TY - JOUR TI - Modelling genomic and metabolic responses of microbial communities to antibiotics AU - Juhász, János AU - Ligeti, Balázs AU - Pongor, Sándor T2 - Jedlik Labor Rep AB - Multispecies bacterial communities can respond to antibiotic challenge both by genomic and by metabolic changes. Agent based modelling shows that in both cases, multiple antibiotic factors will be present in the community which will provide a kind of territorial defense, i.e. external bacteria will have difficulties invading the community.Multispecies bacterial communities, though not always visible to human eyes, represent the largest metabolic potential present in nature. They can be found as large microbial mats on the sea-floor, as gut microflora of warm blooded animals and humans, etc. They are also major contributors to nature?s evolution since they were the predominant life form before foraging animals appeared, and traces of these periods can be seen today as limestone layers of current mountain ranges are believed to be the calcified forms of such microbial mats. Today, of special, medical interest are the microbiota present in the human body and in the human environment, as the emergence of resistance due to the continuing massive application of antibiotic drugs is one of the key public health challenges. The current project was undertaken in order to get insights into the effects of antibiotics on the stability of microbial communities using computer modelling. Since this is a purely theoretical approach we use a generalized definition for antibiotic action, i.e. any molecule that negatively affects the growth of another bacterium is considered an ?antibiotic?. In other words, this definition also includes antimicrobials and bacteriostatic agents, not only lege artis antibiotics manufactured by the pharmaceutical industry. Second, we are using agent based models as the major modelling tools. In this representation, bacteria are the agents that carry out computations at given time steps. Third we are interested in two kinds of community responses. Evolutionary (or genetic) responses involve changes to the genome via horizontal gene transfer; bacteria acquire antibiotic production and resistance genes from the environment, which requires several generations. In contrast, metabolic responses are immediate, bacteria can turn on the production of, say, enzymes capable of digesting the antibiotics present in the environment thereby helping the survival of both themselves as well as other species present in the community. We showed that horizontal transfer of resistance genes may contribute to the formation of stable and diverse communities capable of protecting themselves with a battery of antimicrobial agents while preserving a varied metabolic repertoire. In other words horizontal transfer of resistance genes makes a community compatible in terms of exoproducts and fence off the attack of intruders that cannot adapt to all antimicrobials present within the community.Metabolic adaptation was modelled in the context of microbial communities that share the same secreted signals that turn on certain metabolic activities. Here we showed that differential signal-response thresholds provide a simple way for keeping slower-growing species within the community. High response thresholds can be considered as self-restraint of the faster growing species that allows metabolically useful but slower growing species to remain within a community, and thereby the metabolic repertoire of the community will be maintained. In a similar manner, antibiotic producing (ABP) strains can allow the growth of sensitive (ABS) species present in the same community provided they turn on antibiotic production at higher signal levels. As a result, two species producing antibiotics against each other can stably coexist within the same community. Consequently, such a community will produce a variety of antibiotics that makes it difficult for external species to colonize the community. DA - 2019/// PY - 2019 VL - Vii IS - 1 SP - 77 EP - 78 J2 - Jedlik Laboratories Reports SN - 2064-3942 UR - https://m2.mtmt.hu/api/publication/30762852 ER -