Whereas the infection cycles of many bacterial and eukaryotic viruses have been characterized in detail, those of archaeal viruses remain largely unexplored. Recently, studies on a few model archaeal viruses such as SIRV2 (Sulfolobus islandicus rod-shaped virus) have revealed an unusual lysis mechanism that involves the formation of pyramidal egress structures on the host cell surface. To expand understanding of the infection cycle of SIRV2, we aimed to functionally characterize gp1, which is a SIRV2 gene with unknown function. The SIRV2_Gp1 protein is highly expressed during early stages of infection and it is the only protein that is encoded twice on the viral genome. It harbours a helix-turn-helix motif and was therefore hypothesized to bind DNA. The DNA-binding behavior of SIRV2_Gp1 was characterized with electrophoretic mobility shift assays and atomic force microscopy. We provide evidence that the protein interacts with DNA and that it forms large aggregates, thereby causing extreme condensation of the DNA. Furthermore, the N-terminal domain of the protein mediates toxicity to the viral host Sulfolobus. Our findings may lead to biotechnological applications, such as the development of a toxic peptide for the containment of pathogenic bacteria, and add to our understanding of the Rudiviral infection cycle. Full article

We designed a mini tower fermentor that is suitable to perform adaptive laboratory evolution (ALE) with gravity imposed as selective pressure, and suitable to evolve a weak flocculating industrial brewers’ strain towards a strain with a more extended aggregation phenotype. This phenotype is of particular interest in the brewing industry, since it simplifies yeast removal at the end of the fermentation, and many industrial strains are still not sufficiently flocculent. The flow of particles (yeast cells and flocs) was simulated, and the theoretical retainment advantage of aggregating cells over single cells in the tower fermentor was demonstrated. A desktop stereolithography (SLA) printer was used to construct the mini reactor from transparent methacrylic acid esters resin. The printed structures were biocompatible for yeast growth, and could be sterilised by autoclaving. The flexibility of 3D printing allowed the design to be optimized quickly. During the ALE experiment, yeast flocs were observed within two weeks after the start of the continuous cultivation. The flocs showed a “snowflake” morphology, and were not the result of flocculin interactions, but probably the result of (a) mutation(s) in gene(s) that are involved in the mother/daughter separation process. Full article

Yeast nanobiotechnology is a recent field where nanotechniques are used to manipulate and analyse yeast cells and cell constituents at the nanoscale. The aim of this review is to give an overview and discuss nanobiotechnological analysis and manipulation techniques that have been particularly applied to yeast cells. These techniques have mostly been applied to the model yeasts Saccharomyces cerevisiae and Schizosaccaromyces pombe, and the pathogenic model yeast Candida albicans. Nanoscale imaging techniques, such as Atomic Force Microscopy (AFM), super-resolution fluorescence microscopy, and electron microscopy (scanning electron microscopy (SEM), transmission electron microscopy (TEM), including electron tomography) are reviewed and discussed. Other nano-analysis methods include single-molecule and single-cell force spectroscopy and the AFM-cantilever-based nanomotion analysis of living cells. Next, an overview is given on nano/microtechniques to pattern and manipulate yeast cells. Finally, direct contact cell manipulation methods, such as AFM-based single cell manipulation and micropipette manipulation of yeast cells, as well as non-contact cell manipulation techniques, such as optical, electrical, and magnetic cells manipulation methods are reviewed. Full article

Living cell microarrays have been combined with microfluidic bioreactors, which provide multiple advantages for multiplex dynamic analyses and high-throughput screening. In the last decade, many developments in this new field have been introduced. The technology has evolved from fixed cell analysis towards living single-cell dynamic systems’ biology and high content analyses. The aim of this review is to provide an updated overview of the developments of living cellular microarrays in microfluidic bioreactors. Cell arrays in microfluidic bioreactors constructed with adherent mammalian cells are compared to non-adherent cells (mainly microbial cells). An overview is given on the design and construction of these microfluidic devices with a particular focus on cell patterning techniques. Cell patterning on adhesive micropatterns using techniques such as microcontact printing, microfluidic patterning, dip-pen nanolithography and polymer pen lithography as well as photo-patterning and laser-patterning strategies are discussed. Additionally, developments in mechanical cell patterning methods and robotic cell printing are reviewed. Two-dimensional (2D) as well as recently developed 3D cell arraying are discussed. Finally, cell array microfluidic setups and operation for single-cell types versus cell population variants are illustrated and compared on the basis of some illustrative examples in the field of drug screening, cytotoxicity evaluation, and basic cellular and microbiology research. Full article