Effect Of Soil Inoculation Research Articles

Inhibitory effects of Pseudomonas sp. W112 on cadmium accumulation in wheat grains: Reduced the bioavailability in soil and enhanced the interception by plant organs

Microorganisms play an important role in heavy metal bioremediation and soil fertility. The effects of soil inoculation with Pseudomonas sp. W112 on Cd accumulation in wheat were investigated by analyzing the transport, subcellular distribution and speciation of Cd in the soil and plants. Pseudomonas sp. W112 application significantly decreased Cd content in the roots, internode and grains by 10.2%, 29.5% and 33.0%, respectively, and decreased Cd transfer from the basal nodes to internodes by 63.5%. Treatment with strain W112 decreased the inorganic and water-soluble Cd content in the roots and increased the proportion of residual Cd in both the roots and basal nodes. At the subcellular level, the Cd content in the root cell wall and basal node cytosol increased by 19.6% and 61.8%, respectively, indicating that strain W112 improved the ability of the root cell wall and basal node cytosol to fix Cd. In the rhizosphere soil, strain W112 effectively colonized and significantly decreased the exchangeable Cd, carbonate-bound Cd and iron-manganese oxide-bound Cd content by 43.5%, 27.3% and 17.6%, respectively, while it increased the proportion of residual Cd by up to 65.2%. Moreover, a 3.1% and 23.5% increase in the pH and inorganic nitrogen content in the rhizosphere soil, respectively, was recorded. Similarly, soil bacterial community sequencing revealed that inoculating with strain W112 increased the abundance of Pseudomonas, Thauera and Azoarcus, which are associated with inorganic nitrogen metabolism, and decreased that of Acidobacteria, which is indicative of soil alkalinization. Hence, root application of Pseudomonas sp. W112 improved soil nitrogen availability and inhibited Cd accumulation in the wheat grains in a two-stage process: by reducing the Cd availability in the rhizosphere soil and by improving Cd interception and fixation in the wheat roots and basal nodes. Pseudomonas sp. W112 may be a suitable bioremediation agent for restoring Cd-contaminated wheat fields.

Application of Erythromycin and/or Raoultella sp. Strain MC3 Alters the Metabolic Activity of Soil Microbial Communities as Revealed by the Community Level Physiological Profiling Approach.

Erythromycin (EM), a macrolide antibiotic, by influencing the biodiversity of microorganisms, might change the catabolic activity of the entire soil microbial community. Hence, the goal of this study was to determine the metabolic biodiversity in soil treated with EM (1 and 10 mg/kg soil) using the community-level physiological profiling (CLPP) method during a 90-day experiment. In addition, the effect of soil inoculation with antibiotic-resistant Raoultella sp. strain MC3 on CLPP was evaluated. The resistance and resilience concept as well as multifactorial analysis of data was exploited to interpret the outcomes obtained. EM negatively affected the metabolic microbial activity, as indicated by the values of the CLPP indices, i.e., microbial activity expressed as the average well-color development (AWCD), substrate richness (R), the Shannon–Wiener (H) and evenness (E) indices and the AWCD values for the six groups of carbon substrate present in EcoPlates until 15 days. The introduction of strain MC3 into soil increased the degradative activity of soil microorganisms in comparison with non-inoculated control. In contrast, at the consecutive sampling days, an increase in the values of the CLPP parameters was observed, especially for EM-10 + MC3-treated soil. Considering the average values of the resistance index for all of the measurement days, the resistance of the CLPP indices and the AWCD values for carbon substrate groups were categorized as follows: E > H > R > AWCD and polymers > amino acids > carbohydrates > miscellaneous > amines > carboxylic acids. The obtained results suggest a low level of resistance of soil microorganisms to EM and/or strain MC3 at the beginning of the exposure time, but the microbial community exhibited the ability to recover its initial decrease in catabolic activity over the experimental period. Despite the short-term effects, the balance of the soil ecosystem may be disturbed.

Carry-over effects of soil inoculation on plant growth and health under sequential exposure to soil-borne diseases

Background and aimsMost plant-soil feedback and inoculation studies are limited to one growth cycle. We examined the effects of inoculation with eight plant-conditioned soils on chrysanthemum during two sequential growth cycles. The plants were also exposed sequentially to soil diseases.MethodsIn cycle 1, plants were grown in sterile soil inoculated or not with plant-conditioned soils, and exposed or not to Pythium or root feeding nematodes. In cycle 2, new plants were grown in soil from cycle 1 or in new 100% sterile soil. Plants were exposed again to Pythium, or to soil with pathogens and nematodes collected from a commercial chrysanthemum greenhouse.ResultsAfter two cycles, effects of soil inoculation on plant growth were still present. Chrysanthemum exhibited a negative conspecific feedback response, but this was less strong in inoculated soils. Pythium or nematode addition did not affect plant growth. However, addition of pathogen-containing soil from the commercial greenhouse reduced plant growth in sterile soil but increased growth in plant-conditioned soils.ConclusionsInoculation with plant-conditioned soil can reduce the negative conspecific plant-soil feedback of chrysanthemum. Our study further advances our understanding of the temporal dynamics of conspecific and heterospecific plant-soil feedbacks, and how they interact with soil-borne diseases.

Effect of Bacillus subtilis BD233 on seedlings growth of sweet pepper (Capsicum annuum), Swiss chard (Beta vulgaris) and lettuce (Lactuca sativa)

Bacillus species are ubiquitous microorganisms that enhance growth in several crops as well as provide protection against pathogens. In this study, the effects of soil inoculation with B. subtilis BD233 on growth and development of sweet pepper (Capsicum annuum L.), Swiss chard (Beta vulgaris L.) and lettuce (Lactuca sativa L.), were investigated. Three treatments were employed: i) incubation with a lysogeny broth culture of B. subtilis BD233; ii) broth without B. subtilis BD233 (without BD233/control) and iii) tap water. Potting soil-grown seedlings of the three crops were assayed to measure growth parameters over a period of five weeks (35 days) after exposure to the treatments. Soil inoculation with B. subtilis BD233 significantly improved the growth and development of sweet pepper and lettuce seedlings relative to the other treatments but not for Swiss chard. Bacillus subtilis BD233 in lysogeny broth increased the plant height, stem elongation rate and stem diameter of sweet pepper and lettuce seedlings relative to those treated with water. Furthermore, the biomass of sweet pepper and lettuce seedlings exposed to B. subtilis BD233 was increased by 32.2 and 92.6%, relative to their respective controls. However, no statistical differences for height and biomass were found for Swiss chard in response to the treatments. The results of the study demonstrated the potential of B. subtilis BD233 to enhance the early growth of these non-indigenous vegetables in nutrient-poor African soils.

Effects of using different host plants and long-term fertilization systems on population sizes of infective arbuscular mycorrhizal fungi

The effect of cultivation of mycorrhizal and non-mycorrhizal plants and mineral fertilization on the arbuscular mycorrhizal fungal (AMF) community structure of maize (Zea mays L.) plants was studied. Soil samples were collected from two field experiments treated for 5 years with three fertilization systems (Control – no fertilization; Mineral – NPK fertilization; and Organic – Farmyard manure fertilization). Soil samples containing soil and root fragments of rapeseed (Brassica napus L., non-mycorrhizal plant) and wheat (Triticum aestivum L., mycorrhizal plant) collected from the field plots were used as native microbial inoculum sources to maize plants. Maize plants were sown in pots containing these inoculum sources for four months under glasshouse conditions. Colonization of wheat roots by AMF, AMF community structure, AMF diversity (Shannon’s index), AMF dominance (Simpson’s index) and growth of maize were investigated. Sixteen AMF species were identified from rhizosphere soil samples as different species of genera Acaulospora, Claroideoglomus, Dentiscutata, Funneliformis, Gigaspora, Quatunica, Racocetra, and Rhizoglomus. Maize plants grown in manure-fertilized soils had a distinct AMF community structure from plants either fertilized with mineral NPK-fertilizer or non-fertilized. The results also showed that inoculum from non-mycorrhizal plants combined with mineral fertilization decreased AMF diversity (Shannon’s index), AMF dominance (Simpson’s index) and growth of maize. Our findings suggest that non-mycorrhizal plants, such as B. napus, can negatively affect the presence and the effects of soil inoculation on maize growth. Also, our results highlight the importance of considering the long-term effect of rapeseed cultivation system on the reduction of population sizes of infective AMF, and its effect on succeeding annual crops.

Influence of Bio-fertilization with the Red Yeast (Phaffia rhodozyma) on Growth, Yield and Inulin Content of Jerusalem artichoke

In a clay loamy soil in the Middle Egypt, an experiment was conducted to study the effect of soil inoculation with red yeast (Phaffia rhodozyma) on the growth, physiological characteristics and tubers production of Jerusalem artichoke (Helianthus tuberosus L.). Jerusalem artichoke plants’ growth was motivated as a result of the increased microbial activities in the treated soil; also tubers yield/plant was significantly increased. The soluble, insoluble and total carbohydrates at the yield stage found to be decreased in the treated Jerusalem artichoke shoots than in the control ones. Also, red yeast significantly enhanced the inulin content in tubers of the treated than that of the non-treated Jerusalem artichoke plants. Results also showed that this yeast isolate improved the soil properties by increasing the total count of bacteria, fungi and actinomycetes. Application of red yeast as a bio-fertilizer of a plant promoting microorganisms is promising to enhance plant growth and yield, stimulate translocation of carbohydrates towards tubers and it decreased the need for chemical fertilizers resulting in, organic matter could be obtained with lower costs.

Effects of variety, cropping system and soil inoculation with Aspergillus flavus on aflatoxin levels during storage of maize

The effects of soil inoculation with A. flavus, variety and cropping system on the level of aflatoxin in stored maize were investigated under crop storage conditions in Benin. The experiment was organized in a factorial scheme (two varieties x two cropping system x with or without A. flavus soil inoculation) with eight treatments carried out in a completely randomized block design with three replications. A. flavus incidence in the plots soil was assessed both before and after soil inoculation. The harvested maize was stored for four months and cobs were sampled in a monthly interval and analyzed for the determination of Fusarium spp. colonization, Penicillium spp. and A. flavus cfu levels, insect pests population size and aflatoxin content. Multi-factorial analysis of variance and linear regression analyses with dummy variables were used to compare treatments. The concentrations of aflatoxin B1 and B2 in the kernels tended to increase with time during storage. Variety and fungal inoculation were the main factors influencing the levels of aflatoxins in stored maize. The improved variety showed a higher number of A. flavus cfu and aflatoxin B1 and B2 levels as compared to the local variety.Intercropping with Vigna unguiculata decreased the aflatoxin concentration in the improved variety but not in the local variety. The local variety had higher levels of Penicillium spp. and lower levels of Fusarium spp. than the improved variety. The treatments had no effect on the populations of the most common storage insect pests, but their levels were positively correlated with aflatoxin content. Both the initial inoculum level and the variety effect on the water content of the kernels after harvest played a significant role in A. flavus infection.

Isolados de estreptomicetos no crescimento e nutrição de mudas de tomateiro

Os estreptomicetos são conhecidos pela produção de metabólitos secundários, como antibióticos e enzimas extracelulares, que atuam na degradação de moléculas complexas e recalcitrantes, desempenhando papel importante nos processos de compostagem. Neste sentido, com o objetivo de avaliar o efeito da inoculação e incubação de solo com isolados de estreptomicetos, no crescimento inicial de mudas de tomateiro, foram avaliados seis isolados de estreptomicetos, mais o controle não inoculado. O solo foi inoculado com os estreptomicetos e incubado por 20 dias, antes do plantio. Após 30 dias, as mudas foram coletadas para determinação da altura, diâmetro do caule, massa seca da parte aérea e raízes e acúmulo de nutrientes na parte aérea. Os isolados de estreptomicetos promoveram incrementos significativos no crescimento e acúmulo de nutrientes, nas mudas de tomateiro. Acredita-se que a incubação do solo, por 35 dias, antes do plantio, garanta o tempo necessário para que os estreptomicetos atuem na mineralização da matéria orgânica, disponibilizando nutrientes para o crescimento das plantas.

The influence ofBacillus subtilisRB14-C on the development ofRhizoctonia solaniand indigenous microorganisms in the soil

The effect of soil inoculation with an antagonistic strain Bacillus subtilis RB14-C on the development of Rhizoctonia solani and changes occurring in soil and rhizosphere microbial communities were studied. RB14-C was added to the soil as a water suspension of the cells or as a broth culture. Application of cell suspensions to non-planted soil reduced the number of culturable bacteria. The density of R. solani and the number of filamentous fungi were not significantly affected by RB14-C. A similar effect was observed in the rhizosphere of tomato plants growns in bacterized soil. Broth cultures of RB14-C suppressed R. solani 1 d after inoculation, but after 3 d there was no difference in the pathogen density between soil amended with broth culture and control soil. In microcosm studies, cell suspensions of RB14-C also did not inhibit growth of R. solani on filters buried in soil. However, an inhibitory effect was obtained when a broth culture of the bacterium was used. The effect of RB14-C on fungal biomass was also estimated by measurement of ergosterol concentration in soil. It was found that ergosterol was mostly derived from R. solani and that there were no significant differences in its content between untreated soil and soil treated with RB14-C. The results suggest that suppression of Rhizoctonia damping-off by B. subtilis RB14-C probably is not related to the reduction of the pathogen population in the soil.

Bioremediation of BTEX hydrocarbons: effect of soil inoculation with the toluene-growing fungus Cladophialophora sp. strain T1.

The biodegradation of a mixture of benzene, toluene, ethylbenzene, xylene, (BTEX) and methyl-tert-butyl ether (MTBE) was studied in soil microcosms. Soil inoculation with the toluene-metabolising fungus Cladophialophora sp. strain T1 was evaluated in sterile and non-sterile soil. Induction of biodegradation capacity following BTEX addition was faster in the soil native microflora than in axenic soil cultures of the fungus. Toluene, ethylbenzenes, and the xylenes were metabolized by the fungus but biodegradation of benzene required the activity of the indigenous soil microorganisms. MTBE was not biodegraded under the tested environmental conditions. Biodegradation profiles were also examined under two pH conditions after a long term exposure to BTEX. At neutral conditions the presence of the fungus had little effect on the intrinsic soil biodegradation capacity. At an acidic pH, however, the activity of the indigenous degraders was inhibited and the presence of Cladophialophora sp. increased significantly the biodegradation rates of toluene and ethylbenzene. Comparison of the BTEX biodegradation rates measured in soil batches combining presence and absence of indigenous degraders and the fungal inoculum indicated that no severe antagonism occurred between the indigenous bacteria and Cladophialophora sp. The presence of the fungal inoculum at the end of the experiments was confirmed by PCR-TGGE analysis of small subunits of 18S rDNA.

Inoculation of field-established mulberry and papaya with arbuscular mycorrhizal fungi and a mycorrhiza helper bacterium.

The effects of soil inoculation with arbuscular mycorrhizal (AM) fungi and a mycorrhiza helper bacterium (MHB) were investigated on mulberry and papaya plants already established in the field. Ten-year-old mulberry plants (var. M5) were inoculated with Glomus fasciculatum and 1.5-year-old papaya plants (var. Solo) were inoculated with a mixed culture of G. mosseae and G. caledonium with or without Bacillus coagulans at two levels of P fertilizer. Growth, P uptake, yield and AM colonization levels were monitored. Leaf yield in mulberry and fruit yield in papaya were minimal in uninoculated plants given 50% recommended P. However, crop yields of both mulberry and papaya inoculated with AM fungi alone or together with the bacterium and given 50% recommended P were statistically on a par with that of uninoculated plants given 100% recommended P. As inoculation of B. coagulans increased mycorrhiza levels in AM fungal-inoculated plants, this may be included in the class of MHB. Thus, mulberry and papaya already established in the field may respond to AM inoculation and MHB may increase symbiosis development by efficient AM fungi.

Influence of mycorrhizal fungi on the growth of different tree species and their nutrient uptake in gypsum mine spoil in India

The effect of soil inoculation with an arbuscular mycorrhizal fungus, Glomus fasciculatum, isolated from gypsum mine spoil, on dry matter production, nutrient uptake and rhizosphere microbial activity in five tree species growing in gypsum mine spoil was studied. Dry matter production was significantly enhanced upon inoculation to varying degrees depending on the tree species. The level of root infection increased by 14–36% and spore densities in the rhizosphere increased by 49–81%. AM fungal inoculation resulted in enhanced activities of various soil enzymes viz. dehydrogenase, phosphatases and nitrogenase in the rhizosphere. Total uptake of many nutrients but not of potassium and sodium, was significantly enhanced upon AM fungal inoculation. It is concluded that arbuscular mycorrhizal fungi are important symbionts for use in the revegetation of gypsum mine spoils.

The effect of soil inoculation with microbial pesticide destructors on plant growth and development

Soil inoculation with liquid cultures of Bacillus megaterium 501 and Exophiala nigrum A-29 capable of degrading several organophosphorus pesticides accelerated growth and development of experimental plants, formation of their generative organs, and improved their productivity. This was particularly observed under stress plant growth conditions on phytotoxic peach substrates. The microorganisms inoculated can probably degrade phytotoxins present in soils, thereby favoring the plant development.

Effect of levels and sources of phosphorus and phosphate solubilizing microorganisms on growth, yield and quality of sugarcane

Field investigations were carried out at Regional Research Station, Visweswaraya Canal Farm, Mandya (Karnataka) to study the effect of soil inoculation of phosphate solubilizing organisms (PSM) in conjunction with levels and sources of P on growth, yield and quality of sugarcane-Plant and ratoon during 1995 to 1998. The bacterial cultures viz.,Agrobacterium radiobacter andBacillus megaterium in plant crop and the fungusAspergillus awamori in ratoon crop are efficient P solubilizers. Their inoculation with soluble P source viz., SSP and in combination with pressmud (PM) ascentuates their effect as P solubilizers. Enhanced uptake and higher tissue indices of P besides N and K were indicative of better nutrient use efficiency and their positive influence on various growth and yield parameters. Improvement in cane yields (8 to 10%), economy in fertilizer P (25%) are suggestive of cost effectiveness and higher net returns due to their inoculation.

Effect of cyanobacterial inoculation and fertilizers on rice seedlings and postharvest soil structure

The effect of soil inoculation with urea, Nostoc muscorum, and Tolypothrix tenuis on rice seedlings, nutrient contents, and structure of postharvest soil was studied. Tolypothrix tenuis and T. tenuis + urea produced the highest increase in oxidizable C (54.60% both) which resulted 7.63% higher than urea. Tolypothrix tenuis also produced the highest increase in soluble C (241.14%). Regarding nitrogen (N) soil content all treatments produced a positive difference. No treatment exerted any effect on soil available phosphorus (P). The percentage of aggregates >50 (m increased with all treatments from 6 to 12%, except N. muscorum. Tolypothrix tenuis produce the highest effect, with 50% more of these aggregates than urea. Seedling dry weight and shoot length were higher than control for all treatments. Shoots were longest with N. muscorum + urea being this treatment more effective than each Cyanobacteria alone. There was no effect on the number of leaves. Except for N. muscorum, all treatments increased the seedling N content. Postharvest soil showed a better quality when inoculated with T. tenuis or T. tenuis + urea compared to urea. Cyanobacterial fertilizers are a promising alternative to avoid soil pollution caused by agrochemicals and recover the nutrient content and structure lost after harvest as they bring to soil combined N (some of them are N fixers), exopolysaccharide that improve soil structure and bioactive substances that enhance seedlings growth.

Metabolism of iprodione in adapted and non-adapted soils; Effect of soil inoculation with an iprodione-degrading Arthrobacter strain

Soils previously treated with iprodione degraded the fungicide more rapidly than previously-untreated samples of the same soils. Addition of an iprodione-degrading Arthrobacter sp. culture to a previously-untreated soil enhanced the degradation rate of the fungicide. In previously-untreated soils, chemical and biological transformations of iprodione led to different products. In previously-treated soils and in previously-untreated soils enriched with Arthrobacter sp., the product obtained from the hydrolysis of exocyclic urea function of iprodione was transformed initially into 3,5-dichlorophenylurea acetic acid, which was then further degraded to 3,5-dichloroaniline. Experiments showed that soil adaptation leading to enhanced iprodione degradation was related to the ability of microorganisms to make the first transformation step.

Effect of soil inoculation with vesicular-arbuscular mycorrhizal fungi and either phosphate rock dissolving bacteria or thiobacilli on dry matter production and uptake of phosphorus by tomato plants

Abstract The effect of inoculating soil with phosphate rock dissolving bacteria (PRDB) or sulphur (S) oxidising micro-organisms on shoot dry matter (DM) production and phosphorus (P) uptake of a tomato cultivar (Lycopersicon esculentum Mill, Virosa NT2) colonised with the vesicular-arbuscular mycorrhizal (V AM) fungus Gigaspora margarita (Becker & Hall) was determined in a pot trial. Inoculation with PRDB did not affect shoot DM production and P uptake. Shoot DM and P uptake were also not increased when V AM and PRDB were inoculated together. PRDB were temporarily detrimental to shoot DM production. The PRDB population declined soon after soil inoculation but recovered after addition of a phosphate-free nutrient solution. It is suggested that soil bacteriostasis and a deficiency of easily metabolisable carbon compounds were the causes of the failure of the PRDB culture. Thiobacilli inoculation appeared to be detrimental to shoot DM production, and a combined inoculation of V AM and thiobacilli did not cau...

The Effect of Soil Inoculation with Aspergillus Flavus on the Mycoflora of Groundnut Soil, Rhizosphere and Geocarposphere

SUMMARY A study was made of the effects of massive inoculation of Aspergillus flavus into soil of containers in which groundnuts were sown, on the mycoflora of that soil and of the groundnut rhizosphere and geocarposphere. A total of 115 fungal species was isolated from these mycofloras. In the containers inoculated with A. flavus before sowing, populations of this species in rhizosphere and soil declined strongly after 57 days, but in the geocarposphere prevalence of this species increased greatly at the end of the growing period. Presence of A. flavus in large numbers had no prominent effect on the frequency of most of the other dominant species in the soil, rhizosphere and geocarposphere. Relationships between various groups or species of soil fungi, and comparisons of the fungi in the soil and rhizosphere (R/S ratio) have been investigated for a number of crops, e.g., by Row (1962) for groundnuts, Bilai et al. (1954) for cotton, Katznelson and Richardson (1943) for tomatoes, and Timonin and Lochhead (1948) for tobacco. In general, the mycoflora of the rhizosphere has been found to contain larger numbers of fungi than that of the soil. In the present study we have added the mycoflora of soil adhering to groundnut (Arachis hypogaea L.) geocarps (geocarposphere) to the comparison between that of rhizosphere and soil. However, our work was not primarily concerned with the respective composition of these mycofloras under normal conditions. It aimed at elucidating the changes induced where groundnut soil is massively inoculated with Aspergillus flavus, i.e. the effect of A. flavus on other dominant fungi and conversely the action of the latter on the A. flavits population. METhTODS

The Effect of Soil Inoculation with Aspergillus flavus on the Mycoflora of Groundnut Soil, Rhizosphere and Geocarposphere

The Effect of Soil Inoculation with Aspergillus flavus on the Mycoflora of Groundnut Soil, Rhizosphere and Geocarposphere