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Soil microbial invasions

Patterns, mechanisms, and impacts garnered from observations of Escherichia coli invasions into soil
PhD ceremony:C.A. (Cyrus) Mallon, BSc
When:June 29, 2015
Supervisors:prof. dr. J. (Joana) Falcao Salles, prof. dr. ir. J.D. (Jan Dirk) van Elsas
Where:Academy building RUG
Faculty:Science and Engineering
Soil microbial invasions

By using a model invasion system whereby Escherichia coli, the invader bacterium, is invaded into soil samples, Cyrus Mallon found that the biological diversity of the soil microbial community plays a major role in determining the invader’s fate.

Microbial invasions come in many forms. They could manifest as infections we catch, probiotics we take, or natural expansions of microbes past their native territories. The patterns, process, and mechanisms controlling such invasions have until only recently remained elusive. In his thesis Mallon examined each of these aspects through synthesizing the most recent advances in microbial invasions, and this fusion serves as a foundation that drives his further questioning and experimentation. When the diversity of the soil microbial community is high, invasion is low—and when the diversity of the soil microbial community is low, invasion is high. Further experimentation indicates that more diverse communities use more of the soil’s resources than less diverse communities. This leaves little sustenance available for any invader, making the chance of a successful invasion slim. Yet, even when invasions are not successful, the mere attempt will impact the soil microbial community, causing the population size of some individuals to decrease and others to increase. This observation underscores the dynamic nature and complexity of microbial invasions. By applying the principles that diversity and resource availability determines an invader’s success, there is a promising avenue to improve the efficiency of many practical applications where microbial invasions must be controlled and calculated, such as biocontrol agents, biofertalizers, and probiotic treatments.