Actinomycetes and antibiotics

Antibiotics have been used since the discovery of penicillin in 1929, generating a multibillion pound industry. They are the initial weapon to use against bacterial infections regardless of the rise of resistant bacterial strains developing rapidly. Since the discovery of Streptomycin in 1943, a range of antimicrobials have been made by the most prevalent soil bacteria to exist; actinomycetes of the Actinobacteria. Such antibiotics, discovered through whole cell screening include tetracycline, macrolides (erythromycin), streptomycin and cephalosporin.

There are many other genera of actinomycetes classified due to their roles occupied within nature such as the composition of their cell walls and their unique morphology consisting of branched microfilaments (mycelium) providing many roles; for instance, aiding in the decomposition or the Frankia family working symbiotically to assist nitrogen fixation. However, the full ecology of actinomycetes is unknown, therefore the reason for the production of antibiotics by actinomycetes is still in debate. It’s been suggested antibiotics are secreted to deter competitors for nutrients in soil. These microorganisms are able to produce highly versatile compounds that destroy pathogens in different ways without affecting host tissue. Most antibiotics are collected from natural bacterial production or through partially synthetic, imitated sources of actinomycetes.

More recent methods of introducing bacterial genomics, high throughput screening and combined chemistry are emerging in terms of discovering antibiotics but haven’t been successful. Future prospects for discovering novel actinomycetes antibiotics as well as trying to produce novel, lab synthesised antibiotics (Combinatorial Biosynthesis) will be delineated. In addition, the difficulties scientists have attempted to overcome in the hopes of discovering new antibiotics produced by actinomycetes by trying to filter and exclude common antibiotic compounds in soil to find the undiscovered, less frequent, novel antibiotic compounds is still ongoing due to the need to tackle the vast emergence of antibiotic resistant bacteria. Some efforts have been successful in the discovery of Marine actinomycetes as a source of new antimicrobial as actinomycetes consist of 10% of the bacteria that colonise marine sediments; novel metabolites such as Salinosporamide produced by the Verrucosispora strain isolated from Japan is an example of this.

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