Exploring the microbial savanna: predator-prey interactions in the soil.

Soils host complex multi-trophic communities with diverse, mostly microbial, predator and prey species, including numerous bacterivorous protists and bacterial prey. The molecular mechanisms underlying microbial predator-prey interactions have thus far mainly been explored using reductionist methods, outside the soil environment and independent from the broader life history strategies that microbes display in soils. In this Comment, we advocate for an integrative research approach, combining molecular systems biology and microbial ecology, to investigate how predator-prey interactions shape microbial life history strategies and thereby population dynamics in natural soil communities.

Pleiotropic hubs drive bacterial surface competition through parallel changes in colony composition and expansion.

Bacteria commonly adhere to surfaces where they compete for both space and resources. Despite the importance of surface growth, it remains largely elusive how bacteria evolve on surfaces. We previously performed an evolution experiment where we evolved distinct Bacilli populations under a selective regime that favored colony spreading.

Complex extracellular biology drives surface competition during colony expansion in Bacillus subtilis.

Many bacteria grow on surfaces in nature, where they form cell collectives that compete for space. Within these collectives, cells often secrete molecules that benefit surface spreading by, for example, reducing surface tension or promoting filamentous growth. Although we have a detailed understanding of how these molecules are produced, much remains unknown about their role in surface competition.

Computational pipeline for designing guide RNAs for mismatch-CRISPRi.

CRISPR interference is an increasingly popular method for perturbing gene expression. Guided by single-guide RNAs (sgRNAs), nuclease-deficient Cas9 proteins bind to specific DNA sequences and hinder transcription. Specificity is achieved through complementarity of the sgRNAs to the DNA.

Cryptic surface-associated multicellularity emerges through cell adhesion and its regulation.

The repeated evolution of multicellularity led to a wide diversity of organisms, many of which are sessile, including land plants, many fungi, and colonial animals. Sessile organisms adhere to a surface for most of their lives, where they grow and compete for space. Despite the prevalence of surface-associated multicellularity, little is known about its evolutionary origin.

Short-range quorum sensing controls horizontal gene transfer at micron scale in bacterial communities.

In bacterial communities, cells often communicate by the release and detection of small diffusible molecules, a process termed quorum-sensing. Signal molecules are thought to broadly diffuse in space; however, they often regulate traits such as conjugative transfer that strictly depend on the local community composition. This raises the question how nearby cells within the community can be detected.

A riboswitch gives rise to multi-generational phenotypic heterogeneity in an auxotrophic bacterium.

Auxotrophy, the inability to produce an organic compound essential for growth, is widespread among bacteria. Auxotrophic bacteria rely on transporters to acquire these compounds from their environment. Here, we study the expression of both low- and high-affinity transporters of the costly amino acid methionine in an auxotrophic lactic acid bacterium, Lactococcus lactis.

Microbial life cycles link global modularity in regulation to mosaic evolution.

Microbes are exposed to changing environments, to which they can respond by adopting various lifestyles such as swimming, colony formation or dormancy. These lifestyles are often studied in isolation, thereby giving a fragmented view of the life cycle as a whole. Here, we study lifestyles in the context of this whole.

Emergence of diverse life cycles and life histories at the origin of multicellularity.

The evolution of multicellularity has given rise to a remarkable diversity of multicellular life cycles and life histories. Whereas some multicellular organisms are long-lived, grow through cell division, and repeatedly release single-celled propagules (for example, animals), others are short-lived, form by aggregation, and propagate only once, by generating large numbers of solitary cells (for example, cellular slime moulds). There are no systematic studies that explore how diverse multicellular life cycles can come about.

When We Stop Thinking about Microbes as Cells.

Microbes are often thought of as individual cells. However, in their natural habitats, they typically exist in the context of other cells, be they of the same or different species. How these cells interact in space and time is key to their ecology and evolution.

PolyGlcNAc-containing exopolymers enable surface penetration by non-motile Enterococcus faecalis.

Bacterial pathogens have evolved strategies that enable them to invade tissues and spread within the host. Enterococcus faecalis is a leading cause of local and disseminated multidrug-resistant hospital infections, but the molecular mechanisms used by this non-motile bacterium to penetrate surfaces and translocate through tissues remain largely unexplored. Here we present experimental evidence indicating that E.

On the origin of biological construction, with a focus on multicellularity.

Biology is marked by a hierarchical organization: all life consists of cells; in some cases, these cells assemble into groups, such as endosymbionts or multicellular organisms; in turn, multicellular organisms sometimes assemble into yet other groups, such as primate societies or ant colonies. The construction of new organizational layers results from hierarchical evolutionary transitions, in which biological units (e.g.

Regulatory mechanisms link phenotypic plasticity to evolvability.

Organisms have a remarkable capacity to respond to environmental change. They can either respond directly, by means of phenotypic plasticity, or they can slowly adapt through evolution. Yet, how phenotypic plasticity links to evolutionary adaptability is largely unknown.

Phenotypic Heterogeneity and the Evolution of Bacterial Life Cycles.

Most bacteria live in colonies, where they often express different cell types. The ecological significance of these cell types and their evolutionary origin are often unknown. Here, we study the evolution of cell differentiation in the context of surface colonization.

Division of Labor in Biofilms: the Ecology of Cell Differentiation.

The dense aggregation of cells on a surface, as seen in biofilms, inevitably results in both environmental and cellular heterogeneity. For example, nutrient gradients can trigger cells to differentiate into various phenotypic states. Not only do cells adapt physiologically to the local environmental conditions, but they also differentiate into cell types that interact with each other.

From cell differentiation to cell collectives: Bacillus subtilis uses division of labor to migrate.

The organization of cells, emerging from cell-cell interactions, can give rise to collective properties. These properties are adaptive when together cells can face environmental challenges that they separately cannot. One particular challenge that is important for microorganisms is migration.

New tools for comparing microscopy images: quantitative analysis of cell types in Bacillus subtilis.

Fluorescence microscopy is a method commonly used to examine individual differences between bacterial cells, yet many studies still lack a quantitative analysis of fluorescence microscopy data. Here we introduce some simple tools that microbiologists can use to analyze and compare their microscopy images. We show how image data can be converted to distribution data.

Bet-hedging during bacterial diauxic shift.

When bacteria grow in a medium with two sugars, they first use the preferred sugar and only then start metabolizing the second one. After the first exponential growth phase, a short lag phase of nongrowth is observed, a period called the diauxie lag phase. It is commonly seen as a phase in which the bacteria prepare themselves to use the second sugar.

Density of founder cells affects spatial pattern formation and cooperation in Bacillus subtilis biofilms.

In nature, most bacteria live in surface-attached sedentary communities known as biofilms. Biofilms are often studied with respect to bacterial interactions. Many cells inhabiting biofilms are assumed to express 'cooperative traits', like the secretion of extracellular polysaccharides (EPS).

The evolution of cell-to-cell communication in a sporulating bacterium.

Traditionally microorganisms were considered to be autonomous organisms that could be studied in isolation. However, over the last decades cell-to-cell communication has been found to be ubiquitous. By secreting molecular signals in the extracellular environment microorganisms can indirectly assess the cell density and respond in accordance.

The protective layer of biofilm: a repellent function for a new class of amphiphilic proteins.

Bacteria can survive harsh conditions when growing in complex communities of cells known as biofilms. The matrix of the biofilm presents a scaffold where cells are attached to each other and to the surface. The biofilm matrix is also a protective barrier that confers tolerance against various antimicrobial agents.