Identification of fungi in municipal sewage sludge compost and in peat

Abstract

Municipal sewage sludge compost (MSC) is used as an alternate peat media in ornamental plants. Ornamental producers have demonstrated skepticism toward the use of MSC as a substratum because they understand it may contain pathogenic microorganisms. The objective of this study was the identification of fungi in MSC obtained from the compost plant of the Acueducts and Sewage Authority ¡n Mayagüez, Puerto Rico. The samples were obtained from different piles. The treatments were four samples of MCS and one control, 100% peat, replicated three times. Serial dilutions from 10(-1) to 10(-4) were developed by means of 10 g of each treatment. The medium OHIO was used to grow fungi at 28 and 45° C. For each treatment of MSC and peat, fungi growth was observed at 28° C; at 45° C growth was observed only in the control. Three colonies were selected at random from petri dishes; 21 species of fungi were identified from genus: Aspergillus sp., Conidiobolus sp., Curvularia sp., Mucor sp., Penicillium sp., Rhizopus sp., Trichoderma sp., and Scopulariopsis sp. The fungi identified in MSC were classified as saprophytic and antagonistic. Aspergillus fumigatus Fresen, a species reported as a human pathogen, was identified in peat.