Biodegradation of the herbicide trifluralin by bacteria isolated from soil

Abstract

Trifluralin (alpha,alpha,alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine; TFL) is a pre-emergence, soil-incorporated herbicide that has been in agricultural use since the early 1960s and is moderately persistent in soil. The purpose of this study was to isolate and characterise TFL-resistant bacteria from a soil in which this pesticide has been used for the last four decades and to determine their ability to degrade TFL using HPLC. Eight bacteria were isolated by repeated subculture in liquid medium with TFL as carbon source and a ninth (isolate 9) from growth around TFL crystals on solid medium. The bacteria from enriched liquid culture were identified by biochemical tests and 16S rDNA sequencing. In a mineral salts medium with 0.1% succinate, 0.1% yeast extract and 50 mg l(-1) TFL, reductions in the level of pesticide of 24.6% for Klebsiella sp., 16.4% for Herbaspirillum sp., 25.0% and 16.0% for two strains of Bacillus sp. and 21.0% for unidentified isolate number 9 were obtained after 30 days. These were similar to the level obtained using a known TFL-degrading bacterium, Brevundimonas diminuta (NCIMB 10329). Three Pseudomonas sp. and one Bacillus sp. reduced levels by less than 5%. The five positive isolates can be used to study the biochemical and molecular biology of TFL biodegradation with the aim of optimising the degradative ability of one or more of the isolates for future use in bioremediation processes.

Assessment of Glyphosate and Quizalofop Mediated Toxicity to Greengram [Vigna radiata (L.) Wilczek], Stress Abatement and Growth Promotion by Herbicide Tolerant Bradyrhizobium and Pseudomonas species

“…Hence, microorganisms that have developed resistance to pesticides are capable of frequently degrading them (Curutiu et al, 2017). Resistance against pesticides in general is attributed due to physiological changes that induce microbial metabolism to follow a new metabolic pathway that help organisms to bypass a biochemical reaction which could otherwise be inhibited by some specific pesticides (Bellinaso et al, 2003). Also, the resistance could be due to emergence of mutations inherited by successors of microbes (Herman et al, 2005).…”

Effect of Fungicides on Phosphate Solubilization by Klebsiella oxytoca and Enterobacter ludwigii

“…Therefore, microbial resistance to a pesticide was linked with their capacity to degrade it (Kumar et al, 1996;Ortiz-Herna´ndez and Sa´nchez-Salinas, 2010). As reported by Bellinaso et al (2003), the resistance can be temporal or permanent, where physiological changes occur as the temporal tolerance mechanisms to alleviate the inhibitory effects of the pesticide. Permanent resistance, on the other hand, is expected as a result of genetic modifications, inherited by the subsequent generation of microbes (Herman et al, 2005;Johnsen et al, 2001).…”

Assessment of the resistance of four nitrogen-fixing Bacteria to glyphosate

“…The microorganism's physiology and genetic's play a key role on their tolerance or resistance to pesticides. Generally, the microorganisms resistant to pesticide have a great potential to break the pesticides into simple products, which may be used by them as nutrient sources, such as carbon and phosphorus (Cassigneul et al, 2016;Myresiotis et al, 2012;Bellinaso et al, 2003). According to the results of (Wijekoon et al, 2018) which have shown that Pseudomonas sp.…”