On the possible ecological roles of antimicrobials

Abstract

The Introduction of antibiotics into the clinical use in the middle of the 20th century had a profound impact on modern medicine and human wellbeing. The contribution of these wonder molecules to public health and science is hard to overestimate. Much research has informed our understanding of antibiotic mechanisms of action and resistance at inhibitory concentrations in the lab and in the clinic. Antibiotics, however, are not a human invention as most of them are either natural products produced by soil microorganisms or semisynthetic derivatives of natural products. Because we use antibiotics to inhibit the bacterial growth, it is generally assumed that growth inhibition is also their primary ecological function in the environment. Nevertheless, multiple studies point to diverse nonlethal effects that are exhibited at lower levels of antibiotics. Here we review accumulating evidence of antibiosis and of alternative functions of antibiotics exhibited at subinhibitory concentrations. We also speculate on how these effects might alter phenotypes, fitness, and community composition of microbes in the context of the environment and suggest directions for future research.

Accumulation of dead cells from contact killing facilitates coexistence in bacterial biofilms

“…These results suggest that the T6SS, and perhaps other contact killing 344 mechanisms, may not prompt a microbial 'arms race,' but instead may stabilize diverse 345 communities. Further, these results align with recent works which question the 346 ecological purpose of bacterial production of antibiotics [74,80]. Nevertheless, the fact 347 that contact killing facilitates coexistence suggests that the impact of the T6SS in 348 bacterial consortia is complex, and the T6SS is more than simply a potent weapon.…”

“…The interface between domains 79 of killer and target cells in fluorescence images (Fig. 2a, bottom image) aligns with dark 80 outlines that are visible in images taken in bright-field mode ( Fig. 2a, top image).…”

Synergistic bactericidal profiling of prodigiosin extracted from Serratia marcescens in combination with antibiotics against pathogenic bacteria

“…Most clinically used antibiotics, to date, are either microbial natural metabolites or semisynthetic derivatives of these molecules [ 15 ]. However, the conventional antibiotics are lately failing in their efficacy towards the MDR pathogens.…”

A fungal scent from the cheese

“…Microbes can inhibit the growth of each other by producing specific or general antimicrobial compounds, and they can gain by acquiring beneficial metabolites secreted by surrounding companions, in specific cases resulting in complex cross‐feeding networks (D'Souza et al ., 2018). In addition, the secreted primary‐ and secondary‐metabolites could convey signalling function that affect development of other microbes (Pishchany and Kolter, 2020). To gain deeper understanding how the ‘environment selects’, simplified microbial systems are inspected ranging from two or very few members to complex communities.…”