Determinants of Soil Microbial Communities: Effects of Agricultural Management, Season, and Soil Type on Phospholipid Fatty Acid Profiles

Abstract BackgroundAn insight into the soil microbial functions and spatial distribution of soil resources is an important basis for evaluating and managing plant growth in subtropical forests. Soil samples were collected from five forest stands in Jinyun Mountain Natural Reserve (JMNR) in Chongqing located at the Three Gorges Reservoir area: Gordonia acuminata evergreen broad-leaved forest (GAEBF), Cunninghamia lanceolata forest (CLF), Phyllostachys pubescens forest (PPF), coniferous and broad-leaved mixed forest (CBLMF) dominated by Pinus massoniana and Gordonia acuminata (PM&GA), and the CBLMF dominated by Pinus massoniana and Symplocos setchuensis (PM&SS). Combined with phospholipid fatty acid (PLFA) analysis and Sherlock microbial identification system (MIS), the structure of soil microbial communities in different forest stands was investigated.ResultsThe results showed that the PLFAs of soil microorganisms under the forest in JMNR have a high diversity. The PLFA dominance values of the five stands were 16:0, 19:0 cyclo ω7c, 18:0, 15:0 iso and 16 :0 10-methyl. Furthermore, soil microorganisms are dominated by Gram-negative bacteria, and the PLFAs content of soil bacteria in different forest stands is higher than that of fungi PLFAs. Regarding the phospholipid fatty acid biomarkers, the two CBLMFs are the highest, followed by CLF and GAEBF and PPF is the least. Moreover, the proportion of microorganisms in the soil of different forest stands varies. Among them, MP&SS has the highest gram-negative bacteria, gram-positive bacteria, actinomycetes and fungi.ConclusionsRDA analysis shows that the main influencing factors of PLFAs in the soil of different forest stands are the content of iron oxide, aluminium oxide, organic matter and total nitrogen in the soil, which are considered to be able to reflect the soil nutrient status of JMNR effectively.

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Ester Linked Fatty Acid (ELFA) method should be used with caution for interpretating soil microbial communities and their relationships with environmental variables in forest soils

PLoS ONE ◽

10.1371/journal.pone.0251501 ◽

2021 ◽

Vol 16 (5) ◽

pp. e0251501

Author(s):

Wenjuan Yu ◽

Huanhuan Gao ◽

Hongzhang Kang

Keyword(s):

Fatty Acid ◽

Microbial Biomass ◽

Microbial Communities ◽

Forest Soils ◽

Environmental Variables ◽

Phospholipid Fatty Acid ◽

Soil Microbial Communities ◽

Environmental Drivers ◽

Soil Microbial ◽

Forest Sites

As an alternative for phospholipid fatty acid (PLFA) analysis, a simpler ester linked fatty acid (ELFA) analysis has been developed to characterize soil microbial communities. However, few studies have compared the two methods in forest soils where the contribution of nonmicrobial sources may be larger than that of microbial sources. Moreover, it remains unclear whether the two methods yield similar relationships of microbial biomass and composition with environmental variables. Here, we compared PLFA and ELFA methods with respect to microbial biomass and composition and their relationships with environmental variables in six oriental oak (Quercus variabilis) forest sites along a 1500-km latitudinal gradient in East China. We found that both methods had a low sample-to-sample variability and successfully separated overall community composition of sites. However, total, bacterial, and fungal biomass, the fungal-to-bacterial ratio, and the gram-positive to gram-negative bacteria ratio were not significantly or strongly correlated between the two methods. The relationships of these microbial properties with environmental variables (pH, precipitation, and clay) greatly differed between the two methods. Our study indicates that despite its simplicity, the ELFA method may not be as feasible as the PLFA method for investigating microbial biomass and composition and for identifying their dominant environmental drivers, at least in forest soils.

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