Influence of crop species and weed seedbank density on extracellular DNA degradation, bacterial community structure and functional capabilities in agricultural soils in Manitoba, Canada
| dc.contributor.author | Kamino, Leila | |
| dc.contributor.examiningcommittee | Entz, Martin (Plant Science) | |
| dc.contributor.examiningcommittee | Tenuta, Mario (Soil Science) | |
| dc.contributor.examiningcommittee | Dunfield, Kari (University of Guelph) | |
| dc.contributor.supervisor | Gulden, Rob | |
| dc.date.accessioned | 2024-01-12T21:40:08Z | |
| dc.date.available | 2024-01-12T21:40:08Z | |
| dc.date.issued | 2024-01-01 | |
| dc.date.submitted | 2024-01-02T05:20:06Z | en_US |
| dc.degree.discipline | Plant Science | en_US |
| dc.degree.level | Doctor of Philosophy (Ph.D.) | |
| dc.description.abstract | Nucleic acids are abundant in terrestrial ecosystems and are degraded by DNases, mostly from microbial origin, contributing significant quantities of carbon (C), nitrogen (N) and phosphorus (P), which enter their respective nutrient cycles. However, the impact of agronomic management practices on this important soil function and the bacterial community involved has received little attention. This thesis research consisted of an indoor and a long-term field study used to determine the responsiveness of extracellular DNA (exDNA) degradation, extracellular DNase (exDNase) producing bacteria, bacterial diversity, community composition, and functional capabilities as influenced by crop species and weed seedbank density levels in agricultural soils. A high-throughput DNA methyl green (DNA-MG) spectrophotometric assay was developed and successfully adopted for estimating instantaneous exDNA degradation potential in soils. Potential DNase activity in soils was best estimated using soil leachates, and the assay was observed to be stable over a wide range of temperatures. The assay is simple, affordable, and rapid means to estimate potential DNase activity of soils. The assay demonstrated that crop species, crop developmental stages and soil properties influenced instantaneous exDNA degradation potential in agricultural bulk soils, while weed seedbank density did not have a significant effect on this soil function. Moreover, crop species, crop developmental stages, and soil type greatly shaped the populations of culturable exDNase-producing bacteria inhabiting agricultural soils. Several key exDNase-producing bacteria were identified and were dominated by Bacillota (Firmicutes) and Actinobacteria at the phyla level and the Bacillus genera group. The Proteobacteria and Actinobacteria phyla groups dominated the bacterial species in bulk soils from the field study and those positively associated with instantaneous exDNA degradation potential. The chemical fallow and prairie treatments had distinct bacterial community structures and functional groups from each other and also from the annual crop species. Finally, putative nucleotide metabolism-related genes were better predictors of instantaneous exDNA degradation potential compared with bacterial species. Additionally, the current research showed that the presence of plants significantly reduced instantaneous exDNA degradation potential in agricultural soils. In conclusion, this study provides new insights into the cycle of exDNA degradation by enzymatic restriction in agricultural soils, and how management practices contribute to shaping soil bacterial community and functions. | |
| dc.description.note | February 2024 | |
| dc.identifier.uri | http://hdl.handle.net/1993/37982 | |
| dc.language.iso | eng | |
| dc.rights | open access | en_US |
| dc.subject | Extracellular DNA | |
| dc.subject | Extracellular DNases | |
| dc.subject | DNA producing bacteria | |
| dc.subject | Instanteneous DNA degradation potential | |
| dc.subject | DNA-MG spectrophotometric assay | |
| dc.title | Influence of crop species and weed seedbank density on extracellular DNA degradation, bacterial community structure and functional capabilities in agricultural soils in Manitoba, Canada | |
| dc.type | doctoral thesis | en_US |
| local.subject.manitoba | yes | |
| oaire.awardNumber | 356362-2010 | |
| project.funder.identifier | https://doi.org/10.13039/501100000038 | |
| project.funder.name | NSERC |