Xanthan gum is an anionic polymer derived from the bacterium Xanthomonas campestris, which can be found on cruciferous veggies like cabbage, cauliflower, and broccoli (all of my least favourites!). In the manufacturing of this ingredient, they actually use the bacteria in a fermentation process. It’s permitted in food and cosmetic products and the typical usage is about 0.1% to 0.3% in a lotion, but you can use more when thickening surfactant type product.
It’s good in more acidic pH ranges, but can be compatible with alkaline ingredients that aren’t too basic. it’s good with salts, but there could be solubility issues.