A facile and effective method is described to engineer original bacterial cellulose fibrous networks with tunable porosity. We showed that the pore shape, volume, and size distribution of bacterial nanocellulose membranes can be tailored under appropriate culture conditions specifically carbon sources. Pore characterization techniques such as capillary flow porometry, the bubble point method, and gas adsorption-desorption technique as well as visualization techniques such as scanning electron and atomic force microscopy were utilized to investigate the morphology and shape of the pores within the membranes. Engineering various shape, size and volume characteristics of the pores available in pristine bacterial nanocellulose membranes leads to fabrication and development of eco-friendly materials with required characteristics for a broad range of applications.