Elena Radu, Markus Woegerbauer, Markus Oismüller, Norbert Kreuzinger
Antibiotics
Abstract:
Soil is considered to be the most diverse microbiological ecosystem on Earth.
Microbial soil biodiversity is substantially influenced by animal husbandry, intensive
agricultural practices and soil cultivation (tillage, crop rotation, irrigation, organic and
inorganic fertilization, application of pesticides etc.). Soil mismanagement represents
a worldwide topic that impairs natural ecosystem sustainability as a first consequence.
In order to understand and correctly apply soil management practices a deep insight
in ecological processes is necessary.
Soil microbiota have a great impact on both natural processes (biogeochemical cycles)
as well as various other aspects that could influence human health and the quality of
life (micro- or macro-contaminants, pharmaceuticals, fertilizers, phytosanitary
products). Pharmaceuticals, especially antibiotics are intensively used in animal
husbandry either as therapeutic agents or for prophylactic measures. Antibiotics of
microbial, semi-synthetic or synthetic origin impact the metabolism of bacteria: at
subinhibitory concentrations they act as hormetic intercellular messengers stimulating
gene expression. Higher amounts have bacteriostatic or bactericidal effects according to
their mode of action. Both result in a profound modulation of bacterial community
structure and biodiversity by boosting genotypic and phenotypic variability and
induction of antibiotic resistance. They also pose an indirect effect on the communities
(generating different genotypic and phenotypic variability such as antibiotic resistance).
Agricultural management practices like application of organic fertilizers (e.g. manure)
expose soil microbiota to a variety of hazardous agents of anthropogenic origin
including antibiotics, antibiotic resistant bacteria and antibiotic resistance genes which
interact with the indigenous soil resistome.
This paper describes the impact of human land-use, especially the ecological effects
of antibiotics on natural ecosystems and the increase of antibiotic resistance in soil
communities.