Effects of land application of municipal biosolids on nitrogen-fixing bacteria in agricultural soil

2010 ◽  
Vol 46 (4) ◽  
pp. 407-413 ◽  
Author(s):  
Leigh M. Holt ◽  
Andrew E. Laursen ◽  
Lynda H. McCarthy ◽  
I. Vadim Bostan ◽  
Alison L. Spongberg
2021 ◽  
Author(s):  
Leigh Maxine Holt

The effects of municipal biosolids on nitrogen-fixing bacteria were assessed in a three month soil incubation study. Treatments included reference agricultural soils, soil amended with municipal biosolids or manure, and biosolids without soil. Nitrogen-fixation rates in reference and manure-amended soil were similar, and lower than in biosolids treatments; respiration rates showed similar trends. At test termination there was no difference between soil treatments for nitrogen-fixation, but some enhanced respiration in the biosolids-amended soils. Community structure was assessed using Biolog EcoPlates™ and denaturing gradient gel electrphoresis with a nitrogen-fixing gene (nifH). EcoPlate™ carbon utilization patterns corresponded with activity measures, with no difference among soil treatments at test termination. Nitrogen-fixing gene patterns showed a potential shift in community structure of biosolids-amended soils three months post-amendment. In general, the effects on the activity and structure of nitrogen-fixing communities were largely temporary; however, this study evaluated a one-time biosolids application. The potential for cumulative effects requires further investigation.


2021 ◽  
Author(s):  
Leigh Maxine Holt

The effects of municipal biosolids on nitrogen-fixing bacteria were assessed in a three month soil incubation study. Treatments included reference agricultural soils, soil amended with municipal biosolids or manure, and biosolids without soil. Nitrogen-fixation rates in reference and manure-amended soil were similar, and lower than in biosolids treatments; respiration rates showed similar trends. At test termination there was no difference between soil treatments for nitrogen-fixation, but some enhanced respiration in the biosolids-amended soils. Community structure was assessed using Biolog EcoPlates™ and denaturing gradient gel electrphoresis with a nitrogen-fixing gene (nifH). EcoPlate™ carbon utilization patterns corresponded with activity measures, with no difference among soil treatments at test termination. Nitrogen-fixing gene patterns showed a potential shift in community structure of biosolids-amended soils three months post-amendment. In general, the effects on the activity and structure of nitrogen-fixing communities were largely temporary; however, this study evaluated a one-time biosolids application. The potential for cumulative effects requires further investigation.


2014 ◽  
Vol 71 (3) ◽  
pp. 171-180 ◽  
Author(s):  
Bruno Lima Soares ◽  
Paulo Avelar Ademar Ferreira ◽  
Silvia Maria de Oliveira-Longatti ◽  
Leandro Marciano Marra ◽  
Marcia Rufini ◽  
...  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luz K. Medina-Cordoba ◽  
Aroon T. Chande ◽  
Lavanya Rishishwar ◽  
Leonard W. Mayer ◽  
Lina C. Valderrama-Aguirre ◽  
...  

AbstractPrevious studies have shown the sugarcane microbiome harbors diverse plant growth promoting microorganisms, including nitrogen-fixing bacteria (diazotrophs), which can serve as biofertilizers. The genomes of 22 diazotrophs from Colombian sugarcane fields were sequenced to investigate potential biofertilizers. A genome-enabled computational phenotyping approach was developed to prioritize sugarcane associated diazotrophs according to their potential as biofertilizers. This method selects isolates that have potential for nitrogen fixation and other plant growth promoting (PGP) phenotypes while showing low risk for virulence and antibiotic resistance. Intact nitrogenase (nif) genes and operons were found in 18 of the isolates. Isolates also encode phosphate solubilization and siderophore production operons, and other PGP genes. The majority of sugarcane isolates showed uniformly low predicted virulence and antibiotic resistance compared to clinical isolates. Six strains with the highest overall genotype scores were experimentally evaluated for nitrogen fixation, phosphate solubilization, and the production of siderophores, gibberellic acid, and indole acetic acid. Results from the biochemical assays were consistent and validated computational phenotype predictions. A genotypic and phenotypic threshold was observed that separated strains by their potential for PGP versus predicted pathogenicity. Our results indicate that computational phenotyping is a promising tool for the assessment of bacteria detected in agricultural ecosystems.


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