The arable ecosystem as battleground for emergence of new human pathogens

Abstract

Disease incidences related to Escherichia coli and Salmonella enterica infections by consumption of (fresh) vegetables, sprouts, and occasionally fruits made clear that these pathogens are not only transmitted to humans via the “classical” routes of meat, eggs, and dairy products, but also can be transmitted to humans via plants or products derived from plants. Nowadays, it is of major concern that these human pathogens, especially the ones belonging to the taxonomical family of Enterobacteriaceae, become adapted to environmental habitats without losing their virulence to humans. Adaptation to the plant environment would lead to longer persistence in plants, increasing their chances on transmission to humans via consumption of plant-derived food. One of the mechanisms of adaptation to the plant environment in human pathogens, proposed in this paper, is horizontal transfer of genes from different microbial communities present in the arable ecosystem, like the ones originating from soil, animal digestive track systems (manure), water and plants themselves. Genes that would confer better adaptation to the phytosphere might be genes involved in plant colonization, stress resistance and nutrient acquisition and utilization. Because human pathogenic enterics often were prone to genetic exchanges via phages and conjugative plasmids, it was postulated that these genetic elements may be hold key responsible for horizontal gene transfers between human pathogens and indigenous microbes in agroproduction systems. In analogy to zoonosis, we coin the term phytonosis for a human pathogen that is transmitted via plants and not exclusively via animals.

Interaction between Salmonella and Plants: Potential Hosts and Vectors for Human Infection

“…Sources of HPs in the production chain and factors contributing to the contamination of fruits and vegetables include for example the application of organic fertilizers such as animal manures, contaminated irrigation water, insect and animal vectors but also the use of contaminated seeds [7]. Enterobacteriaceae such as Erwinia, Serratia, and Pantoea belong to bacteria typically associated with the phyllosphere [8][9][10]. However, it is not completely understood how Salmonella persists in the plant environment and which environmental factors trigger its survival.…”

Robust cropping systems to tackle pests under climate change. A review

“…Horizontal gene transfer (Baltrus 2013) between species can easily occur in a joint habitat such as the soil/manure/plant-rhizosphere interphase, which might confer an enhanced fitness to bacteria to live on plant as well as human hosts. In analogy to zoonosis (bacteria transmitted from animal to human), this new class of plant bacteria is termed "phytonosis" (Van Overbeek et al 2014). One of the most important threats of phytonosic bacteria are acquired genes for antibiotic resistance (Lipsitch et al 2002), known for being abundantly present in the bacterial community of the plant rhizosphere.…”

Diversity and distribution of endophytic bacterial community in the Noni (Morinda citrifolia L.) plant

“…Microbes colonizing plant surfaces and interior areas are vital for plant health and productivity (Bonfante, 2010;Berendsen et al, 2012;Ferrara et al, 2012;Monteiro et al, 2012), but some of them could lead to disease development of plants (James and Olivares, 1998;Monteiro et al, 2012;Van Overbeek et al, 2014). Prior reports indicate that *Corresponding author.…”

“…Author(s) agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License plant microbiome could be beneficial for human health through consumption of raw plants (Blaser et al, 2013;Van Overbeek et al, 2014). Therefore, understanding the microbial composition of plants may assist in the development of sustainable agriculture (Berg, 2009;Lugtenberg and Kamilova, 2009).…”