Arsenic precipitation in the bioleaching of enargite by Sulfolobus BC at 70 °C

Enargite (Cu₃AsS₄) was leached at 70°C by Sulfolobus BC in shake-flasks. The highest copper dissolution (52% after 550 h of leaching) was obtained with bacteria and 1 g l^–1 ferric ion. In the absence of ferric ion, Sulfolobus BC catalyzes the bioleaching of enargite through a direct mechanism after adhesion onto the mineral surface. In ferric bioleaching, arsenic precipitated as ferric arsenate and arsenic remained associated to the solid residues, preventing the presence of a high dissolved arsenic concentration in the leaching solution. About 90% inhibition of bacterial growth rate and activity was observed for dissolved arsenic concentrations above 600 mg l^–1 for As(III) and above 1000 mg l^–1 for As(V). Arsenic-bearing copper ores and concentrates could be leached by Sulfolobus BC in the presence of ferric iron due to the favourable precipitation of arsenic ion as ferric arsenate, avoiding significant bacterial inhibition.     

Fluorescence spectroscopy: a tool to characterize humic substances in soil colonized by microorganisms?

The ability of eight soil microfungal species, Alternaria alternata, Clonostachys rosea f. rosea, Exophiala cf. salmonis, Fusarium cf. coeruleum, Fusarium redolens, Paecilomyces lilacinus, Penicillium canescens and Phoma sp., and two known basidiomycete humic acid (HA) degraders, Trametes versicolor and Phanerochaete chrysosporium, to modify fluorescence properties of fulvic acids (FA) and/or HAs was determined. Effects of minerals and/or glucose on the modifications were examined. FA purified on polyvinyl-polypyrrolidone (PVPP) chromatography column was used. Purification of FA on PVPP column removed the low-molar-mass FA-structural components and excess of extractant (NaOH) used during FA preparation. Excitation spectra of FA entering the purification, purified FA and the removal solution indicate that organic compounds rich in carboxylic groups dominate in the removal solution and higher content of phenolic groups is a characteristic of purified FA. Many microfungal species shifted the emission maximum (measured at 470 and 468 nm of excitation wavelength) of FA, and also HA to longer wavelengths. The opposite effect (shift of the HA emission maximum to shorter wavelengths) of microfungi was observed for HA complemented by glucose. Depending on the presence of glucose in the medium, most microfungi changed also the shape of the emission spectra of HA and FA and the excitation spectra of FA. HA excitation spectrum measured at 590 nm of emission wavelength was significantly affected by the presence of glucose. Mineral ions caused a minor shift in the position of excitation maximum (measured at 590 nm of emission wavelength) toward longer wavelengths.     

Biodeterioration of mineral materials by microorganisms—biogenic sulfuric and nitric acid corrosion of concrete and natural stone

In general, microorganisms such as chemolithotrophic and chemo‐organotrophic bacteria, cyanohacteria, algae, fungi, and lichens living on and in stone material may be of importance in biodeterioration. These groups contribute substantially to the deterioration of mineral materials such as natural stone, concrete, ceramics, and glass. The attack on mineral materials may be either strongly or mildly aggressive or both. A strongly aggressive attack is caused by biogenic mineral or organic acids. A mildly aggressive attack results from hydrophilic slimes such as heteropolysaccharides and/or proteins (biofilm) and their ability to accumulate water and salts. Attack by exoenzymes seems to be unimportant.

In recent years it has become possible to test the resistance of mineral materials to microbial attack by means of a biotest. Three simulation apparatuses were constructed; each allowed the incubation of test materials under microbiologically optimized conditions. Biodeterioration involving biogenic sulfuric acid corrosion, which under natural conditions needs eight times as long, was detectable within a few months. The results differed from those of purely chemical and/or physical tests of materials. Physical/chemical test methods are not sufficient to determine the resistance of materials to biological attack, because they do not include the interactions between microorganisms and their substrate, the mineral material. In the case of biogenic sulfuric acid corrosion, simulation experiments demonstrated differences in resistance of various concrete types, which ranged from I to 20% weight loss of test blocks within I year. With chemical testing only negligible differences in weight loss were noted. This was also the case with biogenic nitric acid corrosion. Thus, biotests assist in the selection of appropriate materials from many different ones.     

Long-term changes of the δ15N natural abundance of plants and soil in a temperate grassland

Tracing back the N use efficiency of long-term fertilizer trials is important for future management recommendations. Here we tested the changes in natural N-isotope composition as an indicator for N- management within a long-term fertilization lysimeter experiment in a low mountain range pasture ecosystem at Rengen (Eifel Mountains), Germany. Cattle slurry (δ¹⁵N?=?8.9?±?0.5‰) and mineral fertilizers (calcium ammonium nitrate; δ¹⁵N?=??1.0?±?0.2‰) were applied at a rate between 0 and 480 kg N ha^?1?yr^?1 throughout 20 years from 1985 onwards. In 2006, samples were taken from different grass species, coarse and fine particulate soil organic matter, bulk soil and leachates. Total soil N content hardly changed during fertilization experiment. As also N leaching has been small within the stagnant water regime, most N was lost through the gaseous phase beside plant uptake and cutting. Unlike N uptake by plants, the process of N volatilization resulted in strong discrimination against the ¹⁵N isotope. As a consequence, the δ¹⁵N values of top soil samples increased from 1.8?±?0.4‰ to 6.0?±?0.4‰ and that of the plants from ?1.2?±?1.3‰ to 4.8?±?1.2‰ with increasing N fertilizer rate. Samples receiving organic fertilizer were most enriched in δ¹⁵N. The results suggest that parts of the fertilizer N signal was preserved in soils and even discovered in soil organic matter pools with slow N turnover. However, a ¹⁵N/¹⁴N isotope fractionation of up to 1.5‰ added to the δ¹⁵N values recovered in soils and plants, rendering the increase in δ¹⁵N value a powerful indicator to long-term inefficient N usage and past N management in the terrestrial environment.     

Is growth of soil microorganisms in boreal forests limited by carbon or nitrogen availability?

To study whether the biomass of soil microorganisms in a boreal Pinus sylvestris-Vaccinium vitis-idaea forest was limited by the availability of carbon or nitrogen, we applied sucrose from sugar cane, a C₄ plant, to the organic mor-layer of the C₃–C dominated soil. We can distinguish between microbial mineralization of the added sucrose and respiration of endogenous carbon (root and microbial) by using the C₄-sucrose as a tracer, exploiting the difference in natural abundance of ¹³C between the added C₄-sucrose (¹³C –10.8) and the endogenous C₃–carbon (¹³C –26.6 ). In addition to sucrose, NH₄Cl (340 kg N ha^–1) was added factorially to the mor-layer. We followed the microbial activity for nine days after the treatments, by in situ sampling of CO₂ evolved from the soil and mass spectrometric analyses of ¹³C in the CO₂. We found that microbial biomass was limited by the availability of carbon, rather than nitrogen availability, since there was a 50% increase in soil respiration in situ between 1 h and 5 days after adding the sucrose. However, no further increase was observed unless nitrogen was also added. Analyses of the ¹³C ratios of the evolved CO₂ showed that increases in respiration observed between 1 h and 9 days after the additions could be accounted for by an increase in mineralization of the added C₄–C.     

Preferential utilization of petroleum oil hydrocarbon components by microbial consortia reflects degradation pattern in aliphatic–aromatic hydrocarbon binary mixtures

In this study, the abilities of two microbial consortia (Y and F) to degrade aliphatic–aromatic hydrocarbon mixtures were investigated. Y consortium preferentially degraded the aromatic hydrocarbon fractions in kerosene, while F consortium preferentially degraded the aliphatic hydrocarbon fractions. Degradation experiments were performed under aerobic conditions in sealed bottles containing liquid medium and n-octane or n-decane as representative aliphatic hydrocarbons or toluene, ethylbenzene or p-xylene as representative aromatic hydrocarbons (all at 100 mg/l). Results demonstrated that the Y consortium degraded p-xylene more rapidly than n-octane. It degraded toluene, ethylbenzene and p-xylene more rapidly than decane. In comparison, the F consortium degraded n-octane more rapidly than toluene, ethylbenzene or p-xylene, and n-decane more rapidly than toluene, ethylbenzene or p-xylene. 16S rRNA gene sequencing revealed that the Y consortium was dominated by Betaproteobacteria and the F consortium by Gammaproteobacteria, and in particular Pseudomonas. This could account for their metabolic differences. The substrate preferences of the two consortia showed that the aliphatic–aromatic hydrocarbon binary mixtures, especially the n-decane–toluene/ethylbenzene/p-xylene pairs, reflected their degradation ability of complex hydrocarbon compounds such as kerosene. This suggests that aliphatic–aromatic binary systems could be used as a tool to rapidly determine the degradation preferences of a microbial consortium.     

Morphological details of microorganisms revealed by RCH-microscopy at high magnification —a ready-to-use adaptation of a light microscope

RCH-microscopy (Relief Contrast after Hostounsky) is a new method of optical microscopy in transmitted light developed withLambda Ltd., Prague. This method was used to study bacteria, fungi including yeasts and algae at high magnification. The equipment provides a three-dimensional image of high contrast and resolution. The results of these microscopic observations can be used for both morphological (taxonomical) and ecological studies of microorganisms.     

Bioremediation of a polycyclic aromatic hydrocarbon‐contaminated soil by using different aerobic batch bioreactor systems

The intrinsic depuration capability of a soil contaminated by polycyclic aromatic hydrocarbons (PAHs) originating from a contaminated industrial site was evaluated in this study by using different aerobic batch bioreactors: a slurry‐phase bioreactor, a blade‐agitated bioreactor, and a rotary vessel bioreactor. For each bioreactor, the disappearance of 14 target PAHs and of the total extractable organic matter was monitored. The three treatments exhibited rapid and extensive removal of the PAHs, which disappeared at different degradation rates according to their molecular weight and aromaticity degree. PAHs with two, three, and four aromatic rings were degraded in sequence, with average rates that generally decreased as the number of molecule rings increased. A slight increase in the bacterial biomass concentration and significant CO₂ production were also observed during the time course of the treatments. Among the three treatments, the slurry‐phase system provides the most effective and fastest removal of the PAHs and the organic extractable matter. However, the semisolid‐phase systems exhibited PAH depletion, capabilities higher than those reported in the literature for soils with similar particle size distribution in solid‐phase conditions.     

Spatial and temporal dynamics of hotspots of enzyme activity in soil as affected by living and dead roots—a soil zymography analysis

Aims

Hotspots of enzyme activity in soil strongly depend on carbon inputs such as rhizodeposits and root detritus. In this study, we compare the effect of living and dead Lupinus polyphyllus L. roots on the small-scale distribution of cellulase, chitinase and phosphatase activity in soil.

Methods

Soil zymography, a novel in situ method, was used to analyze extracellular cellulase, chitinase and phosphatase activity in the presence of i. living L. polyphyllus roots prior to shoot cutting and ii. dead/dying roots 10, 20 and 30 days after shoot cutting.

Results

After shoot cutting, cellulase and chitinase activities increased and were highest at the root tips. The areas of high cellulase and phosphatase activity extend up to 55 mm away from the root. Moreover, we observed microhotspots of cellulose, chitinase, and phosphatase activity up to 60 mm away from the next living root. The number and activity of microhotspots of chitinase activity was maximal 10 days after shoot cutting.

Conclusions

The study showed that young root detritus stimulates enzyme activities stronger than living roots. Soil zymography allowed identification of microhotspots of enzyme activity up to several cm away from living and dying roots, which most likely were caused by arbuscular mycorrhizal fungi.     

Aerobic mineralization of 4,4′-dichlorobiphenyl and 4-chlorobenzoic acid by a novel natural bacterial strain that grows poorly on benzoate and biphenyl

Achromobacter xylosoxidans strain IR08 was isolated from soil contaminated with electrical transformer fluid by enrichment culture containing Aroclor 1221 as the sole carbon source. This strain was found to grow on all monochlorobiphenyls, 4,4′-dichlorobiphenyl (4,4′-diCB) and a wide range of other xenobiotic compounds. During growth on 4,4′-diCB, a near-stoichiometric amount of chloride was excreted into the culture fluid in less than 5 days and growth yield was more than twice that achieved on biphenyl. The production of 4-CBA or chlorocatechol as a metabolite was not observed. Quite unusually, coincubation of strain IR08 with 4,4′-diCB and biphenyl at relatively equal concentrations showed preferential utilization of the chlorobiphenyl: 4,4′-diCB was mineralized in less than 5 days concomitant with stoichiometric release of chloride, while biphenyl was poorly degraded. Growth on 2.5 mM CBA also resulted in complete disappearance of the substrate, however, inorganic chloride recovered from the culture broth was less than 65%. The isolation of a dichlorobiphenyl-mineralizing rather than transformation strain such as IR08 is an important advance in an effort to develop effective bioremediation strategy for polychlorinated biphenyl-contaminated soil.     

Isolation and characterization of a thermophilic bacillus strain,that degrades phenol and cresols as sole carbon source at 70 °C

A phenol-degrading thermophilic bacterium, designated Bacillus sp. A2, was isolated from a water and mud sample from a hot spring in Iceland. The aerobic isolate grew optimally on phenol at 65 °C. At 70 °C, 85% of the optimal growth rate was still observed. No growth was observed at 40 °C and 75 °C. Bacillus sp. A2 is a gram-positive spore-forming rod. According to 16S rDNA analysis Bacillus sp. A2 is closely related to Bacillus stearothermophilus, Bacillus kaustophilus and Bacillus thermoleovorans. Bacillus sp. A2 degraded phenol completely in concentrations up to 5 mM. In addition, all three isomers of cresol were utilized as sole carbon and energy sources. The degradation of phenols proceeds via the meta-cleavage pathway and the enzymes involved in its degradation are constitutively expressed. Received: 13 May 1996 / Received revision: 29 July 1996 / Accepted: 12 August 1996     

Aerobic metabolism of pentachlorophenol by spent sawdust culture of “Shiitake” mushroom (Lentinus edodes) in soil

Summary Spent sawdust cultures of the Shiitake mushroom (Lentinus edodes) metabolised pentachlorophenol in soil to a significant (P < 0.05) extent with 60.5, 57.3 and 44.4 % disappearance recorded for strains LE2, 866 and R26, respectively. Addition of H₂O₂ markedly enhanced pentachlorophenol metabolism. Analysis of metabolites by GC/MS showed that pentachloroanisole was a metabolic product. These results suggest that there is potential for commercial application in bioremediation.     

Novozym 435-catalyzed regioselective benzoylation of 1-β-d-arabinofuranosylcytosine in a co-solvent mixture of C4MIm·PF6 and pyridine

Regioselective acylation of 1-β-d-arabinofuranosylcytosine (ara-C), using vinyl benzoate (VB) as acyl donor and Novozym 435 as catalyst, was carried out in various reaction media including pure organic solvents, organic solvent mixtures, and ionic liquid (IL)-containing systems. Although the reaction was highly regioselective in all the media assayed, remarkable enhancement of substrate conversion was achieved with a co-solvent mixture of 1-butyl-3-methylimidazolium hexafluorophosphate (C₄MIm·PF₆) and pyridine as the reaction medium, compared with other media tested. Additionally, the results demonstrated that the anions of ILs had a significant effect on the initial rate and substrate conversion. To better understand the reaction performed in IL-containing system, several variables were examined. The optimum molar ratio of VB to ara-C, initial water activity, temperature and shaking rate were 25:1, 0.11, 40°C and 250rpm, respectively. Under these optimum reaction conditions, the initial rate, substrate conversion, and regioselectivity were 0.49mMmin^?1, 99.4 and 99%, respectively. The product of the lipase-catalyzed reaction was characterized by ¹³C NMR and was shown to be 5′-O-benzoyl ara-C.     

Syntrophic oxidation of propionate in rice field soil at 15 and 30°C under methanogenic conditions

Propionate is one of the major intermediary products in the anaerobic decomposition of organic matter in wetlands and paddy fields. Under methanogenic conditions, propionate is decomposed through syntrophic interaction between proton-reducing and propionate-oxidizing bacteria and H(2)-consuming methanogens. Temperature is an important environmental regulator; yet its effect on syntrophic propionate oxidation has been poorly understood. In the present study, we investigated the syntrophic oxidation of propionate in a rice field soil at 15°C and 30°C. [U-(13)C]propionate (99 atom%) was applied to anoxic soil slurries, and the bacteria and archaea assimilating (13)C were traced by DNA-based stable isotope probing. Syntrophobacter spp., Pelotomaculum spp., and Smithella spp. were found significantly incorporating (13)C into their nucleic acids after [(13)C]propionate incubation at 30°C. The activity of Smithella spp. increased in the later stage, and concurrently that of Syntrophomonas spp. increased. Aceticlastic Methanosaetaceae and hydrogenotrophic Methanomicrobiales and Methanocellales acted as methanogenic partners at 30°C. Syntrophic oxidation of propionate also occurred actively at 15°C. Syntrophobacter spp. were significantly labeled with (13)C, whereas Pelotomaculum spp. were less active at this temperature. In addition, Methanomicrobiales, Methanocellales, and Methanosarcinaceae dominated the methanogenic community, while Methanosaetaceae decreased. Collectively, temperature markedly influenced the activity and community structure of syntrophic guilds degrading propionate in the rice field soil. Interestingly, Geobacter spp. and some other anaerobic organisms like Rhodocyclaceae, Acidobacteria, Actinobacteria, and Thermomicrobia probably also assimilated propionate-derived (13)C. The mechanisms for the involvement of these organisms remain unclear.     

Wetting properties of fungi mycelium alter soil infiltration and soil water repellency in a γ-sterilized wettable and repellent soil

Soil water repellency (SWR) has a drastic impact on soil quality resulting in reduced infiltration, increased runoff, increased leaching, reduced plant growth, and increased soil erosion. One of the causes of SWR is hydrophobic fungal structures and exudates that change the soil–water relationship. The objective of this study was to determine whether SWR and infiltration could be manipulated through inoculation with fungi. The effect of fungi on SWR was investigated through inoculation of three fungal strains (hydrophilic – Fusarium proliferatum, chrono-amphiphilic – Trichoderma harzianum, and hydrophobic – Alternaria sp.) on a water repellent soil (WR-soil) and a wettable soil (W-soil). The change in SWR and infiltration was assessed by the water repellency index and cumulative infiltration respectively. F. proliferatum decreased the SWR on WR-soil and slightly increased SWR in W-soil, while Alternaria sp. increased SWR in both the W-soil and the WR-soil. Conversely T. harzianum increased the SWR in the W-soil and decreased the SWR in the WR-soil. All strains showed a decrease in infiltration in W-soil, while only the F. proliferatum and T. harzianum strain showed improvement in infiltration in the WR-soil. The ability of fungi to alter the SWR and enmesh soil particles results in changes to the infiltration dynamics in soil.     

Population increase and damage by three species of mites on wheat at 20°C and two humidities

Twenty bisected grains of wheat infested with five pairs of the three commonest British grain-storage mites,Acarus siro L., Glycyphagus destructor (Shrank) andTyrophagus longior (Gervais), were examined every week for 20 weeks. Mite populations, the resulting damage to germ and endosperm, and visible fungal growth were observed at 20°C and relative humidities (r.h.) of 90% and 75%.At 90% r.h.,A. siro populations reached nearly 14000 per test-tube before slowly dropping to 5000. The mites ate the germ before the endosperm, leaving an impenetrable layer of crushed endosperm cells between these regions. TheG. destructor population reached only 800 before declining to 300; these mites ate over 75% of the germ and small amounts of endosperm.Tyrophagus longior populations rose to 2200 mites before crashing at week 12 to the initial population level; these mites ate over 75% of the germ and small amounts of endosperm.At 75% r.h., bothA. siro andT. longior populations were lower than at the higher r.h., peaking at 3000 and 1000 respectively and decreasing to 500 and 600 mites respectively.Glycyphagus destructor did markedly better than at 90% r.h., reaching 1500 before falling to 400. The damage at this humidity was slower to occur but was similar to that at 90% r.h. at the end of 20 weeks.At both humidities visible fungus was always less abundant on infested grain that uninfested grain.     

Order parameters of unsaturated phospholipids in membranes and the effect of cholesterol: a 1H–13C solid-state NMR study at natural abundance

Most biological phospholipids contain at least one unsaturated alkyl chain. However, few order parameters of unsaturated lipids have been determined because of the difficulty associated with isotopic labeling of a double bond. Dipolar recoupling on axis with scaling and shape preservation (DROSS) is a solid-state nuclear magnetic resonance technique optimized for measuring ¹H–¹³C dipolar couplings and order parameters in lipid membranes in the fluid phase. It has been used to determine the order profile of 1,2-dimyristoyl-sn-glycero-3-phosphocholine hydrated membranes. Here, we show an application for the measurement of local order parameters in multilamellar vesicles containing unsaturated lipids. Taking advantage of the very good ¹³C chemical shift dispersion, one can easily follow the segmental order along the acyl chains and, particularly, around the double bonds where we have been able to determine the previously misassigned order parameters of each acyl chain of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). We have followed the variation of such order profiles with temperature, unsaturation content and cholesterol addition. We have found that the phase formed by DOPC with 30% cholesterol is analogous to the liquid-ordered (l_o) phase. Because these experiments do not require isotopic enrichment, this technique can, in principle, be applied to natural lipids and biomembranes.Electronic Supplementary Material Supplementary material is available for this article at .     

Exploration type-specific standard values of extramatrical mycelium – a step towards quantifying ectomycorrhizal space occupation and biomass in natural soil

The present study aims at providing standard values for the exploration type (ET)-specific quantification of extramatrical mycelium (EMM) of ectomycorrhizal fungi applicable to ecological field studies. These values were established from mycelial systems of ectomycorrhizae (ECM) synthesized in rhizotrons with near-to-natural peat substrate. Based on image analysis, the “Specific Potential Mycelial Space Occupation” (sPMSO), i.e. the ET-specific complete area that is covered by the EMM systems (mm² cm⁻¹ ECM⁻¹), and the “Specific Actual Mycelial Space Occupation” (sAMSO), i.e. the projection area of mycelial systems (mm² cm⁻¹ ECM⁻¹), were analyzed as an extension of a previously described approach. The “Specific Extramatrical Mycelial Length” (sEML) [m cm⁻¹ ECM⁻¹] and the “Specific Extramatrical Mycelial Biomass” (sEMB) (μg cm⁻¹ ECM⁻¹) were calculated for each of the ET via the proportion of hyphal projected area, hyphal length and biomass, the latter two being derived from previous measurements on Piloderma croceum, a “Medium-Distance” (MD)-ET. Both sPMSO and sAMSO were highest for the “Long-Distance” (LD)-ET, whereas those of the “Short-Distance” (SD)-ET and MD-ET were similar, although showing high variation. In contrast, mycelial density per occupied area of the MD-ET was twice as high as that of the LD-ET. Proportional to the sAMSO, the EMM length and biomass differed considerably between the three ET with values of the MD-ET being 1.9 times higher than those of SD-ET, and those of the LD-ET being 15 times higher than those of the SD-ET. These standards in relation to ECM length may ease quantification of mycelial space occupation and biomass in a relatively simple way. Thereby, the ET-specific contribution of EMM can be distinguished—also of non-cultivable species—and up-scaling to large-scale estimation of cost/benefit relations is possible.     

Analysis of δ13C of CO2 distinguishes between microbial respiration of added C4-sucrose and other soil respiration in a C3-ecosystem

The main aim of this study was to test various hypotheses regarding the changes in ¹³C of emitted CO₂ that follow the addition of C₄-sucrose to the soil of a C₃-ecosystem. It forms part of an experimental series designed to assess whether or not the contributions from C₃-respiration (root and microbial) and C₄-respiration (microbial) to total soil respiration can be calculated from such changes. A series of five experiments, three on sieved (root-free) mor-layer material, and two in the field with intact mor-layer (and consequently with active roots), were performed. Both in the experiments on sieved mor-layer and the field experiments, we found a C₄-sucrose-induced increase in C₃-respiration that accounted for between 30% and 40% of the respiration increase 1 h after sucrose addition. When the course of C₃-, C₄- and total respiration was followed in sieved material over four days following addition of C₄-sucrose, the initially increased respiration of C₃-C was transient, passing within less than 24 h. In a separate pot experiment, neither ectomycorrhizal Pinus sylvestrisL. roots nor non-mycorrhizal roots of this species showed respiratory changes in response to exogenous sucrose. No shift in the ¹³C of the evolved CO₂ after adding C₃-sucrose to sieved mor-layer material was found, confirming that the sucrose-induced increase in respiration of endogenous C was not an artefact of discrimination against ¹³C during respiration. Furthermore, we conclude that the C₄-sucrose induced transient increase in C₃-respiration is most likely the result of accelerated turnover of C in the microbial biomass. Thus, neither respiration of mycorrhizal roots, nor processes discriminating against ¹³C were likely sources of error in the field. The estimated ¹³C of evolved soil CO₂ in three field experiments lay between –25.2 and –23.6. The study shows that we can distinguish between CO₂ evolved from microbial mineralisation of added C₄-sucrose, and CO₂ evolved from endogenous carbon sources (roots and microbial respiration).     

NanoAOX—a novel nanoparticle and antioxidant mixture enhances the growth of plants in vitro and in vivo

In Vitro Cellular & Developmental Biology - Plant - The global food crisis is an issue affecting 1 billion people worldwide—it is critical that a solution be developed to provide the...