In addition, the Bhutanese S. sonnei population is characterized by the presence of numerous non-synonymous mutations, most of which are found in metabolic pathways. The genus Shigella is well known for its adaptive intracellular lifestyle, enabling its shedding of redundant or unnecessary functions during the course of evolution (Prosseda et al., 2012). Our in silico analysis predicted that some mutations could affect metabolic activities, which could lead to degradation. In particular, the affected d-ribose utilization and formate fermentation appear to be redundant as energy production in Shigella predominantly occurs via the uptake and metabolism of pyruvate into acetate (Kentner et al., 2014). Biosynthesis of histidine is also deemed inessential as the bacterium could readily transport it from the host's cytosol. However, the true impacts of the aforementioned mutations should be confirmed by functional analyses in vitro in future studies.