Viruses and bacteria have souls

How bacteria use viruses for themselves

MUNICH. Researchers from Munich gained new insights into the transmission mechanisms of antibiotic resistance between bacteria in experiments with fish. The mechanisms are more diverse than previously assumed, reports the Helmholtz Zentrum München.

For the study, researchers led by Professor Michael Schloter from the Helmholtz Center, together with researchers from the Universities of Copenhagen and Campinas in Brazil, examined fish of the South American species Piaractus mesopotamicus in an aquaculture.

The animals received the antibiotic flfenicol with their food for 34 days, during which and afterwards the scientists took samples from the digestive tract and looked for corresponding genetic changes in the bacteria resident there (Microbiome 2019; 7:24).

"As expected, the administration of the antibiotic led to an increase in the genes that are responsible for the corresponding resistances", Johan Sebastian Sáenz Medina is quoted in the communication, first author and doctoral student in Munich. "One example are genes for pump proteins that simply transport the active ingredient back out of the bacteria."

Mobile genetic elements

"What was particularly interesting for us, however, was the increasing number of mobile genetic elements in the vicinity of these resistance genes," adds Sáenz Medina. "This suggested that the bacteria also exchange resistance through viruses."

Further metagenomic studies confirmed that these mobile genetic elements jump right across the genome, carrying away parts of the genome - including the resistance genes - and reinserting them elsewhere, according to the center's announcement. So far it has been assumed that mainly plasmids are responsible for the exchange of resistance genes.

"The realization that the resistances are also transmitted to a large extent between bacteria apart from plasmids is quite surprising," says Schloter, classifying the study. “Based on this, appropriate dispersion models should be checked and adapted. In addition, our data make you think about whether and to what extent one should operate the increasing number of aquacultures with antibiotics worldwide. " (eb)