by S. Mar­vin Fried­man — High on the list of the ex­cit­ing man­ners bac­te­ria com­mu­ni­cate with one an­other is quo­rum sens­ing (QS), a pop­u­la­tion-de­pen­dent gene reg­u­la­tion sys­tem that op­er­ates within a wide range of species. The gen­eral scheme of QS is as fol­lows: at high pop­u­la­tion den­si­ties, sig­nal mol­e­cules called au­toin­duc­ers reach thresh­old lev­els, at…