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PubMed1979

Effect of environmental parameters on the biodegradation of oil sludge.

A laboratory study was conducted with the aim of evaluating and optimizing the environmental parameters of "landfarming", i.e., the disposal by biodegradation in soil of oily sludges generated in the refining of crude oil and related operations. Oil sludge biodegradation was monitored by CO2 evolution and by periodic analysis of residual hydrocarbons. The parameters studied were soil moisture, pH, mineral nutrients, micronutrients, organic supplements, treatment rate, teratment frequency, and incubation temperature. Oil sludge biodegradation was optimal at a soil water-holding capacity of 30 to 90%, a pH of 7.5 to 7.8, C:N and C:P ratios of 60:1 and 800:1, respectively, and a temperature of 20 degrees C or above. Addition of micronutrients and organic supplements was not beneficial; sewage sludge interfered with hydrocarbon biodegradation. Breakdown of the saturated hydrocarbon (alkane and cycloalkane) fraction was the highest at low application rates, but higher application rates favored the biodegradation of the aromatic and asphaltic fractions. An application rate of 5% (wt/wt) oil sludge hydrocarbon to the soil (100,000 liters/hectare) achieved a good compromise between high biodegradation rates and efficient land use and resulted in the best overall biodegradation rate of all hydrocarbon classes. Frequent small applications resulted in higher biodegradation than single large applications. Two 100,000-liter/hectare (255 barrels per acre) or four 50,000-liter/hectare oil sludge hydrocarbon applications per growing season seem appropriate for most temperate zone disposal sites.

Bacteria↗
PubMed1979

Evaluation of Myrothecium verrucaria as a nutrient source for ruminants.

The soil saprophytic fungus Myrothecium verrucaria was cultivated from glucose, starch, or xylan as the carbon source, and the biomass was compared with three selected feedstuffs. Fungal biomass was analyzed for nitrogen, protein, lipid, water soluble fraction, hemicellulose, cellulose, lignin, and residual ash, and the in vitro dry matter disappearance was determined. The chemical composition of M. verrucaria varied with substrate. In nitrogen content, the fungal biomass was more similar to alfalfa hay than to milo stalks or wheat straw. Content of water soluble fraction of fungal biomass was between those of alfalfa hay and milo stalks; content of hemicellulose was between those of milo stalks and wheat straw. The fungal fractions identified as cellulose and lignin varied widely with substrate. The fungal biomass was less digestible than alfalfa hay but more digestible than milo stalks or wheat straw. There may be potential uses of this organism in upgrading nutritive value of low-quality forages.

Animal Feed↗
PubMed2025

Fast-growing Bacillus sensu lato rhizosphere populations are constrained by antagonistic Pseudomonadota, Actinomycetota and other Bacillus sensu lato.

Copiotrophic Bacillus and related taxa grow rapidly and are commonly isolated from soil. Despite their growth rate, Bacillus sensu lato (BSL) constitute less than one percent of soil bacterial communities, and the nutrient-enriched rhizosphere contains even fewer. Amendment of bulk soil with synthetic root exudate did not lead to increase in Bacillus culturable counts. We hypothesized that BSL populations in soil enriched with growth-supporting carbon are suppressed by various soil microbes. A screen using B. pseudomycoides as tester strain yielded 124 growth inhibiting isolates, aligning by 16S rRNA genes to 3 Alphaproteobacteria, 6 Betaproteobacteria, 5 Gammaproteobacteria, 3 Streptomyces, and 19 Bacillaceae. Most antagonists also suppressed four other BSL, and over 70% of the BSL isolates suppressed each other. The 11 sequenced BSL genomes encoded between 2 and 10 antibiotic biosynthetic gene clusters. Incubation of multiple isolates in artificial soil microcosms resulted in population growth restraint through a high percentage of endospores formed. This indicated that growth suppression by antagonists was due primarily to induction of sporulation. These results support our hypothesis that Bacillus populations in soil enriched with growth-supporting carbon are suppressed by various soil microbes.

Bacillus↗
PubMed2026

Microbial diversity: the essential foundation for life on our planet.

The biological basis of life on Earth is microbial diversity that ensures human health, agricultural productivity, ecological balance, and ecosystem functioning. Microorganisms enable ecosystem restoration through bioremediation, maintain soil fertility, support plant growth, manage vital biogeochemical cycles, and contribute to climate resilience. Precision probiotics, postbiotics, faecal microbiota transplantation, and personalized microbiome medicine are the examples of emerging microbiome-based therapies that offer promising therapeutic opportunities. In humans, the gut microbial community is essential for immune regulation, metabolism, and disease prevention. In terrestrial ecological systems, interactions between plants, fungi, bacteria, and other soil microorganisms improve carbon sequestration, nutrient cycling, stress resilience, and sustainable agricultural productivity in the given effects of climate change. Emerging uses in agriculture, environmental restoration, and medicine are made possible by advancements in multi-omic techniques, synthetic microbial genomes, microbiome engineering, and artificial intelligence. Considering these developments, issues with ecological complexity, long-term validation, standardization, and field scale application still exist. Therefore, preserving microbial diversity is important for conserving ecological resilience and strengthening the One Health framework, which highlights the mutual dependance of health of animal, human, plant, and environment. This review summarizes what has been discovered about ecological and biomedical relevance of microbiome, identifies important research gaps, highlighting emerging technologies, and evaluates potential future directions for using microbiome to support planetary sustainability.

Bioremediation↗
PubMed1976

Microprobe analysis of 60Co uptake in sand microcosm.

1. Microprobe analysis of fungal micro-communities in simple soil microcosms demonstrated the presence of several nutrient elements (Ca, K, P, S), and immobilization of the fission product 60Co in fungal spores. 2. The importance of soil microbes in element cycling is discusses. 3. The utility of the electron microprobe in providing more precise estimates of elements in microbes and their substrates is evaluated.

Biological Transport↗
PubMed2026

Plant-derived and microbial biostimulants in sustainable agriculture: mechanisms, applications, and challenges.

Plant biostimulants have emerged as transformative and sustainable tools for improving crop productivity, resource-use efficiency, and resilience under rapidly intensifying environmental stresses. Unlike conventional agrochemicals, biostimulants function by activating physiological, biochemical, and molecular processes that optimize plant performance without directly supplying nutrients or exerting pesticidal effects. This review comprehensively examines the integrated roles of plant-derived and microbial biostimulants in sustainable agriculture, with particular emphasis on microbial-mediated mechanisms underlying plant stress adaptation and rhizosphere functioning. Plant-derived biostimulants, including seaweed extracts, humic substances, protein hydrolysates, amino acids, and chitosan, enhance nutrient acquisition, root architecture, hormonal regulation, and antioxidant defense systems. More importantly, microbial biostimulants, such as plant growth-promoting rhizobacteria (PGPR), endophytic microorganisms, mycorrhizal fungi, actinomycetes, yeasts, and cyanobacteria, exert multifunctional effects through biological nitrogen fixation, mineral solubilization, phytohormone biosynthesis, volatile signaling, osmolyte accumulation, pathogen suppression, and modulation of stress-responsive genes. These beneficial microorganisms reshape rhizosphere microbial communities, improve nutrient cycling, and enhance plant tolerance to drought, salinity, heat, and heavy metal toxicity. Emerging evidence from genomics, transcriptomics, metabolomics, and microbiome-based investigations has further revealed the molecular networks and signaling pathways governing biostimulant-induced resilience and plant-microbe interactions. Despite their substantial promise, inconsistent field performance, formulation instability, regulatory limitations, and inadequate mechanistic understanding continue to restrict their large-scale adoption. This review highlights recent advances in microbial and plant-derived biostimulants while identifying critical knowledge gaps and future opportunities for precision biostimulant engineering, microbiome manipulation, and climate-resilient crop management. The integration of next generation biostimulant technologies into sustainable agricultural systems may significantly reduce dependence on agrochemicals while improving crop productivity, environmental sustainability, and global food security.

Agriculture↗
PubMed1978

Ion selective electrode for determination of chloride ion in biological materials, food products, soils and waste water.

The chloride ion selective electrode is used for a rapid, simple, and reliable determination of chloride ion in biological materials (blood serum, urine, fish, and plant tissues), food products (milk, beef extract, nutrient broth and orange, tomato, and grapefruit juices), soils, and waste water (industrial and municipal). The method consists of treating the samples with perchloric acid (pH 1) and potassium peroxydisulfate and determining the chloride content either by a calibration curve or by known addition or analyte addition, using the chloride ion selective electrode. Such sample treatment eliminates most of the interferences occurring in the samples, including iodide, complexing and reducing compounds, and macromolecular and surface-active species. The method is suitable for a wide range of chloride concentration, e.g., 5010 ppm Cl- in nutrient broth and 4890 ppm in beef extract and as low as 12 and 80 ppm in soil extracts.

Animals↗
PubMed1978

Soil and plant factors influencing the accumulation of heavy metals by plants.

The use of plants to monitor heavy metal pollution in the terrestrial environment must be based on a cognizance of the complicated, integrated effects of pollutant source and soil-plant variables. To be detectable in plants, pollutant sources must significantly increase the plant available metal concentration in soil. The major factor governing metal availability to plants in soils is the solubility of the metal associated with the solid phase, since in order for root uptake to occur, a soluble species must exist adjacent to the root membrane for some finite period. The rate of release and form of this soluble species will have a strong influence on the rate and extent of uptake and, perhaps, mobility and toxicity in the plant and consuming animals. The factors influencing solubility and form of available metal species in soil vary widely geographically and include the concentration and chemical form of the element entering soil, soil properties (endogenous metal concentration, mineralogy, particle size distribution), and soil processes (e.g., mineral weathering, microbial activity), as these influence the kinetics of sorption reactions, metal concentration in solution and the form of soluble and insoluble chemical species. The plant root represents the first barrier to the selective accumulation of ions present in soil solution. Uptake and kinetic data for nutrient ions and chemically related nonnutrient analogs suggest that metabolic processes associated with root absorption of nutrients regulate both the affinity and rate of absorption of specific nonnutrient ions. Detailed kinetic studies of Ni, Cd, and Tl uptake by intact plants demonstrate multiphasic root absorption processes over a broad concentration range, and the use of transport mechanisms in place for the nutrient ions Cu, Zn, and K. Advantages and limitations of higher plants as indicators of increased levels of metal pollution are discussed in terms of these soil and plant phenomena.

Absorption↗
PubMed1975

Metabolic behaviour of water-soluble fluorescent whitening agents in the rat and bean plant.

The behaviour of three representative water-soluble fluorescent whitening agents (FWAs) was studied in rats and bean plants using 14C-labelled compounds. Following oral doses of 5 mg/kg of each of the FWAs to rats, rapid and complete excretion of radioactive material was observed, with an excretion half life ranging from 7-13 hours. Faeces were practically the only route of excretion, indicating, in combination with the short half life times, that no significant amounts of whitener were absorbed from the digestive tract. No radioactive residues were found in blood, liver, kidney, brain, muscle, or fat 96 hours after dosing (limit of quantitative determination 0.005-0.01 ppm Fwa equivalents). Whereas, after application of compound (1) and compound (3), radioactive material was completely extractable from faeces in the form of unchanged parent compounds, that in the compound (2) experiments was not extractable. When bean plants (Phaseolus vulgaris) were grown in the presence of 14C-labelled compound (3) in nutrient solution (11.5 ppm) and in soil (,7.5 ppm), approximately 55% and 2% of the applied radioactive material, respectively, was absorbed by the plants. More than 90% of thie material was bound to the roots in both experiments 40 days after the application. Eight percent of the radioactive material absorbed in the soil experiment was translocated mainly into the stems whereas only trace amounts of the order of less than 0.1 ppm reached the leaves and bean pods. It is concluded from these experiments with extremely high concentrations of compound (3) that under the conditions which may occur in practice residues of water-soluble FWAs do not appear in substantial amounts in edible parts of crops.

Animals↗
PubMed2025

Whole-Genome Analysis and Growth-Promoting Mechanism of Klebsiella pneumoniae YMK25 from Maize Rhizobacteria.

Plant growth-promoting rhizobacteria (PGPR) are microorganisms that enhance plant growth through various mechanisms. In the context of global agriculture, which faces fertilizer dependency and environmental pollution, developing eco-friendly microbial fertilizers has become crucial for enhancing agricultural sustainability. To identify highly effective PGPR, we isolated 102 bacterial strains from maize rhizosphere soil using the dilution plating method. The strains were screened for growth-promoting abilities using functional media, resulting in the selection of strain YMK25 for its exceptional capabilities in nitrogen fixation, solubilization of inorganic and organic phosphorus, indole-3-acetic acid (IAA) production, and siderophore production. Strain YMK25 produced IAA at a concentration of 80.49 ± 0.68 μg/mL and exhibited a relative siderophore expression level of 43.68%. Morphological analysis, 16S rDNA gene sequence analysis, and whole-genome sequencing confirmed that strain YMK25 is Klebsiella pneumoniae. Whole-genome analysis revealed a total genome length of 5,115,280 bp, a GC content of 57.61%, and it contained 4746 coding genes. Gene annotation results indicated genes involved in siderophore synthesis, phosphatase activity, and other plant growth-promoting functions, which align with the verified characteristics of strain YMK25. Furthermore, this strain exhibited significant metabolic capabilities. The pot experiment demonstrated that strain YMK25 promotes maize plant growth and assists in nutrient fixation in these plants. In conclusion, strain YMK25 is a high-quality PGPR with substantial potential for application in agricultural production, presenting promise for widespread use in sustainable agriculture.

Klebsiella pneumoniae↗
PubMed1977

Dehydrogenase activity and microbial population in a red sandy soil amended and unamended with incubation.

Incubation of single bulk sample of freshly collected red sandy soil in trays showed immediate response to added nutrients both in dehydrogenase activity and bacterial and fungal populations. The prevailing acidic pH might have been responsible for the observed response of fungi as well. Actinomycetes population did not fluctuate. It was therefore suggested that TTC dehydrogenase technique for measuring the biological activity could be applicable to coarse-textured and more open soils. There were indications that fungi contributed to the soil dehydrogenase activity as well.

Actinomycetales↗
PubMedDate not supplied

Metabolic factors and the utilization of phosphorus by plants.

The overall process of entry and transport of phosphate by plants has been separated into its component parts. Rapid esterification is involved but a small proportion of the total transport may occur by a non-metabolic route. Mannose alters the metabolism of phosphate in roots of cereals and thereby reduces the transport to the shoot by as much as 99% whereas dicotyledonous species are much less sensitive. The sequestration of phosphate as mannose 6-phosphate is reversible in some species depending on the extent of its conversion into fructose 6-phosphate and it is possible that in vivo controls of this type operate in whole plants. The factors involved in the control of distribution of inorganic phosphate between cellular organelles and throughout the plant are discussed. Enzymic hydrolysis of organic forms by roots and associated microorganisms may also be important in soils where available orthophosphate is limiting. Other inorganic nutrients, particularly boron, play an important role during the transport of phosphate across membranes. Major differences have been found in the capacities of different species to transport absorbed phosphate to the shoot. Peas and field beans absorb efficiently in the early weeks of growth but the rate of transport is about one thirtieth that of oats, barley, mung bean or sunflower. The relevance of the experimental findings to the wider problem of efficiency of fertilizer use and the possible selection of genotypes with high capacities for absorption and transport are discussed.

Absorption↗
PubMed1975

[Study of the antagonistic action of actinomycetes on anthrax bacilli].

Capacity for the growth inhibition of the highly virulent causative agent of Siberia plague was studied with respect to actinomycetous strains from soil samples of the Ukraine. It was found that on nutrient media 88.4, 88.9, 88.1 and 93.4% of the isolates inhibited the growth of Bac. anthracis, Bac. cereus, Bac. mycoides and Tsenkovsky vaccine strain respectively. Representatives of very different taxonomic groups were found among the antagonistic actinomycetes. Clearance of the soil from Siberia plague bacilli stable to the outer effect with the help of the active strain L-721 of Act. chromofuscus was observed. The effect was chown in sterilized soil, not sterile soil and soil monolith.

Actinomycetales↗
PubMed1978

[Antibiotic activity of cultures of the species of the genus Actinomadura].

Sixty five cultures of Actinomadura were isolated from samples of different soils. The study of their antibiotic activity on liquid nutrient media showed that 49 of them were active against gram-postive bacteria. The antibiotics isolated fromsome cultures of Am. carminata, Am. rubra, Am. coerulea and Am. luteofluorescens had antitumor effect in experiments on animals.

Antibiotics, Antineoplastic↗
PubMed1977

Microbial metabolic activity in soil as measured by dehydrogenase determinations.

The dehydrogenase technique for measuring the metabolic activity of microorganisms in soil was modified to use a 6-h, 37 degrees C incubation with either glucose of yeast extract as the electron-donating substrate. The rate of formazan production remained constant during this time interval, and cellular multiplication apparently did not occur. The technique was used to follow changes in the overall metabolic activities of microorganisms in soil undergoing incubation with a limiting concentration of added nutrient. The sequence of events was similar to that obtained by using the Warburg respirometer to measure O2 consumption. However, the major peaks of activity occurred earlier with the respirometer. This possibly is due to the lack of atmospheric CO2 during the O2 consumption measurements.

Aerobiosis↗
PubMed1977

Interactions of Phytophthora cinnamomi and Trichoderma spp. in relation to propagule production in soil cultures at 26 degrees C1.

Effects of Trichoderma harzianum and T. polysporum on chlamydospore production by two isolates of Phytophthora cinamomi were determined over a 21-day period in nonsterile, sterilized, and sterilized amended soil. Trichoderma was either coinoculated with P. cinnamomi or added to the cultures on day 3 of the incubation period. In nonsterile soil, conversion of mycelial fragments in the P. cinnamomi inoculum to chlamydospores resulted in an initial slight increase in chlamydospore numbers. In cultures where either of the Trichoderma isolates was added on day 3, a significiant reduction in chlamydospore numbers was observed on day 4; however, neither of the Trichoderma isolates at either inoculation time significantly affected clamydospore numbers by day 21. Results from studies with sterilized amended soil indicated that a reduction in P. cinnamomi chlamydospore numbers by either of the Trichoderma isolates was dependent upon availability of simple carbohydrates. In sterilized nonamended soil, the number of chlamydospores was increased in cultures containing either Trichoderma isolate; in sterilized amended soil chlamydospore numbers were initially reduced, followed by a general increase as the nutrients were depleted. Neither of the Trichoderma isolates exhibited significant antagonistic qualities toward P. cinnamomi.

Fungi↗
PubMed1979

Seed inoculation with Azotobacter chroococcum in sand cultures and its effect on nitrogen balance.

The effect of bacterization of barley grains with a selected strain of Azotobacter chroococcum was studied. In nitrogen-deficient sand, seed inoculation increased plant length, dry weight, nitrogen content in addition to a significant increase in soil nitrogen. The density of the organism on grains had a slight positive effect. Irrigation with KNO3-containing nutrient solution suppressed nitrogen fixation, but inoculation still had a pronounced stimulating effect on plants. In presence of mixed soil microflora the beneficial effect of bacterization was less than in monobacterial cultures. Azotobacters naturally present in soil also colonized in heavy densities on the rhizoplane, but their effect on plant growth and soil nitrogen were less if compared with that resulting from bacterization.

Azotobacter↗