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Fate of gram-negative bacterial biomass in soil-mineralization and contribution to SOM [An article from: Soil Biology and Biochemistry]
Book Details
PublisherElsevier
ISBN / ASINB000PAA5OG
ISBN-13978B000PAA5O7
AvailabilityAvailable for download now
MarketplaceUnited States 🇺🇸
Description
This digital document is a journal article from Soil Biology and Biochemistry, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Soil microorganisms contribute to the formation of non-living soil organic matter (SOM) by metabolic transformation of plant-derived material. After cell death, their biomass components with a specific molecular character become incorporated into SOM imprinting its chemical properties, although this process has not yet been quantified. In order to elucidate the contribution to SOM formation, we investigated the fate of gram-negative bacterial model biomass (Escherichia coli usually introduced into soil with manure or feces) during incubation of soil with isotopically (^1^3C) and genetically (lux gene) labeled cells. The decline of living cells was monitored by the loss of bioluminescence. The carbon turnover and mineralization was balanced by bulk soil stable isotope analysis, and the persistence of nucleic acids was investigated by PCR amplification of the lux gene. During incubation, the number of viable E. coli cells decreased rapidly (99.9% within the first 42d) serving as substrate for other microorganisms or for the formation of SOM, and bioluminescent cells could only be detected during the first 56d. However, the lux gene was still detected after 224d, which indicates stabilization of DNA in SOM. Although the survival of E. coli in soil is limited, only about 65% of the added labeled biomass carbon was mineralized to ^1^3CO"2 and 51% remained in soil after 224d with an average ^1^3C recovery of 117%. The amount of ^1^3C found in the PLFA representative of living cells had decreased to 25% of the initial value, suggesting a proportional decrease of the ^1^3C in the soil microbial biomass. The extent of this decrease is higher than the mineralization of the bulk E. coli C and thus the difference of around 25% has to be stabilized as metabolites, or in non-living SOM. The data provide evidence that the genetic information and a considerable part of the carbon from dying bacterial biomass were retained in both the soil microbial food web and in non-living SOM.
Description:
Soil microorganisms contribute to the formation of non-living soil organic matter (SOM) by metabolic transformation of plant-derived material. After cell death, their biomass components with a specific molecular character become incorporated into SOM imprinting its chemical properties, although this process has not yet been quantified. In order to elucidate the contribution to SOM formation, we investigated the fate of gram-negative bacterial model biomass (Escherichia coli usually introduced into soil with manure or feces) during incubation of soil with isotopically (^1^3C) and genetically (lux gene) labeled cells. The decline of living cells was monitored by the loss of bioluminescence. The carbon turnover and mineralization was balanced by bulk soil stable isotope analysis, and the persistence of nucleic acids was investigated by PCR amplification of the lux gene. During incubation, the number of viable E. coli cells decreased rapidly (99.9% within the first 42d) serving as substrate for other microorganisms or for the formation of SOM, and bioluminescent cells could only be detected during the first 56d. However, the lux gene was still detected after 224d, which indicates stabilization of DNA in SOM. Although the survival of E. coli in soil is limited, only about 65% of the added labeled biomass carbon was mineralized to ^1^3CO"2 and 51% remained in soil after 224d with an average ^1^3C recovery of 117%. The amount of ^1^3C found in the PLFA representative of living cells had decreased to 25% of the initial value, suggesting a proportional decrease of the ^1^3C in the soil microbial biomass. The extent of this decrease is higher than the mineralization of the bulk E. coli C and thus the difference of around 25% has to be stabilized as metabolites, or in non-living SOM. The data provide evidence that the genetic information and a considerable part of the carbon from dying bacterial biomass were retained in both the soil microbial food web and in non-living SOM.
