The Effects of Microbial Inoculants on Bacterial Communities of the Rhizosphere Soil of Maize

The bacterial community of rhizosphere soil maintains soil properties, regulates the microbiome, improves productivity, and sustains agriculture. However, the structure and function of bacterial communities have been interrupted or destroyed by unreasonable agricultural practices, especially the excessive use of chemical fertilizers. Microbial inoculants, regarded as harmless, effective, and environmentally friendly amendments, are receiving more attention. Herein, the effects of three microbial inoculants, inoculant M and two commercial inoculants (A and S), on bacterial communities of maize rhizosphere soil under three nitrogen application rates were compared. Bacterial communities treated with the inoculants were different from those of the non-inoculant control. The OTU (operational taxonomic unit) numbers and alpha diversity indices were decreased by three inoculants, except for the application of inoculant M in CF group. Beta diversity showed the different structures of bacterial communities changed by three inoculants compared with control. Furthermore, key phylotypes analyses exhibited the differences of biomarkers between different treatments visually. Overall, inoculant M had shared and unique abilities of regulating bacterial communities compared with the other two inoculants by increasing potentially beneficial bacteria and decreasing the negative. This work provides a theoretical basis for the application of microbial inoculants in sustainable agriculture.

Testing of Commercial Inoculants to Enhance P Uptake and Grain Yield of Promiscuous Soybean in Kenya

The aim of this study was to assess the potential of commercial mycorrhizal inoculants and a rhizobial inoculant to improve soybean yield in Kenya. A promiscuous soybean variety was grown in a greenhouse pot study with two representative soils amended with either water-soluble mineral P or rock P to assess product performance. The performance of selected mycorrhizal inoculants combined with a rhizobial inoculant (Legumefix) was then assessed with farmer groups in three agroecological zones using a small-plot, randomized complete block design to assess soybean root colonization by mycorrhiza, nodulation, and plant biomass production in comparison to rhizobial inoculant alone or with water-soluble mineral P. Greenhouse results showed highly significant root colonization by commercial mycorrhizal inoculant alone (p < 0.001) and in interaction with soil type (p < 0.0001) and P source (p < 0.0001). However, no significant effect was shown in plant P uptake, biomass production, or leaf chlorophyll index. In field conditions, the effects of mycorrhizal and rhizobial inoculants in combination or alone were highly context-specific and may induce either a significant increase or decrease in root mycorrhizal colonization and nodule formation. Mycorrhizal and rhizobial inoculants in combination or alone had limited effect on plant P uptake, biomass production, leaf chlorophyll index, and grain yield. Though some mycorrhizal inoculants induced significant root colonization by mycorrhizal inoculants, this did not lead to higher soybean yield, even in soils with limited P content. Our results are further evidence that inoculant type, soil type, and P source are critical factors to evaluate commercial inoculants on a context-specific basis. However, our results highlight the need for the identification of additional targeting criteria, as inoculant type, soil type, and P source alone were not enough to be predictive of the response. Without the identification of predictive criteria for improved targeting, the economic use of such inoculants will remain elusive.

Analisis Kandungan Nutrisi Kulit Kopi (coffea sp ) yang Difermentasi dengan Berbagai Bahan Inokulan

Abstrak. Tujuanipenelitianiini adalahiuntukimengevaluasi kualitas fermentasi kulit kopi dengan menggunakan inokulan yang berbeda. Penelitianiiniidilakukanidi LaboratoriumiIlmuiNutrisiidani TeknologiiPakan, berlangsung mulai dari bulan Maret hingga April 2018. Penelitian ini menggunakan limbah kulit kopi bagian paling luar yang telah dikeringkan dan dihaluskan. Rancangan yang digunakan adalah Rancangan Acak Lengkap (RAL) terdiri dari 4 perlakuan dan 4 ulangan, sehingga diperoleh 16 unit percobaan. Perlakuan dalam penelitian ini terdiri dari P0 (kontrol/tanpa penggunaan inokulan), P1 (penggunaan inokulan SBP 1%), P2 (penggunaan inokulan EM4 1%), dan P3 (penggunaan inokulan SOC 1%). Parameter yang diamati meliputi, BKi( bahanikeringi), PKi(iproteinikasari), SKi(seratikasari), LKi(lemakikasari), BETNi(ibahan ekstrakitanpainitrogeni) daniAbu. Dataiyangidiperolehidianalisisidenganimenggunakan sidik ragam (Analisis ofiVariancei/ ANOVA). Hasilipenelitianimenunjukkanibahwaipemberian inokulan yang berbeda SBP, EM4 dan SOC dalam fermentasi kulit kopi tidakiberpengaruhinyata (iP0,05i) terhadapiBK,iPK, LK, BETN daniAbuidan berpengaruh nyata (iP0,05i) terhadapiSK.Analysis of Coffee Skin Nutrient Content (Coffea sp) Fermented with Various Inoculant IngredientsAbstracti. Theipurposeiofithisistudyiwasitoievaluateitheiquality ofifermented coffee pulp usingi different commercial inoculants. This study was carried out at Laboratory of Nutrition andiFeediTechnology, from March to April 2018. This study used waste of the outer coffee skin that have been dried out and grinded. The experimental design used aiCompletelyiRandomized Design (CRD), which consisted of 4itreatmentsiand 4ireplications, in orderrtoiobtainii16 experimentaliunits. Treatments in this study consisted of P0 (control/no inoculant was added), P1 (1% of SBP inoculant was added), P2 (1% of EM-4 inoculant was added), and P3 (1% of SOC inoculantiwas added). The parameters were observed including dryiimatter i(DM), crudeiprotein (CP), crude fibre (CF), ether extract (EE), ash and nitrogen-free extract (NFE). The data were analyzediusingiAnalysisiof Variancei(ANOVA). The results showed that different inoculants supplementation (SBP, EM-4, and SOC) in pineapple skin fermentation had no significant effect (P 0.05) on DM, CP, EE, ash and NFE and hadi aisignificanti effecti(Pi0.05) oniCF.

Root Nodule Preparation as a Low-Cost Inoculant for Cowpea

Widely grown in diverse regions of Brazil, cowpea has high nutritional value, is easily cultivated, and can fix nitrogen (N) symbiotically. Although there are commercial inoculants for cowpea, it is difficult for small producers to acquire them. A nodule preparation is an inexpensive and easily prepared option for small farmers. The aim of this study was to test a nodule preparation as a low-cost inoculant, increasing cowpea seed grain production. Thus, different cowpea cultivars were compared in two locations, the municipalities of Crato and Madalena, both in Cear&aacute;. Two field experiments were performed to evaluate gain derived from this inoculation method. The nodule preparation was created from nodules removed from roots of cowpea grown in the experimental locations. The nodules were macerated and added to water, obtaining a liquid (inoculant) that was applied to the seeds. The experiment was conducted following a randomized block design with four replicates and a 4 &times; 3 factorial arrangement (N sources &times; cultivars). Results indicate little interaction between the sources of N and the cultivars because only the shoot dry matter (Crato experiment) exhibited interaction between both. The differences provided by the nodule preparation were more notable among cultivars and between the environments, Crato and Madalena. The nodule preparation differed little from the commercial inoculant; they were comparable. However, gain in relation to the zero control also proved to be reduced, indicating little contribution of the nodule preparation to cowpea under the conditions tested.

Draft Genome Sequence of Bradyrhizobium elkanii Strain SEMIA 938, Used in Commercial Inoculants for Lupinus spp. in Brazil

Due to its high capacity for nitrogen fixation, strain SEMIA 938 is used in commercial inoculants for lupins in Brazil. Its genome was estimated at 8,780,064 bp and indicates that it belongs to the Bradyrhizobium elkanii species, while the analysis of nodulation genes classifies the strain in the symbiovar sojae.

Brazilian-adapted soybean Bradyrhizobium strains uncover IS elements with potential impact on biological nitrogen fixation

ABSTRACTBradyrhizobium diazoefficiens CPAC 7 and Bradyrhizobium japonicum CPAC 15 are broadly used in commercial inoculants in Brazil, contributing to most of the nitrogen required by the soybean crop. These strains differ in their symbiotic properties: CPAC 7 is more efficient in fixing nitrogen, whereas CPAC 15 is more competitive. Comparative genomics revealed many transposases close to genes associated with symbiosis in the symbiotic island of these strains. Given the importance that insertion sequences (IS) elements have to bacterial genomes, we focused on identifying the local impact of these elements in the genomes of these and other related Bradyrhizobium strains to further understand their phenotypic differences. Analyses were performed using bioinformatics approaches. We found IS elements disrupting and inserted at regulatory regions of genes involved in symbiosis. Further comparative analyses with 21 Bradyrhizobium genomes revealed insertional polymorphism with distinguishing patterns between B. diazoefficiens and B. japonicum lineages. Finally, 13 of these potentially impacted genes are differentially expressed under symbiotic conditions in B. diazoefficiens USDA 110. Thus, IS elements are associated with the diversity of Bradyrhizobium, possibly by providing mechanisms for natural variation of symbiotic effectiveness.

Draft Genome Sequences of Azospirillum brasilense Strains Ab-V5 and Ab-V6, Commercially Used in Inoculants for Grasses and Legumes in Brazil

ABSTRACT Azospirillum brasilense strains Ab-V5 and Ab-V6 are largely used in commercial inoculants for grasses and legumes in Brazil. Their genomes were estimated at 6,934,595 and 7,197,196 bp, respectively, and encompass genes related to nitrogen fixation, synthesis of phytohormones, and environmental adaptation. Although the strains differ in phenotypic properties, their genomes are highly similar.