Influence of Captan on some microorganisms and microbial processes related to the nitrogen cycle

Abstract

Captan was applied to laboratory-incubated agricultural soil and to bacterial cultures to determine its effects on total counts of soil microorganisms, nitrification, ammonification of urea and asymbiotic dinitrogen fixation.In Captan-treated soils, total count of fungi, bacteria and actinomycetes decreased significantly only at a relatively high fungicide concentration (1000/~g.g-~). Fungi and actinomycetes were more affected than bacteria.While oxidation of ammonia in an enriched, actively nitrifying culture was almost totally inhibited by Captan, ammonification of urea in incubated soil was only partly depressed. The depressing effect of Captan was more pronounced in cultures of Micrococcus than in those of Proteus.Asymbiotic dinitrogen fixation in nutrient-ammended soil was promoted during the first week and depressed on prolonged exposure to the fungicide depending on its first concentration. In autoclaved Azotobacter-inoculated soil a similar but less pronounced effect was noticed. Fixation by Azotobacter cultures was insensitive to Captan. In contrast, growth of Rhizobium phaseoli, R. leguminosarum and R. japonicum in yeast-extract-mannitol medium was adversly affected by Captan, particularly at 200 #g.ml 1.Nodulation of pea and mung bean (1 month old potted plants) grown from surface-sterilized inoculated seeds in aptan-treated soil was also significantly depressed. Both total number of nodules decreased with increasing concentration of the fungicide, but the inhibitory effect was more pronounced in the number of effective nodules.

Nitrogen turnover in soil and global change

“…The effects of pesticides on bacterial groups involved in N transformation have been thoroughly studied using cultivation‐dependent methods in the past, for example, Rhizobium fixing N in symbiosis with leguminous plants (Aggarwal et al , 1986; Kishinevsky et al , 1988; Mårtensson, 1992; Revellin et al , 1992; Ramos & Ribeiro, 1993; Singh & Wright, 2002), free‐living diazotrophs Azotobacter and Azospirillum (Banerjee & Banerjee, 1987; Jena et al , 1987; Martinez‐Toledo et al , 1988) and nitrifying bacteria (Doneche et al , 1983; Banerjee & Banerjee, 1987; Martinez‐Toledo et al , 1992a, b). On the contrary, only a few recent studies have used culture‐independent approaches to better gain insight into the effects on the structure and function of soil microbial communities (Engelen et al , 1998; Rousseaux et al , 2003; Seghers et al , 2003; Devare et al , 2004; Saeki & Toyota, 2004; Bending et al , 2007).…”

Captan Utilization by a Soil Bacterium Planomicrobium flavidum Strain EF

“…They declared the transformation of captan to tetrahydrophthalimide. In captan-treated soils, total count of fungi, bacteria and actinomycetes decreased at relatively high fungicide concentration (Banerjee & Banerjee 1987) and few articles have been published for captan biodegradation (More et al 2014). Although Planomicrobium flavidum was not reported for captan degradation before, our results showed a dramatic decrease in captan levels in a minimum salt medium contains only one carbon source, captan, when Planomicrobium flavidum was used.…”

Evaluación del efecto in vitro del DMPP (3,4 Dimetilpirazol fosfato) sobre la microbiota fúngica aislada de un suelo

“…Poco se conocía sobre el efecto que otros microorganismos del suelo podían tener sobre el ciclo del N, aunque actualmen te se sabe que los hongos pueden desempeñar diversas transformaciones sobre el N (Huang y Long, 2014): como la desnitrificación (Shoun et al, 1992;Mothapo et al, 2013), realizada por Fusarium oxysporum y Fusarium solani entre otros (Bollag y Tung, 1972), y la oxidación de amonio (Hora e Iyengar et al, 1960;Lang y Jagnow, 1986), conocida como nitrificación heterotrófica (Stojanovic y Alexander, 1958;Hayatsu et al, 2008), que se realiza principalmente en suelos ácidos (Zhu et al, 2015) y en diversos ecosistemas forestales (Sommer et al, 1976, citado por Subbarao et al, 2013, donde los hongos más conocidos son los de los géneros Aspergillus y Penicillium (Focht y Verstraete, 1977). Estás ideas expuestas fueron afianzadas cuando se apreció que las aplicaciones de diversos fungicidas al suelo producían un efecto inhibitorio de la nitrificación (Wainwright y Pugh, 1973; Banerjee y Banerjee, 1987).…”