Exploring the potential of local biomixtures for biopurification systems. Bioaugmentation as strategy to enhance the removal of pesticides

Abstract

In the last decades, point-source pesticides pollution has been rigorously addressed, through the study of bioprophylaxis strategies, in order to reduce or avoid these environmental impacts. For this purpose, biobeds (BB) are among the most promising technologies. BB consist of simple, ecological and cost-effective constructions designed to retain and degrade pesticides, with three main components: a clay layer, a biomixture and a grass layer covering its surface. Biomixture (BM) represents the biologically active core of BB, where the adsorption and degradation of pesticides take place. It is composed of a lignocellulosic substrate, a humic rich component and a soil. The design of a BM should be adapted to each region and will depend on the availability of materials. Also, the efficiency of the BM can be improved by bioaugmentation with microorganisms with specific degrading capacities. Among a wide range of microorganisms, actinobacteria play an important ecological role in the environment due to their ability to remove a large diversity of xenobiotic compounds.Based on the above, this conference will present studies related to the behavior of BM formulated with different and locally available by-products derived from the sugarcane industry in Argentina, and the effect of their bioaugmentation with an autochthonous actinobacterium, on the atrazine (ATZ) removal ability. Three BM were formulated using sugarcane by-products as alternative lignocellulosic substrates. BM formulated with bagasse, filter cake, or harvest residue, reached ATZ removal of 37–41% at 28 d of incubation, with t1/2 between 37.9 and 52.3 d. The bioaugmentation with Streptomyces sp. M7 accelerated the dissipation of the pesticide in the BM, reducing ATZ t1/2 regarding the controls, and achieved up to 72% of ATZ removal. The bioaugmentation improved the development of the microbiota in BM, specially actinobacteria and fungi and enhanced acid phosphatase activity and/or reversed a possible effect of ATZ over this enzymatic activity.