The fate of 2,4-D in microbial cultures

Abstract

Abstract 2,4-D, as one of the most frequently used herbicides nowadays, finds access to treatment plants and receiving waters at a significantly increasing pace. These types of organics are commonly investigated either for their toxic properties or their biodegradability. The accumulated information becomes, at times, misleading since 2,4-D, like most similar chemicals, may be a substrate alternately or concurrently, depending on the characteristics of the environment in which it reacts. In this context, this paper studies the fate and impact of 2,4-D in microbial cultures under different conditions. It is found that (a) 2,4-D at short exposure to a microbial culture grown on a Bacto nutrient/sodium acetate mixture remains non-biodegradable, inhibiting the BNB removal rate. (b) The biodegradation of 2,4-D in the same microbial culture is subject to acclimation after 20–40 days. (c) Upon acclimation, 2,4-D is biodegradable as a single substrate or combined with the BNB solution. Its removal may be interpreted by a non-interactive mechanism suggesting the development of a population solely responsible for its degradation, exhibiting a substrate inhibition type of a growth pattern at high 2,4-D concentration. (d) In multi-substrate environments the BNB removal rate is significantly affected by 2,4-D inhibition. (e) The fate and impact of 2,4-D in microbial cultures under different conditions, shows inherent similarities with those of phenol.