Assessing in situ microbial abilities of soils to degrade pesticides is of great interest giving insight in soil filtering capability, which is a key ecosystem function limiting pollution of groundwater. Quantification of pesticide-degrading gene expression by reverse transcription quantitative PCR (RT-qPCR) was tested as a suitable indicator to monitor pesticide biodegradation performances in soil. RNA extraction protocol was optimized to enhance the yield and quality of RNA recovered from soil samples to perform RT-qPCR assays. As a model, the activity of atrazine-degrading communities was monitored using RT-qPCRs to estimate the level of expression of atzD in five agricultural soils showing different atrazine mineralization abilities. Interestingly, the relative abundance of atzD mRNA copy numbers was positively correlated to the maximum rate and to the maximal amount of atrazine mineralized. Our findings indicate that the quantification of pesticide-degrading gene expression may be suitable to assess biodegradation performance in soil and monitor natural attenuation of pesticide.

Estimating the biodegradation of pesticide in soils by monitoring pesticide-degrading gene expression

Occurrence, distribution, and sources of antimicrobials in a mixed-use watershed

Purpose
Adsorption and desorption are important processes that influence the transport, transformation, and bioavailability of atrazine in soils. Equilibrium batch experiments were carried out to investigate the adsorption–desorption characteristics of atrazine. The objectives of this study were to (1) determine and quantify the main soil parameters governing atrazine adsorption and desorption phenomena; (2) find the correlativity between the identified soil parameters; and (3) investigate the universal desorption hysteresis traits.

Quantifying effects of primary parameters on adsorption–desorption of atrazine in soils

Detection of Helicobacter pylori in the coastal waters of Georgia, Puerto Rico and Trinidad.

Detection of verotoxin producing Escherichia coli in marine environments of the Caribbean.

Aims: To assess the concentration of atrazine in Lake Oconee and develop a qPCR assay as a potential marker for the presence of atrazine-degrading bacteria indicating atrazine contamination.

Methods and Results:  Water and sediment samples were collected from the Oconee Lake at four golf course sites, two residential sites, one cattle farming site and a forested site. Atrazine concentration at the study sites was determined using an ELISA kit and indicated the presence of atrazine from 0·72 ppb at the forested sites to 1·84 ppb at the golf course sites. QPCR results indicate the presence of atzA gene (atrazine chlorohydrolase) from 1·51 × 102 gene copies at the residential sites to 3·31 × 105 gene copies per 100 ml of water at the golf course regions of the lake and correlated (r = 0·64) with atrazine concentration. Sediment samples had higher atzA gene copies compared with the water samples (P < 0·05).

Conclusions:  Atrazine concentration and the highest quantity of atzA gene were detected in the golf course regions of the lake. Overall, atrazine concentration monitored in Lake Oconee was below the Environment Protection Agency (EPA) regulatory standards.

Significance and Impact of the Study:  Quantitative PCR is an efficient technique for assessing the presence of atrazine catabolism gene as a functional marker for atrazine-degrading bacteria and the presence of atrazine contamination.

https://sfamjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2672.2011.05059.x

S.P. Sherchan

Papers

The presence of atrazine and atrazine‐degrading bacteria in the residential, cattle farming, forested and golf course regions of Lake Oconee