Filamentous fungi occurrence in free water and biofilms from drinking water storage tanks

In some regions of Brazil, especially where the water is scarce, drinking water is stored in water storage tanks. This practice gives the consumer the guarantee of available water. The water storage conditions such as the exposure to hot weather when the tanks are on rooftops allow the development of microorganisms and microbial biofilms which can deteriorate the water quality and increase the risk to human health [1,2]. This study describes the filamentous fungi (FF) detected in free water and biofilms in drinking water storage tanks in Recife - Pernambuco, Brazil. Five sampling times in triplicate were performed at two distinct points. Colony-forming units (CFU) of FF fungi were determined with 0.45 μm filtration membranes using peptone glucose rose Bengal agar (PGRBA). From the 30 samples analysed a total of 1136 CFU were obtained. The water biofilms were collected from samplers consisting of polyethylene coupons, previously installed in the reservoirs. These coupons were transferred to PGRBA plates and incubated using with the same conditions described for free FF. For the in situ detection of FF in biofilms the Calcofluor White staining technique was used. This procedure demonstrated FF forming biofilms on the surfaces of the coupons. Brazilian legislation does not define limits for FF in drinking water. However considering the potential risk of fungal contamination, the data obtained in this study will contribute to developing future quantitative and qualitative parameters for the presence of fungi in drinking water distribution systems in Brazil.

Current situation on the occurrence of mycotoxins and toxigenic fungi in Portugal

Mycotoxins are secondary metabolites produced by filamentous fungi that are toxic for humans and animals in small amounts and that are found worldwide in a large number of agricultural commodities. They are usually ingested involuntarily, when contaminated plant products are consumed, and represent a great risk for public health. Therefore, governments throughout the world have imposed strict legal limits for their levels in food and feed products in order to reduce potential health risks for consumers. Despite of its ubiquity, the mycotoxin problem is mainly dependent on regional factors, such as the mycotoxigenic characteristics of the local mycoflora, the local climate conditions, and the local agricultural practices. For this reason, a constant vigilance from local governmental food safety agencies and from the local researcher community is needed. This communication will review the current situation on the occurrence of mycotoxigenic fungi in some Portuguese cultures, such as wine grapes, corn and dried fruits. Particular attention will be given to the incidence of mycotoxigenic Aspergillus strains in those cultures and to the levels of ochratoxin A, aflatoxins, cyclopiazonic acid and fumonisin B2 produced. Data will be discussed taking into account the geographical origin of the isolates and the particular climate conditions of each sampling region. An updated review on the levels of the main mycotoxins found in local products and in imported commodities will also be presented.