Effects of methamidophos on the community structure, antagonism towardsRhizoctonia solani, andphlDdiversity of soilPseudomonas

Abstract

A microcosm incubation study using an aquic brown soil from northeast China (a Cambisol in the UN Food and Agriculture Organization FAO Soil Taxonomy) was conducted to examine the effects of different concentrations (0, 50, 150, and 250 mg kg(-1)) of methamidophos (O,S-dimethyl phosphoramidothioato) on Pseudomonas, one of the most important gram-negative bacteria in soil. Amplified ribosomal DNA restriction analysis (ARDRA) was performed to study the Pseudomonas community structure, an in vitro assay was made to test the antagonistic activity of isolated Pseudomonas strains against soil-borne Rhizoctonia solani, a major member of the pathogens highly related to soil-borne plant diseases, and special primer amplification and sequencing were performed to investigate the diversity of phlD, an essential gene in the biosynthesis of 2, 4-diacetylphloroglucinol (2, 4-DAPG), which has biocontrol activity in phlD(+)isolates. With exposure to increasing methamidophos concentrations, the total number of soil Pseudomonas ARDRA patterns decreased significantly, but with less change in the same treatments over 1, 3, and 5 weeks of incubation. The number of isolated Pseudomonas strains with antagonistic activity against R. solani as well as the diversity and appearance frequency of the strains' phlD gene also decreased with increasing concentrations of methamidophos, especially at high methamidophos concentrations. Applying methamidophos could increase the risk of soil-borne plant diseases by decreasing the diversity of the soil Pseudomonas community and the amount of R. solani antagonists, particularly those with the phlD gene.

A review on sample preparation and chromatographic determination of acephate and methamidophos in different samples

“…The prolonged or continued use of acephate and methamidophos in plant protection may lead to significant dermal exposure with an impact on cholinesterase, genotoxicity and cardiotoxicity activities (Farag et al, 2000;Spassova et al, 2000;Padungtod et al, 1998). Immense toxicity of acephate and methamidophos has been observed in environment including birds (Zinkl et al, 1981;Vyas et al, 1996), animals (Singh and Drewes, 1987), fishes (Szeto et al, 1979), soils and its microorganisms (Wu et al, 2010;Lo, 2010;Battu et al, 2009). Studies have revealed that acephate and methamidophos can persist on soils (Zhang et al, 2005;Battu et al, 2009), fruits and vegetables (Antonious and Snyder, 1994;Bouchard and Lavy, 1982;Chuanjiang et al, 2010;Zhang et al, 2008), in dietary products (WHO, 2003(WHO, , 2005Nougade`re et al, 2012), cereal and other cash crops (Hiemstra & Kok, 2007;Antonious and Snyder, 1994;Bouchard and Lavy, 1982;Chuanjiang et al, 2010).…”

Enantiomeric separations of chiral polychlorinated biphenyls on three polysaccharide-type chiral stationary phases by supercritical fluid chromatography

“…The above observations indicated that the SinoChiral OJ column has a better enantioselective discrimination ability toward PCBs than the Chiralcel OD and Chiralpak IB columns under the chromatographic conditions considered. A previous study, which investigated chiral separation of PCBs on the Sino-Chiral OJ column using HPLC showed that only three PCBs could be baseline resolved [28], while baseline resolution of 14 PCBs was obtained on the Sino-Chiral OJ column by SFC. The observation may be ascribed to the fact that SFC has a higher diffusion coefficient and mass transfer rate than those of HPLC.…”

A procura de bactérias degradadoras de metamidofós.

“…Este resultado está condizente com o maior número de isolados Gram-negativos neste experimento (Tabela 9). Caracterização macroscópica e microscópica das cepas isoladas em meio R2A.Os perfis de ARDRA baseados na especificidade dos sítios de digestão dos genes de rRNA 16s são biomarcadores úteis na análise da estrutura da comunidade das bactérias do solo e tem sido adotado como um método para quantificar a diversidade bacteriana nos solos contaminados por defensivos agrícolas e outro químicos(WU et al, 2010).…”