Impact of Pesticide Contamination on Aquatic Microorganism Populations in the Littoral Zone

Abstract

The effect of pesticide contamination of the littoral zone on the population of bacteria and fungi was analyzed using the example of a eutrophic water reservoir exposed for >30 years to the influence of expired crop-protection chemicals, mainly DDT. For three consecutive years, quantity analyses of bacteria and fungi were conducted and the composition of the microorganism population analyzed against seasonal dynamics. Mold and yeast-like fungi were also isolated and identified. Within the Bacteria domain, in addition to the large groups of microorganisms (Alphaprotobacteria, Betaprobacteria, and Gammaproteobacteria, Actinobacteria, and Cytophaga-Flavobacterium), the analysis also involved the presence of bacteria predisposed to degraded pesticides in natural environments: Pseudomonas spp. and Alcaligenes spp. The quantity dynamics of aquatic microorganisms indicated that bacteria and fungi under the influence of long-term exposure to DDT can adapt to the presence of this pesticide in water. No modifying effect of DDT was observed on the quantity of microorganisms or the pattern of seasonal relationships in the eutrophic lake. Changes were shown in the percentage share of large groups of bacteria in the community of microorganisms as was an effect of contamination on the species diversity of fungi. The data show the effectiveness of aquatic microorganism–community analyses as a tool for indicating changes in the water environment caused by pesticide contamination.

Biodegradation of pesticides using fungi species found in the aquatic environment

“…A similar finding was reported by Lew et al (2013) that reported that the presence of pesticides can limit the occurrence of fungi and bacteria in the aquatic environment. In terms of the fungi identified, A. fumigatus is the only species in common between the two studies (this study and the study conducted by Lew et al (2013)). Besides being able to resist to a constant input of atrazine, diuron, isoproturon and chlorfenvinphos (in this study), A. fumigatus was also found to resist to the presence of DDT in the lakes sampled by Lew et al (2013).…”

“…A possible reason for this observation is probably the toxicity exerted by the pesticides that may affect the survival of certain species (Lo 2010) or that the reactor population entered into a nutrient shortage enabling only the resistant species to survive (Tripathi et al 2013). A similar finding was reported by Lew et al (2013) that reported that the presence of pesticides can limit the occurrence of fungi and bacteria in the aquatic environment. In terms of the fungi identified, A. fumigatus is the only species in common between the two studies (this study and the study conducted by Lew et al (2013)).…”

“…In terms of the fungi identified, A. fumigatus is the only species in common between the two studies (this study and the study conducted by Lew et al (2013)). Besides being able to resist to a constant input of atrazine, diuron, isoproturon and chlorfenvinphos (in this study), A. fumigatus was also found to resist to the presence of DDT in the lakes sampled by Lew et al (2013). Bordjiba et al (2001) isolated many fungi species from pesticide-contaminated soils being A. fumigatus and A. terreus two of the most frequently encountered species which shows that they are at least resistant to the constant input of pesticides.…”

“…Even though several studies reported the ability of fungi to degrade different pollutants in other matrices, few research studies have reported the ability of fungi to resist and degrade pesticides in real water matrices (Lew et al 2013). In this study, fungi were found to be able to degrade chlorfenvinphos in a real surface water matrix.…”

A P450 gene associated with robust resistance to DDT in ciliated protozoan, Tetrahymena thermophila by efficient degradation

“…However, the metabolic mechanism of DDT degradation in microorganism is not clear. Under the influence of long-term exposure to DDT, microorganisms can adapt to the presence of this pesticide (Lew et al, 2013), allowing it to accumulate and be serially transferred to higher levels in the food chain (ATSDR, 2002). Therefore, the analysis of the metabolism of DDT in aquatic microorganism (e.g., protozoa, bacteria) is important.…”