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Streptomyces are a large genus of multicellular bacteria best known for their prolific production of bioactive natural products. In addition, they play key roles in the mineralisation of insoluble resources, such as chitin and cellulose. Because of their multicellular mode of growth, colonies of interconnected hyphae extend over a large area that may experience different conditions in different parts of the colony. Here, we argue that within-colony phenotypic heterogeneity can allow colonies to simultaneously respond to divergent inputs from resources or competitors that are spatially and temporally dynamic. We discuss causal drivers of heterogeneity, including competitors, precursor availability, metabolic diversity and division of labour, that facilitate divergent phenotypes within Streptomyces colonies. We discuss the adaptive causes and consequences of within-colony heterogeneity, highlight current knowledge (gaps) and outline key questions for future studies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Producing specialised metabolites such as antibiotics, immunosuppressives, anti-cancer agents and anti-helminthics draws on primary metabolism to provide the building blocks for biosynthesis. The growth phase-dependent nature of production means that producing organisms must deal with the metabolic conflicts of declining growth rate, reduced nutrient availability, specialised metabolite production and potentially morphological development. In recent years, our understanding of gene expansion events, integration of metabolic function and gene regulation events that facilitate the sensing and responding to metabolite concentrations has grown, but new data are constantly expanding our horizons. This review highlights the role evolutionary gene or pathway expansion plays in primary metabolism and examine the adoption of enzymes for specialised metabolism. We also look at recent insights into sensing and responding to metabolites., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Most bacteria encode proteins for defence against infection by bacteriophages. The mechanisms that bring about phage defence are extremely diverse, suggesting frequent independent evolution of novel processes. Phage defence determinants are often plasmid or phage-encoded and many that are chromosomal show evidence of lateral transfer. Recent studies on restriction-modification (R-M) systems show that these genes are amongst the most rapidly evolving. Some bacteria have contingency genes that encode alternative target specificity determinants for Type I or Type III R-M systems, thus expanding the range of phages against which the host population is immune. The most counter-intuitive observation, however, is the prevalence of phase variation in many restriction systems, but recent arguments suggest that switching off expression of R-M systems can aid phage defence.