Chemical ecology of antibiotic production by actinomycetes

Abstract

Actinomycetes are a diverse family of filamentous bacteria that produce a plethora of natural products relevant for agriculture, biotechnology and medicine, including the majority of the antibiotics we use in the clinic. Rather than as free-living bacteria, many actinomycetes have evolved to live in symbiosis with among others plants, fungi, insects and sponges. As a common theme, these organisms profit from the natural products and enzymes produced by the actinomycetes, for example, for protection against pathogenic microbes, for growth promotion or for the degradation of complex natural polymers such as lignocellulose. At the same time, the actinomycetes benefit from the resources of the hosts they interact with. Evidence is accumulating that these interactions control the expression of biosynthetic gene clusters and have played a major role in the evolution of the high chemical diversity of actinomycete-produced secondary metabolites. Many of the biosynthetic gene clusters for antibiotics are poorly expressed under laboratory conditions, but they are likely expressed in response to host-specific demands. Here, we review the environmental triggers and cues that control natural product formation by actinomycetes and provide pointers as to how these insights may be harnessed for drug discovery.

Plant growth promotion and chilli anthracnose disease suppression ability of rhizosphere soil actinobacteria

“…Many of the biosynthetic gene clusters for antibiotics are poorly expressed under laboratory conditions, but they are likely expressed in response to host or habitat specific demands (Van der Meij et al . ). In the present study, a minimum quantity of fungal spores added to actinobacterial mass culturing media served an agent of biosynthetic induction.…”

A heme‐binding protein produced by Haemophilus haemolyticus inhibits non‐typeable Haemophilus influenzae

“…The intrinsic heterogeneity of NTHi has hampered vaccine development, and despite significant effort, an effective vaccine is not currently available (Cerquetti & Giufre, 2016). There has been an increase in both the incidence and spectrum of antimicrobial resistance in NTHi (Tristram, Jacobs, & Appelbaum, 2007) Antibiotics typically target a broad spectrum of organisms and function in a wide range of ecological settings (van der Meij, Worsley, Hutchings, & Wezel, 2017). In addition, many bacteria produce bacteriocins, which are strain-specific toxins that target bacterial neighbours competing for the same ecological niche (interference competition), or sequester nutrients to gain a growth advantage (exploitative competition) (Ghoul & Mitri, 2016).…”

Antibiotic production is organized by a division of labour inStreptomyces

“…non-ribosomal peptide or polyketide synthases, are likely to be highest at the initiation of antibiotic production but diminish thereafter, meaning that producing cells become more efficient at making antibiotics through time 11 ; furthermore, we show that antibiotic production trades-off with reproduction. Finally, many antibiotics are secreted, so the entire colony, but not susceptible competitors, can benefit from the protection they provide 44 .…”