Competitive Suppression of Prototrophs

Abstract

IN a recent publication¹, Jinks has compounded the erroneous impression, first given by Grigg², that competitive suppression is a neglected source of error in studies of prototrophs or reversions of nutritional requirement in micro-organisms. Kølmark and Westergaard³ have shown that Grigg's criticism is inapplicable to their case; but since Jinks's publication is subsequent to this, and expresses the belief that “it is not easy to see a simple way of avoiding [the] effects” of competitive suppression, a brief recollection of the facts published elsewhere on the matter seems called for. Competitive suppression is certainly a real phenomenon and has been studied experimentally in some detail^4–6. The findings relevant to the present issue are that: (1) the addition of prototrophs to the culture of organisms from which prototrophs it contains are being screened measures the extent of competitive suppression; (2) when competitive suppression is not acting, dilution of the culture results in a corresponding decrease in the number of prototrophs, and added prototrophs are recovered.