ß-Cyclodextrin (ß-CD) inclusion complex containing geranyl acetone as a guest was prepared by saturated water solution method. Furthermore, the structure and properties of the inclusion complex were studied. The formation of the inclusion complex was demonstrated by. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-RD), thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The thermodynamic analysis of the inclusion complex showed that the inclusion reaction is an endothermic spontaneous reaction. The average of △H, △S and △G is 11.66 kJ mol-1, 0.082 kJ mol-1 and - 14.49 kJ mol-1, respectively. Moreover, the kinetic analysis of thermal decomposition of the inclusion compound showed that the thermal decomposition reaction is a first-order reaction (the inclusion ratio is 1:1), the average activation energy of the reaction is 180.90 kJ mol-1, and the binding force in the inclusion compound is mainly Van der Waals force. The flavor test of cigarettes showed that the inclusion compound improved the stability of geranyl acetone and the sensory quality of cigarettes. This study improves the solubility and thermal stability of geranyl acetone, and provides theoretical support and technical guidance for expanding the application of geranyl acetone.

Regioselective C-H sulfenylation of N-sulfonyl protected 7-azaindoles promoted by TBAI: a rapid synthesis of 3-thio-7-azaindoles.

This paper describes the regioselective C-3 sulfenylation of N-sulfonyl protected 7-azaindoles with sulfonyl chlorides. In this transformation, dual roles of TBAI serving as both promoter and desulfonylation reagent have been demonstrated. The reaction proceeded smoothly under simple conditions to afford 3-thio-7-azaindoles in moderate to good yields with broad substrate scopes. This protocol refrains from using transition-metal catalysts, strong oxidants or bases, and shows its practical synthetic value in organic synthesis.

[Effect of Biochar Amendment on Physicochemical Properties and Fungal Community Structures of Cinnamon Soil].

To identify the effect of biochar addition on soil abiotic and biotic properties and provide evidence for the soil improvement with biochar input, the soil physiochemical properties and fungal community were investigated in a cinnamon soil after 3-year biochar additions of 10, 20, and 40 t ·hm-2. The relationship between the fungal community and edaphic physicochemical characteristics was also analyzed. The results showed that soil pH, moisture, total nitrogen (TN), and total organic carbon (TOC) significantly increased but dissolved organic carbon (DOC) content and soil bulk density decreased with biochar addition. High-throughput sequencing results indicated that biochar amendment had little influence on fungal α diversity but significantly changed the fungal community structure. The taxonomic classification showed that the dominant fungal phyla were Ascomycota, Zygomycota, and Basidiomycota, and these phyla accounted for more than 90% of the total sequences. The relative abundance of Ascomycota and Basidiomycota increased, while the abundance of Zygomycota decreased with biochar addition. At the genus level, biochar addition increased the relative abundances of Alternaria, Conocybe, and Aspergillus but decreased the relative abundances of Actinomucor and Gibberella. Redundancy analysis (RDA) showed that soil DOC, pH, and moisture were key environmental factors leading to the shift in the soil fungal community composition. In summary, the application of biochar changed the soil physicochemical properties, which drove the ecological succession of soil fungal communities.

The preparation and ethanol fermentation of high-concentration sugars from steam-explosion corn stover.

In the field of biofuel ethanol, high-concentration- reducing sugars made from cellulosic materials lay the foundation for high-concentration ethanol fermentation. In this study, corn stover was pre-treated in a process combining chemical methods and steam explosion; the cellulosic hydrolyzed sugars obtained by fed-batch saccharification were then used as the carbon source for high-concentration ethanol fermentation. Saccharomyces cerevisiae 1308, Angel yeast, and Issatchenkia orientalis were shake-cultured with Pachysolen tannophilus P-01 for fermentation. Results implied that the ethanol yields from the three types of mixed strains were 4.85 g/100 mL, 4.57 g/100 mL, and 5.02 g/100 mL (separately) at yield rates of 91.6, 89.3, and 92.2%, respectively. Therefore, it was inferred that shock-fermentation using mixed strains achieved a higher ethanol yield at a greater rate in a shorter fermentation period. This study provided a theoretical basis and technical guidance for the fermentation of industrial high-concentrated cellulosic ethanol.

[Optimization of corn stover hydrolysis by fed-batch process].

High-concentration sugars production from stover is an important perspective technology for the cellulosic ethanol industrialization. Fed-batch process is an effective way to achieve this goal in the fermentation industry. In this study, based on fed-batch process, high-concentration sugars were produced from pretreated corn stover by enzymatic hydrolysis. After being pretreated by the dilute sulphuric acid, the impacts of the ratio of solid raw material to liquid culture, the content of supplementary materials and the refilling time on the saccharification rate were investigated. Results showed that the initial ratio of solid raw material to liquid culture was 20% (W/V) and the initial concentrations of enzymes for xylanase, cellulose and pectinase were 220 U, 6 FPU, and 50 U per gram of substrates, respectively. After 24 hours and 48 hours, 8% pretreated corn stovers were added respectively together with the additions of xylanase (20 U) and cellulose (2 FPU) per gram of substrates. After 72 hours, the final concentration of reducing sugar was increased to 138.5 g/L from 48.5 g/L of the non fed-batch process. The rate of enzyme hydrolysis of the raw material was 62.5% of the thoretical value in the fed-batch process. This study demonstrated that the fed-batch process could significantly improve the concentration of reducing sugar.