Viral, bacterial, fungal and protozoal biology is of cardinal importance for the evolutionary history of life, ecology, biotechnology and infectious diseases. Various microbiological model systems have fundamentally contributed to the understanding of molecular and cellular processes, including the cell cycle, cell death, mitochondrial biogenesis, vesicular fusion and autophagy, among many others. Microbial interactions within the environment have profound effects on many fields of biology, from ecological diversity to the highly complex and multifaceted impact of the microbiome on human health. Also, biotechnological innovation and corresponding industrial operations strongly depend on microbial engineering. With this wide range of impact in mind, the peer-reviewed and open access journal Microbial Cell was founded in 2014 and celebrates its 100^th issue this month. Here, we briefly summarize how the vast diversity of microbiological subjects influences our personal and societal lives and shortly review the milestones achieved by Microbial Cell during the last years.

The budding yeast Saccharomyces cerevisiae has long been an outstanding platform for understanding the biology of eukaryotic cells. Robust genetics, cell biology, molecular biology, and biochemistry complement deep and detailed genome annotation, a multitude of genome-scale strain collections for functional genomics, and substantial gene conservation with Metazoa to comprise a powerful model for modern biological research. Recently, the yeast model has demonstrated its utility in a perhaps unexpected area, that of eukaryotic virology. Here we discuss three innovative applications of the yeast model system to reveal functions and investigate variants of proteins encoded by the SARS-CoV-2 virus.

Not all treasure is silver and gold; for pathogenic bacteria, iron is the most precious and the most pillaged of metallic elements. Iron is essential for the survival and growth of all life; however free iron is scarce for bacteria inside human hosts. As a mechanism of defence, humans have evolved ways to store iron so as to render it inaccessible for invading pathogens, such as keeping the metal bound to iron-carrying proteins. For bacteria to survive within humans, they must therefore evolve counters to this defence to compete with these proteins for iron binding, or directly steal iron from them. The most populous form of iron in humans is haem: a functionally significant coordination complex that is central to oxygen transport and predominantly bound by haemoglobin. Haemoglobin is therefore the largest source of iron in humans and, as a result, bacterial pathogens in critical need of iron have evolved complex and creative ways to acquire haem from haemoglobin. Bacteria of all cell wall types have the ability to bind haemoglobin at their cell surface, to accept the haem from it and transport this to the cytoplasm for downstream uses. This review describes the systems employed by various pathogenic bacteria to utilise haemoglobin as an iron source within human hosts and discusses their contribution to virulence.