Soil organic matter and the extracellular microbial matrix show contrasting responses to C and N availability

Redmile-Gordon, Marc; Evershed, Richard P.; Hirsch, P. R.; White, Ronald P.; Goulding, Keith

doi:10.1016/j.soilbio.2015.05.025

Cited by 57 publications

(26 citation statements)

References 69 publications

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“…produces auxins (Yin et al, 2015), which support the root system of plants (Takahashi, 2013), and extracellular phosphatases (Pfeiffer, 1996), which exposes phosphorus to plants (Lee, 1988); Chlorella vulgaris helps to start initial bacterial growth (Cole, 1982;Watanabe et al, 2005); Azotobacter sp. produces extracellular biopolymers (Remminghorst and Rehm, 2006), which are necessary for aquaretence capacity cover Redmile-Gordon et al, 2015); while Azotobacter sp. and Azospirillum sp.…”

Section: Biological Materialsmentioning

confidence: 99%

Effect of Bacterial-algal Biostimulant on the Yield and Internal Quality of Lettuce (Lactuca sativa L.) Produced for Spring and Summer Crop

Kopta

Pavlíková

Sękara

et al. 2018

Not Bot Horti Agrobo

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Plant biostimulants can enhance crop nutrition status, stress tolerance, yield and quality in environment-friendly manner. The aim of this study was to determine the effect of an algae and bacteria preparations on the yield and nutritional parameters of leaf and romaine lettuce cultivated for spring and summer crop. The application of a combined biostimulant consisting of plant growth-promoting bacteria (Bacillus licheniformis, Bacillus megatherium, Azotobacter sp., Azospirillum sp., and Herbaspirillum sp.) and fresh water algae (Chlorella vulgaris) was done by watering the lettuce every 14 days, and a determination of the fresh weight, total antioxidant capacity, and total carotenoids content was performed. The result revealed that the application of bacterial-algal preparation significantly affected the plant weight of both romaine and leaf lettuce in spring and summer seasons. The highest increase in the weight of romaine lettuce reached 18.9% in the spring crop, while in the case of leaf lettuce, biostimulant treatment led to a 22.7% higher weight in the summer crop. Total antioxidant capacity and total carotenoids content showed increased values in the summer crop of romaine lettuce, while for the leaf lettuce there were no differences between treatments. Therefore, the positive effect of bacterial-algal treatment on lettuce yield, total antioxidant capacity and total carotenoids confirm that it could be applied for improving romaine lettuce yield quality and quantity, especially in stress, summer conditions.

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Section: Biological Materialsmentioning

confidence: 99%

Effect of Bacterial-algal Biostimulant on the Yield and Internal Quality of Lettuce (Lactuca sativa L.) Produced for Spring and Summer Crop

Kopta

Pavlíková

Sękara

et al. 2018

Not Bot Horti Agrobo

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“…Importantly, no studies are known to show an increase in microbial biomass due to contamination with Zn 2+ . The EPS production efficiencies in uncontaminated soils (also amended with glycerol and BCP) were previously found to depend on the C/N ratio of available substrates for microbial growth (Redmile-Gordon et al., 2015a). While the effect of Zn 2+ addition on EPS production efficiency per se (μg EPS nmol −1 microbial ATP, or μg EPS nmol −1 biomass C) was not an objective of the present study, the addition of excess Zn 2+ is highly unlikely to have increased the microbial biomass (again, as no soil studies have ever shown this), and so the clear increase in EPS and SMP production between soils given BCP and those given BCP plus Zn 2+ points towards microbial allocation of metabolites into Zn tolerance mechanisms.…”

Section: Resultsmentioning

confidence: 98%

“…This step was repeated each day thereafter to simultaneously re-moisten the soil, remove excess substrate C from soil pores, and redistribute solutes as would occur in a more natural system exposed to weather in an open environment (Redmile-Gordon et al., 2015a). Dilute CaCl 2 is commonly used in preference to deionized water in soil laboratory studies as a surrogate for rainwater owing to osmotic similarity (Jalali and Rowell, 2003).…”

Section: Methodsmentioning

confidence: 99%

“…Redmile-Gordon et al., 2014b). While easily accessible/labile C is now understood to be a pre-requisite for substantial production of EPS from soil biota (Nunan et al., 2003, Redmile-Gordon et al., 2015a), the influence of any heavy metal contamination on proteinaceous and polysaccharide exudate production by soil native microbial populations in situ has not yet been reported.…”

Section: Introductionmentioning

confidence: 99%

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Zinc toxicity stimulates microbial production of extracellular polymers in a copiotrophic acid soil

Redmile-Gordon

Chen

2017

International Biodeterioration & Biodegradation

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The production of extracellular polymeric substances (EPS) is crucial for biofilm structure, microbial nutrition and proximal stability of habitat in a variety of environments. However, the production patterns of microbial EPS in soils as affected by heavy metal contamination remain uncertain. Here we investigate the extracellular response of the native microbial biomass in a grassland soil treated with refined glycerol or crude unrefined biodiesel co-product (BCP) with and without ZnCl2. We extracted microbial EPS and more readily soluble microbial products (SMP), and quantified total polysaccharide, uronic acid, and protein content in these respective extracts. Organic addition, especially BCP, significantly stimulated the production of EPS-polysaccharide and protein but had no impact on EPS-uronic acids, while in the SMP-fraction, polysaccharides and uronic acids were both significantly increased. In response to the inclusion of Zn2+, both EPS- and SMP-polysaccharides increased. This implies firstly that a tolerance mechanism of soil microorganisms against Zn2+ toxicity exists through the stimulation of SMP and EPS production, and secondly that co-products of biofuel industries may have value-added use in bioremediation efforts to support in-situ production of microbial biopolymers. Microbial films and mobile polymers are likely to impact a range of soil properties. The recent focus on EPS research in soils is anticipated to help contribute an improved understanding of biofilm dynamics in other complex systems - such as continuously operated bioreactors.

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“…This could probably be explained by pre-incubation of soil aggregates given 0.2 mM NH 4 NO 3 and further addition of NH 4 NO 3 with enzyme application: Redmile-Gordon et al (2015) proposed that low C / N ratios of substrates available to soil microorganisms reduce cell-specific EPS production rates and may trigger microbial consumption of EPSs to acquire C for cell-growth, which could weaken the biofilm. The observations leading to this proposed dynamic were also found by addition of NH 4 NO 3 .…”

Section: Discussionmentioning

confidence: 99%

Enzymatic biofilm digestion in soil aggregates facilitates the release of particulate organic matter by sonication

Büks

Kaupenjohann

2016

SOIL

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Abstract. The stability of soil aggregates against shearing and compressive forces as well as water-caused dispersion is an integral marker of soil quality. High stability results in less compaction and erosion and has been linked to enhanced water retention, dynamic water transport and aeration regimes, increased rooting depth, and protection of soil organic matter (SOM) against microbial degradation. In turn, particulate organic matter is supposed to support soil aggregate stabilization. For decades the importance of biofilm extracellular polymeric substances (EPSs) regarding particulate organic matter (POM) occlusion and aggregate stability has been canonical because of its distribution, geometric structure and ability to link primary particles. However, experimental proof is still missing. This lack is mainly due to methodological reasons. Thus, the objective of this work is to develop a method of enzymatic biofilm detachment for studying the effects of EPSs on POM occlusion. The method combines an enzymatic pre-treatment with different activities of α-glucosidase, β-galactosidase, DNAse and lipase with a subsequent sequential ultrasonic treatment for disaggregation and density fractionation of soils. POM releases of treated samples were compared to an enzyme-free control. To test the efficacy of biofilm detachment the ratio of bacterial DNA from suspended cells and the remaining biofilm after enzymatic treatment were measured by quantitative real-time PCR. Although the enzyme treatment was not sufficient for total biofilm removal, our results indicate that EPSs may attach POM within soil aggregates. The tendency to additional POM release with increased application of enzymes was attributed to a slight loss in aggregate stability. This suggests that an effect of agricultural practices on soil microbial populations could influence POM occlusion/aggregate stability and thereby carbon cycle/soil quality.

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Soil organic matter and the extracellular microbial matrix show contrasting responses to C and N availability

Cited by 57 publications

References 69 publications

Effect of Bacterial-algal Biostimulant on the Yield and Internal Quality of Lettuce (Lactuca sativa L.) Produced for Spring and Summer Crop

Effect of Bacterial-algal Biostimulant on the Yield and Internal Quality of Lettuce (Lactuca sativa L.) Produced for Spring and Summer Crop

Zinc toxicity stimulates microbial production of extracellular polymers in a copiotrophic acid soil

Enzymatic biofilm digestion in soil aggregates facilitates the release of particulate organic matter by sonication

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