Current understandings of colibactin regulation.

The biosynthetic machinery for the production of colibactin is encoded by 19 genes (clbA - S) within the pks pathogenicity island harboured by many E. coli of the B2-phylogroup. Colibactin is a potent genotoxic metabolite which causes DNA-damage and which has potential roles in microbial competition and fitness of pks+ bacteria. Colibactin has also been strongly implicated in the development of colorectal cancer. Given the genotoxicity of colibactin and the metabolic cost of its synthesis, the regulatory system governing the clb cluster is accordingly highly complex, and many of the mechanisms remain to be elucidated. In this review we summarise the current understanding of regulation of colibactin biosynthesis by internal molecular components and how these factors are modulated by signals from the external environment.

ActinoBase: tools and protocols for researchers working on Streptomyces and other filamentous actinobacteria.

Actinobacteria is an ancient phylum of Gram-positive bacteria with a characteristic high GC content to their DNA. The ActinoBase Wiki is focused on the filamentous actinobacteria, such as Streptomyces species, and the techniques and growth conditions used to study them. These organisms are studied because of their complex developmental life cycles and diverse specialised metabolism which produces many of the antibiotics currently used in the clinic. ActinoBase is a community effort that provides valuable and freely accessible resources, including protocols and practical information about filamentous actinobacteria. It is aimed at enabling knowledge exchange between members of the international research community working with these fascinating bacteria. ActinoBase is an anchor platform that underpins worldwide efforts to understand the ecology, biology and metabolic potential of these organisms. There are two key differences that set ActinoBase apart from other Wiki-based platforms: [1] ActinoBase is specifically aimed at researchers working on filamentous actinobacteria and is tailored to help users overcome challenges working with these bacteria and [2] it provides a freely accessible resource with global networking opportunities for researchers with a broad range of experience in this field.

Advances in actinomycete research: an ActinoBase review of 2019.

The actinomycetes are Gram-positive bacteria belonging to the order Actinomycetales within the phylum Actinobacteria. They include members with significant economic and medical importance, for example filamentous actinomycetes such as Streptomyces species, which have a propensity to produce a plethora of bioactive secondary metabolites and form symbioses with higher organisms, such as plants and insects. Studying these bacteria is challenging, but also fascinating and very rewarding. As a Microbiology Society initiative, members of the actinomycete research community have been developing a Wikipedia-style resource, called ActinoBase, the purpose of which is to aid in the study of these filamentous bacteria. This review will highlight 10 publications from 2019 that have been of special interest to the ActinoBase community, covering 4 major components of actinomycete research: (i) development and regulation; (ii) specialized metabolites; (iii) ecology and host interactions; and (iv) technology and methodology.

Rapid antibiotic susceptibility testing using low-cost, commercially available screen-printed electrodes.

Antimicrobial resistance (AMR) is an issue of upmost global importance, with an annually increasing mortality rate and growing economic burden. Poor antimicrobial stewardship has resulted in an abundance and diverse range of antimicrobial resistance mechanisms. To tackle AMR effectively, better diagnostic tests must be developed in order to improve antibiotic stewardship and reduce the emergence of antibiotic resistant organisms. This study employs a low-cost, commercially available screen printed electrode modified with an agarose-based hydrogel deposit to monitor bacterial growth using the techniques of electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) giving rise to a new approach to measuring susceptibility. Susceptible and drug resistant Staphylococcus aureus strains were deposited onto agarose gel modified electrodes which contained clinically important antibiotics to establish growth profiles for each bacterial strain and monitor the influence of the antibiotic on bacterial growth. The results show that S. aureus is able to grow on electrodes modified with gel containing no antibiotic, but is inhibited when the gel modified electrode is seeded with antibiotic. Conversely, methicillin-resistant S. aureus (MRSA; the drug resistant strain) is able to grow on gel modified electrodes containing clinically relevant concentrations of antibiotic. Results show rapid growth profiles, with possible time to results for antibiotic susceptibility <45 min, a significant improvement on the current gold standards of at least 1-2 days.