aJiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, PR China
bKey Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China
cHanlin College, Nanjing University of Chinese Medicine, Taizhou, 225300, PR China
dQiyang Red Soil Experimental Station, Chinese Academy of Agricultural Sciences, Qiyang, 426182, PR China
Received 13 August 2015. Revised 16 February 2016. Accepted 19 February 2016. Available online 3 March 2016.
Highlights
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Fertilizations enhanced soil parent material maturation compared with cultivation alone.
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Chemical fertilization was effective on enriching copiotrophic bacteria during soil maturation.
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Chemical fertilization decreased soil bacterial diversity and richness during soil maturation.
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Straw returning has less negative effect on bacterial diversity compared to chemical fertilization.
Abstract
Soil parent materials are potential arable land resources that have great value for utilization. Soil bacteria play vital roles in soil formation, and soil parent material provides the basic nutritional environment for the development of the microbial community. Due to the extremely limited available nutrients in most parent materials, fertilization management is important for providing necessary available nutrients and for enhancing the maturation process of the parent materials. After 30 years of artificial maturation driven by different fertilization treatments, the soil development of three different parental materials was evaluated, and the bacterial community compositions were investigated using a high-throughput nucleic acid sequencing approach. The results showed that fertilization management increased the soil fertility and microbial biomass and enhanced soil parent material maturation compared with cultivation alone. Supplying available nutrients via chemical fertilization was more effective than cultivation alone for soil nutrient accumulation, microbial biomass promotion, and copiotrophic bacterial enrichment during soil parent material development. The soil bacterial community structure was determined by both parent material and fertilization strategies. Compared to straw returning, chemical fertilization-driven parent material maturation decreased soil bacterial diversity and significantly changed the soil bacterial community structure. However, compared to chemical fertilization, straw returning had a less negative effect on soil bacterial diversity, but was not as efficient in resolving the nutrient limitation during soil parent material maturation. This study provided insight into the maturation of soil parent materials for agriculture production to support the ever constant need for food by an increasing human population.
May 2016, Vol.96:176–179, doi:10.1016/j.soilbio.2016.02.001
Short communication
Title
Protease encoding microbial communities and protease activity of the rhizosphere and bulk soils of two maize lines with different N uptake efficiency
Author
Divyashri Baraniya a,,
Edoardo Puglisi b
Maria Teresa Ceccherini a
Giacomo Pietramellara a
Laura Giagnoni a
Mariarita Arenella a
Paolo Nannipieri a
Giancarlo Renella a
aDepartment of Agrifood Production and Environmental Sciences, University of Florence, Piazzale delle Cascine 28, 50144 Florence, Italy
bIstituto di Microbiologia, Facoltà di Scienze Agrarie, Alimentari ed Ambientali, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza, Italy
Received 3 September 2015. Revised 28 January 2016. Accepted 8 February 2016. Available online 22 February 2016.
Highlights
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Rhizosphere and bulk soil from maize plants with different NUEs are studied.
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Soil proteolytic communities are studied using DGGE, Illumina sequencing and qPCR.
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Higher NUE plant harbor higher abundance and diversity of proteolytic communities.
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Most of the neutral protease gene sequences belong to uncultured bacterial species.
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Rhizosphere effect due to different NUEs is stronger on apr gene than on npr gene.
Abstract
This study was carried out to understand the interplay of plant Nitrogen Utilizing Efficiency (NUE) with protease activity and microbial proteolytic community composition in the rhizosphere and bulk soils. Protease activity, diversity and abundance of protease genes (using DGGE and qPCR respectively of two key bacterial protease encoding genes: alkaline metallo-peptidase (apr) and neutral-metallopeptidases (npr)) were monitored in both rhizosphere and bulk soils from two maize in-bred lines L05 and T250 with higher and lower NUE respectively, using a rhizobox approach. Illumina sequencing was employed to assess the diversity of proteolytic communities encoding for the above-mentioned protease genes. Our results show higher enzyme activity, higher abundance and diversity of proteolytic genes in L05 maize rhizosphere, with higher NUE than in T250 maize rhizosphere.
May 2016, Vol.96:216–228, doi:10.1016/j.soilbio.2016.02.012
Title
Do shifts in life strategies explain microbial community responses to increasing nitrogen in tundra soil?
Author
Minna Männistö a,,
Lars Ganzert a,b
Marja Tiirola c
Max M. Häggblom d
Sari Stark e
aNatural Resources Institute Finland, P.O. Box 16, FI-96301 Rovaniemi, Finland
bDepartment of Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
cDepartment of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland
dDepartment of Biochemistry and Microbiology, Rutgers University, NJ, USA
eArctic Centre, University of Lapland, P.O. Box 122, FI-96101 Rovaniemi, Finland
Received 27 October 2015. Revised 19 February 2016. Accepted 20 February 2016. Available online 3 March 2016.
Highlights
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Similar bacterial community structure in soils under different grazing intensities.
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N amendment decreased respiration in tundra soil.
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N amendment decreased biomass but increased rRNA copy numbers per unit DNA.
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Copiotrophic taxa were more abundant in N amended soils.
Abstract
Subarctic tundra soils store large quantities of the global organic carbon (C) pool as the decomposition of plant litter and soil organic matter is limited by low temperatures and limiting nutrients. Mechanisms that drive organic matter decomposition are still poorly understood due to our limited knowledge of microbial communities and their responses to changing conditions. In subarctic tundra large grazers, in particular reindeer, exert a strong effect on vegetation and nutrient availability causing drastic nutrient pulses in the soils located along the migratory routes. Here we studied the effect of increased nitrogen (N) availability on microbial community structure and activities by laboratory incubations of soil collected from two sites with contrasting grazing intensities. We hypothesized that heavily grazed soil experiencing nutrient pulses harbor more copiotrophic taxa that are able to respond positively to increases in available N leading to increased enzyme activities and respiration. Contrary to our hypothesis, there were only minor differences in the microbial community composition between the lightly and heavily grazed soils. N amendment shifted the bacterial community composition drastically, but the changes were similar at both grazing intensities. The relative abundance of diverse Actinobacteria and Rhodanobacter-affiliated Gammaproteobacteria increased in the N amended microcosms, while the abundance of Acidobacteria, Alphaproteobacteria, Deltaproteobacteria, Verrucomicrobia and Bacteroidetes decreased. Contrary to our hypotheses, increased N availability decreased respiration and microbial biomass at both grazing intensities, while increased N availability had little influence on the extracellular enzyme activities. We propose that similar to what has been reported in other systems, elevated N availability suppressed microbial respiration and biomass by favoring copiotrophic species with faster growth rates and with limited capabilities to decompose recalcitrant organic matter. Similar responses in soils from contrasting vegetation types, soil organic matter (SOM) quality and N availabilities in response to grazing intensity indicate that nutrient pulses may have a strong direct impact on the microbial communities. Responses detected using laboratory incubations are likely amplified in the field where the direct effect of increased N availability is combined with increase in labile C through changes in plant production and species composition.
