In this research, atomic force microscopy (AFM) with a flat tip cantilever is utilized to measure Young's modulus of a whole yeast cell (Saccharomyces cerevisiae BY4741). The results acquired from AFM are similar to those obtained using a microfluidic chip compression system. The mechanical properties of single yeast cells are important parameters which can be examined using AFM. Conventional studies apply AFM with a sharp cantilever tip to indent the cell and measure the force-indentation curve, from which Young's modulus can be calculated. However, sharp tips introduce problems because the shape variation can lead to a different result and cannot represent the stiffness of the whole cell. It can lead to a lack of broader meaning when evaluating Young's modulus of yeast cells. In this report, we confirm the differences in results obtained when measuring the compression of a poly(dimethylsiloxane) bead using a commercial sharp tip versus a unique flat tip. The flat tip effectively avoids tip-derived errors, so we use this method to compress whole yeast cells and generate a force–deformation curve. We believe our proposed method is effective for evaluating Young's modulus of whole yeast cells.

The changes in the immune function of birds obtained during decades of intensive selection are rather disadvantageous. Today's chickens and turkeys are more susceptible to different infectious and metabolic diseases and exhibit a high mortality rate. Subsequently in recent years there is growing interest in the use of feed additives with immunomodulatory properties in intensive poultry production. This article reviews and discusses the results of current studies on the effects of yeast cell products on the different mechanisms of the immune system in poultry. The majority of the experiments presented in this review indicate that the use of yeast derivatives may have a beneficial influence on the immune system and resistance to the colonisation of pathogenic microorganisms. However, the positive effect of yeast derivatives on the immune system is not always reflected in an improvement in production parameters, especially when the experiments are conducted on healthy (non-challenged) birds.