The microbial degradation of azimsulfuron and its effect on the soil bacterial community

Abstract

Aims: Azimsulfuron is a recently introduced sulfonylurea herbicide useful in controlling weeds in paddy fields. To date very little information is available on the biodegradation of this pesticide and on its effect on the soil microbial community. The aim of this work was to study its biodegradation both in slurry soil microcosms and in batch tests with mixed and pure cultures. Methods and Results: Azimsulfuron was applied to forest bulk soil in order to study its effect on the structure of the bacterial soil community, as detectable by denaturant gradient gel electrophoresis (DGGE) analyses. Biodegradation and abiotic processes were investigated by HPLC analyses. In addition, a microbial consortium was selected, that was able to use azimsulfuron as the sole energy and carbon source. One of the metabolites produced by the consortium was isolated and identified through LC‐MS analyses. Cultivable bacteria of the consortium were isolated and identified by 16S rDNA sequencing (1400 bp). Conclusions: Azimsulfuron treatment seems to have the ability to cause changes in the bacterial community structure that are detectable by DGGE analyses. It is easily biodegraded both in microcosms and in batch tests, with the formation of an intermediate that was identified as 2‐methyl‐4‐(2‐methyl‐2H‐tetrazol‐5‐yl)‐2H‐pyrazole‐3‐sulfonamide. Significance and Impact of the Study: The study increases the knowledge on the biodegradation of azimsulfuron and its effects on the soil microbiota.

Biodegradation of bensulfuron-methyl and its effect on bacterial community in paddy soils

“…In the last decade more than 20 different products of sulfonylurea herbicides have been commercialized for the worldwide application and other active compounds are under investigation (Valle et al 2006). Until now there are some reports about the influences of sulfonylurea herbicides on soil microorganisms (microbial biomass, soil respiration, soil enzymes activity, and nitrogen and carbon metabolism) by conventional culture methods (Gigliotti et al 1998;Yamamoto et al 1998;El-Ghamry et al 2002).…”

“…Although DGGE was used to study the impact of pesticides and some sulfonylurea herbicides on soil communities (Johnsen et al 2001;Valle et al 2006), until now it has been rarely used to study the effect of bensulfuronmethyl (Saeki and Toyota 2004). In this work, application of BSM affected the diversity of the soil microbial community structure from week 1 to week 3; whereas, the effects of BSM was mitigated at the end of the experiment (week 5) where no obvious different bands were observed in the banding profile of a DGGE gel (Fig.…”

“…While photolysis was considered as an alternative degradation pathway sulfonylurea herbicides (Pelentridou et al 2009;Aziz et al 2010). Chemical hydrolysis and microbial degradation were thought to be the main mechanisms of reducing sulfonylurea herbicides in soil and water (Blair and Martin 1988;Valle et al 2006). However, a number of studies have demonstrated these herbicides as being deleterious to crop rotations (Langeland 1996;Huang and Xiong 2009;Peng et al 2010).…”

A multiphasic characterization of the impact of the herbicide acetochlor on freshwater bacterial communities

“…Although DGGE is an established method for examining the impact of herbicide exposure in soils (Seghers et al, 2003;de Lipthay et al, 2004;Saeki and Toyota, 2004;Seghers et al, 2005;Ros et al, 2006;Valle et al, 2006), few studies have used DGGE analysis to examine the impact of herbicides on aquatic microorganisms. Our data revealed that exposure to acetochlor decreased bacterial community complexity, as the fingerprints collectively representing water samples exposed to 1, 5, 50 and 100 mg acetochlor l À1 contained significantly fewer bands relative to those representing the control treatment.…”

Isolation of Effective 3-Chlorobenzoate-Degraders in Soil Using Community Analyses by PCR-DGGE

“…PCR-denaturing gradient gel electrophoresis (DGGE) and PCR-temperature gradient gel electrophoresis (TGGE) are among the most established methods for molecular community profiling 27) . Until now, the impacts of various pollutants on microbial communities in environmental samples have been studied by PCR-DGGE/TGGE, and many studies indicated changes in the community or dominance of certain members following pollution 8,23,32,37) . Such observations are helpful to find key members involved in the degradation of pollutants under environmental conditions.…”