Integrative analysis of microbiome and metabolome revealed the effect of microbial inoculant on microbial community diversity and function in rhizospheric soil under tobacco monoculture.

Over-application of chemical fertilizers and continuous cropping obstacles seriously restrict the sustainable development of tobacco production. Localized fertilization of beneficial microbes has potential advantages in achieving higher productivity, but the underlying biological mechanisms of interactions between rhizospheric microorganisms and the related metabolic cycle remain poorly characterized. Here, an integrative analysis of microbiomes with non-targeted metabolomics was performed on 30 soil samples of rhizosphere, root surrounding, and bulk soils from flue-cured tobacco under continuous and non-continuous monocropping systems. The analysis was conducted using UPLC-MS/MS platforms and high-throughput amplicon sequencing targeting the bacterial 16S rRNA gene and fungal ITS gene. The microbial inoculant consisted of Bacillus subtilis, B. velezensis, and B. licheniformis at the ratio of 1:1:1 in effective microbial counts, improved the cured leaf yield and disease resistance of tobacco, and enhanced nicotine and nitrogen contents of tobacco leaves. The bacterial taxa Rhizobium, Pseudomonas, Sphingomonadaceae, and Burkholderiaceae of the phylum Proteobacteria accumulated in high relative abundance and were identified as biomarkers following the application of the microbial inoculant. Under continuous monocropping, metabolomics demonstrated that the application of the microbial inoculant significantly affected the soil metabolite spectrum, and the differential metabolites were significantly enriched to the synthesis and degradation of nicotine (nicotinate and nicotinamide metabolism and biosynthesis of alkaloids derived from nicotinic acid). In addition, microbes were closely related to the accumulation of metabolites through correlation analysis. The interactions between plant roots and rhizospheric microorganisms provide valuable information for understanding how these beneficial microbes affect complex biological processes and the adaption capacity of plants to environments.IMPORTANCEThis study elaborated on how the microbial fertilizer significantly changed overall community structures and metabolite spectrum of rhizospheric microbes, which provide insights into the process of rhizosphere microbial remolding in response to continuous monocropping. we verified the hypothesis that the application of the microbial inoculant in continuous cropping would lead to the selection of distinct microbiota communities by establishing models to correlate biomarkers. Through correlation analysis of the microbiome and metabolome, we proved that rhizospheric microbes were closely related to the accumulation of metabolites, including the synthesis and degradation of nicotine. The interactions between plant roots and rhizospheric microorganisms provide valuable information for understanding how these beneficial microbes affect complex biological processes and the adaption capacity of plants to environments.

Effect of In Situ NbC-Cr7C3@graphene/Fe Nanocomposite Inoculant Modification and Refinement on the Microstructure and Properties of W18Cr4V High-Speed Steel.

A novel graphene-coated nanocrystalline ceramic particle, iron-based composite inoculant was developed in this study to optimize the as-cast microstructure and mechanical properties of W18Cr4V high-speed steel (HSS). The effects of the composite inoculant on the microstructure, crystal structure, and mechanical properties of HSS were analyzed using transmission electron microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The (002-) and (020) crystal planes of the Fe3C and Cr7C3 phases, respectively, were collinear at two points in the reciprocal space, indicating a coherent relationship between the Fe3C and Cr7C3 phases in the tempered modified HSS. This contributed to an improved non-uniform nucleation rate and refining of the HSS grains. The mechanical properties of the modified steel exhibited a general improvement. Specifically, the modification treatment enhanced the hardness of HSS from HRC 63.2 to 66.4 and the impact toughness by 48.3%.

The Effect of CoAl2O4 as a Nucleating Agent and Pouring Temperature on the Microstructure and Properties of Inconel 713C® Nickel-Based Superalloy Castings.

In this work, three melt-pouring temperatures (1450 °C, 1480 °C, 1520 °C) and CoAl2O4 inoculant contents in the shell mold's primary coating (0 wt%, 5 wt%, and 10 wt%) were selected to study microstructural and mechanical property changes of the Inconel 713C® nickel-based superalloy. The castings' phase transformation temperatures, phase constitution, microstructure, and mechanical properties at room and elevated temperatures were investigated via thermodynamical simulations, differential thermal analysis, light and scanning electron microscopy, energy-dispersive X-ray spectroscopy, and tensile and stress-rupture tests. The pouring temperature and inoculant content strongly influenced the mean equiaxed grain size, which ranged between 2.36 and 6.55 mm. The primary microstructure of Inconel 713C® castings, owing to its complex chemical composition, comprised multiple phases, including γ, γ', MC, M3B2, and Ni7Zr2. The mean size of γ' was in the 0.446-0.613 µm range, depending on the casting variant. Grain refinement with CoAl2O4 at ambient temperature for each melt-pouring temperature led to increased yield strength (YS) and ultimate tensile strength (UTS). YS was in the range of 775-835 MPa, while UTS was in the range of 868-1010 MPa. A reverse trend was observed in samples that crept in 982 °C/152 MPa, while for each variant, the time to rupture exceeded 30 h. The maximum time to rupture was 46.1 h obtained in the unmodified casting poured at 1480 °C.

Characterization and in vitro evaluations of Baru pulp from almond production waste ensiled with different additives.

The silage process is an efficient way of storing nutrients for animal nutrition. Our hypothesis was that the Baru pulp can be preserved in the form of silage, regardless of the use of additives to aid the process. Silages of Baru pulp containing different additives were evaluated through in vitro analysis, fermentation parameters, and composition and thermal analysis including differential scanning calorimetry and thermogravimetry. The treatments consisted of (1) silage with Baru pulp (BP) in natura without additive; (2) BP in natura with acetic acid; (3) BP in natura with formic acids; and (4) BP in natura added with microbial inoculums in a randomized experimental design with three replications per treatment and analyzed in duplicate. The ensiled material was kept in anaerobic conditions for a period of 30 days. BP before and after the silage process presented averages of 67.31 and 66.24% for in vitro digestibility of DM (IVDMD). Microbial inoculant additive was the most effective in reducing pH, followed by acetic acid and formic acid. There were effects of additives on silages for all degradation parameters in ruminal liquid in vitro. It was observed that BP before ensiling had the highest A fraction (7.9 mL gas/100 mg DM), without differing from the silage treated with formic acid (7.1 mL gas/100 mg DM). Similar effects were observed on mass loss (TG) and heat flux (DSC) between the silages. Our findings suggest that Baru pulp with formic acid is more efficient in the conservation and preservation of fermentable carbohydrates as well as in silage production.

Integrated effects of microbial decomposing inoculant on greenhouse gas emissions, grain yield and economic profit from paddy fields under different water regimes.

Few studies have comprehensively evaluated the impacts of microbial decomposing inoculants on greenhouse gas emissions and economic profit from paddy fields under different water regimes. Here, this study evaluated the effects of microbial decomposing inoculant treatments (straw returning without or with microbial decomposing inoculants (S and SMD)) on rice yield, CH4 and N2O emissions, economic profit and net ecosystem economic profit (NEEP) from paddy fields under different water regimes (continuous flooding (CF) and alternate wetting and drying irrigation (AWD)) in central China with a two-year field experiment. Compared with S treatment, SMD treatment significantly increased the rice yield and crop water productivity by 6.6-7.2% and 5.6-7.9%, respectively. AWD treatment significantly enhanced the crop water productivity by 56.9-73.7% while did not affect rice yield relative to CF treatment. Regardless of water regimes, SMD treatment did not affect N2O emissions, but significantly increased CH4 emissions by 13.8-39.6% relative to S treatment, resulting in a remarkable enhancement of global warming potential by 13.5-32.5%. Compared with S treatment, SMD treatment improved the economic profit and NEEP. By contrast, AWD treatment significantly increased N2O emissions by 19.1-64.8% compared with CF treatment, but significantly reduced CH4 emissions by 35.3-79.1%. Accordingly, AWD treatment significantly decreased the global warming potential by 33.4-73.9% compared with CF treatment. In addition, AWD treatment resulted in 39.9-96.4% higher economic profit and 48.0-124.4% higher NEEP relative to CF treatment. In summary, AWD treatment is a sustainable water regime that can maintain rice yield, mitigate global warming potential, and increase economic income. However, regardless of water regimes, SMD treatment led to higher rice yield and economic profit, as well as higher global warming potential than S treatment, suggesting that other appropriate treatments of crop straw are needed to mitigate CH4 emissions while improving economic profit for rice sustainable production.

Efecto de inoculantes y aditivos sobre fracciones de fermentación ruminal y degradación in vitro en ensilaje de sorgo (Sorghum sp) / Effect of inoculants and additives on fractions of ruminal fermentation and in vitro degradation in sorghum silage (Sorghum sp)

Resumen La acción de inoculantes y aditivos sobre la composición química y degradación ruminal de la materia seca (MS) de ensilaje de sorgo ya ha sido reportada. Sin embargo, se desconoce el efecto que estos tienen sobre la actividad microbiana, y por lo tanto, sobre su potencial de asimilación a nivel ruminal. El objetivo de este estudio fue evaluar el efecto de la adición de inoculantes y aditivos en ensilaje de la planta completa de Sorghum sp. sobre las fracciones de fermentación ruminal y degradación in vitro. Se utilizó un diseño experimental completamente al azar, con 7 tratamientos (control, 3 inoculantes, 2 aditivos y una combinación de inoculante con aditivo) y 21 repeticiones por tratamiento. Se usaron diferentes tipos de inoculantes y aditivos en el proceso de ensilaje de sorgo: lactosuero, yogur, ácido fosfórico, Lactobacillus plantarum y mezcla mineral. Después de 60 d de fermentación, se cuantificaron MS, pH, proteína cruda (PC), degradación in vitro de la MS a 24 h (DIVMS), parámetros de la cinética de fermentación (Vmáx = volumen máximo, L = fase lag, S = tasa de fermentación) y volumen fraccional (fermentación rápida = 0 h a 8 h, media = 8 h a 24 h y lenta = 24 h a 72 h) por producción de gas in vitro. El análisis estadístico indicó que los inoculantes y aditivos modificaron la composición química, los parámetros L, Vmáx, DIVMS y las fracciones de fermentación rápida y media (P < 0.05). El uso de lactosuero y L. plantarum como inoculantes en ensilaje de sorgo redujo la pérdida de PC y, en general, los inoculantes y aditivos mejoraron el pH de los ensilajes; no obstante, disminuyeron el aprovechamiento de las fracciones de fermentación rápida y media, modificaron el potencial de fermentación y provocaron efecto negativo en la DIVMS.

Abstract The action of inoculants and additives on the chemical composition and ruminal degradation of sorghum silage dry matter (DM) has already been reported. However, the effect that these have on the microbial activity and, therefore, on its potential for assimilation at the ruminal level is unknown. For that reason, the objective of this study was to evaluate the effect of the addition of inoculants and additisves in silage of the entire plant of Sorghum sp. on fractions of ruminal fermentation and in vitro degradation. The experimental design was completely random, with 7 treatments (3 inoculants, 2 additives and a combination of inoculate with additive) and 21 repetitions per treatment. Different types of inoculants and additives were used in the process of sorghum silage: cheese whey, yogurt, phosphoric acid, Lactobacillus plantarum and mineral mixture. After 60 d of fermentation, dry matter (DM), hydrogen potential (Hp), crude protein (CP), in vitro dry matter degradation to 24 h (IVDMD), parameters of fermentation kinetics (Vmax= maximum volume L = lag phase, S = fermentation rate) and fractional volume (rapid fermentation = 0 h to 8 h, intermediate = 8 h to 24 h and slow = 24 h to 72 h) were quantified through the in vitro gas production technique. The results indicated that the inoculants and additives modified the chemical composition, the L parameters, Vmax, IVDMD and the rapid and intermediate fermentation fractions (P < 0.05). The use of cheese whey and L. plantarum as inoculants in sorghum silage reduced the loss of CP. Overall, the use of inoculants and additives improved silage Hp; however, it decreased the use of rapid and intermediate fermentation fractions, modified the fermentation potential of the silage and provoked a negative effect on the IVDMD.

Impact of pesticides in properties of Bradyrhizobium spp. and in the symbiotic performance with soybean.

Soybean [Glycine max (L.) Merr.] has great economic and nutritional importance mainly due to its high protein content. All plant's N needs can be met by the symbiosis with elite Bradyrhizobium strains applied as inoculants to the seeds at sowing time; however, the increasing use of pesticides in seed treatments can impair the contribution of the biological nitrogen fixation. In this study, we report decreases in cell survival of two strains, B. japonicum SEMIA 5079 and B. elkanii SEMIA 587 in seeds inoculated and treated with StandakTop™, composed of the fungicides pyraclostrobin and thiophanate-methyl and the insecticide fipronil, the pesticides most used in soybean seed treatment in several countries. Cell death was enhanced with the time of exposure to the pesticides, and B. elkanii was less tolerant, with almost no detectable viable cells after 15 days. Change in colony morphology with smaller colonies was observed in the presence of the pesticides, being more drastic with the time of exposure, and attributed to an adaptive response towards survival in the presence of the abiotic stress. However, morphological changes were reversible after elimination of the stressing agent and symbiotic performance under controlled greenhouse conditions was similar between strains that had been or not exposed to the pesticides. In addition, no changes in DNA profiles (BOX-PCR) of both strains were observed after the contact with the pesticides. In two field experiments, impacting effects of the pesticides were observed mainly on the total N accumulated in grains of plants relying on both N2-fixation and N-fertilizer. Our data indicate that StandakTop® affects parameters never reported before, including colony morphology of Bradyrhizobium spp. and N metabolism and/or N remobilization to soybean grains.

Yield increase of corn inoculated with a commercial arbuscular mycorrhizal inoculant in Brazil / Rendimento de grãos da cultura do milho com inoculante micorrízico arbuscular comercial no Brasil

ABSTRACT: Arbuscular mycorrhizal fungi (AMF) play an important role in plant growth. However, there are no reports of legally commercialized AMF-based inoculants for agricultural crops in Brazil. The objective of this research was to evaluate the agronomic efficiency of a Rhizophagus intraradices inoculant in combination with phosphate fertilization in grain yield of corn under different edaphoclimatic conditions in Brazil. Experiments were conducted in five Brazilian states (Goiás, Mato Grosso, Minas Gerais, Rio Grande do Sul and Santa Catarina) in a 2 x 3 factorial scheme, with two inoculation treatments (inoculated and non-inoculated seeds) and three doses of phosphate fertilization (0, 50 and 100% of the recommended P). At the end of the crop cycle (stages R4-R5), inoculation provided increases in biomass (average of 48%) regardless of the applied dose of P, higher P absorption, and 54% average increase in grain yield. In conclusion, the mycorrhizal inoculant increases biomass yield, P uptake and corn grain yield under different edaphoclimatic conditions in Brazil, especially in soils that originally had low or medium levels of available P.

RESUMO: Os fungos micorrízicos arbusculares (FMA) desempenham um papel importante no crescimento das plantas, no entanto, não há relatos de inoculantes legais baseados em AMF para culturas agrícolas no Brasil. O objetivo deste trabalho foi avaliar a eficiência agronômica de um inoculante a base de Rhizophagus intraradices em combinação com a adubação fosfatada no rendimento de grãos de milho sob diferentes condições edafoclimáticas no Brasil. Os experimentos foram conduzidos em cinco estados brasileiros (Goiás, Mato Grosso, Minas Gerais, Rio Grande do Sul e Santa Catarina) em esquema fatorial 2 x 3, com dois tratamentos de inoculação (sementes inoculadas e não inoculadas) e três doses de adubação fosfatada (0, 50 e 100% do P recomendado). No final do ciclo da cultura (estágios R4-R5), a inoculação proporcionou aumentos na biomassa (média de 48%), independentemente da dose aplicada de P, maior absorção de P e aumento médio de 54% no rendimento de grãos. Conclui-se que o inoculante micorrízico arbuscular aumenta a produção de biomassa, a absorção de P e a produtividade de grãos de milho em diferentes condições edafoclimáticas no Brasil, especialmente em solos que originalmente apresentavam níveis baixos ou médios de P.

Assessing the ability of silage lactic acid bacteria to incorporate and transform inorganic selenium within laboratory scale silos.

Selenium (Se) is a non-metallic trace element essential for normal cellular function, which has been linked with reduced risk of cancer, cardiovascular disease, cognitive decline and thyroid disease in humans. Se deficiency in livestock is associated with white muscle disease, retained placenta, ill-thrift and mastitis. Where Se status or bioavailability from the soil for plants is poor, livestock rely on supplemental Se in their diets predominantly as either sodium selenite (inorganic form) or selenised-yeast (organic form). As lactic acid bacteria (LAB) have been shown to incorporate Se as either organic or elemental (Nano-Se) there may be potential to use silage inoculant bacteria to improve the Se status of feed to provide the Se requirements of livestock. We screened twenty-seven LAB in MRS broth in the presence of sodium selenite for growth and uptake of Se as organic (selenocysteine and selenomethionine), inorganic (selenite and selenate) or/and Nano-Se, with the aim to identify potential candidates for a mini-silo study. Sodium selenite addition into the growth medium of LAB reduced growth rates but also resulted in the conversion of the inorganic sodium selenite into predominately Nano-Se and small quantities of organic-Se. Based on a rank analysis of growth and ability to take up (total Se content) and convert inorganic Se (Nano and organic Se content), three LAB were selected for further investigation as silage inoculants: L. brevis DSMZ (A), L. plantarum LF1 (B), and L. plantarum SSL MC15 (C). Each LAB was used as an inoculant within a grass mini-silo trial, either cultured in the presence of sodium selenite before inoculation or sodium selenite added to the inoculum at inoculation versus controls with no Se. The addition of sodium selenite either into the growth media of LAB or applied at inoculation of grass silage did not interfere with the ability of the LAB to act as a silage inoculant with no difference in silage fermentation characteristic between LAB with no Se added. The addition of sodium selenite either to the LAB growth medium or at inoculation resulted in the conversion of sodium selenite into Nano-Se and organic-Se (Nano-Se, ca. 103 higher than organic), as previously shown in the screening trial. There was no difference between the three LAB for incorporation of Se or in silage quality, indicating the potential to develop silage inoculants to increase the bioavailable form of Se (elemental and organic) to livestock through conversion of inorganic forms during ensiling.

Phenotypic, genetic and symbiotic characterization of Erythrina velutina rhizobia from Caatinga dry forest

Abstract Erythrina velutina ("mulungu") is a legume tree from Caatinga that associates with rhizobia but the diversity and symbiotic ability of "mulungu" rhizobia are poorly understood. The aim of this study was to characterize "mulungu" rhizobia from Caatinga. Bacteria were obteined from Serra Talhada and Caruaru in Caatinga under natural regeneration. The bacteria were evaluated to the amplification of nifH and nodC and to metabolic characteristics. Ten selected bacteria identified by 16S rRNA sequences. They were tested in vitro to NaCl and temperature tolerance, auxin production and calcium phosphate solubilization. The symbiotic ability were assessed in an greenhouse experiment. A total of 32 bacteria were obtained and 17 amplified both symbiotic genes. The bacteria showed a high variable metabolic profile. Bradyrhizobium (6), Rhizobium (3) and Paraburkholderia (1) were identified, differing from their geographic origin. The isolates grew up to 45 °C to 0.51 mol L-1 of NaCl. Bacteria which produced more auxin in the medium with l-tryptophan and two Rhizobium and one Bradyrhizobium were phosphate solubilizers. All bacteria nodulated and ESA 90 (Rhizobium sp.) plus ESA 96 (Paraburkholderia sp.) were more efficient symbiotically. Diverse and efficient rhizobia inhabit the soils of Caatinga dry forests, with the bacterial differentiation by the sampling sites.