Here, we have presented a method to bio-exfoliate graphite sheets into few-layers graphene, which was elucidated using different structural and spectroscopic analyses. The changes in the thickness reduction were thoroughly examined using AFM, which suggested the reduction to ~10 nm thickness in one week of incubation and Raman spectroscopy also validated the formation of few-layers graphene structures. The IR spectroscopic examination revealed the presence of functional groups on the prepared graphene which enabled its application for the ammonium ions sensing via UV-Vis absorption spectroscopy with LoD to be 20 ppm. The affinity of the yeast cells for graphene was studied using molecular dynamics simulation which suggested the exfoliation results from shear stress induced by the yeast and the yield to be determined by the thickness and surface area of graphite. In summary, we present a new bioexfoliation method to obtain few-layers graphene from graphite. The method is very simple and it uses widely available yeast cells. It is non-expensive, green and scalable (industrial scale). In principle, it can be used to exfoliate other layered materials (as demonstrated for MoS2 in the supplementary data), which opens new perspectives to obtain and use few-layer structures.