Flat Drops, Elastic Sheets, and Microcapsules by Interfacial Assembly of a Bacterial Biofilm Protein, BslA

Abstract

Protein adsorption and assembly at interfaces provide a potentially versatile route to create useful constructs for fluid compartmentalization. In this context, we consider the interfacial assembly of a bacterial biofilm protein, BslA, at air-water and oil-water interfaces. Densely packed, high modulus monolayers form at air-water interfaces, leading to the formation of flattened sessile water drops. BslA forms elastic sheets at oil-water interfaces, leading to the production of stable monodisperse oil-in-water microcapsules. By contrast, water-in-oil microcapsules are unstable but display arrested rather than full coalescence on contact. The disparity in stability likely originates from a low areal density of BslA hydrophobic caps on the exterior surface of water-in-oil microcapsules, relative to the inverse case. In direct analogy with small molecule surfactants, the lack of stability of individual water-in-oil microcapsules is consistent with the large value of the hydrophilic-lipophilic balance (HLB number) calculated based on the BslA crystal structure. The occurrence of arrested coalescence indicates that the surface activity of BslA is similar to that of colloidal particles that produce Pickering emulsions, with the stability of partially coalesced structures ensured by interfacial jamming. Micropipette aspiration and flow in tapered capillaries experiments reveal intriguing reversible and nonreversible modes of mechanical deformation, respectively. The mechanical robustness of the microcapsules and the ability to engineer their shape and to design highly specific binding responses through protein engineering suggest that these microcapsules may be useful for biomedical applications.

Biocontrol of Postharvest Fruit Fungal Diseases by Bacterial Antagonists: A Review

“…The matrix of this bacterium consists of proteins called TasA and TapA [63,64] besides a secreted polysaccharide of high molecular weight [65]. The assemblage of the mature biofilm also requires the presence of a coating protein called biofilm BsIA, previously known as YuaB [65][66][67]. Haggag and Timmusk [68] demonstrated that the bacteria Paenibacillus polymyxa colonizes plant roots, forming structures that look like biofilms and thus protecting the roots against diseases caused by phytopathogens.…”

Characteristics and Functions of Hydrophobins and Their Use in Manifold Industries

“…In addition, the process of air bubble stabilisation reduces the formation of ice crystals, which ensures smooth consistency of the product. The use of the Bs1A protein may allow manufacturers to reduce saturated fats content, and thus calorific value of ice cream [31,69]. The ability to form foams can be much greater for class II than for class I proteins.…”

“…Ponadto proces stabilizacji pęcherzyków powietrza ogranicza powstawanie kryształków lodu, co zapewnia gładką konsystencję produktu. Zastosowanie białka Bs1A może pozwolić producentom zmniejszyć zawartość tłuszczów nasyconych, a więc i kaloryczność lodów [31,69]. Zdolność do formowania pian może być znacznie większa dla białek klasy II niż klasy I. Ta zależność niesie ze sobą potencjalne nowe zastosowania w przemyśle spożywczym.…”

Droplet shape control using microfluidics and designer biosurfactants

“…Another strategy is through interfacial tension driven evolution of droplet morphology where the local accumulation of surface-active emulsifiers at interfaces can partially change the droplet curvature. [25][26] A widely used approach is microchannel confinement, which offers unrivalled performance for the controlled generation of droplets of varying size, shape, morphology, internal structure and chemistry. 8,27 Using microfluidics to control local flows, the flexible design of microscale geometries and the applicability of auxiliary forces allow a high degree of control over the manipulation of individual droplets.…”