Using multigenerational, single-cell tracking we explore the earliest events of biofilm formation by Pseudomonas aeruginosa. During initial stages of surface engagement (≤20 h), the surface cell population of this microbe comprises overwhelmingly cells that attach poorly (∼95% stay <30 s, well below the ∼1-h division time) with little increase in surface population. If we harvest cells previously exposed to a surface and direct them to a virgin surface, we find that these surface-exposed cells and their descendants attach strongly and then rapidly increase the surface cell population. This “adaptive,” time-delayed adhesion requires determinants we showed previously are critical for surface sensing: type IV pili (TFP) and cAMP signaling via the Pil-Chp-TFP system. We show that these surface-adapted cells exhibit damped, coupled out-of-phase oscillations of intracellular cAMP levels and associated TFP activity that persist for multiple generations, whereas surface-naïve cells show uncorrelated cAMP and TFP activity. These correlated cAMP–TFP oscillations, which effectively impart intergenerational memory to cells in a lineage, can be understood in terms of a Turing stochastic model based on the Pil-Chp-TFP framework. Importantly, these cAMP–TFP oscillations create a state characterized by a suppression of TFP motility coordinated across entire lineages and lead to a drastic increase in the number of surface-associated cells with near-zero translational motion. The appearance of this surface-adapted state, which can serve to define the historical classification of “irreversibly attached” cells, correlates with family tree architectures that facilitate exponential increases in surface cell populations necessary for biofilm formation. Significance Bacteria use multigenerational memory based on coupled oscillations of cAMP levels and type IV pili (TFP) activity to adaptively adhere to surfaces. These oscillations create cells with a “surface-sentient” state intermediate between planktonic and sessile, characterized by coordinated surface motility suppression. This intermediate state drastically increases the number of surface nonmotile cells and correlates with a transition in family tree architectures toward exponential surface population growth. Our data support the idea that reversible attachment is vital for irreversible attachment. That is, repeated sensing, division, and detachment cycles create a planktonic population with robust cAMP–TFP-based memory of the surface, allowing cells to return to the surface progressively better adapted for sensing and attachment, ultimately dominating the surface ecology via exponential surface population increase.

Significance: The origin of disorder in glasses is one of the most important unresolved questions in materials science. In many cases, for materials made of monodisperse components that are not attractive and have the capacity to crystallize, such as dispersions of colloidal hard spheres, the disorder is typically associated with rapid, out-of-equilibrium quenching of the density that causes components to jam into disordered configurations. By contrast, here we reveal that hard colloidal kite-shaped particles, which have the geometric capacity to crystallize, instead form a disordered glass when compressed very slowly and quasi-statically. We show that this glassy disorder results from a high diversity of different local configurations of kites, effectively masking the one global crystal phase.

Bacterial predation plays multiple essential roles in bacterial selection and mortality within microbial ecosystems. In addition to its ecological and evolutionary importance, many potential applications of bacterial predation have been proposed. The myxobacterium Myxococcus xanthus is a well-known predatory member of the soil microbial community. Its predation is commonly considered a collective behavior comparable to a wolf pack attack; however, individual M. xanthus cells are also able to competently lead to the lysis of a prey cell. Using a bacterial tracking technique, we are able to observe and analyze solitary predation by M. xanthus on Escherichia coli at the single-cell level and reveal the dynamics of both predator and prey during the process. The present study will not only provide a comprehensive understanding of M. xanthus solitary predation but also help to explain why M. xanthus often displays multicellular characteristic predatory behaviors in nature, while a single cell is capable of predation.

Considering multi-body systems of monodisperse hard Brownian particles, it remains challenging to predict the forms of order that can emerge in their dense assembled structures. Surprisingly, here, using Monte Carlo simulations, we show that tetratic-ordered phases emerge in a dense two-dimensional system of hard kites that are rotationally asymmetric and have opposite 72° and α ≈ 90° internal angles. We observe a new tetragonal rectangular crystal (TRX) phase possessing (quasi-)long-range fourfold molecular-orientational order. We propose a method based on local polymorphic configurations of neighboring particle pairs (LPC-NPPs) to understand this emergent tetratic order and show that LPC-NPPs can be useful for predicting orientational order in such systems. To examine the dependence of the tetratic order on α, we apply LPC-NPP analysis to other hard kites for 54° ≤ α ≤ 144°. Our work provides insight into the creation of novel ordered materials by rationally designing particle shape based on anticipated LPC-NPPs.