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Profile Changes in the Soil Microbial Community When Desert Becomes Oasis.

Li CH, Tang LS, Jia ZJ, Li Y - PLoS ONE (2015)

Bottom Line: To assess the effects of cultivation, the following treatments were compared with the virgin desert: CK (no fertilizer), PK, NK, NP, NPK, NPKR, and NPKM (R: straw residue; M: manure fertilizer).The proportions of extremophilic and photosynthetic groups (e.g., Deinococcus-Thermus and Cyanobacteria) decreased, while the proportions of R-strategy (e.g., Gammaproteobacteria including Xanthomonadales), nitrifying (e.g., Nitrospirae), and anaerobic bacteria (e.g., Anaerolineae) increased throughout the oasis profile.Furthermore, difference in fertilization and crop growth altered the organic carbon contents in the soil, which resulted in differences of microbial communities within oasis.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China.

ABSTRACT
The conversion of virgin desert into oasis farmland creates two contrasting types of land-cover. During oasis formation with irrigation and fertilizer application, however, the changes in the soil microbial population, which play critical roles in the ecosystem, remain poorly understood. We applied high-throughput pyrosequencing to investigate bacterial and archaeal communities throughout the profile (0-3 m) in an experimental field, where irrigation and fertilization began in 1990 and cropped with winter wheat since then. To assess the effects of cultivation, the following treatments were compared with the virgin desert: CK (no fertilizer), PK, NK, NP, NPK, NPKR, and NPKM (R: straw residue; M: manure fertilizer). Irrigation had a greater impact on the overall microbial community than fertilizer application. The greatest impact occurred in topsoil (0-0.2 m), e.g., Cyanobacteria (25% total abundance) were most abundant in desert soil, while Actinobacteria (26%) were most abundant in oasis soil. The proportions of extremophilic and photosynthetic groups (e.g., Deinococcus-Thermus and Cyanobacteria) decreased, while the proportions of R-strategy (e.g., Gammaproteobacteria including Xanthomonadales), nitrifying (e.g., Nitrospirae), and anaerobic bacteria (e.g., Anaerolineae) increased throughout the oasis profile. Archaea occurred only in oasis soil. The impact of fertilizer application was mainly reflected in the non-dominant communities or finer taxonomic divisions. Oasis formation led to a dramatic shift in microbial community and enhanced soil enzyme activities. The rapidly increased soil moisture and decreased salt caused by irrigation were responsible for this shift. Furthermore, difference in fertilization and crop growth altered the organic carbon contents in the soil, which resulted in differences of microbial communities within oasis.

No MeSH data available.


Schematic diagram of the profile changes of dominated microbial community when desert becomes oasis at the southern periphery of the Gurbantonggut Desert.Actinobacteria = Act, Alphaproteobacteria = α-pr, Acidobacteria = Aci, Bacillales = Baci, Bacteroidetes = Bact, Betaproteobacteria = β-pr, Chloroflexi = Chl, Clostridiales = Clo, Crenarchaeota = Cre, Cyanobacteria = Cya, Deinococcus-Thermus = Dei, Deltaproteobacteria = δ-pr, Enterobacteriales = Ent, Gammaproteobacteria = γ-pr, Gemmatimonadetes = Gem, Firmicutes = Fir, Nitrospirae = Nit, Rhizobiales = Rhi, Rhodobaterales = Rh1, Rhodospirillales = Rh2, Sphingomonadales = Sph, Xanthomonadales = Xan.
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pone.0139626.g005: Schematic diagram of the profile changes of dominated microbial community when desert becomes oasis at the southern periphery of the Gurbantonggut Desert.Actinobacteria = Act, Alphaproteobacteria = α-pr, Acidobacteria = Aci, Bacillales = Baci, Bacteroidetes = Bact, Betaproteobacteria = β-pr, Chloroflexi = Chl, Clostridiales = Clo, Crenarchaeota = Cre, Cyanobacteria = Cya, Deinococcus-Thermus = Dei, Deltaproteobacteria = δ-pr, Enterobacteriales = Ent, Gammaproteobacteria = γ-pr, Gemmatimonadetes = Gem, Firmicutes = Fir, Nitrospirae = Nit, Rhizobiales = Rhi, Rhodobaterales = Rh1, Rhodospirillales = Rh2, Sphingomonadales = Sph, Xanthomonadales = Xan.

Mentions: The results in this study confirmed our basic hypothesis. It demonstrated that cultivation in the desert soil resulted in a strong shift in the microbial community structure throughout the soil profile (0–3 m) (Fig 5). The largest change in the overall microbial community was observed in the topsoil. While converting desert into oasis, the relative abundance of Cyanobacteria decreased from 25.4 to 2.5% on average, and that of Actinobacteria increased from 10.8 to 26.4% on average. The Cyanobacteria were therefore the most abundant group in desert topsoil and the Actinobacteria became the most abundant group in oasis topsoil (Fig 1). Cyanobacteria participate in both carbon and nitrogen fixation, and generally occur in harsh desert environments [31–32]. In addition to Cyanobacteria, other photosynthetic groups (e.g., the Rhizobiales, Sphingomonadales, and Rhodobaterales) were also present in lower proportions in the oasis (Table 2). Actinobacteria participate in the decomposition of lignin and chitin [33]. Wheat cover/ lack of light and return of wheat residues to the soil in the oasis may explain above-mentioned community shift. Meanwhile, there were also higher proportions of the Deinococcus-Thermus, α-proteobacteria, and Bacillales present in desert soil (Figs 1 and 2), all of which are extremophilic groups or antagonists, with a strong tolerance to desiccation, radiation, and high levels salinity [34]. The oasis soil had higher proportions of the R-strategy (e.g., γ-, β-proteobacteria), facultative vegetative (e.g., Rhodospirillales) and nitrifying bacteria (e.g., Nitrospirae) (Table 2 and Fig 2). Archaea occurred only in oasis soil. There is increasing evidence showing that archaea are involved in ammonia-oxidizing process, and may play significant role in the carbon and nitrogen cycles [24]


Profile Changes in the Soil Microbial Community When Desert Becomes Oasis.

Li CH, Tang LS, Jia ZJ, Li Y - PLoS ONE (2015)

Schematic diagram of the profile changes of dominated microbial community when desert becomes oasis at the southern periphery of the Gurbantonggut Desert.Actinobacteria = Act, Alphaproteobacteria = α-pr, Acidobacteria = Aci, Bacillales = Baci, Bacteroidetes = Bact, Betaproteobacteria = β-pr, Chloroflexi = Chl, Clostridiales = Clo, Crenarchaeota = Cre, Cyanobacteria = Cya, Deinococcus-Thermus = Dei, Deltaproteobacteria = δ-pr, Enterobacteriales = Ent, Gammaproteobacteria = γ-pr, Gemmatimonadetes = Gem, Firmicutes = Fir, Nitrospirae = Nit, Rhizobiales = Rhi, Rhodobaterales = Rh1, Rhodospirillales = Rh2, Sphingomonadales = Sph, Xanthomonadales = Xan.
© Copyright Policy
Related In: Results  -  Collection

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pone.0139626.g005: Schematic diagram of the profile changes of dominated microbial community when desert becomes oasis at the southern periphery of the Gurbantonggut Desert.Actinobacteria = Act, Alphaproteobacteria = α-pr, Acidobacteria = Aci, Bacillales = Baci, Bacteroidetes = Bact, Betaproteobacteria = β-pr, Chloroflexi = Chl, Clostridiales = Clo, Crenarchaeota = Cre, Cyanobacteria = Cya, Deinococcus-Thermus = Dei, Deltaproteobacteria = δ-pr, Enterobacteriales = Ent, Gammaproteobacteria = γ-pr, Gemmatimonadetes = Gem, Firmicutes = Fir, Nitrospirae = Nit, Rhizobiales = Rhi, Rhodobaterales = Rh1, Rhodospirillales = Rh2, Sphingomonadales = Sph, Xanthomonadales = Xan.
Mentions: The results in this study confirmed our basic hypothesis. It demonstrated that cultivation in the desert soil resulted in a strong shift in the microbial community structure throughout the soil profile (0–3 m) (Fig 5). The largest change in the overall microbial community was observed in the topsoil. While converting desert into oasis, the relative abundance of Cyanobacteria decreased from 25.4 to 2.5% on average, and that of Actinobacteria increased from 10.8 to 26.4% on average. The Cyanobacteria were therefore the most abundant group in desert topsoil and the Actinobacteria became the most abundant group in oasis topsoil (Fig 1). Cyanobacteria participate in both carbon and nitrogen fixation, and generally occur in harsh desert environments [31–32]. In addition to Cyanobacteria, other photosynthetic groups (e.g., the Rhizobiales, Sphingomonadales, and Rhodobaterales) were also present in lower proportions in the oasis (Table 2). Actinobacteria participate in the decomposition of lignin and chitin [33]. Wheat cover/ lack of light and return of wheat residues to the soil in the oasis may explain above-mentioned community shift. Meanwhile, there were also higher proportions of the Deinococcus-Thermus, α-proteobacteria, and Bacillales present in desert soil (Figs 1 and 2), all of which are extremophilic groups or antagonists, with a strong tolerance to desiccation, radiation, and high levels salinity [34]. The oasis soil had higher proportions of the R-strategy (e.g., γ-, β-proteobacteria), facultative vegetative (e.g., Rhodospirillales) and nitrifying bacteria (e.g., Nitrospirae) (Table 2 and Fig 2). Archaea occurred only in oasis soil. There is increasing evidence showing that archaea are involved in ammonia-oxidizing process, and may play significant role in the carbon and nitrogen cycles [24]

Bottom Line: To assess the effects of cultivation, the following treatments were compared with the virgin desert: CK (no fertilizer), PK, NK, NP, NPK, NPKR, and NPKM (R: straw residue; M: manure fertilizer).The proportions of extremophilic and photosynthetic groups (e.g., Deinococcus-Thermus and Cyanobacteria) decreased, while the proportions of R-strategy (e.g., Gammaproteobacteria including Xanthomonadales), nitrifying (e.g., Nitrospirae), and anaerobic bacteria (e.g., Anaerolineae) increased throughout the oasis profile.Furthermore, difference in fertilization and crop growth altered the organic carbon contents in the soil, which resulted in differences of microbial communities within oasis.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, China.

ABSTRACT
The conversion of virgin desert into oasis farmland creates two contrasting types of land-cover. During oasis formation with irrigation and fertilizer application, however, the changes in the soil microbial population, which play critical roles in the ecosystem, remain poorly understood. We applied high-throughput pyrosequencing to investigate bacterial and archaeal communities throughout the profile (0-3 m) in an experimental field, where irrigation and fertilization began in 1990 and cropped with winter wheat since then. To assess the effects of cultivation, the following treatments were compared with the virgin desert: CK (no fertilizer), PK, NK, NP, NPK, NPKR, and NPKM (R: straw residue; M: manure fertilizer). Irrigation had a greater impact on the overall microbial community than fertilizer application. The greatest impact occurred in topsoil (0-0.2 m), e.g., Cyanobacteria (25% total abundance) were most abundant in desert soil, while Actinobacteria (26%) were most abundant in oasis soil. The proportions of extremophilic and photosynthetic groups (e.g., Deinococcus-Thermus and Cyanobacteria) decreased, while the proportions of R-strategy (e.g., Gammaproteobacteria including Xanthomonadales), nitrifying (e.g., Nitrospirae), and anaerobic bacteria (e.g., Anaerolineae) increased throughout the oasis profile. Archaea occurred only in oasis soil. The impact of fertilizer application was mainly reflected in the non-dominant communities or finer taxonomic divisions. Oasis formation led to a dramatic shift in microbial community and enhanced soil enzyme activities. The rapidly increased soil moisture and decreased salt caused by irrigation were responsible for this shift. Furthermore, difference in fertilization and crop growth altered the organic carbon contents in the soil, which resulted in differences of microbial communities within oasis.

No MeSH data available.