Fungal diversity of an apple and pear processing wastewater treatment system

TARIFA, MARÍA CLARA; BRUGNONI, LORENA INÉS

San Miguel de Tucumán

Congreso; VII Congreso Argentino de Microbiología General; 2011

Sociedad Argentina de Microbiología General

Aerated and facultative lagoons are commonly used for domestic and industrial wastewater treatment due to their low cost and minimal need of operational requirements. The microbial diversity growing in these lagoons largely depends on the nature of the effluent and geographical conditions, being temperature and pH the major selective factors. The fruit juice industry generate large volumes of wastewater seasonally, and the major problem of this effluent treatment are the low pH, imbalance of nutrients and the very considerable fluctuations in the amount of effluents and waste matter produced. In this work, we studied fungal diversity associated with the effluent treatment systems of juice producers belonging to the industrial park of Villa Regina, Río Negro (Argentina).Samples were taken monthly to determine the effect of the fruit processing seasons (peak and off-peak season). In the aerated lagoon (deep=2.5 m, volume=15,000 m3, area=6,250 m2) the samples were taken from superficial zone. The facultative lagoon (deep=3.0 m, volume=55,000 m3, area=18,750 m2) was divided in superficial zone (0.30 m below the surface) and middle zone (1.20 m below the surface). We performed total fungal counting (filamentous fungi and yeasts) using the method of dilution in plates by surface spreading in Yeast extract-Glucose-Chloramphenicol agar medium (YGC agar). The plates were incubated at 25 ºC for 5 days. The different yeast colonies were identified by their morphological and physiological characteristics as described by Kurtzman and Fell (1998). The filamentous fungi were identified by their morphological characteristics.A total of twenty five yeast strains and five filamentous fungi were isolated and identified. Ninety six percent of yeast strains and eighty percent of filamentous fungi were isolated in peak season. Among the filamentous fungi, the identified genera with their corresponding percentage of occurrence were: Aspergillus 41%, Cladosporium 25%, Penicillium and Mucor 17%. More than 91% of isolates were obtained from aerated lagoons and the superficial zone from facultative lagoon. Between the unicellular fungi, the genus Candida represents the majority of the isolates (47%) with a great variation of species. Species of Cryptococcus, Rhodotorula, Kloeckera and Geotrichum were isolated in lower percentages. The major yeast diversity was observed in aerated lagoons, with fermenting and non- fermenting strains. In the middle zone of facultative lagoons, only yeast belonging Candida genus was isolated. More than 50% of Candida isolates showed a seudomicelial configuration. This invasive pattern could explain its high occurrence in fruit juice wastewater treatment lagoons. The general trend clearly showed the impact of the peak season in fungal diversity.