Dentifrice compositions are well known for dental and oral hygiene care. High water (e.g., >45 wt %) and high carbonate (e.g., >25 wt %) formulation chassis are cost effective for many markets and consumers. These compositions are typically formulated at a higher pH given the carbonate content. Benzyl alcohol and parabens are generally known as preservatives. However, there is a need to reduce their use for cost and other reasons. It is also well known that each microbe species has a preferred pH range and a pH tolerance range. Halomonas is a well known genus of bacteria that is known to be able to grow in alkaline pH. Many approaches for optimizing preservatives in dentifrice formulations are directed to neutral pH systems (as in silicate based dentifrice formulations). However, there is a need to optimize preservatives in a high pH (e.g., pH˜9) system and to do so based-upon a microbe system that is more relevant to this high pH system.