Fungal composition of air and precipitation in southern New Mexico

As part of an on-going air quality project in southern New Mexico, West Texas, and Northwest Chihuahua, air and precipitation samples were collected and assayed for fungi. Petri plates containing acidified potato dextrose agar medium were exposed for duration from 1 hour to 3 hours to air. Following exposure, petri plates were maintained at room temperature for 5 to 7 days on laboratory bench. Emerging fungal colonies were enumerated and catalogued in groups of similar characteristics based on morphological attributes. Fungal genera or species identified so far include Alternaria, Aureobasidium, Aspergillus niger, Aspergillus fumigatus, Clasdosporium, Penicillium, Rhizopus, and Stemphylium. Of these fungal microorganisms, many have been reported to be associated with medical conditions. Rainwater was collected in plastic zipper bags and transported to the laboratory for assay. Aliquots of rainwater were spread over acidified potato dextrose medium in petri plates, which were incubated at room temperatures and emerging colonies were enumerated. Both fungi and bacteria were found in samples of rainwater. The average number of fungal colonies varied from 5 to over 30 colonies per ml of rainwater. Fungi encountered included species of fungal genera such as Alternaria, Aspergillus, Fusarium, and Trichoderma. Analysis of rainwater for fungi provides a complement to our work examining the fungal composition in dust particulates.