Microbial Evolution During Degradation of Fungicide in an Organic Biomixture

Biological systems are being developed all over the EU coun- tries to protect water-bodies from pesticides contamination at farm level. Biobeds are on-farm biological system developed in Sweden to retain and attenuate pesticides contamination coming from inappropriate procedures at pesticide mixing and handling sites and inappropriate disposal of pesticide sprayer rinse water (Coppola et al., 2007; Castillo et al., 2008). The experiment was conducted when equipments were washed in a biobed after treatments. Commercial formulates of dimetomorph(DF), pen- conazole(PC), azoxystrobin(AZ), metalaxyl(MX), fludioxonil(FL) and cyprodinil(CY) were mixed and downloaded onto the bio mix- ture following concentrations and time schedule of treatments for grapevine season during 112 days. Pesticides degradation was monitored by measuring the residual concentration over the time. he evolution of microbial community were monitored using culture-dependent and independent methods such as viable plate count and Denaturing Gradient Gel Electrophoresis (DGGE) to describe the influence of fungicides on microbial diversity. Rela- tion between microorganisms variation and fungicide degradation was investigated to improve the system efficiency. Results showed a good capability of biomix to degrade pesticides. At the end of the experimentation time the concentration of most of pesticides was nearly to the complete degradation. No significant differences were observed in culture-dependent heterotrophic bacterial and fungal evolution during the treatment. DGGE analysis of bacterial community after two consecutive treatments with PC+DF and after the treatment with AZ+CY+FL showed the highest differences between treated samples and their controls. DGGE analysis showed a strong reduction of fungal com- munity after PC+DF addition (10th and 23th day). At 64th day fungicides were almost degraded and an evident enhancement of fungal biodiversity with the appearance of new species was shown. Interestingly, at the end of the experiment the microbial commu- nity exhibited a strong similarity between treated and untreated sample indicating that the variations of microbial community was only temporally.