Diversity and dynamics of bacterial and fungal communities in cider for distillation.

Bacterial and fungal population dynamics in cider for distillation have so far been explored by culture-dependant methods. Cider for distillation can be produced by the spontaneous fermentation of apples that do not undergo any intervention during the process. In this study, cider microbiomes extracted from six tanks containing ciders for distillation from four producers in Normandy were characterized at three main stages of the fermentation process: fermentation Initiation (I), end of the alcoholic Fermentation (F) and end of the Maturation period (M). Cider samples were subjected to Illumina MiSeq sequencing (rRNA 16S V1-V3 and ITS1 region targeting) to determine bacterial and fungal communities. Yeasts (YGC), Zymomonas (mZPP) and lactic acid bacteria selective media (mMRS, mMLO, mPSM) were also used to collect 807 isolates. Alcoholic levels, glycerol, sugar content (glucose, fructose and sucrose), pH, total and volatile acidity, nitrogen, malic and lactic acid contents were determined at all sampling points. Alpha diversity indexes show significant differences (p < 0.05) in microbial populations between I, F and M. Fungal communities were characterized by microorganisms from the environment and phytopathogens at I followed by the association of yearsts with alcoholic fermentation like Saccharomyces and non-Saccharomyces yeasts (Hanseniaspora, Candida). A maturation period for cider leads to an increase of the Dekkera/Brettanomyces population, which is responsible for off-flavors in cider for all producers. Among bacterial communities, the genera community associated to malolactic fermentation (Lactobacillus sp., Leuconostoc sp., Oenococcus sp.) was the most abundant at F and M. Acetic acid bacteria such as Acetobacter sp., Komagataeibacter sp. and Gluconobacter sp. were also detected during the process. Significant differences (p < 0.05) were found in fungal and bacterial populations between the four producers and during the fermentation process. The development of microorganisms associated with cider spoilage such as Zymomonas mobilis, Lactobacillus collinoides or Brettanomyces/Dekkera sp. was anticipated by a metagenomic approach. The monitoring of microbial diversity via high throughput sequencing combined with physical-chemical analysis is an interesting approach to improve the fermentation performance of cider for distillation and therefore, the quality of Calvados.

Levels and determinants of pesticide exposure in re-entry workers in vineyards: results of the PESTEXPO study.

Physical contact with branches, leaves, fruit or vegetables in previously treated crops is responsible for the transfer of pesticides to the worker's skin in agricultural tasks such as harvesting, pruning, thinning, cutting or sorting. Few studies have documented workers' exposure during re-entry in vineyards. In the PESTEXPO study, we described levels of exposure and analyzed their determinants during re-entry and harvesting in vineyards in the Bordeaux area, France. Between 2002 and 2007, volunteers performing re-entry tasks (N=46 days) or harvesting (N=48 days) after dithiocarbamate or folpet treatment were observed. Detailed information on the tasks was collected and dermal contamination was assessed using patches placed on the skin and hand-washing at the end of each working phase. Daily median contamination was 1 967.7 µl of mixture during re-entry (90(e) percentile: 5 045.3 µl) and 18.7 µl during harvesting (90(e) percentile: 911.4 µl). The type of task was the parameter found to be the most strongly associated with contamination. For re-entry, the highest contaminations were observed during raising of wires and cutting of branches. During the harvest, the contamination was maximal for grape-picking. The delay since the last treatment and the rate of active ingredient per hectare played a role, together with other factors such as meteorological factors, crop and farm characteristics, gloves and clothes. Our results underline the necessity to take into account exposures during re-entry and harvest when considering pesticide exposure, both for epidemiological research and preventive action.

Toxigenic fungi and mycotoxins in mature corn silage.

To investigate the exposure of livestock and farm workers to mycotoxins during the last months of silage use, the mycoflora and the mycotoxins in a mature silage (11-months-old) were studied. A multimycotoxin method was developed to evaluate the toxigenic in vitro ability of fungal strains. The screening of potentially toxigenic fungi isolated from the mature silage showed that six Fusaria (Fusarium culmorum, Fusarium equiseti, Fusarium graminearum, Fusarium oxysporum, Fusarium solani and Fusarium verticillioides) and one Aspergillus (Aspergillus fumigatus) were able to produce mycotoxins on nutrient agar. Seven major mycotoxins (aflatoxin B(1), citrinin, deoxynivalenol, fumonisin B(1), gliotoxin, ochratoxin A and zearalenone) were also searched in the corn silage by high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS). Among the three mycotoxins (citrinin, gliotoxin and deoxynivalenol) detected in the silage, gliotoxin, a strongly immunosuppressive mycotoxin, occurred in the mature silage at level up to 877 ppb, which was associated with the presence of A. fumigatus in the silage.