Methanol is an abundant atmospheric volatile organic compound that is released from both living and decaying plant material. In forest and other aerated soils, methanol can be consumed by methanol-utilizing microorganisms that constitute a known terrestrial sink. However, the environmental factors that drive the biodiversity of such methanol-utilizers have been hardly resolved. Soil-derived iso...

The ecological significance of rare microorganisms within microbial communities remains an important, unanswered question. Microorganisms of extremely low abundance (the 'rare biosphere') are believed to be largely inaccessible and unknown. To understand the structure of complex environmental microbial communities, including the representation of rare and prevalent community members, we coupled...

Plant-associated microbial diversity encompasses symbionts, protecting their host against various aggressions. Mycorrhizal and rhizospheric microorganisms buffer effects of soil toxic compounds and soil-borne pathogens. Endophytic bacteria and fungi, some of which are vertically inherited through seeds, take part in plant protection by acting directly on aggressive factors (mainly pathogens and...

Higher plant diversity is often associated with higher soil microbial biomass and diversity, which is assumed to be partly due to elevated root exudate diversity. However, there is little experimental evidence that diversity of root exudates shapes soil microbial communities. We tested whether higher root exudate diversity enhances soil microbial biomass and diversity in a plant diversity gradi...

BREED, R. S., MURRAY, E. G. D., AND HITCHENS, A. P. 1948 Bergey's manual of determinative bacteriology. 6th ed. The Williams & Wilkins Co., Baltimore, Md. FRED, E. B., AND WAKSMAN, S. A. 1928 Laboratory manual of general microbiology. McGraw-Hill Book Co., Inc. New York. HOOVER, MINTON E. 1952 The action of some herbicides upon the microflora of the soil. M. S. Thesis, Louisiana State Universit...

Soil, the living terrestrial skin of the Earth, plays a central role in supporting life and is home to an unimaginable diversity of microorganisms. This review explores key drivers for microbial life in soils under different climates and land-use practices at scales ranging from soil pores to landscapes. We delineate special features of soil as a microbial habitat (focusing on bacteria) and the...

Introduction Soil organisms facilitate key ecosystem processes such as nutrient cycling and organic matter decomposition, and also influence soil porosity and water infiltration through the production of bacterial polymers and fungal hyphae that hold soil particles together to form aggregates [1, 2]. Rhizosphere microorganisms can greatly influence the ability of a plant to acquire macroand mic...

List of Abbreviations CIIAPTER ONE General Introduction Pollution of Saudi Arabian soil with crude oil Chemistry and biodegradability of petroleum hydrocarbon Environmental fate of petroleum Factors influencing petroleum hydrocarbon biodegradation Distribution of petroleum-utilizing microorganisms in the environment Biological degradation of petroleum hydrocarbon Bacterial degradation of oil Fu...

Using a network representation for real soil samples and mathematical models for microbial spread, we show that the structural heterogeneity of the soil habitat may have a very significant influence on the size of microbial invasions of the soil pore space. In particular, neglecting the soil structural heterogeneity may lead to a substantial underestimation of microbial invasion. Such effects a...