Soil organic matter decomposition/stabilization with relation to microbial community functioning in Arctic degraded permafrost soils

Muhammad WAQAS

Disertační práce

Abstract:

In the present work, I investigated the microbial community composition and their potential functional roles in soil organic matter (SOM) decomposition and stabilization under contrasting hydrological conditions in the active layer of degraded permafrost soils. In addition to community analyses, extracellular polymeric substances (EPS), soil physicochemical properties, and extracellular enzymatic activities were assessed to evaluate their contributions to SOC dynamics and soil aggregate formation. Microbial communities were further characterized across soil aggregate fractions to identify taxa preferentially inhabiting microaggregates and macroaggregates. Psychrotolerant EPS-producing bacterial strains were isolated from the active layer of dry and wet degraded sites as well as non-degraded intact permafrost sites, and their EPS yield and carbohydrate composition were determined to infer potential roles in aggregate formation and SOM protection. Together, these analyses provide insights into how microbial processes, EPS production, and hydrological regimes interact to shape SOC distribution, aggregate formation, and long-term stability in degraded permafrost landscapes.

Abstract:

In the present work, I investigated the microbial community composition and their potential functional roles in soil organic matter (SOM) decomposition and stabilization under contrasting hydrological conditions in the active layer of degraded permafrost soils. In addition to community analyses, extracellular polymeric substances (EPS), soil physicochemical properties, and extracellular enzymatic activities were assessed to evaluate their contributions to SOC dynamics and soil aggregate formation. Microbial communities were further characterized across soil aggregate fractions to identify taxa preferentially inhabiting microaggregates and macroaggregates. Psychrotolerant EPS-producing bacterial strains were isolated from the active layer of dry and wet degraded sites as well as non-degraded intact permafrost sites, and their EPS yield and carbohydrate composition were determined to infer potential roles in aggregate formation and SOM protection. Together, these analyses provide insights into how microbial processes, EPS production, and hydrological regimes interact to shape SOC distribution, aggregate formation, and long-term stability in degraded permafrost landscapes.

Keywords

Permafrost soils, Permafrost thaw, Microorganisms, Microbial decomposition, SOM stabilization, Extracellular Enzymes, Extracellular polymeric substances, Sequencing, Bacteria, Isolation ?

Jazyk práce: angličtina

Datum vytvoření / odevzdání či podání práce: 26. 3. 2026

Obhajoba závěrečné práce

• Vedoucí: doc. Ing. Jiří Bárta, Ph.D.

JIHOČESKÁ UNIVERZITA V ČESKÝCH BUDĚJOVICÍCH

Přírodovědecká fakulta

Doktorský studijní program / obor:
Ecosystem Biology and Ecology / Ecosystem Biology and Ecology