Combined Inoculation Research Articles

Combined application of earthworms and plant growth promoting rhizobacteria improve metal uptake, photosynthetic efficiency and modulate secondary metabolites levels under chromium metal toxicity in Brassica juncea L

Chromium (Cr) toxicity impairs essential morphological and metabolic activities in plants. The present investigation was carried out to evaluate the beneficial role of plant growth promoting rhizobacterial strains namely Pseudomonas aeruginosa (M1), Burkholderia gladioli (M2) and earthworms (Eisenia fetida) in alleviating Cr toxicity in 10 days old Brassica juncea L. The findings delineated that addition of earthworms and PGPR restored growth, boosted Cr uptake and showed upregulation of metal transporter genes (SULTR 1-4). Supplementation of rhizospheric amendments reinstated Cr induced impairment in photosynthetic attributes. Gaseous exchange attributes, the efficiency of PS II, the content of total phenols, anthocyanin and flavonoids was enhanced with application of earthworms along with PGPR. Confocal imaging of primary photosynthetic pigment (chlorophyll), accessory photosynthetic pigment (carotenoids) and total phenols showed maximum fluorescence with combined inoculation of earthworms and both microbial strains (M1M2). The gene expression analysis revealed that Phyotene synthase (PSY), Photosystem II core protein psb A, psb B were down regulated in Cr stressed seedlings which upon supplementation with earthworms and PGPR were upregulated. Further, Phenylalanine ammonialyase (PAL), chalcone synthase (CHS) were upregulated with addition of earthworms and PGPR. Increased nitric oxide content, enhanced activity and upregulation of nitrate reductase (NR) gene was observed with addition of PGPR and earthworms

Influence of inoculation with different non-Saccharomyces yeasts and Saccharomyces cerevisiae on the aroma chemical composition and sensorial features of red dragon fruit wine

Abstract In this investigation, we focused on elucidating the impact of non-Saccharomyces yeasts on both the aromatic chemical composition and sensory attributes of red dragon fruit wine. This was achieved through the introduction of Hanseniaspora uvarum or Pichia guilliermondii concurrently with Saccharomyces cerevisiae, employing methodologies encompassing co-inoculation or sequential inoculation. The findings suggested that the combined inoculation of non-Saccharomyces yeasts and S. cerevisiae is capable of modulating the sensory properties of wines. Additionally, varying inoculation methods exerted a significant impact on the aromatic qualities of the wine. Co-inoculation and sequential inoculation of H. uvarum or P. guilliermondii with S. cerevisiae demonstrated a remarkable augmentation in the quantity of volatile chemicals while effectively regulating the number of odor activity value (OAV) > 1 in the wine. Therefore, the utilization of mixed fermentation emerges as a viable strategy for regulating the flavor profile of red dragon wine. This methodology stands as a valuable guideline for making various fruit wines, including red dragon fruit wine.

Co-inoculation of cyanobacteria, rhizobia, and azospirilla associated with fertilizer N increases the common bean grain yield

A large number of beneficial microorganisms have been used as inoculants in agriculture to increase grain yield. The objective of the study was to evaluate the response of common bean (Phaseolus vulgaris) to inoculation and co-inoculation with rhizobia, azospirilla and cyanobacteria combined with doses of N-fertilizer. A field experiment was carried out in two growing seasons to assess twelve treatments using single and combined inoculation of rhizobia (Rhizobium tropici + R. freirei), Azospirillum brasilense, Anabaena cylindrica, and Calothrix brevissima, and application of 30 and 60 kg N kg ha−1 as topdressing in a factorial design. A control without N-mineral and inoculation was included. Co-inoculation of common bean (cv. IPR Curió) using A. cylindrica, C. brevissima with rhizobia, and A. brasilense, with the application of 30 kg N ha−1 in topdressing increases grain yields. Regardless of the growing season and the N dose, the dual inoculation of rhizobia and C. brevissima stood out in the increase of grain yield concerning the control without inoculation, showing that it is an efficient agronomic practice for common bean under tropical conditions.

Microbiomes-Plant Interactions and K-Humate Application for Salinity Stress Mitigation and Yield Enhancement in Wheat and Faba Bean in Egypt’s Northeastern Delta

Salinity, resulting from climate change and excessive mineral fertilization, burdens farmers and negatively impacts soil and water ecosystems in the Northeastern Nile Delta. Organic and biological approaches are crucial for addressing these issues. This study examined the effects of individual and combined inoculations with cyanobacteria, yeast, and Arbuscular Mycorrhizal Fungi (AMF), with or without K-Humate and reducing Nitrogen, phosphorus and potassium (NPK) mineral fertilizers application rates to crop quality of wheat and faba bean. In preliminary laboratory experiments, the interactive effects of these microbiomes on plant antioxidant and soil enzyme production were examined under salinity stress. Results showed that co-inoculation, especially with K-Humate, yielded superior outcomes compared to individual inoculations. These findings were validated by a field trial conducted in saline-alkaline soil in the Northeastern Nile Delta region. All biological treatments 25% of recommended doses, and enhancing salinity tolerance, increasing yield, and improving enhanced rhizosphere microbial activity, including soil enzyme activity, AMF colonization, spore density, and the total numbers of bacteria, cyanobacteria, and yeast. These effects were further amplified by K-Humate and were more pronounced with combined inoculations than with individual ones, leading to improved soil fertility and significant increases in both crop quantity and quality compared to control treatments. The triple treatment, combining cyanobacteria, yeast, and mycorrhizae in the presence of K-Humate while reducing the mineral NPK rate by 75%, achieved superior increases in the productivity of wheat grains and faba bean seeds, reaching 54.72% and 128.92%, respectively, compared to the 100% NPK mineral control. This treatment also significantly improved crop quality, with notable increases in nitrogen, potassium, phosphorus, and protein percentages in wheat grains and faba bean seeds. Microbiomes-interaction increased potassium uptake over sodium, enhancing the plant’s potassium/sodium ratio and improving salt stress tolerance. This approach reduces reliance on costly mineral fertilizers, enabling bio-organic farming in marginal lands, optimizing resource utilization, and preserving natural resources.

Synergistic interactions of biocontrol agents and chemical fungicides enhance the disease resistance in Vigna radiata (L.) against Macrophomina phaseolina-associated with dry root rot

Macrophomina phaseolina, a necrotrophic fungus responsible for dry root rot disease in Vigna radiata L. (greengram) causes extensive yield losses. Biocontrol agents are reported to suppress phytopathogens, mitigate biotic stress, and improve growth and yield of plants. Here, Bacillus subtilis PSB-5 and Trichoderma sp. TD-6 along with chemical fungicides; mancozeb (MZB) and carbendazim (CBZM) were evaluated alone/or in combination for their effectiveness against M. phaseolina-induced root rot disease in greengram. B. subtilis and Trichoderma sp. suppressed phyto-fungal growth by 72 and 78 %, respectively. Both bioagents synthesized indole-3-acetic acid, ammonia, and solubilized insoluble phosphate, released antimicrobial substances including siderophore, hydrogen cyanide, and various extracellular lytic enzymes. Further, efficacy of bioagents and fungicides (at 50 and 100 ppm) were tested (single and combined) against M. phaseolina-infected greengram cultivated in pot soils. While evaluating, bioagents and fungicides increased plant height, biomass, and vigor indices of infected greengram in order: PSB-5 + TD-6 > PSB-5 > TD-6 > MZB + CBZM (100 ppm) > CBZM (100 ppm) > MZB (100 ppm). Further, among treatment, dual inoculation of bioagents (B. subtilis + Trichoderma), maximally increased total chlorophyll (59.4 %), carotenoid (68 %), root phosphorous (69.6 %), root nitrogen (65.7 %), total soluble protein (80 %), soluble sugar (76 %), pod yield (82.3 %) and seed protein (68 %) over infected plants. Moreover, biotic stress-induced oxidative stress biomarkers (proline, malondialdehyde, electrolyte leakage) and reactive oxygen species were significantly (p ≤ 0.05) lowered in fungal-infected greengram following fungicides and bioagents application. Furthermore, combined inoculation of bioagents significantly (p ≤ 0.05) reduced percent disease index (PDI) and increased % protection in biotic-stressed greengram. Besides, bioagents potentially increased disease resistance in M. phaseolina-infected greengram plants by modulating defense responses such as activities of β-1, 3 glucanase, catalase, phenylalanine ammonia lyase, polyphenol oxidase, peroxidase, and superoxide dismutase which significantly protected plants from fungal pathogen. Soil populations of pathogen and bioagents declined and considerably increased, respectively, at harvest. Application of antagonistic bacterial and fungal strains enhances greengram resistance to M. phaseolina while concurrently offering agriculture an environmentally friendly choice. Also, these strains can be applied as biocontrol agents in disease suppression over chemical fungicides.

Enhancing the flavor quality of Chinese rice wine (Huangjiu) through inoculation with Lactobacillus plantarum and Leuconostoc mesenteroides

This study investigates the modulation of flavor in Chinese rice wine (Huangjiu) by inoculating with Lactobacillus plantarum (L. plantarum) and Leuconostoc mesenteroides (L. mesenteroides). Firmicutes and lactic acid bacteria (LAB) were predominant in both inoculated and spontaneously fermented samples. We observed an enhanced bacterial diversity in treatments involving single and combined inoculations, which corresponded with increases in volatile components, organic acids, and amino acids compared to spontaneously fermented controls. Sensory evaluations, assessing alcohol aroma, sourness, and full-bodiedness, identified the co-inoculated samples as superior, outperforming those from single inoculations and spontaneous fermentations. These results elucidate the impact of starter cultures on the fermentation process and flavor profile of Huangjiu, providing insights for selecting optimal starters to engineer desired flavor characteristics.

Synergistic effect of Pseudomonas putida and endomycorrhizal inoculation on the physiological response of onion (Allium cepa L.) to saline conditions

Salinity stress negatively affects the growth and yield of crops worldwide. Onion (Allium cepa L.) is moderately sensitive to salinity. Beneficial microorganisms can potentially confer salinity tolerance. This study investigated the effects of endomycorrhizal fungi (M), Pseudomonas putida (Ps) and their combination (MPs) on onion growth under control (0 ppm), moderate (2000 ppm) and high (4000 ppm) NaCl salinity levels. A pot experiment was conducted with sandy loam soil and onion cultivar Giza 20. Results showed that salinity reduced growth attributes, leaf pigments, biomass and bulb yield while increasing oxidative stress markers. However, individual or combined inoculations significantly increased plant height, bulb diameter and biomass production compared to uninoculated plants under saline conditions. MPs treatment provided the highest stimulation, followed by Pseudomonas and mycorrhizae alone. Overall, dual microbial inoculation showed synergistic interaction, conferring maximum benefits for onion growth, bulbing through integrated physiological and biochemical processes under salinity. Bulb yield showed 3.5, 36 and 83% increase over control at 0, 2000 and 4000 ppm salinity, respectively. In conclusion, combined application of mycorrhizal-Pseudomonas inoculations (MPs) effectively mitigate salinity stress. This approach serves as a promising biotechnology for ensuring sustainable onion productivity under saline conditions.

Unravelling the Complexity of Ginger Rhizome Rot Disease: A Focus on Pathogen Interactions

ABSTRACTRhizome rot poses a significant threat to ginger cultivation, caused by a complex interaction of pathogens such as Pythium aphanidermatum, Fusarium oxysporum, Ralstonia solanacearum, Sclerotium rolfsii and Meloidogyne incognita. The pathogens were individually inoculated at 75, 105 and 135 days after planting (DAP), as well as in various combinations, to evaluate disease severity and symptom development. Results revealed that R. solanacearum exhibited the highest disease severity and fastest symptom development across all stages of inoculation, followed by P. aphanidermatum, F. oxysporum, S. rolfsii and M. incognita. The combined inoculation of pathogens significantly increased disease incidence and rhizome rot compared to individual inoculations, indicating synergistic interactions among the pathogens. Sequential inoculation experiments demonstrated that pre‐infection by M. incognita exacerbated disease severity, highlighting the role of nematodes in predisposing plants to secondary infections.

Combined inoculation of arbuscular mycorrhiza fungi with Meso‐rhizobium improves nutrient uptake, growth performance, and moisture stress tolerance of chickpea (Cicer arietinum L.)

AbstractBiofertilizers can be better alternatives to chemical fertilizers to enhance plant nutrition and productivity as they improve the soil fertility and crop productivity in an eco‐friendly and cost‐effective manner. A pot experiment was conducted between December 2018 and March 2019 in southern Ethiopia to evaluate the combined inoculation of arbuscular mycorrhizal fungi (AMF) and Meso‐rhizobium (MR) on biomass yield, nutrient uptake, and moisture stress tolerance of chickpea (Cicer arietinum L.) (variety: Habru). The experiment was executed as a factorial arrangement using a completely randomized design with three replications. The treatments were control (non‐fertilized), sole AM fungi inoculation, AM fungi inoculation with phosphorus fertilizer (20 kg P ha−1) and MR, and sole inorganic fertilizers (20 kg P;10 kg N ha−1) at four different moisture levels (optimum throughout the growing season, stressed at vegetative, flowering, and seed filling stages). The results demonstrated that biomass yields were limited by moisture stress, especially at vegetative and flowering stages of chickpea. Sole and co‐application of AMF with MR and inorganic P increased biomass yields on average by 19%, 39%, and 33% under water stress conditions, respectively, compared to the non‐inoculated control. The application of AMF with MR and inorganic P also significantly increased nodulation, AMF colonization, and nutrient uptake, but these effects were dependent on soil moisture status. In conclusion, there are potential advantages to be gained from sole and combined AMF application with rhizobium to improve growth and productivity of chickpea through enhanced nutrient and water uptake, though the results of this pot experiment should be validated through field trials.

The potential of soil endemic microorganisms in ameliorating the physicochemical properties of soil subjected to a freeze-thaw cycle

Establishing soil biological crusts will result in the long-term restoration of ecosystems. Nonetheless, little research has been conducted to demonstrate the influence of soil endemic microorganisms on suppressing the adverse effects of freezing-thawing on soil properties. This current study evaluated the formation of biological crusts, the enhancement of physical and chemical characteristics of soil, and surface soil stability by inoculating native bacteria and cyanobacteria into the soil during a freezing-thawing cycle. The soil was collected from the Badranlou Region in North Khorasan Province, Northern Iran, and native bacteria and cyanobacteria were isolated, identified, chosen, and cultured. The native treatments of bacteria and cyanobacteria were then inoculated in individual bacteria, cyanobacteria, and combined inoculation of cyanobacteria and bacteria onto an experimental soil in six replications. After 60 days, they were subjected to freezing-thawing conditions to have maximum effect on the soil environment, and finally, the soil surface properties were statistically compared. The results of the significant effect (p<0.001) of inoculation treatments on the physical and chemical properties of the study soil revealed that the carbon, nitrogen, organic matter, phosphorus, potassium, and surface soil stability in bacterial treatment compared to the control treatment increased by 68, 39, 68, 17, 25, 99 %, respectively. While under cyanobacterial treatment, they rose by 83, 61, 83, 18, 73, and 172 %, respectively. The combination inoculation treatment of bacteria and cyanobacteria enhanced the study variables by 73, 66, 73, 25, 58, and 189 %, respectively. Compared to control plots, the soil bulk density in bacterial, cyanobacterial, and compound inoculation treatments was substantially reduced (p<0.001) by 9, 15, and 12 %, respectively. The soil stability, carbon, and organic matter were among the most essential properties of the soil, and they best showed the difference between the various treatments applied. It confirmed the region's potential restoration by inoculating native soil microorganisms.

Co-application of biochars and Piriformospora indica improved the quality of coastal saline soil and promoted the growth of forage.

Soil quality is defined as the ability of soil to maintain the soil environment and the biosphere. Due to the limitation of salt and alkali stress, soil quality can be reduced, which in turn affects agricultural production. Biochar is widely used in saline-alkali land improvement because of its special pore structure and strong ion exchange ability, while Piriformospora indica is widely used in saline-alkali land improvement because it can symbiose with plants and improve plant stress resistance. However, the synergistic effect of combined biochar application and inoculation of P. indica on the quality of saline-alkali soil and plant development is uncertain. Hence, we investigated the combined influences of biochar and P. indica on the soil physicochemical characteristics, as well as the growth and chlorophyll florescence of sorghum-sudangrass hybrids (Sorghum bicolor × Sorghum sudane) in our study. The results indicated that after applying biochar and P. indica together, there was a considerable drop in soil pH, conductivity, Na+, and Cl- concentrations. Meanwhile, the soil organic matter (SOM), available phosphorus (AP), and alkaline hydrolyzable nitrogen (AN) increased by 151.81%, 50.84%, and 103.50%, respectively, when the Bamboo biochar was combined with 120 ml/pot of P. indica. Eventually, sorghum-sudangrass hybrid biomass, transpiration rate, and chlorophyll content increased by 111.69%, 204.98%, and 118.54%, respectively. According to our findings, using P. indica and biochar together can enhance soil quality and plant growth. The results also provide insights to enhance the quality of saline-alkali soils and the role of microorganisms in nutrient cycling.

Impact of inoculating Staphylococcus xylosus CICC21445 and Staphylococcus vitulinus CICC10850 on lipid metabolism and flavor development in dry-cured duck

The metabolic activity of microorganisms can influence the characteristics of dry-cured meat. This study aimed to investigate the impact of single or combined inoculation of Staphylococcus vitulinus CICC10850 and Staphylococcus xylosus CICC21445 on the quality of dry-cured duck. The results showed that co-inoculation significantly inhibited the lipid oxidation of dry-cured duck compared to single inoculation S. vitulinus CICC10850 or S. xylosus CICC21445, and the viable cell counts of Staphylococcus were higher (8.3 ± 0.04 log CFU/g, on the 7th day). Co-inoculation significantly increased the activities of neutral lipase (1.68 ± 0.12 U/g) and phospholipase (1.78 ± 0.10 U/g) on the 7th day. The contents of 12 free fatty acids in the dry-cured duck were significantly altered, with notable changes in the levels of C16:0, C18:0, and C18:6n9c. 43 flavor compounds were detected, and the aldehydic flavor compounds were significantly influenced by Staphylococcus inoculation. Compared to the control, co-inoculation led to significant changes in the contents of 333 non-volatile metabolites, 150 of which were lipid-related. KEGG analysis identified 11 differented metabolic pathways, primarily involving amino acid and lipid metabolism. Furthermore, the human-machine interaction evaluation demonstrated that the co-inoculation of S. xylosus CICC21445 and S. vitulinus CICC10850 significantly enhanced the sensory attributes of dry-cured ducks.

Plant growth promotion activities of Bacillus spp. isolated from Jakrem hot water spring of Meghalaya, North East India

The study aims to investigate plant growth promotion (PGP) activities of thermophilic bacteria isolated from the Jakrem hot spring in Meghalaya, North-East India, and determine their effect on Brassica juncea's growth. The bacteria were isolated by a culture-dependent approach following a serial dilution method in a nutrient agar medium. All the isolates were determined for PGP attributes such as indole acetic acid, phosphate solubilization, hydrolytic enzymes, and siderophore production. The potent bacterial isolates were characterized by 16S rDNA sequencing and phylogenetic analysis. Altogether, 53 bacterial isolates were obtained, most belonging to the genus Bacillus. Of the total isolates, 37.7% exhibited both PGP and hydrolytic enzyme activities. Three isolates, namely JAB1, JAB8, and JAB100, showed promising PGP and were identified as Bacillus velezensis, B. proteolyticus, and Bacillus sp., respectively. The PGP attributes of these isolates were determined in vivo on B. juncea, and their effects were measured in terms of shoot and root length biomass and biochemical contents. It was observed that combined inoculation of all three isolates significantly enhanced the growth and development of B. juncea, evident by increased shoot and root length, fresh and dry weight, and higher levels of protein, phenol, flavonoid, and chlorophyll content compared to the control. In conclusion, the study highlights the potential application of thermophilic Bacillus spp. from hot springs as bioinoculants to enhance crop productivity in sustainable agricultural practices.

Malaria prevalence and transmission in the Zakpota sub-district of central Benin: baseline characteristics for a community randomised trial of a new insecticide for indoor residual spraying

BackgroundMalaria transmission is known to be perennial and heterogeneous in Benin. Studies assessing local malaria prevalence, transmission levels and vector characteristics are critical for designing, monitoring and evaluating new vector control interventions in community trials. We conducted a study in the Zakpota sub-district of central Benin to collect baseline data on household characteristics, malaria prevalence, vector characteristics and transmission dynamics in preparation for a randomised controlled trial to evaluate the community impact of VECTRON™ T500, a new broflanilide indoor residual spraying (IRS) product.MethodsA total of 480 children under 5 years of age from the 15 villages of the sub-district were tested for malaria by rapid diagnostic tests (RDTs). Mosquitoes were collected by human landing catches (HLCs), pyrethrum spray catches (PSCs) and Centers for Disease Control and Prevention miniature light traps (CDC-LTs) in selected houses in each village to assess vector density, composition, vector infectivity and prevalence of insecticide resistance markers. Bioassays were performed to detect vector susceptibility to pyrethroids, broflanilide (6 µg/bottle) and clothianidin (90 µg/bottle).ResultsA total of 9080 households were enumerated in the 15 study villages. Insecticide-treated net (ITN) usage was > 90%, with 1–2 ITNs owned per household. Houses were constructed mainly with cement (44%) and mud (38%) substrates or a mixture of cement and mud (18%), and 60% of them had open eaves. The overall prevalence of P. falciparum infection was 19% among surveyed children: 20% among females and 18% among males. The haemoglobin rate showed an anaemia (< 11 g/dl) prevalence of 66%. Anopheles coluzzii and An. gambiae sensu stricto (s.s.) were the two vector species present at an overall proportion of 46% versus 54%, respectively. The human biting rate was 2.3 bites per person per night (b/p/n) and biting occurred mostly indoors compared with outdoors (IRR = 0.776; P = 0.001). The overall proportion of outdoor biting was 44% and exceeded indoor biting in three villages. The sporozoite rate was 2% with a combined yearly entomological inoculation rate (EIR) of 16.1 infected bites per person per year (ib/p/y). There was great variability in malaria transmission risk across the villages, with EIR ranging from 0 to 29.3 ib/p/y. The vector population showed a high intensity of resistance to pyrethroids across the study villages but was largely susceptible to broflanilide and clothianidin.ConclusionsThis study found high levels of malaria prevalence, vector density and transmission in the Zakpota sub-district despite the wide use of insecticide-treated nets. The vector population was mostly indoor resting and showed a high intensity of pyrethroid resistance but was generally fully susceptible to broflanilide. These findings demonstrated the suitability of the study area for the assessment of VECTRON™ T500 in a community randomised trial.Graphical

Plant growth‐promoting rhizobacteria and Trichoderma shift common vetch (Vicia sativa) physiology and phyllosphere bacteria toward antagonism against anthracnose caused by Colletotrichum spinaciae

AbstractBackgroundPlant phyllosphere microbes are important for the host plant's protection. Plant growth‐promoting rhizobacteria (PGPR) and Trichoderma are common biocontrol agents (BCAs) for disease management. Pathogens and BCAs can change the rhizosphere microbial composition; however, the effect of PGPR or Trichoderma on plant phyllosphere microbes, particularly for mesocosms involving the interaction between pathogens and BCAs, is not well known.MethodsHigh‐throughput sequencing was used to identify the phyllosphere bacterial community of common vetch interacting with Colletotrichum spinaciae, two PGPRs (Bacillus subtilis and Bacillus licheniformis), and Trichoderma longibrachiatum. We evaluated anthracnose severity, phyllosphere bacteria diversity and composition, and the relationship between the activities of plant defense enzymes and hormonal molecules in plants treated with individual and combined inoculations of PGPRs, Trichoderma, and C. spinaciae.ResultsPGPR or Trichoderma alone reduced disease severity. Trichoderma reduced the salicylic acid content, PGPR increased the catalase activity in plants, and co‐inoculation of PGPR and Trichoderma decreased the salicylic acid content. Inoculation of PGPR and Trichoderma individually or in combination changed the disease‐associated phyllosphere bacteria, and this effect was related to plant defense enzymes and hormonal molecules.ConclusionsWe suggest that the plant defense response induced by PGPR and Trichoderma results in the enrichment of a fraction of favorable chloroplastic bacteria, which facilitates plant defense against diseases.

Respuesta del maíz harinoso (zea mays l. Var. Amylacea) a la inoculación de azospirillum y pseudomonas

Plant growth-promoting bacteria (PGPB) that inhabit root rhizosphere of plants are of great agricultural importance due to their ability to produce phytohormones during root colonization. These phytohormones produce physiological changes in the plant that favor a greater absorption of nutrients, promote growth and increase production. This study analyzed the effect of inoculation of two of these bacteria, Azospirillum sp. And Pseudomonas fluorescens, under field conditions representative of the Andean Highlands. The experiment was carried out using flour corn seed of the INIAP-101 variety in a randomized complete block design with six repetitions. The treatments corresponded to: T1 (Azospirillum sp.), T2 (P. fluorescens), T3 (Azospirillum sp. and P. fluorescens), T4 (control, conventional chemical fertilization) and T5 (absolute control). The application of these bacteria significantly increased (p&lt;0.05) the root length, the diameter of the cob, and the yield of fresh corn (“elotes” or “choclos”). The combined inoculation of these bacteria (T3) obtained the highest yield, with 19.70 t ha-1 of fresh corn; while the chemical control and the absolute control got 17.12 and 13.58 t ha-1 of fresh corn, respectively. The economic analysis of T3 reported a benefit/cost of 1.35, which indicates that the synergism of these two bacteria could be a sustainable strategy to improve yields and reduce the use of chemical fertilizers for corn production in the Andean region.

The effects of Lactiplantibacillus plantarum 3-19 and Pediococcus pentosaceus 18-1 on preventing the accumulation of biogenic amines and promoting the production of volatile organic compounds during sour meat fermentation

Lactic acid bacteria (LAB) are frequently used in meat fermentation, and mixed stater cultures are reported to perform better than single ones. Lactiplantibacillus plantarum 3-19 and Pediococcus pentosaceus 18-1 were chosen from 28 sour-meat-origin strains to examine the effects of single and combined inoculation on sour meat quality. Natural fermentation was used as a control to investigate changes in pH, water activity (aw), amino acid nitrogen (AN), texture, microbial diversity, and volatile organic compounds (VOCs) during fermentation. The pH and aw of each inoculation group were significantly decreased, and AN content was significantly increased. The inoculation of P. pentosaceus 18-1 significantly reduced putrescine, cadaverine, and tryptamine content (p < 0.05), while the inoculation of Lpb. plantarum 3-19 significantly reduced cadaverine amounts (p < 0.05). At the fermentation endpoint, the total biogenic amines content in the C group was 992.96 ± 14.07, which was 1.65, 2.57, and 3.07 times higher than that in the Lp, Pe, and M groups, respectively. The mixed inoculation group combined the advantages of both strains and decreased total biogenic amines most significantly. At the end of fermentation, the VOCs in C, Lp, Pe, and M groups were 10.11, 11.56, 12.45, and 13.39 times higher than those at the beginning of fermentation. Inoculation promoted the production of key VOCs (OAV > 2000) such as heptanal, octanal, and (E)-2-nonanal. The mixed inoculation group had the highest variety and content of VOCs and the highest content of the above key VOCs, significantly enhancing its fruity, floral, ester, and other aromas. Sensory evaluation indicated that the M group had the best overall acceptability. Finally, it was suggested that a combination of Lpb. plantarum 3-19 and P. pentosaceus 18-1 is a novel and efficient starter culture for processing sour meat since they lower the amounts of biogenic amines in the meat and promote the production of VOCs.

Synergistic impact of Serendipita indica and Zhihengliuella sp. ISTPL4 on the mitigation of arsenic stress in rice.

Arsenic (As) is a highly toxic metal that interferes with plant growth and disrupts various biochemical and molecular processes in plants. In this study, the harmful effects of As on rice were mitigated using combined inoculation of a root endophyte Serendipita indica and an actinobacterium Zhihengliuella sp. ISTPL4. A randomized experiment was conducted, in which rice plants were grown under controlled conditions and As-stressed conditions. The control and treatment groups consisted of untreated and non-stressed plants (C1), treated and non-stressed plants (C2), stressed and untreated plants (T1), and stressed and treated plants (T2). Various phenotypic characteristics such as shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW), and root dry weight (RDW) and biochemical parameters such as chlorophyll content, protein content, and antioxidant enzymatic activities were evaluated. The activity of various antioxidant enzymes was increased in T2 followed by T1 plants. Furthermore, high concentrations of phytohormones such as ethylene (ET), gibberellic acid (GA), and cytokinin (CK) were found at 4.11 μmol mg-1, 2.53 μmol mg-1, and 3.62 μmol mg-1 of FW of plant, respectively. The results of AAS indicated an increased As accumulation in roots of T2 plants (131.5 mg kg-1) than in roots of T1 plants (120 mg kg-1). It showed that there was an increased As accumulation and sequestration in roots of microbial-treated plants (T2) than in uninoculated plants (T1). Our data suggest that this microbial combination can be used to reduce the toxic effects of As in plants by increasing the activity of antioxidant enzymes such as SOD, CAT, PAL, PPO and POD. Furthermore, rice plants can withstand As stress owing to the active synthesis of phytohormones in the presence of microbial combinations.

Preliminary Results of the Impact of Beneficial Soil Microorganisms on Okra Plants and Their Polyphenol Components

Okra (Abelmoschus esculentus L.) is a highly nutritious vegetable rich in vitamins, minerals, and bioactive compounds, including polyphenols, offering numerous health benefits. Despite its nutritional value, okra remains underutilized in Europe; however, its cultivation and popularity may rise in the future with increasing awareness of its advantages. In agricultural practices, beneficial soil microorganisms, such as arbuscular mycorrhizal fungi (AMF), Trichoderma spp., Streptomyces spp., and Aureobasidium spp., play crucial roles in promoting plant health, enhancing agricultural productivity together with improved crop nutritional value. This study aimed to investigate the effects of individual and combined inoculation on the polyphenol content of okra fruits, as analyzed by HPLC. Moreover, growth parameters and glutathione-S-transferase enzyme (GST) activities of okra leaves were also estimated. Tested microorganisms significantly increased the yield of okra plants except for A. pullulans strain DSM 14950 applied individually. All microorganisms led to increased GST enzyme activity of leaves, suggesting a general response to biotic impacts, with individual inoculation showing higher enzyme activity globally compared to combined treatments. According to the polyphenol compound analysis, the application of tested microorganisms held various but generally positive effects on it. Only the combined treatment of F. mosseae and Streptomyces strain K61 significantly increased the coumaric acid content, and the application of Aureobasidium strain DSM 14950 had a positive influence on the levels of quercetin and quercetin-3-diglucoside. Our preliminary results show how distinct polyphenolic compound contents can be selectively altered via precise inoculation with different beneficial microorganisms.

Synergistic interaction of Piriformospora indica and microbial inoculants on symbiotic potential, plant nutrition and productivity of chickpea (Cicer arietinum)

The present study was carried out during the winter season of 2011–12 and 2012–13 at Indian Agricultural Re search Institute, New Delhi, to evaluate the efficacy of microbial bioinoculants in chickpea (Cicer arietinum L.) us ing combinatorial approach. A group of microbial inoculants (Mesorhizobium ciceri). Phosphate-solubilizing micro organisms and plant growth-promoting rhizobacteria) in presence and absence of P fertilizer was used to testify its synergistic effect with Piriformospora indica on symbiotic traits, growth and yield of chickpea under field condi tions. Significant differences were observed with respect to symbiotic potential and other associated parameters with combined inoculation. Inoculation with Mesorhizobium ciceri enhanced nitrogenase activity and leghemoglobin content significantly over un-inoculated control. Significant improvement in N and P nutrition with combined inoculation amended with 30 kg P/ha emphasized the beneficial effect of these and similar trend was reflected in productivity enhancement as well.