Soil contamination by diesel fuel destabilizes the soil microbial pools: Insights from permafrost soil incubations.

Arctic contamination by diesel fuel (DF) is of great concern because of the uncertain feedback of permafrost carbon (C) and soil microbiota to DF in the context of climate change in high latitudes. We conducted a laboratory incubation experiment with a gradient of DF addition ratios to examine the responses of the soil microbiota of the typical permafrost soils in the tundra ecosystems of the Norilsk region (Siberia). The study revealed initial heterogeneity in the microbial activity of the studied soils (Histic Gleyic Cryosols (CR-hi,gl), Turbic Cryosols (CR-tu), Turbic Spodic Folic Cryosols (CR-tu,sd,fo), Gleyic Fluvisols (FL-gl)). We applied the two-pool model for evaluation of the effect of DF on the proportions of C pools and revealed significant differences between soil types in the fast and slow C pools in response to DF addition. The results showed that DF addition treatments had varying effects on the fast and slow C pools, microbial activity, and microbial community structure in the studied soils. For minor exceptions, DF dramatically accelerated C loss from the slow C pool in all soil types. We assume that differences in C pool and microbiota responses to DF addition were caused by soil texture and changes in microbial community structure. We isolated Serratia proteamaculans, S. liquefaciens, S. plymuthica, Rhodococcus erythropolis, Pseudomonas antarctica, P. libanensis, P. brassicacearum, and P. chlororaphis from the DF-polluted soils. These species are recommended for bioremediation to mitigate the DF contamination of permafrost soils, especially regarding climate change and the sustainable well-being of Arctic ecosystems.

Effectiveness of slow-release fungicide formulations for suppressing potato pathogens.

BACKGROUND: For the first time, the biological activity of slow-release fungicide formulations for suppressing potato pathogens deposited in a degradable poly-3-hydroxybutyrate/sawdust base has been obtained and investigated. RESULTS: The slow-release fungicide formulations (azoxystrobin, azoxystrobin + mefenoxam, and difenoconazole) were studied in vitro and in vivo in comparison with commercial analogues. In in vitro cultures of phytopathogens, the deposited fungicides showed an inhibitory effect comparable to commercial analogues, limiting the growth of colonies of Phytophthora infestans, Alternaria longipes, Rhizoctonia solani and Fusarium solan (2.0-2.3 times relative to the negative control). In laboratory experiments, the use of deposited fungicides was accompanied by earlier germination and more active growth of potatoes against the background of a decrease in the area of plant damage and an increase in yield. In the field experiment, the deposited fungicides suppressed the development of Phytophthora and Alternariosis in the rhizosphere during the entire growing season and reduced the area of plant damage by pathogens by 10-15%, which is two times less than in the groups of plants treated with commercial preparations. The higher biological activity of the embedded fungicides ensured the maximum number of tubers undamaged by pathogens and the total yield of 22-23 t ha-1 , which exceeded the yields in the groups with commercial fungicides (18.4-20.8 t ha-1 ). CONCLUSION: The slow-release fungicide formulations deposited in a degradable P(3HB)/sawdust base are effective in protecting potatoes from pathogens and increasing yields and have an advantage over commercial counterparts. © 2022 Society of Chemical Industry.

Degradable Poly(3-hydroxybutyrate)-The Basis of Slow-Release Fungicide Formulations for Suppressing Potato Pathogens.

Three-component slow-release fungicide formulations with different modes of action of the active ingredients for suppressing potato pathogens were constructed for the first time. The difenoconazole, mefenoxam, prothioconazole, and azoxystrobin fungicides were embedded in the degradable polymer P(3HB)/birch wood flour blend and examined using SEM, IR spectroscopy, X-ray analysis, DTA, and DSC. Results showed that no chemical bonds were established between the components and that they were physical mixtures that had a lower degree of crystallinity compared to the initial P(3HB), which suggested different crystallization kinetics in the mixtures. The degradation behavior of the experimental formulations was investigated in laboratory micro-ecosystems with pre-characterized field soil. The slow-release fungicide formulations were prolonged-action forms with a half-life of at least 50-60 d, enabling gradual and sustained delivery of the active ingredients to plants. All slow-release fungicide formulations had a strong inhibitory effect on the most common and harmful potato pathogens (Phytophthorainfestans, Alternarialongipes, Rhizoctoniasolani, and Fusariumsolani).

Bacterial Cellulose (BC) and BC Composites: Production and Properties.

The synthesis of bacterial cellulose (BC) by Komagataeibacter xylinus strain B-12068 was investigated on various C-substrates, under submerged conditions with stirring and in static surface cultures. We implemented the synthesis of BC on glycerol, glucose, beet molasses, sprat oil, and a mixture of glucose with sunflower oil. The most productive process was obtained during the production of inoculum in submerged culture and subsequent growth of large BC films (up to 0.2 m2 and more) in a static surface culture. The highest productivity of the BC synthesis process was obtained with the growth of bacteria on molasses and glycerol, 1.20 and 1.45 g/L per day, respectively. We obtained BC composites with silver nanoparticles (BC/AgNPs) and antibacterial drugs (chlorhexidine, baneocin, cefotaxime, and doripenem), and investigated the structure, physicochemical, and mechanical properties of composites. The disc-diffusion method showed pronounced antibacterial activity of BC composites against E. coli ATCC 25922 and S. aureus ATCC 25923.

Metabolic activity of cryogenic soils in the subarctic zone of Siberia towards "green" bioplastics.

The present study investigates, for the first time, the structure of the microbial community of cryogenic soils in the subarctic region of Siberia and the ability of the soil microbial community to metabolize degradable microbial bioplastic - poly-3-hydroxybutyrate [P(3HB)]. When the soil thawed, with the soil temperature between 5-7 and 9-11 °C, the total biomass of microorganisms at a 10-20-cm depth was 226-234 mg g-1 soil and CO2 production was 20-46 mg g-1 day-1. The total abundance of microscopic fungi varied between (7.4 ± 2.3) × 103 and (18.3 ± 2.2) × 103 CFU/g soil depending on temperature; the abundance of bacteria was several orders of magnitude greater: (1.6 ± 0.1) × 106 CFU g-1 soil. The microbial community in the biofilm formed on the surface of P(3HB) films differed from the background soil in concentrations and composition of microorganisms. The activity of microorganisms caused changes in the surface microstructure of polymer films, a decrease in molecular weight, and an increase in the degree of crystallinity of P(3HB), indicating polymer biodegradation due to metabolic activity of microorganisms. The clear-zone technique - plating of isolates on the mineral agar with polymer as sole carbon source - was used to identify P(3HB)-degrading microorganisms inhabiting cryogenic soil in Evenkia. Analysis of nucleotide sequences of rRNA genes was performed to identify the following P(3HB)-degrading species: Bacillus pumilus, Paraburkholderia sp., Pseudomonas sp., Rhodococcus sp., Stenotrophomonas rhizophila, Streptomyces prunicolor, and Variovorax paradoxus bacteria and the Penicillium thomii, P. arenicola, P. lanosum, Aspergillus fumigatus, and A. niger fungi.

Constructing sustained-release herbicide formulations based on poly-3-hydroxybutyrate and natural materials as a degradable matrix.

BACKGROUND: The purpose of the present study was to develop ecofriendly herbicide formulations. Its main aim was to develop and investigate slow-release formulations of herbicides (metribuzin, tribenuron-methyl, and fenoxaprop-P-ethyl) of different structure, solubility, and specificity, which were loaded into a degradable matrix of poly-3-hydroxybutyrate (P(3HB)) blended with available natural materials (peat, clay, and wood flour). RESULTS: Differences in the structure and physicochemical properties of the formulations were studied depending on the type of the matrix. Herbicide release and accumulation in soil were associated with the solubility of the herbicide. Fourier-transform infrared spectroscopy showed that no chemical bonds were formed between the components in the experimental formulations. Degradation of the formulations in agro-transformed soil in laboratory conditions was chiefly influenced by the shape of the specimens (granules or pellets) while the effect of the type of filler (peat, clay, or wood flour) was insignificant. The use of granules enabled more rapid accumulation of the herbicides in soil: their peak concentrations were reached after 3 weeks of incubation while the concentrations of the herbicides released from the pellets were the highest after 5-7 weeks. Loading of the herbicides into the polymer matrix composed of the slowly degraded P(3HB) and natural materials enabled both sustained function of the formulations in soil (lasting between 1.5 and ≥3 months) and stable activity of the otherwise rapidly inactivated herbicides such as tribenuron-methyl and fenoxaprop-P-ethyl. CONCLUSION: The experimental herbicide formulations enabled slow release of the active ingredients to soil. © 2019 Society of Chemical Industry.

Bio-functionalization of phytogenic Ag and ZnO nanobactericides onto cellulose films for bactericidal activity against multiple drug resistant pathogens.

The present study describes the synthesis of silver and zinc oxide nanobactericides from the phytogenic source Bupleurum aureum. The synthesized nanobactericides were characterized and evaluated for bio-functionalization onto bacterial cellulose membrane which was synthesized by Komagataeibacterxylinus B-12068 culture strain. The synthesis of nanobacterides were initially confirmed using UV-Visible spectroscopy which indicated localized surface resonance (LSPR) peaks at 415 nm for silver nanobactericides and 280 nm for zinc nanobactericides. The nature of the capping agent for synthesized nanobactericides was predicted using FTIR which confirmed the presence of functional moieties. XRD analysis revealed their crystalline nature while morphological characteristics were studied using TEM which confirmed the polydispersity of nanobactericides with the average size in the range of 20-25 nm. The nanobactericides were tested for their antimicrobial activity against seven multi-drug resistant pathogens which were clinically isolated from patients suffering from a myriad of microbial infections. The tested pathogens had antimicrobial resistance to ten different antibiotics and have been reported to be the major cause of nosocomial infections. The nanobactericides displayed significant activity against the test pathogens. Silver nanobactericides showed the highest activity against Escherichia coli strain 55 with a 24 mm zone of inhibition while zinc oxide nanobactericides displayed the highest activity against methicillin-resistant Staphylococcus aureus (MRSA) with a 20 mm inhibition zone. The bio- functionalized cellulose films (BCF) were characterized using SEM along with physicochemical analysis. The BCF's were evaluated for antibacterial activity against test pathogens which resulted in marked antimicrobial potential against multi-drug resistant bacteria and therefore has the potential to be utilized as an efficient alternative to counter drug resistant pathogens.

Production and properties of bacterial cellulose by the strain Komagataeibacter xylinus B-12068.

A strain of acetic acid bacteria, Komagataeibacter xylinus B-12068, was studied as a source for bacterial cellulose (BC) production. The effects of cultivation conditions (carbon sources, temperature, and pH) on BC production and properties were studied in surface and submerged cultures. Glucose was found to be the best substrate for BC production among the sugars tested; ethanol concentration of 3% (w/v) enhanced the productivity of BC. Optimization of medium and cultivation conditions ensures a high production of BC on glucose and glycerol, up to 2.4 and 3.3 g/L/day, respectively. C/N elemental analysis, emission spectrometry, SEM, DTA, and X-ray were used to investigate the structure and physical and mechanical properties of the BC produced under different conditions. MTT assay and SEM showed that native cellulose membrane did not cause cytotoxicity upon direct contact with NIH 3T3 mouse fibroblast cells and was highly biocompatible.

Fungicidal activity of slow-release P(3HB)/TEB formulations in wheat plant communities infected by Fusarium moniliforme.

Fungicidal activity of experimental tebuconazole (TEB) formulations was investigated in laboratory soil ecosystems in wheat plant communities infected by Fusarium moniliforme. TEB was embedded in the matrix of poly-3-hydroxybutyrate, shaped as films and microgranules. These formulations were buried in the soil with wheat plants, and their efficacy was compared with that of commercial formulation Raxil and with the effect of pre-sowing treatment of seeds. In the experiment with the initially infected seeds and a relatively low level of natural soil infection caused by Fusarium fungi, the effects of the experimental P(3HB)/TEB formulations and Raxil were comparable. However, when the level of soil infection was increased by adding F. moniliforme spores, P(3HB)/TEB granules and films reduced the total counts of fungi and the abundance of F. moniliforme more effectively than Raxil. Seed treatment or soil treatment with Raxil solution showed an increase in the percentage of rot-damaged roots in the later stages of the experiment. In the early stage (between days 10 and 20), the percentage of rot-damaged roots in the soil with TEB embedded in the slowly degraded P(3HB) matrix was similar to that in the soil with Raxil. However, the efficacy of P(3HB)/TEB formulations lasted longer, and in later stages (between days 20 and 30), the percentage of rot-damaged roots in that group did not grow. In experiments with different TEB formulations and, hence, different fungicidal activities, the increase in plant biomass was 15-17 to 40-60% higher than in the groups where TEB was applied by using conventional techniques.

Nanoagroparticles emerging trends and future prospect in modern agriculture system.

Increment of technical knowledge has remarkably uplifted logical thinking among scientific communities to shape the theoretical concepts into near product-oriented research. The concept of nanotechnology has overwhelmed almost all forms of lives and has traded its applications in myriad fields. Despite rapid expansion of nanotechnology, sustainable competitions still do exist in the field of agriculture. In current scenario, agriculture is a manifestation demand to provide adequate nutrition for relentless growing global population. It is estimated that nearly one-third of the global crop production is destroyed annually. The loss owes to various stresses such as pest infestation, microbial pathogens, weeds, natural calamities, lack of soil fertility and much more. In order to overcome these limitations, various technological strategies are implemented but a majority of these have their own repercussions. Hence there is a scrawling progress on the evaluation of nanoparticles into agriculture sector which can reform the modern agricultural system. Applications of these nanomaterials can add tremendous value in the current scenario of a global food scarcity. Nanotechnology can address the adverse effects posed by the abundant use of chemical agrochemicals which are reported to cause biomagnification in an ecosystem. Based on these facts and consideration, present review envisages on nanoparticles as nanoherbicides, nanopesticides, onsite detection agro-pathogens and nanoparticles in post harvest management. The review also elucidates on the importance of nanoparticles in soil fertility, irrigation management and its influence on improving crop yield. With scanty reports available on nanotechnology in agriculture system, present review attributes toward developing nanoagroparticles as the future prospect which can give new facelift for existing agriculture system.

Efficacy of tebuconazole embedded in biodegradable poly-3-hydroxybutyrate to inhibit the development of Fusarium moniliforme in soil microecosystems.

BACKGROUND: An important line of research is the development of a new generation of formulations with targeted and controlled release of the pesticide, using matrices made from biodegradable materials. In this study, slow-release formulations of the fungicide tebuconazole (TEB) have been prepared by embedding it into the matrix of poly-3-hydroxybutyrate (P3HB) in the form of films, microgranules and pellets. RESULTS: The average rates of P3HB degradation were determined by the geometry of the formulation, reaching, for 63 days, 0.095-0.116, 0.081-0.083 and 0.030-0.055 mg day-1 for films, microgranules and pellets respectively. The fungicidal activity of P3HB/TEB against the plant pathogen Fusarium moniliforme was compared with that of the commercial formulation Raxil Ultra. A pronounced fungicidal effect of the experimental P3HB/TEB formulations was observed in 2-4 weeks after application, and it was retained for 8 weeks, without affecting significantly the development of soil aboriginal microflora. CONCLUSION: TEB release can be regulated by the process employed to fabricate the formulation and the fungicide loading, and the TEB accumulates in the soil gradually, as the polymer is degraded. The experimental forms of TEB embedded in the slowly degraded P3HB can be used as a basis for developing slow-release fungicide formulations. © 2016 Society of Chemical Industry.

Microbial Degradation of Polyhydroxyalkanoates with Different Chemical Compositions and Their Biodegradability.

The study addresses degradation of polyhydroxyalkanoates (PHA) with different chemical compositions-the polymer of 3-hydroxybutyric acid [P(3HB)] and copolymers of P(3HB) with 3-hydroxyvalerate [P(3HB/3HV)], 4-hydroxybutyrate [P(3HB/4HB)], and 3-hydroxyhexanoate [P(3HB/3HHx)] (10-12 mol%)-in the agro-transformed field soil of the temperate zone. Based on their degradation rates at 21 and 28 °C, polymers can be ranked as follows: P(3HB/4HB) > P(3HB/3HHx) > P(3HB/3HV) > P(3HB). The microbial community on the surface of the polymers differs from the microbial community of the soil with PHA specimens in the composition and percentages of species. Thirty-five isolates of bacteria of 16 genera were identified as PHA degraders by the clear zone technique, and each of the PHA had both specific and common degraders. P(3HB) was degraded by bacteria of the genera Mitsuaria, Chitinophaga, and Acidovorax, which were not among the degraders of the three other PHA types. Roseateles depolymerans, Streptomyces gardneri, and Cupriavidus sp. were specific degraders of P(3HB/4HB). Roseomonas massiliae and Delftia acidovorans degraded P(3HB/3HV), and Pseudoxanthomonas sp., Pseudomonas fluorescens, Ensifer adhaerens, and Bacillus pumilus were specific P(3HB/3HHx) degraders. All four PHA types were degraded by Streptomyces.

Biodegradable poly-3-hydroxybutyrate as a fertiliser carrier.

BACKGROUND: Increasing use of mineral fertilisers can lead to accumulation of fertilisers in soil, water and foodstuffs. One of the approaches to preventing these problems is to develop controlled release forms of fertilisers. RESULTS: Experimental formulations of the nitrogen fertiliser urea loaded in a degradable matrix of the natural polymer poly-3-hydroxybutyrate (P3HB) in the form of films, pellets and coated granules were constructed and investigated. Nitrogen release into soil occurred as the polymer was degraded, and it was dependent on the geometry of the carrier and the amount of nitrogen loaded in it, showing that nitrogen release can last for 30 days or longer and that release rates can be controlled by varying the fabrication technique employed. P3HB/urea formulations have a favourable effect on the soil microbial community. The use of embedded urea has a beneficial influence on the growth of creeping bentgrass (Agrostis stolonifera) and lettuce (Latuca sativa) and reduces removal of nitrogen with drain water. CONCLUSION: The slow-release nitrogen formulations developed in this study can be buried in soil together with seeds preventing nitrogen deficiency. The use of such slow-release formulations can decrease the amounts of chemicals in the environment and prevent their adverse effects on the biosphere. © 2016 Society of Chemical Industry.